Resolved merge conflicts with master

183 files changed, 5794 insertions, 1779 deletions

diff --git a/src/compiler/cpp_generator.cc b/src/compiler/cpp_generator.cc
index 75659947df..ea487bcd89 100644
--- a/src/compiler/cpp_generator.cc
+++ b/src/compiler/cpp_generator.cc
@@ -119,6 +119,7 @@ grpc::string GetHeaderIncludes(const grpc::protobuf::FileDescriptor *file,
       "#include <grpc++/async_unary_call.h>\n"
       "#include <grpc++/status.h>\n"
       "#include <grpc++/stream.h>\n"
+      "#include <grpc++/stub_options.h>\n"
       "\n"
       "namespace grpc {\n"
       "class CompletionQueue;\n"
@@ -574,8 +575,8 @@ void PrintHeaderService(grpc::protobuf::io::Printer *printer,
   printer->Print("};\n");
   printer->Print(
       "static std::unique_ptr<Stub> NewStub(const std::shared_ptr< "
-      "::grpc::ChannelInterface>& "
-      "channel);\n");
+      "::grpc::ChannelInterface>& channel, "
+      "const ::grpc::StubOptions& options = ::grpc::StubOptions());\n");
 
   printer->Print("\n");
 
@@ -966,7 +967,8 @@ void PrintSourceService(grpc::protobuf::io::Printer *printer,
   printer->Print(
       *vars,
       "std::unique_ptr< $ns$$Service$::Stub> $ns$$Service$::NewStub("
-      "const std::shared_ptr< ::grpc::ChannelInterface>& channel) {\n"
+      "const std::shared_ptr< ::grpc::ChannelInterface>& channel, "
+      "const ::grpc::StubOptions& options) {\n"
       "  std::unique_ptr< $ns$$Service$::Stub> stub(new "
       "$ns$$Service$::Stub(channel));\n"
       "  return stub;\n"
diff --git a/src/compiler/csharp_generator.cc b/src/compiler/csharp_generator.cc
index e0c1bcda19..9432bdda96 100644
--- a/src/compiler/csharp_generator.cc
+++ b/src/compiler/csharp_generator.cc
@@ -246,6 +246,8 @@ void GenerateStaticMethodField(Printer* out, const MethodDescriptor *method) {
   out->Indent();
   out->Print("$methodtype$,\n", "methodtype",
              GetCSharpMethodType(GetMethodType(method)));
+  out->Print("$servicenamefield$,\n", "servicenamefield",
+               GetServiceNameFieldName());
   out->Print("\"$methodname$\",\n", "methodname", method->name());
   out->Print("$requestmarshaller$,\n", "requestmarshaller",
              GetMarshallerFieldName(method->input_type()));
@@ -273,6 +275,13 @@ void GenerateClientInterface(Printer* out, const ServiceDescriptor *service) {
           "methodname", method->name(), "request",
           GetClassName(method->input_type()), "response",
           GetClassName(method->output_type()));
+
+      // overload taking CallOptions as a param
+      out->Print(
+          "$response$ $methodname$($request$ request, CallOptions options);\n",
+          "methodname", method->name(), "request",
+          GetClassName(method->input_type()), "response",
+          GetClassName(method->output_type()));
     }
 
     std::string method_name = method->name();
@@ -284,6 +293,13 @@ void GenerateClientInterface(Printer* out, const ServiceDescriptor *service) {
         "methodname", method_name, "request_maybe",
         GetMethodRequestParamMaybe(method), "returntype",
         GetMethodReturnTypeClient(method));
+
+    // overload taking CallOptions as a param
+    out->Print(
+        "$returntype$ $methodname$($request_maybe$CallOptions options);\n",
+        "methodname", method_name, "request_maybe",
+        GetMethodRequestParamMaybe(method), "returntype",
+        GetMethodReturnTypeClient(method));
   }
   out->Outdent();
   out->Print("}\n");
@@ -340,10 +356,23 @@ void GenerateClientStub(Printer* out, const ServiceDescriptor *service) {
           GetClassName(method->output_type()));
       out->Print("{\n");
       out->Indent();
-      out->Print("var call = CreateCall($servicenamefield$, $methodfield$, headers, deadline);\n",
-                 "servicenamefield", GetServiceNameFieldName(), "methodfield",
-                 GetMethodFieldName(method));
-      out->Print("return Calls.BlockingUnaryCall(call, request, cancellationToken);\n");
+      out->Print("var call = CreateCall($methodfield$, new CallOptions(headers, deadline, cancellationToken));\n",
+                 "methodfield", GetMethodFieldName(method));
+      out->Print("return Calls.BlockingUnaryCall(call, request);\n");
+      out->Outdent();
+      out->Print("}\n");
+
+      // overload taking CallOptions as a param
+      out->Print(
+                "public $response$ $methodname$($request$ request, CallOptions options)\n",
+                "methodname", method->name(), "request",
+                GetClassName(method->input_type()), "response",
+                GetClassName(method->output_type()));
+      out->Print("{\n");
+      out->Indent();
+      out->Print("var call = CreateCall($methodfield$, options);\n",
+                 "methodfield", GetMethodFieldName(method));
+      out->Print("return Calls.BlockingUnaryCall(call, request);\n");
       out->Outdent();
       out->Print("}\n");
     }
@@ -359,26 +388,55 @@ void GenerateClientStub(Printer* out, const ServiceDescriptor *service) {
         GetMethodReturnTypeClient(method));
     out->Print("{\n");
     out->Indent();
-    out->Print("var call = CreateCall($servicenamefield$, $methodfield$, headers, deadline);\n",
-               "servicenamefield", GetServiceNameFieldName(), "methodfield",
-               GetMethodFieldName(method));
+    out->Print("var call = CreateCall($methodfield$, new CallOptions(headers, deadline, cancellationToken));\n",
+               "methodfield", GetMethodFieldName(method));
     switch (GetMethodType(method)) {
       case METHODTYPE_NO_STREAMING:
-        out->Print("return Calls.AsyncUnaryCall(call, request, cancellationToken);\n");
+        out->Print("return Calls.AsyncUnaryCall(call, request);\n");
         break;
       case METHODTYPE_CLIENT_STREAMING:
-        out->Print("return Calls.AsyncClientStreamingCall(call, cancellationToken);\n");
+        out->Print("return Calls.AsyncClientStreamingCall(call);\n");
         break;
       case METHODTYPE_SERVER_STREAMING:
         out->Print(
-            "return Calls.AsyncServerStreamingCall(call, request, cancellationToken);\n");
+            "return Calls.AsyncServerStreamingCall(call, request);\n");
         break;
       case METHODTYPE_BIDI_STREAMING:
-        out->Print("return Calls.AsyncDuplexStreamingCall(call, cancellationToken);\n");
+        out->Print("return Calls.AsyncDuplexStreamingCall(call);\n");
         break;
       default:
         GOOGLE_LOG(FATAL)<< "Can't get here.";
-      }
+    }
+    out->Outdent();
+    out->Print("}\n");
+
+    // overload taking CallOptions as a param
+    out->Print(
+        "public $returntype$ $methodname$($request_maybe$CallOptions options)\n",
+        "methodname", method_name, "request_maybe",
+        GetMethodRequestParamMaybe(method), "returntype",
+        GetMethodReturnTypeClient(method));
+    out->Print("{\n");
+    out->Indent();
+    out->Print("var call = CreateCall($methodfield$, options);\n",
+               "methodfield", GetMethodFieldName(method));
+    switch (GetMethodType(method)) {
+      case METHODTYPE_NO_STREAMING:
+        out->Print("return Calls.AsyncUnaryCall(call, request);\n");
+        break;
+      case METHODTYPE_CLIENT_STREAMING:
+        out->Print("return Calls.AsyncClientStreamingCall(call);\n");
+        break;
+      case METHODTYPE_SERVER_STREAMING:
+        out->Print(
+            "return Calls.AsyncServerStreamingCall(call, request);\n");
+        break;
+      case METHODTYPE_BIDI_STREAMING:
+        out->Print("return Calls.AsyncDuplexStreamingCall(call);\n");
+        break;
+      default:
+        GOOGLE_LOG(FATAL)<< "Can't get here.";
+    }
     out->Outdent();
     out->Print("}\n");
   }
diff --git a/src/core/channel/client_channel.c b/src/core/channel/client_channel.c
index 2cfca399b6..6c2e6b38a8 100644
--- a/src/core/channel/client_channel.c
+++ b/src/core/channel/client_channel.c
@@ -56,6 +56,8 @@ typedef struct {
   grpc_mdctx *mdctx;
   /** resolver for this channel */
   grpc_resolver *resolver;
+  /** have we started resolving this channel */
+  int started_resolving;
   /** master channel - the grpc_channel instance that ultimately owns
       this channel_data via its channel stack.
       We occasionally use this to bump the refcount on the master channel
@@ -398,6 +400,13 @@ static void perform_transport_stream_op(grpc_call_element *elem,
           } else if (chand->resolver != NULL) {
             calld->state = CALL_WAITING_FOR_CONFIG;
             add_to_lb_policy_wait_queue_locked_state_config(elem);
+            if (!chand->started_resolving && chand->resolver != NULL) {
+              GRPC_CHANNEL_INTERNAL_REF(chand->master, "resolver");
+              chand->started_resolving = 1;
+              grpc_resolver_next(chand->resolver,
+                                 &chand->incoming_configuration,
+                                 &chand->on_config_changed);
+            }
             gpr_mu_unlock(&chand->mu_config);
             gpr_mu_unlock(&calld->mu_state);
           } else {
@@ -518,6 +527,7 @@ static void cc_on_config_changed(void *arg, int iomgr_success) {
   }
 
   if (old_lb_policy != NULL) {
+    grpc_lb_policy_shutdown(old_lb_policy);
     GRPC_LB_POLICY_UNREF(old_lb_policy, "channel");
   }
 
@@ -690,12 +700,18 @@ void grpc_client_channel_set_resolver(grpc_channel_stack *channel_stack,
   /* post construction initialization: set the transport setup pointer */
   grpc_channel_element *elem = grpc_channel_stack_last_element(channel_stack);
   channel_data *chand = elem->channel_data;
+  gpr_mu_lock(&chand->mu_config);
   GPR_ASSERT(!chand->resolver);
   chand->resolver = resolver;
-  GRPC_CHANNEL_INTERNAL_REF(chand->master, "resolver");
   GRPC_RESOLVER_REF(resolver, "channel");
-  grpc_resolver_next(resolver, &chand->incoming_configuration,
-                     &chand->on_config_changed);
+  if (chand->waiting_for_config_closures != NULL ||
+      chand->exit_idle_when_lb_policy_arrives) {
+    chand->started_resolving = 1;
+    GRPC_CHANNEL_INTERNAL_REF(chand->master, "resolver");
+    grpc_resolver_next(resolver, &chand->incoming_configuration,
+                       &chand->on_config_changed);
+  }
+  gpr_mu_unlock(&chand->mu_config);
 }
 
 grpc_connectivity_state grpc_client_channel_check_connectivity_state(
@@ -709,6 +725,12 @@ grpc_connectivity_state grpc_client_channel_check_connectivity_state(
       grpc_lb_policy_exit_idle(chand->lb_policy);
     } else {
       chand->exit_idle_when_lb_policy_arrives = 1;
+      if (!chand->started_resolving && chand->resolver != NULL) {
+        GRPC_CHANNEL_INTERNAL_REF(chand->master, "resolver");
+        chand->started_resolving = 1;
+        grpc_resolver_next(chand->resolver, &chand->incoming_configuration,
+                           &chand->on_config_changed);
+      }
     }
   }
   gpr_mu_unlock(&chand->mu_config);
diff --git a/src/core/channel/compress_filter.c b/src/core/channel/compress_filter.c
index 9fc8589fbb..8963c13b0f 100644
--- a/src/core/channel/compress_filter.c
+++ b/src/core/channel/compress_filter.c
@@ -204,7 +204,7 @@ static void process_send_ops(grpc_call_element *elem,
           }
           grpc_metadata_batch_add_tail(
               &(sop->data.metadata), &calld->compression_algorithm_storage,
-              grpc_mdelem_ref(channeld->mdelem_compression_algorithms
+              GRPC_MDELEM_REF(channeld->mdelem_compression_algorithms
                                   [calld->compression_algorithm]));
           calld->written_initial_metadata = 1; /* GPR_TRUE */
         }
@@ -295,7 +295,7 @@ static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
     channeld->mdelem_compression_algorithms[algo_idx] =
         grpc_mdelem_from_metadata_strings(
             mdctx,
-            grpc_mdstr_ref(channeld->mdstr_outgoing_compression_algorithm_key),
+            GRPC_MDSTR_REF(channeld->mdstr_outgoing_compression_algorithm_key),
             grpc_mdstr_from_string(mdctx, algorithm_name, 0));
   }
 
@@ -307,11 +307,11 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
   channel_data *channeld = elem->channel_data;
   grpc_compression_algorithm algo_idx;
 
-  grpc_mdstr_unref(channeld->mdstr_request_compression_algorithm_key);
-  grpc_mdstr_unref(channeld->mdstr_outgoing_compression_algorithm_key);
+  GRPC_MDSTR_UNREF(channeld->mdstr_request_compression_algorithm_key);
+  GRPC_MDSTR_UNREF(channeld->mdstr_outgoing_compression_algorithm_key);
   for (algo_idx = 0; algo_idx < GRPC_COMPRESS_ALGORITHMS_COUNT;
        ++algo_idx) {
-    grpc_mdelem_unref(channeld->mdelem_compression_algorithms[algo_idx]);
+    GRPC_MDELEM_UNREF(channeld->mdelem_compression_algorithms[algo_idx]);
   }
 }
 
diff --git a/src/core/client_config/subchannel.c b/src/core/client_config/subchannel.c
index 17773bd2f4..ca52c75beb 100644
--- a/src/core/client_config/subchannel.c
+++ b/src/core/client_config/subchannel.c
@@ -322,8 +322,8 @@ static void continue_connect(grpc_subchannel *c) {
 static void start_connect(grpc_subchannel *c) {
   c->backoff_delta = gpr_time_from_seconds(
       GRPC_SUBCHANNEL_INITIAL_CONNECT_BACKOFF_SECONDS, GPR_TIMESPAN);
-  c->next_attempt = gpr_time_add(
-      gpr_now(GPR_CLOCK_MONOTONIC), c->backoff_delta);
+  c->next_attempt =
+      gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC), c->backoff_delta);
   continue_connect(c);
 }
 
@@ -511,8 +511,6 @@ static void publish_transport(grpc_subchannel *c) {
   connection *destroy_connection = NULL;
   grpc_channel_element *elem;
 
-  gpr_log(GPR_DEBUG, "publish_transport: %p", c->master);
-
   /* build final filter list */
   num_filters = c->num_filters + c->connecting_result.num_filters + 1;
   filters = gpr_malloc(sizeof(*filters) * num_filters);
diff --git a/src/core/httpcli/httpcli.c b/src/core/httpcli/httpcli.c
index 65997d5f44..9012070e8e 100644
--- a/src/core/httpcli/httpcli.c
+++ b/src/core/httpcli/httpcli.c
@@ -40,9 +40,7 @@
 #include "src/core/iomgr/resolve_address.h"
 #include "src/core/iomgr/tcp_client.h"
 #include "src/core/httpcli/format_request.h"
-#include "src/core/httpcli/httpcli_security_connector.h"
 #include "src/core/httpcli/parser.h"
-#include "src/core/security/secure_transport_setup.h"
 #include "src/core/support/string.h"
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
@@ -57,7 +55,7 @@ typedef struct {
   char *host;
   gpr_timespec deadline;
   int have_read_byte;
-  int use_ssl;
+  const grpc_httpcli_handshaker *handshaker;
   grpc_httpcli_response_cb on_response;
   void *user_data;
   grpc_httpcli_context *context;
@@ -68,6 +66,16 @@ typedef struct {
 static grpc_httpcli_get_override g_get_override = NULL;
 static grpc_httpcli_post_override g_post_override = NULL;
 
+static void plaintext_handshake(void *arg, grpc_endpoint *endpoint,
+                                const char *host,
+                                void (*on_done)(void *arg,
+                                                grpc_endpoint *endpoint)) {
+  on_done(arg, endpoint);
+}
+
+const grpc_httpcli_handshaker grpc_httpcli_plaintext = {"http",
+                                                        plaintext_handshake};
+
 void grpc_httpcli_context_init(grpc_httpcli_context *context) {
   grpc_pollset_set_init(&context->pollset_set);
 }
@@ -163,18 +171,16 @@ static void start_write(internal_request *req) {
   }
 }
 
-static void on_secure_transport_setup_done(void *rp,
-                                           grpc_security_status status,
-                                           grpc_endpoint *wrapped_endpoint,
-                                           grpc_endpoint *secure_endpoint) {
-  internal_request *req = rp;
-  if (status != GRPC_SECURITY_OK) {
-    gpr_log(GPR_ERROR, "Secure transport setup failed with error %d.", status);
-    finish(req, 0);
-  } else {
-    req->ep = secure_endpoint;
-    start_write(req);
+static void on_handshake_done(void *arg, grpc_endpoint *ep) {
+  internal_request *req = arg;
+
+  if (!ep) {
+    next_address(req);
+    return;
   }
+
+  req->ep = ep;
+  start_write(req);
 }
 
 static void on_connected(void *arg, grpc_endpoint *tcp) {
@@ -184,25 +190,7 @@ static void on_connected(void *arg, grpc_endpoint *tcp) {
     next_address(req);
     return;
   }
-  req->ep = tcp;
-  if (req->use_ssl) {
-    grpc_channel_security_connector *sc = NULL;
-    const unsigned char *pem_root_certs = NULL;
-    size_t pem_root_certs_size = grpc_get_default_ssl_roots(&pem_root_certs);
-    if (pem_root_certs == NULL || pem_root_certs_size == 0) {
-      gpr_log(GPR_ERROR, "Could not get default pem root certs.");
-      finish(req, 0);
-      return;
-    }
-    GPR_ASSERT(grpc_httpcli_ssl_channel_security_connector_create(
-                   pem_root_certs, pem_root_certs_size, req->host, &sc) ==
-               GRPC_SECURITY_OK);
-    grpc_setup_secure_transport(&sc->base, tcp, on_secure_transport_setup_done,
-                                req);
-    GRPC_SECURITY_CONNECTOR_UNREF(&sc->base, "httpcli");
-  } else {
-    start_write(req);
-  }
+  req->handshaker->handshake(req, tcp, req->host, on_handshake_done);
 }
 
 static void next_address(internal_request *req) {
@@ -245,18 +233,17 @@ void grpc_httpcli_get(grpc_httpcli_context *context, grpc_pollset *pollset,
   req->on_response = on_response;
   req->user_data = user_data;
   req->deadline = deadline;
-  req->use_ssl = request->use_ssl;
+  req->handshaker =
+      request->handshaker ? request->handshaker : &grpc_httpcli_plaintext;
   req->context = context;
   req->pollset = pollset;
   gpr_asprintf(&name, "HTTP:GET:%s:%s", request->host, request->path);
   grpc_iomgr_register_object(&req->iomgr_obj, name);
   gpr_free(name);
-  if (req->use_ssl) {
-    req->host = gpr_strdup(request->host);
-  }
+  req->host = gpr_strdup(request->host);
 
   grpc_pollset_set_add_pollset(&req->context->pollset_set, req->pollset);
-  grpc_resolve_address(request->host, req->use_ssl ? "https" : "http",
+  grpc_resolve_address(request->host, req->handshaker->default_port,
                        on_resolved, req);
 }
 
@@ -279,18 +266,17 @@ void grpc_httpcli_post(grpc_httpcli_context *context, grpc_pollset *pollset,
   req->on_response = on_response;
   req->user_data = user_data;
   req->deadline = deadline;
-  req->use_ssl = request->use_ssl;
+  req->handshaker =
+      request->handshaker ? request->handshaker : &grpc_httpcli_plaintext;
   req->context = context;
   req->pollset = pollset;
   gpr_asprintf(&name, "HTTP:GET:%s:%s", request->host, request->path);
   grpc_iomgr_register_object(&req->iomgr_obj, name);
   gpr_free(name);
-  if (req->use_ssl) {
-    req->host = gpr_strdup(request->host);
-  }
+  req->host = gpr_strdup(request->host);
 
   grpc_pollset_set_add_pollset(&req->context->pollset_set, req->pollset);
-  grpc_resolve_address(request->host, req->use_ssl ? "https" : "http",
+  grpc_resolve_address(request->host, req->handshaker->default_port,
                        on_resolved, req);
 }
 
diff --git a/src/core/httpcli/httpcli.h b/src/core/httpcli/httpcli.h
index ab98178f8a..c45966714c 100644
--- a/src/core/httpcli/httpcli.h
+++ b/src/core/httpcli/httpcli.h
@@ -38,6 +38,7 @@
 
 #include <grpc/support/time.h>
 
+#include "src/core/iomgr/endpoint.h"
 #include "src/core/iomgr/pollset_set.h"
 
 /* User agent this library reports */
@@ -58,6 +59,15 @@ typedef struct grpc_httpcli_context {
   grpc_pollset_set pollset_set;
 } grpc_httpcli_context;
 
+typedef struct {
+  const char *default_port;
+  void (*handshake)(void *arg, grpc_endpoint *endpoint, const char *host,
+                    void (*on_done)(void *arg, grpc_endpoint *endpoint));
+} grpc_httpcli_handshaker;
+
+extern const grpc_httpcli_handshaker grpc_httpcli_plaintext;
+extern const grpc_httpcli_handshaker grpc_httpcli_ssl;
+
 /* A request */
 typedef struct grpc_httpcli_request {
   /* The host name to connect to */
@@ -69,8 +79,8 @@ typedef struct grpc_httpcli_request {
        Host, Connection, User-Agent */
   size_t hdr_count;
   grpc_httpcli_header *hdrs;
-  /* whether to use ssl for the request */
-  int use_ssl;
+  /* handshaker to use ssl for the request */
+  const grpc_httpcli_handshaker *handshaker;
 } grpc_httpcli_request;
 
 /* A response */
diff --git a/src/core/httpcli/httpcli_security_connector.c b/src/core/httpcli/httpcli_security_connector.c
index ce0d3d5a70..7887f9d530 100644
--- a/src/core/httpcli/httpcli_security_connector.c
+++ b/src/core/httpcli/httpcli_security_connector.c
@@ -31,7 +31,7 @@
  *
  */
 
-#include "src/core/httpcli/httpcli_security_connector.h"
+#include "src/core/httpcli/httpcli.h"
 
 #include <string.h>
 
@@ -96,7 +96,7 @@ static grpc_security_status httpcli_ssl_check_peer(grpc_security_connector *sc,
 static grpc_security_connector_vtable httpcli_ssl_vtable = {
     httpcli_ssl_destroy, httpcli_ssl_create_handshaker, httpcli_ssl_check_peer};
 
-grpc_security_status grpc_httpcli_ssl_channel_security_connector_create(
+static grpc_security_status httpcli_ssl_channel_security_connector_create(
     const unsigned char *pem_root_certs, size_t pem_root_certs_size,
     const char *secure_peer_name, grpc_channel_security_connector **sc) {
   tsi_result result = TSI_OK;
@@ -130,3 +130,48 @@ grpc_security_status grpc_httpcli_ssl_channel_security_connector_create(
   *sc = &c->base;
   return GRPC_SECURITY_OK;
 }
+
+/* handshaker */
+
+typedef struct {
+  void (*func)(void *arg, grpc_endpoint *endpoint);
+  void *arg;
+} on_done_closure;
+
+static void on_secure_transport_setup_done(void *rp,
+                                           grpc_security_status status,
+                                           grpc_endpoint *wrapped_endpoint,
+                                           grpc_endpoint *secure_endpoint) {
+  on_done_closure *c = rp;
+  if (status != GRPC_SECURITY_OK) {
+    gpr_log(GPR_ERROR, "Secure transport setup failed with error %d.", status);
+    c->func(c->arg, NULL);
+  } else {
+    c->func(c->arg, secure_endpoint);
+  }
+  gpr_free(c);
+}
+
+static void ssl_handshake(void *arg, grpc_endpoint *tcp, const char *host,
+                          void (*on_done)(void *arg, grpc_endpoint *endpoint)) {
+  grpc_channel_security_connector *sc = NULL;
+  const unsigned char *pem_root_certs = NULL;
+  on_done_closure *c = gpr_malloc(sizeof(*c));
+  size_t pem_root_certs_size = grpc_get_default_ssl_roots(&pem_root_certs);
+  if (pem_root_certs == NULL || pem_root_certs_size == 0) {
+    gpr_log(GPR_ERROR, "Could not get default pem root certs.");
+    on_done(arg, NULL);
+    gpr_free(c);
+    return;
+  }
+  c->func = on_done;
+  c->arg = arg;
+  GPR_ASSERT(httpcli_ssl_channel_security_connector_create(
+                 pem_root_certs, pem_root_certs_size, host, &sc) ==
+             GRPC_SECURITY_OK);
+  grpc_setup_secure_transport(&sc->base, tcp, on_secure_transport_setup_done,
+                              c);
+  GRPC_SECURITY_CONNECTOR_UNREF(&sc->base, "httpcli");
+}
+
+const grpc_httpcli_handshaker grpc_httpcli_ssl = {"https", ssl_handshake};
diff --git a/src/core/iomgr/fd_posix.c b/src/core/iomgr/fd_posix.c
index a2df838d4a..2d08a77a70 100644
--- a/src/core/iomgr/fd_posix.c
+++ b/src/core/iomgr/fd_posix.c
@@ -168,13 +168,19 @@ int grpc_fd_is_orphaned(grpc_fd *fd) {
   return (gpr_atm_acq_load(&fd->refst) & 1) == 0;
 }
 
+static void pollset_kick_locked(grpc_pollset *pollset) {
+  gpr_mu_lock(GRPC_POLLSET_MU(pollset));
+  grpc_pollset_kick(pollset, NULL);
+  gpr_mu_unlock(GRPC_POLLSET_MU(pollset));
+}
+
 static void maybe_wake_one_watcher_locked(grpc_fd *fd) {
   if (fd->inactive_watcher_root.next != &fd->inactive_watcher_root) {
-    grpc_pollset_force_kick(fd->inactive_watcher_root.next->pollset);
+    pollset_kick_locked(fd->inactive_watcher_root.next->pollset);
   } else if (fd->read_watcher) {
-    grpc_pollset_force_kick(fd->read_watcher->pollset);
+    pollset_kick_locked(fd->read_watcher->pollset);
   } else if (fd->write_watcher) {
-    grpc_pollset_force_kick(fd->write_watcher->pollset);
+    pollset_kick_locked(fd->write_watcher->pollset);
   }
 }
 
@@ -188,13 +194,13 @@ static void wake_all_watchers_locked(grpc_fd *fd) {
   grpc_fd_watcher *watcher;
   for (watcher = fd->inactive_watcher_root.next;
        watcher != &fd->inactive_watcher_root; watcher = watcher->next) {
-    grpc_pollset_force_kick(watcher->pollset);
+    pollset_kick_locked(watcher->pollset);
   }
   if (fd->read_watcher) {
-    grpc_pollset_force_kick(fd->read_watcher->pollset);
+    pollset_kick_locked(fd->read_watcher->pollset);
   }
   if (fd->write_watcher && fd->write_watcher != fd->read_watcher) {
-    grpc_pollset_force_kick(fd->write_watcher->pollset);
+    pollset_kick_locked(fd->write_watcher->pollset);
   }
 }
 
@@ -376,13 +382,15 @@ gpr_uint32 grpc_fd_begin_poll(grpc_fd *fd, grpc_pollset *pollset,
     return 0;
   }
   /* if there is nobody polling for read, but we need to, then start doing so */
-  if (read_mask && !fd->read_watcher && gpr_atm_acq_load(&fd->readst) > READY) {
+  if (read_mask && !fd->read_watcher &&
+      (gpr_uintptr)gpr_atm_acq_load(&fd->readst) > READY) {
     fd->read_watcher = watcher;
     mask |= read_mask;
   }
   /* if there is nobody polling for write, but we need to, then start doing so
    */
-  if (write_mask && !fd->write_watcher && gpr_atm_acq_load(&fd->writest) > READY) {
+  if (write_mask && !fd->write_watcher &&
+      (gpr_uintptr)gpr_atm_acq_load(&fd->writest) > READY) {
     fd->write_watcher = watcher;
     mask |= write_mask;
   }
diff --git a/src/core/iomgr/fd_posix.h b/src/core/iomgr/fd_posix.h
index 4e8e267ffd..835e9b339a 100644
--- a/src/core/iomgr/fd_posix.h
+++ b/src/core/iomgr/fd_posix.h
@@ -109,7 +109,8 @@ grpc_fd *grpc_fd_create(int fd, const char *name);
    on_done is called when the underlying file descriptor is definitely close()d.
    If on_done is NULL, no callback will be made.
    Requires: *fd initialized; no outstanding notify_on_read or
-   notify_on_write. */
+   notify_on_write.
+   MUST NOT be called with a pollset lock taken */
 void grpc_fd_orphan(grpc_fd *fd, grpc_iomgr_closure *on_done,
                     const char *reason);
 
@@ -122,11 +123,13 @@ void grpc_fd_orphan(grpc_fd *fd, grpc_iomgr_closure *on_done,
    i.e. a combination of read_mask and write_mask determined by the fd's current
    interest in said events.
    Polling strategies that do not need to alter their behavior depending on the
-   fd's current interest (such as epoll) do not need to call this function. */
+   fd's current interest (such as epoll) do not need to call this function.
+   MUST NOT be called with a pollset lock taken */
 gpr_uint32 grpc_fd_begin_poll(grpc_fd *fd, grpc_pollset *pollset,
                               gpr_uint32 read_mask, gpr_uint32 write_mask,
                               grpc_fd_watcher *rec);
-/* Complete polling previously started with grpc_fd_begin_poll */
+/* Complete polling previously started with grpc_fd_begin_poll
+   MUST NOT be called with a pollset lock taken */
 void grpc_fd_end_poll(grpc_fd_watcher *rec, int got_read, int got_write);
 
 /* Return 1 if this fd is orphaned, 0 otherwise */
diff --git a/src/core/iomgr/pollset.h b/src/core/iomgr/pollset.h
index c40188b3c9..c474e4dbf1 100644
--- a/src/core/iomgr/pollset.h
+++ b/src/core/iomgr/pollset.h
@@ -37,6 +37,8 @@
 #include <grpc/support/port_platform.h>
 #include <grpc/support/time.h>
 
+#define GRPC_POLLSET_KICK_BROADCAST ((grpc_pollset_worker *)1)
+
 /* A grpc_pollset is a set of file descriptors that a higher level item is
    interested in. For example:
     - a server will typically keep a pollset containing all connected channels,
@@ -63,13 +65,24 @@ void grpc_pollset_destroy(grpc_pollset *pollset);
    descriptors.
    Requires GRPC_POLLSET_MU(pollset) locked.
    May unlock GRPC_POLLSET_MU(pollset) during its execution.
-   
+
+   worker is a (platform-specific) handle that can be used to wake up
+   from grpc_pollset_work before any events are received and before the timeout
+   has expired. It is both initialized and destroyed by grpc_pollset_work.
+   Initialization of worker is guaranteed to occur BEFORE the
+   GRPC_POLLSET_MU(pollset) is released for the first time by
+   grpc_pollset_work, and it is guaranteed that GRPC_POLLSET_MU(pollset) will
+   not be released by grpc_pollset_work AFTER worker has been destroyed.
+
    Returns true if some work has been done, and false if the deadline
-   got attained. */
-int grpc_pollset_work(grpc_pollset *pollset, gpr_timespec deadline);
+   expired. */
+int grpc_pollset_work(grpc_pollset *pollset, grpc_pollset_worker *worker,
+                      gpr_timespec deadline);
 
 /* Break one polling thread out of polling work for this pollset.
-   Requires GRPC_POLLSET_MU(pollset) locked. */
-void grpc_pollset_kick(grpc_pollset *pollset);
+   If specific_worker is GRPC_POLLSET_KICK_BROADCAST, kick ALL the workers.
+   Otherwise, if specific_worker is non-NULL, then kick that worker. */
+void grpc_pollset_kick(grpc_pollset *pollset,
+                       grpc_pollset_worker *specific_worker);
 
 #endif /* GRPC_INTERNAL_CORE_IOMGR_POLLSET_H */
diff --git a/src/core/iomgr/pollset_kick_posix.c b/src/core/iomgr/pollset_kick_posix.c
deleted file mode 100644
index 51021784f2..0000000000
--- a/src/core/iomgr/pollset_kick_posix.c
+++ /dev/null
@@ -1,168 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/support/port_platform.h>
-
-#ifdef GPR_POSIX_SOCKET
-#include "src/core/iomgr/pollset_kick_posix.h"
-
-#include <errno.h>
-#include <string.h>
-#include <unistd.h>
-
-#include "src/core/iomgr/socket_utils_posix.h"
-#include "src/core/iomgr/wakeup_fd_posix.h"
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-
-/* This implementation is based on a freelist of wakeup fds, with extra logic to
- * handle kicks while there is no attached fd. */
-
-/* TODO(klempner): Autosize this, and consider providing a way to disable the
- * cap entirely on systems with large fd limits */
-#define GRPC_MAX_CACHED_WFDS 50
-
-static grpc_kick_fd_info *fd_freelist = NULL;
-static int fd_freelist_count = 0;
-static gpr_mu fd_freelist_mu;
-
-static grpc_kick_fd_info *allocate_wfd(void) {
-  grpc_kick_fd_info *info = NULL;
-  gpr_mu_lock(&fd_freelist_mu);
-  if (fd_freelist != NULL) {
-    info = fd_freelist;
-    fd_freelist = fd_freelist->next;
-    --fd_freelist_count;
-  }
-  gpr_mu_unlock(&fd_freelist_mu);
-  if (info == NULL) {
-    info = gpr_malloc(sizeof(*info));
-    grpc_wakeup_fd_create(&info->wakeup_fd);
-    info->next = NULL;
-  }
-  return info;
-}
-
-static void destroy_wfd(grpc_kick_fd_info *wfd) {
-  grpc_wakeup_fd_destroy(&wfd->wakeup_fd);
-  gpr_free(wfd);
-}
-
-static void free_wfd(grpc_kick_fd_info *fd_info) {
-  gpr_mu_lock(&fd_freelist_mu);
-  if (fd_freelist_count < GRPC_MAX_CACHED_WFDS) {
-    fd_info->next = fd_freelist;
-    fd_freelist = fd_info;
-    fd_freelist_count++;
-    fd_info = NULL;
-  }
-  gpr_mu_unlock(&fd_freelist_mu);
-
-  if (fd_info) {
-    destroy_wfd(fd_info);
-  }
-}
-
-void grpc_pollset_kick_init(grpc_pollset_kick_state *kick_state) {
-  gpr_mu_init(&kick_state->mu);
-  kick_state->kicked = 0;
-  kick_state->fd_list.next = kick_state->fd_list.prev = &kick_state->fd_list;
-}
-
-void grpc_pollset_kick_destroy(grpc_pollset_kick_state *kick_state) {
-  gpr_mu_destroy(&kick_state->mu);
-  GPR_ASSERT(kick_state->fd_list.next == &kick_state->fd_list);
-}
-
-grpc_kick_fd_info *grpc_pollset_kick_pre_poll(
-    grpc_pollset_kick_state *kick_state) {
-  grpc_kick_fd_info *fd_info;
-  gpr_mu_lock(&kick_state->mu);
-  if (kick_state->kicked) {
-    kick_state->kicked = 0;
-    gpr_mu_unlock(&kick_state->mu);
-    return NULL;
-  }
-  fd_info = allocate_wfd();
-  fd_info->next = &kick_state->fd_list;
-  fd_info->prev = fd_info->next->prev;
-  fd_info->next->prev = fd_info->prev->next = fd_info;
-  gpr_mu_unlock(&kick_state->mu);
-  return fd_info;
-}
-
-void grpc_pollset_kick_consume(grpc_pollset_kick_state *kick_state,
-                               grpc_kick_fd_info *fd_info) {
-  grpc_wakeup_fd_consume_wakeup(&fd_info->wakeup_fd);
-}
-
-void grpc_pollset_kick_post_poll(grpc_pollset_kick_state *kick_state,
-                                 grpc_kick_fd_info *fd_info) {
-  gpr_mu_lock(&kick_state->mu);
-  fd_info->next->prev = fd_info->prev;
-  fd_info->prev->next = fd_info->next;
-  free_wfd(fd_info);
-  gpr_mu_unlock(&kick_state->mu);
-}
-
-void grpc_pollset_kick_kick(grpc_pollset_kick_state *kick_state) {
-  gpr_mu_lock(&kick_state->mu);
-  if (kick_state->fd_list.next != &kick_state->fd_list) {
-    grpc_wakeup_fd_wakeup(&kick_state->fd_list.next->wakeup_fd);
-  } else {
-    kick_state->kicked = 1;
-  }
-  gpr_mu_unlock(&kick_state->mu);
-}
-
-void grpc_pollset_kick_global_init_fallback_fd(void) {
-  gpr_mu_init(&fd_freelist_mu);
-  grpc_wakeup_fd_global_init_force_fallback();
-}
-
-void grpc_pollset_kick_global_init(void) {
-  gpr_mu_init(&fd_freelist_mu);
-  grpc_wakeup_fd_global_init();
-}
-
-void grpc_pollset_kick_global_destroy(void) {
-  while (fd_freelist != NULL) {
-    grpc_kick_fd_info *current = fd_freelist;
-    fd_freelist = fd_freelist->next;
-    destroy_wfd(current);
-  }
-  grpc_wakeup_fd_global_destroy();
-  gpr_mu_destroy(&fd_freelist_mu);
-}
-
-#endif /* GPR_POSIX_SOCKET */
diff --git a/src/core/iomgr/pollset_kick_posix.h b/src/core/iomgr/pollset_kick_posix.h
deleted file mode 100644
index 77e32a8d51..0000000000
--- a/src/core/iomgr/pollset_kick_posix.h
+++ /dev/null
@@ -1,93 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_INTERNAL_CORE_IOMGR_POLLSET_KICK_POSIX_H
-#define GRPC_INTERNAL_CORE_IOMGR_POLLSET_KICK_POSIX_H
-
-#include "src/core/iomgr/wakeup_fd_posix.h"
-#include <grpc/support/sync.h>
-
-/* pollset kicking allows breaking a thread out of polling work for
-   a given pollset.
-   writing a byte to a pipe is used as a posix-ly portable base
-   mechanism, and eventfds are utilized on Linux for better performance. */
-
-typedef struct grpc_kick_fd_info {
-  grpc_wakeup_fd_info wakeup_fd;
-  /* used for polling list and free list */
-  struct grpc_kick_fd_info *next;
-  /* only used when polling */
-  struct grpc_kick_fd_info *prev;
-} grpc_kick_fd_info;
-
-typedef struct grpc_pollset_kick_state {
-  gpr_mu mu;
-  int kicked;
-  struct grpc_kick_fd_info fd_list;
-} grpc_pollset_kick_state;
-
-#define GRPC_POLLSET_KICK_GET_FD(kick_fd_info) \
-  GRPC_WAKEUP_FD_GET_READ_FD(&(kick_fd_info)->wakeup_fd)
-
-/* This is an abstraction around the typical pipe mechanism for waking up a
-   thread sitting in a poll() style call. */
-
-void grpc_pollset_kick_global_init(void);
-void grpc_pollset_kick_global_destroy(void);
-
-void grpc_pollset_kick_init(grpc_pollset_kick_state *kick_state);
-void grpc_pollset_kick_destroy(grpc_pollset_kick_state *kick_state);
-
-/* Guarantees a pure posix implementation rather than a specialized one, if
- * applicable. Intended for testing. */
-void grpc_pollset_kick_global_init_fallback_fd(void);
-
-/* Must be called before entering poll(). If return value is NULL, this consumed
-   an existing kick. Otherwise the return value is an FD to add to the poll set.
- */
-grpc_kick_fd_info *grpc_pollset_kick_pre_poll(
-    grpc_pollset_kick_state *kick_state);
-
-/* Consume an existing kick. Must be called after poll returns that the fd was
-   readable, and before calling kick_post_poll. */
-void grpc_pollset_kick_consume(grpc_pollset_kick_state *kick_state,
-                               grpc_kick_fd_info *fd_info);
-
-/* Must be called after pre_poll, and after consume if applicable */
-void grpc_pollset_kick_post_poll(grpc_pollset_kick_state *kick_state,
-                                 grpc_kick_fd_info *fd_info);
-
-/* Actually kick */
-void grpc_pollset_kick_kick(grpc_pollset_kick_state *kick_state);
-
-#endif /* GRPC_INTERNAL_CORE_IOMGR_POLLSET_KICK_POSIX_H */
diff --git a/src/core/iomgr/pollset_multipoller_with_epoll.c b/src/core/iomgr/pollset_multipoller_with_epoll.c
index d697b59e4c..1320c64579 100644
--- a/src/core/iomgr/pollset_multipoller_with_epoll.c
+++ b/src/core/iomgr/pollset_multipoller_with_epoll.c
@@ -36,6 +36,7 @@
 #ifdef GPR_LINUX_MULTIPOLL_WITH_EPOLL
 
 #include <errno.h>
+#include <poll.h>
 #include <string.h>
 #include <sys/epoll.h>
 #include <unistd.h>
@@ -44,23 +45,28 @@
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 
+typedef struct wakeup_fd_hdl {
+  grpc_wakeup_fd wakeup_fd;
+  struct wakeup_fd_hdl *next;
+} wakeup_fd_hdl;
+
+typedef struct {
+  grpc_pollset *pollset;
+  grpc_fd *fd;
+  grpc_iomgr_closure closure;
+} delayed_add;
+
 typedef struct {
   int epoll_fd;
-  grpc_wakeup_fd_info wakeup_fd;
+  wakeup_fd_hdl *free_wakeup_fds;
 } pollset_hdr;
 
-static void multipoll_with_epoll_pollset_add_fd(grpc_pollset *pollset,
-                                                grpc_fd *fd,
-                                                int and_unlock_pollset) {
+static void finally_add_fd(grpc_pollset *pollset, grpc_fd *fd) {
   pollset_hdr *h = pollset->data.ptr;
   struct epoll_event ev;
   int err;
   grpc_fd_watcher watcher;
 
-  if (and_unlock_pollset) {
-    gpr_mu_unlock(&pollset->mu);
-  }
-
   /* We pretend to be polling whilst adding an fd to keep the fd from being
      closed during the add. This may result in a spurious wakeup being assigned
      to this pollset whilst adding, but that should be benign. */
@@ -80,6 +86,52 @@ static void multipoll_with_epoll_pollset_add_fd(grpc_pollset *pollset,
   grpc_fd_end_poll(&watcher, 0, 0);
 }
 
+static void perform_delayed_add(void *arg, int iomgr_status) {
+  delayed_add *da = arg;
+  int do_shutdown_cb = 0;
+
+  if (!grpc_fd_is_orphaned(da->fd)) {
+    finally_add_fd(da->pollset, da->fd);
+  }
+
+  gpr_mu_lock(&da->pollset->mu);
+  da->pollset->in_flight_cbs--;
+  if (da->pollset->shutting_down) {
+    /* We don't care about this pollset anymore. */
+    if (da->pollset->in_flight_cbs == 0 && !da->pollset->called_shutdown) {
+      GPR_ASSERT(!grpc_pollset_has_workers(da->pollset));
+      da->pollset->called_shutdown = 1;
+      do_shutdown_cb = 1;
+    }
+  }
+  gpr_mu_unlock(&da->pollset->mu);
+
+  GRPC_FD_UNREF(da->fd, "delayed_add");
+
+  if (do_shutdown_cb) {
+    da->pollset->shutdown_done_cb(da->pollset->shutdown_done_arg);
+  }
+
+  gpr_free(da);
+}
+
+static void multipoll_with_epoll_pollset_add_fd(grpc_pollset *pollset,
+                                                grpc_fd *fd,
+                                                int and_unlock_pollset) {
+  if (and_unlock_pollset) {
+    gpr_mu_unlock(&pollset->mu);
+    finally_add_fd(pollset, fd);
+  } else {
+    delayed_add *da = gpr_malloc(sizeof(*da));
+    da->pollset = pollset;
+    da->fd = fd;
+    GRPC_FD_REF(fd, "delayed_add");
+    grpc_iomgr_closure_init(&da->closure, perform_delayed_add, da);
+    pollset->in_flight_cbs++;
+    grpc_iomgr_add_callback(&da->closure);
+  }
+}
+
 static void multipoll_with_epoll_pollset_del_fd(grpc_pollset *pollset,
                                                 grpc_fd *fd,
                                                 int and_unlock_pollset) {
@@ -103,12 +155,14 @@ static void multipoll_with_epoll_pollset_del_fd(grpc_pollset *pollset,
 #define GRPC_EPOLL_MAX_EVENTS 1000
 
 static void multipoll_with_epoll_pollset_maybe_work(
-    grpc_pollset *pollset, gpr_timespec deadline, gpr_timespec now,
-    int allow_synchronous_callback) {
+    grpc_pollset *pollset, grpc_pollset_worker *worker, gpr_timespec deadline,
+    gpr_timespec now, int allow_synchronous_callback) {
   struct epoll_event ep_ev[GRPC_EPOLL_MAX_EVENTS];
   int ep_rv;
+  int poll_rv;
   pollset_hdr *h = pollset->data.ptr;
   int timeout_ms;
+  struct pollfd pfds[2];
 
   /* If you want to ignore epoll's ability to sanely handle parallel pollers,
    * for a more apples-to-apples performance comparison with poll, add a
@@ -116,43 +170,58 @@ static void multipoll_with_epoll_pollset_maybe_work(
    * here.
    */
 
-  pollset->counter += 1;
   gpr_mu_unlock(&pollset->mu);
 
   timeout_ms = grpc_poll_deadline_to_millis_timeout(deadline, now);
 
-  do {
-    ep_rv = epoll_wait(h->epoll_fd, ep_ev, GRPC_EPOLL_MAX_EVENTS, timeout_ms);
-    if (ep_rv < 0) {
-      if (errno != EINTR) {
-        gpr_log(GPR_ERROR, "epoll_wait() failed: %s", strerror(errno));
-      }
-    } else {
-      int i;
-      for (i = 0; i < ep_rv; ++i) {
-        if (ep_ev[i].data.ptr == 0) {
-          grpc_wakeup_fd_consume_wakeup(&h->wakeup_fd);
-        } else {
-          grpc_fd *fd = ep_ev[i].data.ptr;
-          /* TODO(klempner): We might want to consider making err and pri
-           * separate events */
-          int cancel = ep_ev[i].events & (EPOLLERR | EPOLLHUP);
-          int read = ep_ev[i].events & (EPOLLIN | EPOLLPRI);
-          int write = ep_ev[i].events & EPOLLOUT;
-          if (read || cancel) {
-            grpc_fd_become_readable(fd, allow_synchronous_callback);
+  pfds[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd);
+  pfds[0].events = POLLIN;
+  pfds[0].revents = 0;
+  pfds[1].fd = h->epoll_fd;
+  pfds[1].events = POLLIN;
+  pfds[1].revents = 0;
+
+  poll_rv = poll(pfds, 2, timeout_ms);
+
+  if (poll_rv < 0) {
+    if (errno != EINTR) {
+      gpr_log(GPR_ERROR, "poll() failed: %s", strerror(errno));
+    }
+  } else if (poll_rv == 0) {
+    /* do nothing */
+  } else {
+    if (pfds[0].revents) {
+      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd);
+    }
+    if (pfds[1].revents) {
+      do {
+        ep_rv = epoll_wait(h->epoll_fd, ep_ev, GRPC_EPOLL_MAX_EVENTS, 0);
+        if (ep_rv < 0) {
+          if (errno != EINTR) {
+            gpr_log(GPR_ERROR, "epoll_wait() failed: %s", strerror(errno));
           }
-          if (write || cancel) {
-            grpc_fd_become_writable(fd, allow_synchronous_callback);
+        } else {
+          int i;
+          for (i = 0; i < ep_rv; ++i) {
+            grpc_fd *fd = ep_ev[i].data.ptr;
+            /* TODO(klempner): We might want to consider making err and pri
+             * separate events */
+            int cancel = ep_ev[i].events & (EPOLLERR | EPOLLHUP);
+            int read = ep_ev[i].events & (EPOLLIN | EPOLLPRI);
+            int write = ep_ev[i].events & EPOLLOUT;
+            if (read || cancel) {
+              grpc_fd_become_readable(fd, allow_synchronous_callback);
+            }
+            if (write || cancel) {
+              grpc_fd_become_writable(fd, allow_synchronous_callback);
+            }
           }
         }
-      }
+      } while (ep_rv == GRPC_EPOLL_MAX_EVENTS);
     }
-    timeout_ms = 0;
-  } while (ep_rv == GRPC_EPOLL_MAX_EVENTS);
+  }
 
   gpr_mu_lock(&pollset->mu);
-  pollset->counter -= 1;
 }
 
 static void multipoll_with_epoll_pollset_finish_shutdown(
@@ -160,21 +229,14 @@ static void multipoll_with_epoll_pollset_finish_shutdown(
 
 static void multipoll_with_epoll_pollset_destroy(grpc_pollset *pollset) {
   pollset_hdr *h = pollset->data.ptr;
-  grpc_wakeup_fd_destroy(&h->wakeup_fd);
   close(h->epoll_fd);
   gpr_free(h);
 }
 
-static void epoll_kick(grpc_pollset *pollset) {
-  pollset_hdr *h = pollset->data.ptr;
-  grpc_wakeup_fd_wakeup(&h->wakeup_fd);
-}
-
 static const grpc_pollset_vtable multipoll_with_epoll_pollset = {
     multipoll_with_epoll_pollset_add_fd,
     multipoll_with_epoll_pollset_del_fd,
     multipoll_with_epoll_pollset_maybe_work,
-    epoll_kick,
     multipoll_with_epoll_pollset_finish_shutdown,
     multipoll_with_epoll_pollset_destroy};
 
@@ -182,8 +244,6 @@ static void epoll_become_multipoller(grpc_pollset *pollset, grpc_fd **fds,
                                      size_t nfds) {
   size_t i;
   pollset_hdr *h = gpr_malloc(sizeof(pollset_hdr));
-  struct epoll_event ev;
-  int err;
 
   pollset->vtable = &multipoll_with_epoll_pollset;
   pollset->data.ptr = h;
@@ -196,16 +256,6 @@ static void epoll_become_multipoller(grpc_pollset *pollset, grpc_fd **fds,
   for (i = 0; i < nfds; i++) {
     multipoll_with_epoll_pollset_add_fd(pollset, fds[i], 0);
   }
-
-  grpc_wakeup_fd_create(&h->wakeup_fd);
-  ev.events = EPOLLIN;
-  ev.data.ptr = 0;
-  err = epoll_ctl(h->epoll_fd, EPOLL_CTL_ADD,
-                  GRPC_WAKEUP_FD_GET_READ_FD(&h->wakeup_fd), &ev);
-  if (err < 0) {
-    gpr_log(GPR_ERROR, "Wakeup fd epoll_ctl failed: %s", strerror(errno));
-    abort();
-  }
 }
 
 grpc_platform_become_multipoller_type grpc_platform_become_multipoller =
diff --git a/src/core/iomgr/pollset_multipoller_with_poll_posix.c b/src/core/iomgr/pollset_multipoller_with_poll_posix.c
index 0084e83953..b5b2d7534d 100644
--- a/src/core/iomgr/pollset_multipoller_with_poll_posix.c
+++ b/src/core/iomgr/pollset_multipoller_with_poll_posix.c
@@ -53,12 +53,6 @@ typedef struct {
   size_t fd_count;
   size_t fd_capacity;
   grpc_fd **fds;
-  /* fds being polled by the current poller: parallel arrays of pollfd, and
-     a grpc_fd_watcher */
-  size_t pfd_count;
-  size_t pfd_capacity;
-  grpc_fd_watcher *watchers;
-  struct pollfd *pfds;
   /* fds that have been removed from the pollset explicitly */
   size_t del_count;
   size_t del_capacity;
@@ -102,80 +96,60 @@ static void multipoll_with_poll_pollset_del_fd(grpc_pollset *pollset,
   }
 }
 
-static void end_polling(grpc_pollset *pollset) {
-  size_t i;
-  pollset_hdr *h;
-  h = pollset->data.ptr;
-  for (i = 1; i < h->pfd_count; i++) {
-    grpc_fd_end_poll(&h->watchers[i], h->pfds[i].revents & POLLIN,
-                     h->pfds[i].revents & POLLOUT);
-  }
-}
-
 static void multipoll_with_poll_pollset_maybe_work(
-    grpc_pollset *pollset, gpr_timespec deadline, gpr_timespec now,
-    int allow_synchronous_callback) {
+    grpc_pollset *pollset, grpc_pollset_worker *worker, gpr_timespec deadline,
+    gpr_timespec now, int allow_synchronous_callback) {
   int timeout;
   int r;
-  size_t i, np, nf, nd;
+  size_t i, j, pfd_count, fd_count;
   pollset_hdr *h;
-  grpc_kick_fd_info *kfd;
+  /* TODO(ctiller): inline some elements to avoid an allocation */
+  grpc_fd_watcher *watchers;
+  struct pollfd *pfds;
 
   h = pollset->data.ptr;
   timeout = grpc_poll_deadline_to_millis_timeout(deadline, now);
-  if (h->pfd_capacity < h->fd_count + 1) {
-    h->pfd_capacity = GPR_MAX(h->pfd_capacity * 3 / 2, h->fd_count + 1);
-    gpr_free(h->pfds);
-    gpr_free(h->watchers);
-    h->pfds = gpr_malloc(sizeof(struct pollfd) * h->pfd_capacity);
-    h->watchers = gpr_malloc(sizeof(grpc_fd_watcher) * h->pfd_capacity);
-  }
-  nf = 0;
-  np = 1;
-  kfd = grpc_pollset_kick_pre_poll(&pollset->kick_state);
-  if (kfd == NULL) {
-    /* Already kicked */
-    return;
-  }
-  h->pfds[0].fd = GRPC_POLLSET_KICK_GET_FD(kfd);
-  h->pfds[0].events = POLLIN;
-  h->pfds[0].revents = POLLOUT;
+  /* TODO(ctiller): perform just one malloc here if we exceed the inline case */
+  pfds = gpr_malloc(sizeof(*pfds) * (h->fd_count + 1));
+  watchers = gpr_malloc(sizeof(*watchers) * (h->fd_count + 1));
+  fd_count = 0;
+  pfd_count = 1;
+  pfds[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd);
+  pfds[0].events = POLLIN;
+  pfds[0].revents = POLLOUT;
   for (i = 0; i < h->fd_count; i++) {
     int remove = grpc_fd_is_orphaned(h->fds[i]);
-    for (nd = 0; nd < h->del_count; nd++) {
-      if (h->fds[i] == h->dels[nd]) remove = 1;
+    for (j = 0; !remove && j < h->del_count; j++) {
+      if (h->fds[i] == h->dels[j]) remove = 1;
     }
     if (remove) {
       GRPC_FD_UNREF(h->fds[i], "multipoller");
     } else {
-      h->fds[nf++] = h->fds[i];
-      h->watchers[np].fd = h->fds[i];
-      h->pfds[np].fd = h->fds[i]->fd;
-      h->pfds[np].revents = 0;
-      np++;
+      h->fds[fd_count++] = h->fds[i];
+      watchers[pfd_count].fd = h->fds[i];
+      pfds[pfd_count].fd = h->fds[i]->fd;
+      pfds[pfd_count].revents = 0;
+      pfd_count++;
     }
   }
-  h->pfd_count = np;
-  h->fd_count = nf;
-  for (nd = 0; nd < h->del_count; nd++) {
-    GRPC_FD_UNREF(h->dels[nd], "multipoller_del");
+  for (j = 0; j < h->del_count; j++) {
+    GRPC_FD_UNREF(h->dels[j], "multipoller_del");
   }
   h->del_count = 0;
-  if (h->pfd_count == 0) {
-    end_polling(pollset);
-    return;
-  }
-  pollset->counter++;
+  h->fd_count = fd_count;
   gpr_mu_unlock(&pollset->mu);
 
-  for (i = 1; i < np; i++) {
-    h->pfds[i].events = grpc_fd_begin_poll(h->watchers[i].fd, pollset, POLLIN,
-                                           POLLOUT, &h->watchers[i]);
+  for (i = 1; i < pfd_count; i++) {
+    pfds[i].events = grpc_fd_begin_poll(watchers[i].fd, pollset, POLLIN,
+                                        POLLOUT, &watchers[i]);
   }
 
-  r = poll(h->pfds, h->pfd_count, timeout);
+  r = poll(pfds, pfd_count, timeout);
 
-  end_polling(pollset);
+  for (i = 1; i < pfd_count; i++) {
+    grpc_fd_end_poll(&watchers[i], pfds[i].revents & POLLIN,
+                     pfds[i].revents & POLLOUT);
+  }
 
   if (r < 0) {
     if (errno != EINTR) {
@@ -184,35 +158,31 @@ static void multipoll_with_poll_pollset_maybe_work(
   } else if (r == 0) {
     /* do nothing */
   } else {
-    if (h->pfds[0].revents & POLLIN) {
-      grpc_pollset_kick_consume(&pollset->kick_state, kfd);
+    if (pfds[0].revents & POLLIN) {
+      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd);
     }
-    for (i = 1; i < np; i++) {
-      if (h->watchers[i].fd == NULL) {
+    for (i = 1; i < pfd_count; i++) {
+      if (watchers[i].fd == NULL) {
         continue;
       }
-      if (h->pfds[i].revents & (POLLIN | POLLHUP | POLLERR)) {
-        grpc_fd_become_readable(h->watchers[i].fd, allow_synchronous_callback);
+      if (pfds[i].revents & (POLLIN | POLLHUP | POLLERR)) {
+        grpc_fd_become_readable(watchers[i].fd, allow_synchronous_callback);
       }
-      if (h->pfds[i].revents & (POLLOUT | POLLHUP | POLLERR)) {
-        grpc_fd_become_writable(h->watchers[i].fd, allow_synchronous_callback);
+      if (pfds[i].revents & (POLLOUT | POLLHUP | POLLERR)) {
+        grpc_fd_become_writable(watchers[i].fd, allow_synchronous_callback);
       }
     }
   }
-  grpc_pollset_kick_post_poll(&pollset->kick_state, kfd);
 
-  gpr_mu_lock(&pollset->mu);
-  pollset->counter--;
-}
+  gpr_free(pfds);
+  gpr_free(watchers);
 
-static void multipoll_with_poll_pollset_kick(grpc_pollset *p) {
-  grpc_pollset_force_kick(p);
+  gpr_mu_lock(&pollset->mu);
 }
 
 static void multipoll_with_poll_pollset_finish_shutdown(grpc_pollset *pollset) {
   size_t i;
   pollset_hdr *h = pollset->data.ptr;
-  GPR_ASSERT(pollset->counter == 0);
   for (i = 0; i < h->fd_count; i++) {
     GRPC_FD_UNREF(h->fds[i], "multipoller");
   }
@@ -226,8 +196,6 @@ static void multipoll_with_poll_pollset_finish_shutdown(grpc_pollset *pollset) {
 static void multipoll_with_poll_pollset_destroy(grpc_pollset *pollset) {
   pollset_hdr *h = pollset->data.ptr;
   multipoll_with_poll_pollset_finish_shutdown(pollset);
-  gpr_free(h->pfds);
-  gpr_free(h->watchers);
   gpr_free(h->fds);
   gpr_free(h->dels);
   gpr_free(h);
@@ -237,7 +205,6 @@ static const grpc_pollset_vtable multipoll_with_poll_pollset = {
     multipoll_with_poll_pollset_add_fd,
     multipoll_with_poll_pollset_del_fd,
     multipoll_with_poll_pollset_maybe_work,
-    multipoll_with_poll_pollset_kick,
     multipoll_with_poll_pollset_finish_shutdown,
     multipoll_with_poll_pollset_destroy};
 
@@ -250,10 +217,6 @@ void grpc_poll_become_multipoller(grpc_pollset *pollset, grpc_fd **fds,
   h->fd_count = nfds;
   h->fd_capacity = nfds;
   h->fds = gpr_malloc(nfds * sizeof(grpc_fd *));
-  h->pfd_count = 0;
-  h->pfd_capacity = 0;
-  h->pfds = NULL;
-  h->watchers = NULL;
   h->del_count = 0;
   h->del_capacity = 0;
   h->dels = NULL;
diff --git a/src/core/iomgr/pollset_posix.c b/src/core/iomgr/pollset_posix.c
index c8646af615..d3a9193af1 100644
--- a/src/core/iomgr/pollset_posix.c
+++ b/src/core/iomgr/pollset_posix.c
@@ -55,22 +55,60 @@
 #include <grpc/support/useful.h>
 
 GPR_TLS_DECL(g_current_thread_poller);
+GPR_TLS_DECL(g_current_thread_worker);
 
-void grpc_pollset_kick(grpc_pollset *p) {
-  if (gpr_tls_get(&g_current_thread_poller) != (gpr_intptr)p && p->counter) {
-    p->vtable->kick(p);
-  }
+static void remove_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
+  worker->prev->next = worker->next;
+  worker->next->prev = worker->prev;
+}
+
+int grpc_pollset_has_workers(grpc_pollset *p) {
+  return p->root_worker.next != &p->root_worker;
 }
 
-void grpc_pollset_force_kick(grpc_pollset *p) {
-  if (gpr_tls_get(&g_current_thread_poller) != (gpr_intptr)p) {
-    grpc_pollset_kick_kick(&p->kick_state);
+static grpc_pollset_worker *pop_front_worker(grpc_pollset *p) {
+  if (grpc_pollset_has_workers(p)) {
+    grpc_pollset_worker *w = p->root_worker.next;
+    remove_worker(p, w);
+    return w;
+  } else {
+    return NULL;
   }
 }
 
-static void kick_using_pollset_kick(grpc_pollset *p) {
-  if (gpr_tls_get(&g_current_thread_poller) != (gpr_intptr)p) {
-    grpc_pollset_kick_kick(&p->kick_state);
+static void push_back_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
+  worker->next = &p->root_worker;
+  worker->prev = worker->next->prev;
+  worker->prev->next = worker->next->prev = worker;
+}
+
+static void push_front_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
+  worker->prev = &p->root_worker;
+  worker->next = worker->prev->next;
+  worker->prev->next = worker->next->prev = worker;
+}
+
+void grpc_pollset_kick(grpc_pollset *p, grpc_pollset_worker *specific_worker) {
+  if (specific_worker != NULL) {
+    if (specific_worker == GRPC_POLLSET_KICK_BROADCAST) {
+      for (specific_worker = p->root_worker.next;
+           specific_worker != &p->root_worker;
+           specific_worker = specific_worker->next) {
+        grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd);
+      }
+      p->kicked_without_pollers = 1;
+    } else if (gpr_tls_get(&g_current_thread_worker) !=
+               (gpr_intptr)specific_worker) {
+      grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd);
+    }
+  } else if (gpr_tls_get(&g_current_thread_poller) != (gpr_intptr)p) {
+    specific_worker = pop_front_worker(p);
+    if (specific_worker != NULL) {
+      push_back_worker(p, specific_worker);
+      grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd);
+    } else {
+      p->kicked_without_pollers = 1;
+    }
   }
 }
 
@@ -78,16 +116,12 @@ static void kick_using_pollset_kick(grpc_pollset *p) {
 
 void grpc_pollset_global_init(void) {
   gpr_tls_init(&g_current_thread_poller);
-
-  /* Initialize kick fd state */
-  grpc_pollset_kick_global_init();
+  grpc_wakeup_fd_global_init();
 }
 
 void grpc_pollset_global_shutdown(void) {
-  /* destroy the kick pipes */
-  grpc_pollset_kick_global_destroy();
-
   gpr_tls_destroy(&g_current_thread_poller);
+  grpc_wakeup_fd_global_destroy();
 }
 
 /* main interface */
@@ -96,7 +130,7 @@ static void become_basic_pollset(grpc_pollset *pollset, grpc_fd *fd_or_null);
 
 void grpc_pollset_init(grpc_pollset *pollset) {
   gpr_mu_init(&pollset->mu);
-  grpc_pollset_kick_init(&pollset->kick_state);
+  pollset->root_worker.next = pollset->root_worker.prev = &pollset->root_worker;
   pollset->in_flight_cbs = 0;
   pollset->shutting_down = 0;
   pollset->called_shutdown = 0;
@@ -134,27 +168,44 @@ static void finish_shutdown(grpc_pollset *pollset) {
   pollset->shutdown_done_cb(pollset->shutdown_done_arg);
 }
 
-int grpc_pollset_work(grpc_pollset *pollset, gpr_timespec deadline) {
+int grpc_pollset_work(grpc_pollset *pollset, grpc_pollset_worker *worker,
+                      gpr_timespec deadline) {
   /* pollset->mu already held */
   gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
+  int added_worker = 0;
   if (gpr_time_cmp(now, deadline) > 0) {
     return 0;
   }
+  /* this must happen before we (potentially) drop pollset->mu */
+  worker->next = worker->prev = NULL;
+  /* TODO(ctiller): pool these */
+  grpc_wakeup_fd_init(&worker->wakeup_fd);
   if (grpc_maybe_call_delayed_callbacks(&pollset->mu, 1)) {
-    return 1;
+    goto done;
   }
   if (grpc_alarm_check(&pollset->mu, now, &deadline)) {
-    return 1;
+    goto done;
   }
   if (pollset->shutting_down) {
-    return 1;
+    goto done;
+  }
+  if (!pollset->kicked_without_pollers) {
+    push_front_worker(pollset, worker);
+    added_worker = 1;
+    gpr_tls_set(&g_current_thread_poller, (gpr_intptr)pollset);
+    pollset->vtable->maybe_work(pollset, worker, deadline, now, 1);
+    gpr_tls_set(&g_current_thread_poller, 0);
+  } else {
+    pollset->kicked_without_pollers = 0;
+  }
+done:
+  grpc_wakeup_fd_destroy(&worker->wakeup_fd);
+  if (added_worker) {
+    remove_worker(pollset, worker);
   }
-  gpr_tls_set(&g_current_thread_poller, (gpr_intptr)pollset);
-  pollset->vtable->maybe_work(pollset, deadline, now, 1);
-  gpr_tls_set(&g_current_thread_poller, 0);
   if (pollset->shutting_down) {
-    if (pollset->counter > 0) {
-      grpc_pollset_kick(pollset);
+    if (grpc_pollset_has_workers(pollset)) {
+      grpc_pollset_kick(pollset, NULL);
     } else if (!pollset->called_shutdown && pollset->in_flight_cbs == 0) {
       pollset->called_shutdown = 1;
       gpr_mu_unlock(&pollset->mu);
@@ -177,15 +228,13 @@ void grpc_pollset_shutdown(grpc_pollset *pollset,
   GPR_ASSERT(!pollset->shutting_down);
   pollset->shutting_down = 1;
   if (!pollset->called_shutdown && pollset->in_flight_cbs == 0 &&
-      pollset->counter == 0) {
+      !grpc_pollset_has_workers(pollset)) {
     pollset->called_shutdown = 1;
     call_shutdown = 1;
   }
   pollset->shutdown_done_cb = shutdown_done;
   pollset->shutdown_done_arg = shutdown_done_arg;
-  if (pollset->counter > 0) {
-    grpc_pollset_kick(pollset);
-  }
+  grpc_pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST);
   gpr_mu_unlock(&pollset->mu);
 
   if (call_shutdown) {
@@ -196,8 +245,8 @@ void grpc_pollset_shutdown(grpc_pollset *pollset,
 void grpc_pollset_destroy(grpc_pollset *pollset) {
   GPR_ASSERT(pollset->shutting_down);
   GPR_ASSERT(pollset->in_flight_cbs == 0);
+  GPR_ASSERT(!grpc_pollset_has_workers(pollset));
   pollset->vtable->destroy(pollset);
-  grpc_pollset_kick_destroy(&pollset->kick_state);
   gpr_mu_destroy(&pollset->mu);
 }
 
@@ -248,8 +297,8 @@ static void basic_do_promote(void *args, int success) {
 
   gpr_mu_lock(&pollset->mu);
   /* First we need to ensure that nobody is polling concurrently */
-  if (pollset->counter != 0) {
-    grpc_pollset_kick(pollset);
+  if (grpc_pollset_has_workers(pollset)) {
+    grpc_pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST);
     grpc_iomgr_add_callback(&up_args->promotion_closure);
     gpr_mu_unlock(&pollset->mu);
     return;
@@ -264,7 +313,8 @@ static void basic_do_promote(void *args, int success) {
   pollset->in_flight_cbs--;
   if (pollset->shutting_down) {
     /* We don't care about this pollset anymore. */
-    if (pollset->in_flight_cbs == 0 && pollset->counter == 0 && !pollset->called_shutdown) {
+    if (pollset->in_flight_cbs == 0 && !pollset->called_shutdown) {
+      GPR_ASSERT(!grpc_pollset_has_workers(pollset));
       pollset->called_shutdown = 1;
       do_shutdown_cb = 1;
     }
@@ -307,7 +357,7 @@ static void basic_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd,
   GPR_ASSERT(fd);
   if (fd == pollset->data.ptr) goto exit;
 
-  if (!pollset->counter) {
+  if (!grpc_pollset_has_workers(pollset)) {
     /* Fast path -- no in flight cbs */
     /* TODO(klempner): Comment this out and fix any test failures or establish
      * they are due to timing issues */
@@ -343,7 +393,7 @@ static void basic_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd,
   up_args->promotion_closure.cb_arg = up_args;
   grpc_iomgr_add_callback(&up_args->promotion_closure);
 
-  grpc_pollset_kick(pollset);
+  grpc_pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST);
 
 exit:
   if (and_unlock_pollset) {
@@ -365,12 +415,12 @@ static void basic_pollset_del_fd(grpc_pollset *pollset, grpc_fd *fd,
 }
 
 static void basic_pollset_maybe_work(grpc_pollset *pollset,
+                                     grpc_pollset_worker *worker,
                                      gpr_timespec deadline, gpr_timespec now,
                                      int allow_synchronous_callback) {
   struct pollfd pfd[2];
   grpc_fd *fd;
   grpc_fd_watcher fd_watcher;
-  grpc_kick_fd_info *kfd;
   int timeout;
   int r;
   int nfds;
@@ -387,16 +437,10 @@ static void basic_pollset_maybe_work(grpc_pollset *pollset,
     fd = pollset->data.ptr = NULL;
   }
   timeout = grpc_poll_deadline_to_millis_timeout(deadline, now);
-  kfd = grpc_pollset_kick_pre_poll(&pollset->kick_state);
-  if (kfd == NULL) {
-    /* Already kicked */
-    return;
-  }
-  pfd[0].fd = GRPC_POLLSET_KICK_GET_FD(kfd);
+  pfd[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd);
   pfd[0].events = POLLIN;
   pfd[0].revents = 0;
   nfds = 1;
-  pollset->counter++;
   if (fd) {
     pfd[1].fd = fd->fd;
     pfd[1].revents = 0;
@@ -428,7 +472,7 @@ static void basic_pollset_maybe_work(grpc_pollset *pollset,
     /* do nothing */
   } else {
     if (pfd[0].revents & POLLIN) {
-      grpc_pollset_kick_consume(&pollset->kick_state, kfd);
+      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd);
     }
     if (nfds > 1) {
       if (pfd[1].revents & (POLLIN | POLLHUP | POLLERR)) {
@@ -440,14 +484,10 @@ static void basic_pollset_maybe_work(grpc_pollset *pollset,
     }
   }
 
-  grpc_pollset_kick_post_poll(&pollset->kick_state, kfd);
-
   gpr_mu_lock(&pollset->mu);
-  pollset->counter--;
 }
 
 static void basic_pollset_destroy(grpc_pollset *pollset) {
-  GPR_ASSERT(pollset->counter == 0);
   if (pollset->data.ptr != NULL) {
     GRPC_FD_UNREF(pollset->data.ptr, "basicpoll");
     pollset->data.ptr = NULL;
@@ -455,14 +495,13 @@ static void basic_pollset_destroy(grpc_pollset *pollset) {
 }
 
 static const grpc_pollset_vtable basic_pollset = {
-    basic_pollset_add_fd,    basic_pollset_del_fd,  basic_pollset_maybe_work,
-    kick_using_pollset_kick, basic_pollset_destroy, basic_pollset_destroy};
+    basic_pollset_add_fd, basic_pollset_del_fd, basic_pollset_maybe_work,
+    basic_pollset_destroy, basic_pollset_destroy};
 
 static void become_basic_pollset(grpc_pollset *pollset, grpc_fd *fd_or_null) {
   pollset->vtable = &basic_pollset;
-  pollset->counter = 0;
   pollset->data.ptr = fd_or_null;
-  if (fd_or_null) {
+  if (fd_or_null != NULL) {
     GRPC_FD_REF(fd_or_null, "basicpoll");
   }
 }
diff --git a/src/core/iomgr/pollset_posix.h b/src/core/iomgr/pollset_posix.h
index 37de1276d1..1c1b736193 100644
--- a/src/core/iomgr/pollset_posix.h
+++ b/src/core/iomgr/pollset_posix.h
@@ -35,8 +35,7 @@
 #define GRPC_INTERNAL_CORE_IOMGR_POLLSET_POSIX_H
 
 #include <grpc/support/sync.h>
-
-#include "src/core/iomgr/pollset_kick_posix.h"
+#include "src/core/iomgr/wakeup_fd_posix.h"
 
 typedef struct grpc_pollset_vtable grpc_pollset_vtable;
 
@@ -45,6 +44,12 @@ typedef struct grpc_pollset_vtable grpc_pollset_vtable;
    use the struct tag */
 struct grpc_fd;
 
+typedef struct grpc_pollset_worker {
+  grpc_wakeup_fd wakeup_fd;
+  struct grpc_pollset_worker *next;
+  struct grpc_pollset_worker *prev;
+} grpc_pollset_worker;
+
 typedef struct grpc_pollset {
   /* pollsets under posix can mutate representation as fds are added and
      removed.
@@ -52,11 +57,11 @@ typedef struct grpc_pollset {
      few fds, and an epoll() based implementation for many fds */
   const grpc_pollset_vtable *vtable;
   gpr_mu mu;
-  grpc_pollset_kick_state kick_state;
-  int counter;
+  grpc_pollset_worker root_worker;
   int in_flight_cbs;
   int shutting_down;
   int called_shutdown;
+  int kicked_without_pollers;
   void (*shutdown_done_cb)(void *arg);
   void *shutdown_done_arg;
   union {
@@ -70,9 +75,9 @@ struct grpc_pollset_vtable {
                  int and_unlock_pollset);
   void (*del_fd)(grpc_pollset *pollset, struct grpc_fd *fd,
                  int and_unlock_pollset);
-  void (*maybe_work)(grpc_pollset *pollset, gpr_timespec deadline,
-                     gpr_timespec now, int allow_synchronous_callback);
-  void (*kick)(grpc_pollset *pollset);
+  void (*maybe_work)(grpc_pollset *pollset, grpc_pollset_worker *worker,
+                     gpr_timespec deadline, gpr_timespec now,
+                     int allow_synchronous_callback);
   void (*finish_shutdown)(grpc_pollset *pollset);
   void (*destroy)(grpc_pollset *pollset);
 };
@@ -85,22 +90,16 @@ void grpc_pollset_add_fd(grpc_pollset *pollset, struct grpc_fd *fd);
    poll after an fd is orphaned) */
 void grpc_pollset_del_fd(grpc_pollset *pollset, struct grpc_fd *fd);
 
-/* Force any current pollers to break polling: it's the callers responsibility
-   to ensure that the pollset indeed needs to be kicked - no verification that
-   the pollset is actually performing polling work is done. At worst this will
-   result in spurious wakeups if performed at the wrong moment.
-   Does not touch pollset->mu. */
-void grpc_pollset_force_kick(grpc_pollset *pollset);
 /* Returns the fd to listen on for kicks */
 int grpc_kick_read_fd(grpc_pollset *p);
 /* Call after polling has been kicked to leave the kicked state */
 void grpc_kick_drain(grpc_pollset *p);
 
 /* Convert a timespec to milliseconds:
-   - very small or negative poll times are clamped to zero to do a 
+   - very small or negative poll times are clamped to zero to do a
      non-blocking poll (which becomes spin polling)
    - other small values are rounded up to one millisecond
-   - longer than a millisecond polls are rounded up to the next nearest 
+   - longer than a millisecond polls are rounded up to the next nearest
      millisecond to avoid spinning
    - infinite timeouts are converted to -1 */
 int grpc_poll_deadline_to_millis_timeout(gpr_timespec deadline, gpr_timespec now);
@@ -114,4 +113,8 @@ extern grpc_platform_become_multipoller_type grpc_platform_become_multipoller;
 void grpc_poll_become_multipoller(grpc_pollset *pollset, struct grpc_fd **fds,
                                   size_t fd_count);
 
+/* Return 1 if the pollset has active threads in grpc_pollset_work (pollset must
+ * be locked) */
+int grpc_pollset_has_workers(grpc_pollset *pollset);
+
 #endif /* GRPC_INTERNAL_CORE_IOMGR_POLLSET_POSIX_H */
diff --git a/src/core/iomgr/pollset_windows.c b/src/core/iomgr/pollset_windows.c
index a9c4739c7c..22dc5891c3 100644
--- a/src/core/iomgr/pollset_windows.c
+++ b/src/core/iomgr/pollset_windows.c
@@ -42,6 +42,38 @@
 #include "src/core/iomgr/pollset.h"
 #include "src/core/iomgr/pollset_windows.h"
 
+static void remove_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
+  worker->prev->next = worker->next;
+  worker->next->prev = worker->prev;
+}
+
+static int has_workers(grpc_pollset *p) {
+  return p->root_worker.next != &p->root_worker;
+}
+
+static grpc_pollset_worker *pop_front_worker(grpc_pollset *p) {
+  if (has_workers(p)) {
+    grpc_pollset_worker *w = p->root_worker.next;
+    remove_worker(p, w);
+    return w;
+  }
+  else {
+    return NULL;
+  }
+}
+
+static void push_back_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
+  worker->next = &p->root_worker;
+  worker->prev = worker->next->prev;
+  worker->prev->next = worker->next->prev = worker;
+}
+
+static void push_front_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
+  worker->prev = &p->root_worker;
+  worker->next = worker->prev->next;
+  worker->prev->next = worker->next->prev = worker;
+}
+
 /* There isn't really any such thing as a pollset under Windows, due to the
    nature of the IO completion ports. We're still going to provide a minimal
    set of features for the sake of the rest of grpc. But grpc_pollset_work
@@ -50,7 +82,8 @@
 void grpc_pollset_init(grpc_pollset *pollset) {
   memset(pollset, 0, sizeof(*pollset));
   gpr_mu_init(&pollset->mu);
-  gpr_cv_init(&pollset->cv);
+  pollset->root_worker.next = pollset->root_worker.prev = &pollset->root_worker;
+  pollset->kicked_without_pollers = 0;
 }
 
 void grpc_pollset_shutdown(grpc_pollset *pollset,
@@ -58,34 +91,66 @@ void grpc_pollset_shutdown(grpc_pollset *pollset,
                            void *shutdown_done_arg) {
   gpr_mu_lock(&pollset->mu);
   pollset->shutting_down = 1;
-  gpr_cv_broadcast(&pollset->cv);
+  grpc_pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST);
   gpr_mu_unlock(&pollset->mu);
   shutdown_done(shutdown_done_arg);
 }
 
 void grpc_pollset_destroy(grpc_pollset *pollset) {
   gpr_mu_destroy(&pollset->mu);
-  gpr_cv_destroy(&pollset->cv);
 }
 
-int grpc_pollset_work(grpc_pollset *pollset, gpr_timespec deadline) {
+int grpc_pollset_work(grpc_pollset *pollset, grpc_pollset_worker *worker, gpr_timespec deadline) {
   gpr_timespec now;
+  int added_worker = 0;
   now = gpr_now(GPR_CLOCK_MONOTONIC);
   if (gpr_time_cmp(now, deadline) > 0) {
     return 0 /* GPR_FALSE */;
   }
+  worker->next = worker->prev = NULL;
+  gpr_cv_init(&worker->cv);
   if (grpc_maybe_call_delayed_callbacks(&pollset->mu, 1 /* GPR_TRUE */)) {
-    return 1 /* GPR_TRUE */;
+    goto done;
   }
   if (grpc_alarm_check(&pollset->mu, now, &deadline)) {
-    return 1 /* GPR_TRUE */;
+    goto done;
   }
-  if (!pollset->shutting_down) {
-    gpr_cv_wait(&pollset->cv, &pollset->mu, deadline);
+  if (!pollset->kicked_without_pollers && !pollset->shutting_down) {
+    push_front_worker(pollset, worker);
+    added_worker = 1;
+    gpr_cv_wait(&worker->cv, &pollset->mu, deadline);
+  } else {
+    pollset->kicked_without_pollers = 0;
+  }
+done:
+  gpr_cv_destroy(&worker->cv);
+  if (added_worker) {
+    remove_worker(pollset, worker);
   }
   return 1 /* GPR_TRUE */;
 }
 
-void grpc_pollset_kick(grpc_pollset *p) { gpr_cv_signal(&p->cv); }
+void grpc_pollset_kick(grpc_pollset *p, grpc_pollset_worker *specific_worker) {
+  if (specific_worker != NULL) {
+    if (specific_worker == GRPC_POLLSET_KICK_BROADCAST) {
+      for (specific_worker = p->root_worker.next;
+        specific_worker != &p->root_worker;
+        specific_worker = specific_worker->next) {
+        gpr_cv_signal(&specific_worker->cv);
+      }
+      p->kicked_without_pollers = 1;
+    } else {
+      gpr_cv_signal(&specific_worker->cv);
+    }
+  } else {
+    specific_worker = pop_front_worker(p);
+    if (specific_worker != NULL) {
+      push_back_worker(p, specific_worker);
+      gpr_cv_signal(&specific_worker->cv);
+    } else {
+      p->kicked_without_pollers = 1;
+    }
+  }
+}
 
 #endif /* GPR_WINSOCK_SOCKET */
diff --git a/src/core/iomgr/pollset_windows.h b/src/core/iomgr/pollset_windows.h
index c9b8d3f374..4efa5a1717 100644
--- a/src/core/iomgr/pollset_windows.h
+++ b/src/core/iomgr/pollset_windows.h
@@ -40,12 +40,20 @@
 
 /* There isn't really any such thing as a pollset under Windows, due to the
    nature of the IO completion ports. A Windows "pollset" is merely a mutex
-   and a condition variable, used to synchronize with the IOCP. */
+   used to synchronize with the IOCP, and workers are condition variables
+   used to block threads until work is ready. */
+
+typedef struct grpc_pollset_worker {
+  gpr_cv cv;
+  struct grpc_pollset_worker *next;
+  struct grpc_pollset_worker *prev;
+} grpc_pollset_worker;
 
 typedef struct grpc_pollset {
   gpr_mu mu;
-  gpr_cv cv;
   int shutting_down;
+  int kicked_without_pollers;
+  grpc_pollset_worker root_worker;
 } grpc_pollset;
 
 #define GRPC_POLLSET_MU(pollset) (&(pollset)->mu)
diff --git a/src/core/iomgr/sockaddr_utils.c b/src/core/iomgr/sockaddr_utils.c
index 71ac12e87b..65ec1f94ac 100644
--- a/src/core/iomgr/sockaddr_utils.c
+++ b/src/core/iomgr/sockaddr_utils.c
@@ -170,6 +170,11 @@ int grpc_sockaddr_to_string(char **out, const struct sockaddr *addr,
 char *grpc_sockaddr_to_uri(const struct sockaddr *addr) {
   char *temp;
   char *result;
+  struct sockaddr_in addr_normalized;
+
+  if (grpc_sockaddr_is_v4mapped(addr, &addr_normalized)) {
+    addr = (const struct sockaddr *)&addr_normalized;
+  }
 
   switch (addr->sa_family) {
     case AF_INET:
diff --git a/src/core/iomgr/tcp_server_windows.c b/src/core/iomgr/tcp_server_windows.c
index bcd2aa8536..0adbe9507c 100644
--- a/src/core/iomgr/tcp_server_windows.c
+++ b/src/core/iomgr/tcp_server_windows.c
@@ -186,6 +186,17 @@ error:
   return -1;
 }
 
+static void decrement_active_ports_and_notify(server_port *sp) {
+  sp->shutting_down = 0;
+  sp->socket->read_info.outstanding = 0;
+  gpr_mu_lock(&sp->server->mu);
+  GPR_ASSERT(sp->server->active_ports > 0);
+  if (0 == --sp->server->active_ports) {
+    gpr_cv_broadcast(&sp->server->cv);
+  }
+  gpr_mu_unlock(&sp->server->mu);
+}
+
 /* start_accept will reference that for the IOCP notification request. */
 static void on_accept(void *arg, int from_iocp);
 
@@ -234,6 +245,15 @@ static void start_accept(server_port *port) {
   return;
 
 failure:
+  if (port->shutting_down) {
+    /* We are abandoning the listener port, take that into account to prevent
+       occasional hangs on shutdown. The hang happens when sp->shutting_down
+       change is not seen by on_accept and we proceed to trying new accept,
+       but we fail there because the listening port has been closed in the
+       meantime. */
+    decrement_active_ports_and_notify(port);
+    return;
+  }
   utf8_message = gpr_format_message(WSAGetLastError());
   gpr_log(GPR_ERROR, message, utf8_message);
   gpr_free(utf8_message);
@@ -277,14 +297,7 @@ static void on_accept(void *arg, int from_iocp) {
     if (sp->shutting_down) {
       /* During the shutdown case, we ARE expecting an error. So that's well,
          and we can wake up the shutdown thread. */
-      sp->shutting_down = 0;
-      sp->socket->read_info.outstanding = 0;
-      gpr_mu_lock(&sp->server->mu);
-      GPR_ASSERT(sp->server->active_ports > 0);
-      if (0 == --sp->server->active_ports) {
-        gpr_cv_broadcast(&sp->server->cv);
-      }
-      gpr_mu_unlock(&sp->server->mu);
+      decrement_active_ports_and_notify(sp);
       return;
     } else {
       char *utf8_message = gpr_format_message(WSAGetLastError());
diff --git a/src/core/iomgr/tcp_windows.c b/src/core/iomgr/tcp_windows.c
index 5e0457a37b..89aa741470 100644
--- a/src/core/iomgr/tcp_windows.c
+++ b/src/core/iomgr/tcp_windows.c
@@ -369,14 +369,16 @@ static grpc_endpoint_write_status win_write(grpc_endpoint *ep,
 }
 
 static void win_add_to_pollset(grpc_endpoint *ep, grpc_pollset *ps) {
+  grpc_tcp *tcp;
   (void) ps;
-  grpc_tcp *tcp = (grpc_tcp *) ep;
+  tcp = (grpc_tcp *) ep;
   grpc_iocp_add_socket(tcp->socket);
 }
 
 static void win_add_to_pollset_set(grpc_endpoint *ep, grpc_pollset_set *pss) {
+  grpc_tcp *tcp;
   (void) pss;
-  grpc_tcp *tcp = (grpc_tcp *) ep;
+  tcp = (grpc_tcp *) ep;
   grpc_iocp_add_socket(tcp->socket);
 }
 
diff --git a/src/core/iomgr/wakeup_fd_eventfd.c b/src/core/iomgr/wakeup_fd_eventfd.c
index 99c32bb9db..52912235f8 100644
--- a/src/core/iomgr/wakeup_fd_eventfd.c
+++ b/src/core/iomgr/wakeup_fd_eventfd.c
@@ -42,7 +42,7 @@
 #include "src/core/iomgr/wakeup_fd_posix.h"
 #include <grpc/support/log.h>
 
-static void eventfd_create(grpc_wakeup_fd_info *fd_info) {
+static void eventfd_create(grpc_wakeup_fd *fd_info) {
   int efd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
   /* TODO(klempner): Handle failure more gracefully */
   GPR_ASSERT(efd >= 0);
@@ -50,7 +50,7 @@ static void eventfd_create(grpc_wakeup_fd_info *fd_info) {
   fd_info->write_fd = -1;
 }
 
-static void eventfd_consume(grpc_wakeup_fd_info *fd_info) {
+static void eventfd_consume(grpc_wakeup_fd *fd_info) {
   eventfd_t value;
   int err;
   do {
@@ -58,14 +58,14 @@ static void eventfd_consume(grpc_wakeup_fd_info *fd_info) {
   } while (err < 0 && errno == EINTR);
 }
 
-static void eventfd_wakeup(grpc_wakeup_fd_info *fd_info) {
+static void eventfd_wakeup(grpc_wakeup_fd *fd_info) {
   int err;
   do {
     err = eventfd_write(fd_info->read_fd, 1);
   } while (err < 0 && errno == EINTR);
 }
 
-static void eventfd_destroy(grpc_wakeup_fd_info *fd_info) {
+static void eventfd_destroy(grpc_wakeup_fd *fd_info) {
   close(fd_info->read_fd);
 }
 
diff --git a/src/core/iomgr/wakeup_fd_pipe.c b/src/core/iomgr/wakeup_fd_pipe.c
index f895478990..9fc4ee2388 100644
--- a/src/core/iomgr/wakeup_fd_pipe.c
+++ b/src/core/iomgr/wakeup_fd_pipe.c
@@ -44,7 +44,7 @@
 #include "src/core/iomgr/socket_utils_posix.h"
 #include <grpc/support/log.h>
 
-static void pipe_create(grpc_wakeup_fd_info *fd_info) {
+static void pipe_init(grpc_wakeup_fd *fd_info) {
   int pipefd[2];
   /* TODO(klempner): Make this nonfatal */
   GPR_ASSERT(0 == pipe(pipefd));
@@ -54,7 +54,7 @@ static void pipe_create(grpc_wakeup_fd_info *fd_info) {
   fd_info->write_fd = pipefd[1];
 }
 
-static void pipe_consume(grpc_wakeup_fd_info *fd_info) {
+static void pipe_consume(grpc_wakeup_fd *fd_info) {
   char buf[128];
   int r;
 
@@ -74,13 +74,13 @@ static void pipe_consume(grpc_wakeup_fd_info *fd_info) {
   }
 }
 
-static void pipe_wakeup(grpc_wakeup_fd_info *fd_info) {
+static void pipe_wakeup(grpc_wakeup_fd *fd_info) {
   char c = 0;
   while (write(fd_info->write_fd, &c, 1) != 1 && errno == EINTR)
     ;
 }
 
-static void pipe_destroy(grpc_wakeup_fd_info *fd_info) {
+static void pipe_destroy(grpc_wakeup_fd *fd_info) {
   close(fd_info->read_fd);
   close(fd_info->write_fd);
 }
@@ -91,7 +91,7 @@ static int pipe_check_availability(void) {
 }
 
 const grpc_wakeup_fd_vtable grpc_pipe_wakeup_fd_vtable = {
-  pipe_create, pipe_consume, pipe_wakeup, pipe_destroy, pipe_check_availability
-};
+    pipe_init, pipe_consume, pipe_wakeup, pipe_destroy,
+    pipe_check_availability};
 
 #endif  /* GPR_POSIX_WAKUP_FD */
diff --git a/src/core/iomgr/wakeup_fd_posix.c b/src/core/iomgr/wakeup_fd_posix.c
index d3cc3ec570..e48f5223fa 100644
--- a/src/core/iomgr/wakeup_fd_posix.c
+++ b/src/core/iomgr/wakeup_fd_posix.c
@@ -57,19 +57,19 @@ void grpc_wakeup_fd_global_destroy(void) {
   wakeup_fd_vtable = NULL;
 }
 
-void grpc_wakeup_fd_create(grpc_wakeup_fd_info *fd_info) {
-  wakeup_fd_vtable->create(fd_info);
+void grpc_wakeup_fd_init(grpc_wakeup_fd *fd_info) {
+  wakeup_fd_vtable->init(fd_info);
 }
 
-void grpc_wakeup_fd_consume_wakeup(grpc_wakeup_fd_info *fd_info) {
+void grpc_wakeup_fd_consume_wakeup(grpc_wakeup_fd *fd_info) {
   wakeup_fd_vtable->consume(fd_info);
 }
 
-void grpc_wakeup_fd_wakeup(grpc_wakeup_fd_info *fd_info) {
+void grpc_wakeup_fd_wakeup(grpc_wakeup_fd *fd_info) {
   wakeup_fd_vtable->wakeup(fd_info);
 }
 
-void grpc_wakeup_fd_destroy(grpc_wakeup_fd_info *fd_info) {
+void grpc_wakeup_fd_destroy(grpc_wakeup_fd *fd_info) {
   wakeup_fd_vtable->destroy(fd_info);
 }
 
diff --git a/src/core/iomgr/wakeup_fd_posix.h b/src/core/iomgr/wakeup_fd_posix.h
index 1b0ff70c7f..a4da4df51f 100644
--- a/src/core/iomgr/wakeup_fd_posix.h
+++ b/src/core/iomgr/wakeup_fd_posix.h
@@ -69,28 +69,28 @@ void grpc_wakeup_fd_global_destroy(void);
  * purposes only.*/
 void grpc_wakeup_fd_global_init_force_fallback(void);
 
-typedef struct grpc_wakeup_fd_info grpc_wakeup_fd_info;
+typedef struct grpc_wakeup_fd grpc_wakeup_fd;
 
 typedef struct grpc_wakeup_fd_vtable {
-  void (*create)(grpc_wakeup_fd_info *fd_info);
-  void (*consume)(grpc_wakeup_fd_info *fd_info);
-  void (*wakeup)(grpc_wakeup_fd_info *fd_info);
-  void (*destroy)(grpc_wakeup_fd_info *fd_info);
+  void (*init)(grpc_wakeup_fd *fd_info);
+  void (*consume)(grpc_wakeup_fd *fd_info);
+  void (*wakeup)(grpc_wakeup_fd *fd_info);
+  void (*destroy)(grpc_wakeup_fd *fd_info);
   /* Must be called before calling any other functions */
   int (*check_availability)(void);
 } grpc_wakeup_fd_vtable;
 
-struct grpc_wakeup_fd_info {
+struct grpc_wakeup_fd {
   int read_fd;
   int write_fd;
 };
 
 #define GRPC_WAKEUP_FD_GET_READ_FD(fd_info) ((fd_info)->read_fd)
 
-void grpc_wakeup_fd_create(grpc_wakeup_fd_info *fd_info);
-void grpc_wakeup_fd_consume_wakeup(grpc_wakeup_fd_info *fd_info);
-void grpc_wakeup_fd_wakeup(grpc_wakeup_fd_info *fd_info);
-void grpc_wakeup_fd_destroy(grpc_wakeup_fd_info *fd_info);
+void grpc_wakeup_fd_init(grpc_wakeup_fd *fd_info);
+void grpc_wakeup_fd_consume_wakeup(grpc_wakeup_fd *fd_info);
+void grpc_wakeup_fd_wakeup(grpc_wakeup_fd *fd_info);
+void grpc_wakeup_fd_destroy(grpc_wakeup_fd *fd_info);
 
 /* Defined in some specialized implementation's .c file, or by
  * wakeup_fd_nospecial.c if no such implementation exists. */
diff --git a/src/core/security/client_auth_filter.c b/src/core/security/client_auth_filter.c
index e86b5430b2..0e699874bc 100644
--- a/src/core/security/client_auth_filter.c
+++ b/src/core/security/client_auth_filter.c
@@ -77,10 +77,9 @@ typedef struct {
 
 static void bubble_up_error(grpc_call_element *elem, const char *error_msg) {
   call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
-  grpc_transport_stream_op_add_cancellation(
-      &calld->op, GRPC_STATUS_UNAUTHENTICATED,
-      grpc_mdstr_from_string(chand->md_ctx, error_msg, 0));
+  gpr_log(GPR_ERROR, "Client side authentication failure: %s", error_msg);
+  grpc_transport_stream_op_add_cancellation(&calld->op,
+                                            GRPC_STATUS_UNAUTHENTICATED);
   grpc_call_next_op(elem, &calld->op);
 }
 
diff --git a/src/core/security/credentials.c b/src/core/security/credentials.c
index 15268cefbe..6421ce673d 100644
--- a/src/core/security/credentials.c
+++ b/src/core/security/credentials.c
@@ -149,6 +149,12 @@ grpc_security_status grpc_server_credentials_create_security_connector(
   return creds->vtable->create_security_connector(creds, sc);
 }
 
+void grpc_server_credentials_set_auth_metadata_processor(
+    grpc_server_credentials *creds, grpc_auth_metadata_processor processor) {
+  if (creds == NULL) return;
+  creds->processor = processor;
+}
+
 /* -- Ssl credentials. -- */
 
 static void ssl_destroy(grpc_credentials *creds) {
@@ -679,7 +685,7 @@ static void service_account_fetch_oauth2(
   request.path = GRPC_GOOGLE_OAUTH2_SERVICE_TOKEN_PATH;
   request.hdr_count = 1;
   request.hdrs = &header;
-  request.use_ssl = 1;
+  request.handshaker = &grpc_httpcli_ssl;
   grpc_httpcli_post(httpcli_context, pollset, &request, body, strlen(body),
                     deadline, response_cb, metadata_req);
   gpr_free(body);
@@ -738,7 +744,7 @@ static void refresh_token_fetch_oauth2(
   request.path = GRPC_GOOGLE_OAUTH2_SERVICE_TOKEN_PATH;
   request.hdr_count = 1;
   request.hdrs = &header;
-  request.use_ssl = 1;
+  request.handshaker = &grpc_httpcli_ssl;
   grpc_httpcli_post(httpcli_context, pollset, &request, body, strlen(body),
                     deadline, response_cb, metadata_req);
   gpr_free(body);
@@ -765,19 +771,19 @@ grpc_credentials *grpc_refresh_token_credentials_create(
       grpc_auth_refresh_token_create_from_string(json_refresh_token));
 }
 
-/* -- Fake Oauth2 credentials. -- */
+/* -- Metadata-only credentials. -- */
 
-static void fake_oauth2_destroy(grpc_credentials *creds) {
-  grpc_fake_oauth2_credentials *c = (grpc_fake_oauth2_credentials *)creds;
-  grpc_credentials_md_store_unref(c->access_token_md);
+static void md_only_test_destroy(grpc_credentials *creds) {
+  grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)creds;
+  grpc_credentials_md_store_unref(c->md_store);
   gpr_free(c);
 }
 
-static int fake_oauth2_has_request_metadata(const grpc_credentials *creds) {
+static int md_only_test_has_request_metadata(const grpc_credentials *creds) {
   return 1;
 }
 
-static int fake_oauth2_has_request_metadata_only(
+static int md_only_test_has_request_metadata_only(
     const grpc_credentials *creds) {
   return 1;
 }
@@ -785,19 +791,19 @@ static int fake_oauth2_has_request_metadata_only(
 void on_simulated_token_fetch_done(void *user_data, int success) {
   grpc_credentials_metadata_request *r =
       (grpc_credentials_metadata_request *)user_data;
-  grpc_fake_oauth2_credentials *c = (grpc_fake_oauth2_credentials *)r->creds;
+  grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)r->creds;
   GPR_ASSERT(success);
-  r->cb(r->user_data, c->access_token_md->entries,
-        c->access_token_md->num_entries, GRPC_CREDENTIALS_OK);
+  r->cb(r->user_data, c->md_store->entries,
+        c->md_store->num_entries, GRPC_CREDENTIALS_OK);
   grpc_credentials_metadata_request_destroy(r);
 }
 
-static void fake_oauth2_get_request_metadata(grpc_credentials *creds,
+static void md_only_test_get_request_metadata(grpc_credentials *creds,
                                              grpc_pollset *pollset,
                                              const char *service_url,
                                              grpc_credentials_metadata_cb cb,
                                              void *user_data) {
-  grpc_fake_oauth2_credentials *c = (grpc_fake_oauth2_credentials *)creds;
+  grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)creds;
 
   if (c->is_async) {
     grpc_credentials_metadata_request *cb_arg =
@@ -806,26 +812,26 @@ static void fake_oauth2_get_request_metadata(grpc_credentials *creds,
                             on_simulated_token_fetch_done, cb_arg);
     grpc_iomgr_add_callback(cb_arg->on_simulated_token_fetch_done_closure);
   } else {
-    cb(user_data, c->access_token_md->entries, 1, GRPC_CREDENTIALS_OK);
+    cb(user_data, c->md_store->entries, 1, GRPC_CREDENTIALS_OK);
   }
 }
 
-static grpc_credentials_vtable fake_oauth2_vtable = {
-    fake_oauth2_destroy, fake_oauth2_has_request_metadata,
-    fake_oauth2_has_request_metadata_only, fake_oauth2_get_request_metadata,
+static grpc_credentials_vtable md_only_test_vtable = {
+    md_only_test_destroy, md_only_test_has_request_metadata,
+    md_only_test_has_request_metadata_only, md_only_test_get_request_metadata,
     NULL};
 
-grpc_credentials *grpc_fake_oauth2_credentials_create(
-    const char *token_md_value, int is_async) {
-  grpc_fake_oauth2_credentials *c =
-      gpr_malloc(sizeof(grpc_fake_oauth2_credentials));
-  memset(c, 0, sizeof(grpc_fake_oauth2_credentials));
+grpc_credentials *grpc_md_only_test_credentials_create(const char *md_key,
+                                                       const char *md_value,
+                                                       int is_async) {
+  grpc_md_only_test_credentials *c =
+      gpr_malloc(sizeof(grpc_md_only_test_credentials));
+  memset(c, 0, sizeof(grpc_md_only_test_credentials));
   c->base.type = GRPC_CREDENTIALS_TYPE_OAUTH2;
-  c->base.vtable = &fake_oauth2_vtable;
+  c->base.vtable = &md_only_test_vtable;
   gpr_ref_init(&c->base.refcount, 1);
-  c->access_token_md = grpc_credentials_md_store_create(1);
-  grpc_credentials_md_store_add_cstrings(
-      c->access_token_md, GRPC_AUTHORIZATION_METADATA_KEY, token_md_value);
+  c->md_store = grpc_credentials_md_store_create(1);
+  grpc_credentials_md_store_add_cstrings(c->md_store, md_key, md_value);
   c->is_async = is_async;
   return &c->base;
 }
diff --git a/src/core/security/credentials.h b/src/core/security/credentials.h
index 8d40da47c1..04736525dc 100644
--- a/src/core/security/credentials.h
+++ b/src/core/security/credentials.h
@@ -190,9 +190,10 @@ grpc_oauth2_token_fetcher_credentials_parse_server_response(
     grpc_credentials_md_store **token_md, gpr_timespec *token_lifetime);
 void grpc_flush_cached_google_default_credentials(void);
 
-/* Simulates an oauth2 token fetch with the specified value for testing. */
-grpc_credentials *grpc_fake_oauth2_credentials_create(
-    const char *token_md_value, int is_async);
+/* Metadata-only credentials with the specified key and value where
+   asynchronicity can be simulated for testing. */
+grpc_credentials *grpc_md_only_test_credentials_create(
+    const char *md_key, const char *md_value, int is_async);
 
 /* Private constructor for jwt credentials from an already parsed json key.
    Takes ownership of the key. */
@@ -216,6 +217,7 @@ typedef struct {
 struct grpc_server_credentials {
   const grpc_server_credentials_vtable *vtable;
   const char *type;
+  grpc_auth_metadata_processor processor;
 };
 
 grpc_security_status grpc_server_credentials_create_security_connector(
@@ -297,13 +299,13 @@ typedef struct {
   grpc_credentials_md_store *access_token_md;
 } grpc_access_token_credentials;
 
-/* -- Fake Oauth2 credentials. -- */
+/* --  Metadata-only Test credentials. -- */
 
 typedef struct {
   grpc_credentials base;
-  grpc_credentials_md_store *access_token_md;
+  grpc_credentials_md_store *md_store;
   int is_async;
-} grpc_fake_oauth2_credentials;
+} grpc_md_only_test_credentials;
 
 /* -- IAM credentials. -- */
 
diff --git a/src/core/security/google_default_credentials.c b/src/core/security/google_default_credentials.c
index de1929fe76..d1f228665f 100644
--- a/src/core/security/google_default_credentials.c
+++ b/src/core/security/google_default_credentials.c
@@ -80,10 +80,12 @@ static void on_compute_engine_detection_http_response(
   }
   gpr_mu_lock(GRPC_POLLSET_MU(&detector->pollset));
   detector->is_done = 1;
-  grpc_pollset_kick(&detector->pollset);
+  grpc_pollset_kick(&detector->pollset, NULL);
   gpr_mu_unlock(GRPC_POLLSET_MU(&detector->pollset));
 }
 
+static void destroy_pollset(void *p) { grpc_pollset_destroy(p); }
+
 static int is_stack_running_on_compute_engine(void) {
   compute_engine_detector detector;
   grpc_httpcli_request request;
@@ -112,12 +114,14 @@ static int is_stack_running_on_compute_engine(void) {
      called once for the lifetime of the process by the default credentials. */
   gpr_mu_lock(GRPC_POLLSET_MU(&detector.pollset));
   while (!detector.is_done) {
-    grpc_pollset_work(&detector.pollset, gpr_inf_future(GPR_CLOCK_REALTIME));
+    grpc_pollset_worker worker;
+    grpc_pollset_work(&detector.pollset, &worker,
+                      gpr_inf_future(GPR_CLOCK_MONOTONIC));
   }
   gpr_mu_unlock(GRPC_POLLSET_MU(&detector.pollset));
 
   grpc_httpcli_context_destroy(&context);
-  grpc_pollset_destroy(&detector.pollset);
+  grpc_pollset_shutdown(&detector.pollset, destroy_pollset, &detector.pollset);
 
   return detector.success;
 }
diff --git a/src/core/security/jwt_verifier.c b/src/core/security/jwt_verifier.c
index 1276693da7..38ad134a6a 100644
--- a/src/core/security/jwt_verifier.c
+++ b/src/core/security/jwt_verifier.c
@@ -628,7 +628,7 @@ static void on_openid_config_retrieved(void *user_data,
     goto error;
   }
   jwks_uri += 8;
-  req.use_ssl = 1;
+  req.handshaker = &grpc_httpcli_ssl;
   req.host = gpr_strdup(jwks_uri);
   req.path = strchr(jwks_uri, '/');
   if (req.path == NULL) {
@@ -685,7 +685,7 @@ static void retrieve_key_and_verify(verifier_cb_ctx *ctx) {
   const char *iss;
   grpc_httpcli_request req;
   memset(&req, 0, sizeof(grpc_httpcli_request));
-  req.use_ssl = 1;
+  req.handshaker = &grpc_httpcli_ssl;
 
   GPR_ASSERT(ctx != NULL && ctx->header != NULL && ctx->claims != NULL);
   iss = ctx->claims->iss;
diff --git a/src/core/security/security_connector.c b/src/core/security/security_connector.c
index 726b4c1e12..a354536dcd 100644
--- a/src/core/security/security_connector.c
+++ b/src/core/security/security_connector.c
@@ -263,9 +263,9 @@ static grpc_security_status fake_check_peer(grpc_security_connector *sc,
     goto end;
   }
   GRPC_AUTH_CONTEXT_UNREF(sc->auth_context, "connector");
-  sc->auth_context = grpc_auth_context_create(NULL, 1);
-  sc->auth_context->properties[0] = grpc_auth_property_init_from_cstring(
-      GRPC_TRANSPORT_SECURITY_TYPE_PROPERTY_NAME,
+  sc->auth_context = grpc_auth_context_create(NULL);
+  grpc_auth_context_add_cstring_property(
+      sc->auth_context, GRPC_TRANSPORT_SECURITY_TYPE_PROPERTY_NAME,
       GRPC_FAKE_TRANSPORT_SECURITY_TYPE);
 
 end:
@@ -409,31 +409,35 @@ static int ssl_host_matches_name(const tsi_peer *peer, const char *peer_name) {
 grpc_auth_context *tsi_ssl_peer_to_auth_context(const tsi_peer *peer) {
   size_t i;
   grpc_auth_context *ctx = NULL;
+  const char *peer_identity_property_name = NULL;
 
   /* The caller has checked the certificate type property. */
   GPR_ASSERT(peer->property_count >= 1);
-  ctx = grpc_auth_context_create(NULL, peer->property_count);
-  ctx->properties[0] = grpc_auth_property_init_from_cstring(
-      GRPC_TRANSPORT_SECURITY_TYPE_PROPERTY_NAME,
+  ctx = grpc_auth_context_create(NULL);
+  grpc_auth_context_add_cstring_property(
+      ctx, GRPC_TRANSPORT_SECURITY_TYPE_PROPERTY_NAME,
       GRPC_SSL_TRANSPORT_SECURITY_TYPE);
-  ctx->property_count = 1;
   for (i = 0; i < peer->property_count; i++) {
     const tsi_peer_property *prop = &peer->properties[i];
     if (prop->name == NULL) continue;
     if (strcmp(prop->name, TSI_X509_SUBJECT_COMMON_NAME_PEER_PROPERTY) == 0) {
       /* If there is no subject alt name, have the CN as the identity. */
-      if (ctx->peer_identity_property_name == NULL) {
-        ctx->peer_identity_property_name = GRPC_X509_CN_PROPERTY_NAME;
+      if (peer_identity_property_name == NULL) {
+        peer_identity_property_name = GRPC_X509_CN_PROPERTY_NAME;
       }
-      ctx->properties[ctx->property_count++] = grpc_auth_property_init(
-          GRPC_X509_CN_PROPERTY_NAME, prop->value.data, prop->value.length);
+      grpc_auth_context_add_property(ctx, GRPC_X509_CN_PROPERTY_NAME,
+                                     prop->value.data, prop->value.length);
     } else if (strcmp(prop->name,
                       TSI_X509_SUBJECT_ALTERNATIVE_NAME_PEER_PROPERTY) == 0) {
-      ctx->peer_identity_property_name = GRPC_X509_SAN_PROPERTY_NAME;
-      ctx->properties[ctx->property_count++] = grpc_auth_property_init(
-          GRPC_X509_SAN_PROPERTY_NAME, prop->value.data, prop->value.length);
+      peer_identity_property_name = GRPC_X509_SAN_PROPERTY_NAME;
+      grpc_auth_context_add_property(ctx, GRPC_X509_SAN_PROPERTY_NAME,
+                                     prop->value.data, prop->value.length);
     }
   }
+  if (peer_identity_property_name != NULL) {
+    GPR_ASSERT(grpc_auth_context_set_peer_identity_property_name(
+                   ctx, peer_identity_property_name) == 1);
+  }
   return ctx;
 }
 
diff --git a/src/core/security/security_context.c b/src/core/security/security_context.c
index 8ce7876bd8..1ef0fc9255 100644
--- a/src/core/security/security_context.c
+++ b/src/core/security/security_context.c
@@ -42,6 +42,19 @@
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
 
+/* --- grpc_process_auth_metadata_func --- */
+
+static grpc_auth_metadata_processor server_processor = {NULL, NULL};
+
+grpc_auth_metadata_processor grpc_server_get_auth_metadata_processor(void) {
+  return server_processor;
+}
+
+void grpc_server_register_auth_metadata_processor(
+    grpc_auth_metadata_processor processor) {
+  server_processor = processor;
+}
+
 /* --- grpc_call --- */
 
 grpc_call_error grpc_call_set_credentials(grpc_call *call,
@@ -120,15 +133,15 @@ void grpc_server_security_context_destroy(void *ctx) {
 
 static grpc_auth_property_iterator empty_iterator = {NULL, 0, NULL};
 
-grpc_auth_context *grpc_auth_context_create(grpc_auth_context *chained,
-                                            size_t property_count) {
+grpc_auth_context *grpc_auth_context_create(grpc_auth_context *chained) {
   grpc_auth_context *ctx = gpr_malloc(sizeof(grpc_auth_context));
   memset(ctx, 0, sizeof(grpc_auth_context));
-  ctx->properties = gpr_malloc(property_count * sizeof(grpc_auth_property));
-  memset(ctx->properties, 0, property_count * sizeof(grpc_auth_property));
-  ctx->property_count = property_count;
   gpr_ref_init(&ctx->refcount, 1);
-  if (chained != NULL) ctx->chained = GRPC_AUTH_CONTEXT_REF(chained, "chained");
+  if (chained != NULL) {
+    ctx->chained = GRPC_AUTH_CONTEXT_REF(chained, "chained");
+    ctx->peer_identity_property_name =
+        ctx->chained->peer_identity_property_name;
+  }
   return ctx;
 }
 
@@ -162,11 +175,11 @@ void grpc_auth_context_unref(grpc_auth_context *ctx) {
   if (gpr_unref(&ctx->refcount)) {
     size_t i;
     GRPC_AUTH_CONTEXT_UNREF(ctx->chained, "chained");
-    if (ctx->properties != NULL) {
-      for (i = 0; i < ctx->property_count; i++) {
-        grpc_auth_property_reset(&ctx->properties[i]);
+    if (ctx->properties.array != NULL) {
+      for (i = 0; i < ctx->properties.count; i++) {
+        grpc_auth_property_reset(&ctx->properties.array[i]);
       }
-      gpr_free(ctx->properties);
+      gpr_free(ctx->properties.array);
     }
     gpr_free(ctx);
   }
@@ -177,6 +190,20 @@ const char *grpc_auth_context_peer_identity_property_name(
   return ctx->peer_identity_property_name;
 }
 
+int grpc_auth_context_set_peer_identity_property_name(grpc_auth_context *ctx,
+                                                      const char *name) {
+  grpc_auth_property_iterator it =
+      grpc_auth_context_find_properties_by_name(ctx, name);
+  const grpc_auth_property *prop = grpc_auth_property_iterator_next(&it);
+  if (prop == NULL) {
+    gpr_log(GPR_ERROR, "Property name %s not found in auth context.",
+            name != NULL ? name : "NULL");
+    return 0;
+  }
+  ctx->peer_identity_property_name = prop->name;
+  return 1;
+}
+
 int grpc_auth_context_peer_is_authenticated(
     const grpc_auth_context *ctx) {
   return ctx->peer_identity_property_name == NULL ? 0 : 1;
@@ -193,16 +220,16 @@ grpc_auth_property_iterator grpc_auth_context_property_iterator(
 const grpc_auth_property *grpc_auth_property_iterator_next(
     grpc_auth_property_iterator *it) {
   if (it == NULL || it->ctx == NULL) return NULL;
-  while (it->index == it->ctx->property_count) {
+  while (it->index == it->ctx->properties.count) {
     if (it->ctx->chained == NULL) return NULL;
     it->ctx = it->ctx->chained;
     it->index = 0;
   }
   if (it->name == NULL) {
-    return &it->ctx->properties[it->index++];
+    return &it->ctx->properties.array[it->index++];
   } else {
-    while (it->index < it->ctx->property_count) {
-      const grpc_auth_property *prop = &it->ctx->properties[it->index++];
+    while (it->index < it->ctx->properties.count) {
+      const grpc_auth_property *prop = &it->ctx->properties.array[it->index++];
       GPR_ASSERT(prop->name != NULL);
       if (strcmp(it->name, prop->name) == 0) {
         return prop;
@@ -229,24 +256,37 @@ grpc_auth_property_iterator grpc_auth_context_peer_identity(
       ctx, ctx->peer_identity_property_name);
 }
 
-grpc_auth_property grpc_auth_property_init_from_cstring(const char *name,
-                                                        const char *value) {
-  grpc_auth_property prop;
-  prop.name = gpr_strdup(name);
-  prop.value = gpr_strdup(value);
-  prop.value_length = strlen(value);
-  return prop;
+static void ensure_auth_context_capacity(grpc_auth_context *ctx) {
+  if (ctx->properties.count == ctx->properties.capacity) {
+    ctx->properties.capacity =
+        GPR_MAX(ctx->properties.capacity + 8, ctx->properties.capacity * 2);
+    ctx->properties.array =
+        gpr_realloc(ctx->properties.array,
+                    ctx->properties.capacity * sizeof(grpc_auth_property));
+  }
 }
 
-grpc_auth_property grpc_auth_property_init(const char *name, const char *value,
-                                           size_t value_length) {
-  grpc_auth_property prop;
-  prop.name = gpr_strdup(name);
-  prop.value = gpr_malloc(value_length + 1);
-  memcpy(prop.value, value, value_length);
-  prop.value[value_length] = '\0';
-  prop.value_length = value_length;
-  return prop;
+void grpc_auth_context_add_property(grpc_auth_context *ctx, const char *name,
+                                    const char *value, size_t value_length) {
+  grpc_auth_property *prop;
+  ensure_auth_context_capacity(ctx);
+  prop = &ctx->properties.array[ctx->properties.count++];
+  prop->name = gpr_strdup(name);
+  prop->value = gpr_malloc(value_length + 1);
+  memcpy(prop->value, value, value_length);
+  prop->value[value_length] = '\0';
+  prop->value_length = value_length;
+}
+
+void grpc_auth_context_add_cstring_property(grpc_auth_context *ctx,
+                                            const char *name,
+                                            const char *value) {
+  grpc_auth_property *prop;
+  ensure_auth_context_capacity(ctx);
+  prop = &ctx->properties.array[ctx->properties.count++];
+  prop->name = gpr_strdup(name);
+  prop->value = gpr_strdup(value);
+  prop->value_length = strlen(value);
 }
 
 void grpc_auth_property_reset(grpc_auth_property *property) {
@@ -255,3 +295,35 @@ void grpc_auth_property_reset(grpc_auth_property *property) {
   memset(property, 0, sizeof(grpc_auth_property));
 }
 
+grpc_arg grpc_auth_metadata_processor_to_arg(grpc_auth_metadata_processor *p) {
+  grpc_arg arg;
+  memset(&arg, 0, sizeof(grpc_arg));
+  arg.type = GRPC_ARG_POINTER;
+  arg.key = GRPC_AUTH_METADATA_PROCESSOR_ARG;
+  arg.value.pointer.p = p;
+  return arg;
+}
+
+grpc_auth_metadata_processor *grpc_auth_metadata_processor_from_arg(
+    const grpc_arg *arg) {
+  if (strcmp(arg->key, GRPC_AUTH_METADATA_PROCESSOR_ARG) != 0) return NULL;
+  if (arg->type != GRPC_ARG_POINTER) {
+    gpr_log(GPR_ERROR, "Invalid type %d for arg %s", arg->type,
+            GRPC_AUTH_METADATA_PROCESSOR_ARG);
+    return NULL;
+  }
+  return arg->value.pointer.p;
+}
+
+grpc_auth_metadata_processor *grpc_find_auth_metadata_processor_in_args(
+    const grpc_channel_args *args) {
+  size_t i;
+  if (args == NULL) return NULL;
+  for (i = 0; i < args->num_args; i++) {
+    grpc_auth_metadata_processor *p =
+        grpc_auth_metadata_processor_from_arg(&args->args[i]);
+    if (p != NULL) return p;
+  }
+  return NULL;
+}
+
diff --git a/src/core/security/security_context.h b/src/core/security/security_context.h
index 76a45910bb..7fcd438cf6 100644
--- a/src/core/security/security_context.h
+++ b/src/core/security/security_context.h
@@ -34,29 +34,31 @@
 #ifndef GRPC_INTERNAL_CORE_SECURITY_SECURITY_CONTEXT_H
 #define GRPC_INTERNAL_CORE_SECURITY_SECURITY_CONTEXT_H
 
+#include "src/core/iomgr/pollset.h"
 #include "src/core/security/credentials.h"
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 /* --- grpc_auth_context ---
 
    High level authentication context object. Can optionally be chained. */
 
 /* Property names are always NULL terminated. */
 
+typedef struct {
+  grpc_auth_property *array;
+  size_t count;
+  size_t capacity;
+} grpc_auth_property_array;
+
 struct grpc_auth_context {
   struct grpc_auth_context *chained;
-  grpc_auth_property *properties;
-  size_t property_count;
+  grpc_auth_property_array properties;
   gpr_refcount refcount;
   const char *peer_identity_property_name;
+  grpc_pollset *pollset;
 };
 
-/* Constructor. */
-grpc_auth_context *grpc_auth_context_create(grpc_auth_context *chained,
-                                            size_t property_count);
+/* Creation. */
+grpc_auth_context *grpc_auth_context_create(grpc_auth_context *chained);
 
 /* Refcounting. */
 #ifdef GRPC_AUTH_CONTEXT_REFCOUNT_DEBUG
@@ -76,12 +78,6 @@ grpc_auth_context *grpc_auth_context_ref(grpc_auth_context *policy);
 void grpc_auth_context_unref(grpc_auth_context *policy);
 #endif
 
-grpc_auth_property grpc_auth_property_init_from_cstring(const char *name,
-                                                        const char *value);
-
-grpc_auth_property grpc_auth_property_init(const char *name, const char *value,
-                                           size_t value_length);
-
 void grpc_auth_property_reset(grpc_auth_property *property);
 
 /* --- grpc_client_security_context ---
@@ -107,9 +103,14 @@ typedef struct {
 grpc_server_security_context *grpc_server_security_context_create(void);
 void grpc_server_security_context_destroy(void *ctx);
 
-#ifdef __cplusplus
-}
-#endif
+/* --- Auth metadata processing. --- */
+#define GRPC_AUTH_METADATA_PROCESSOR_ARG "grpc.auth_metadata_processor"
+
+grpc_arg grpc_auth_metadata_processor_to_arg(grpc_auth_metadata_processor *p);
+grpc_auth_metadata_processor *grpc_auth_metadata_processor_from_arg(
+    const grpc_arg *arg);
+grpc_auth_metadata_processor *grpc_find_auth_metadata_processor_in_args(
+    const grpc_channel_args *args);
 
 #endif  /* GRPC_INTERNAL_CORE_SECURITY_SECURITY_CONTEXT_H */
 
diff --git a/src/core/security/server_auth_filter.c b/src/core/security/server_auth_filter.c
index 69789c2f0d..2fc689caec 100644
--- a/src/core/security/server_auth_filter.c
+++ b/src/core/security/server_auth_filter.c
@@ -31,20 +31,140 @@
  *
  */
 
+#include <string.h>
+
 #include "src/core/security/auth_filters.h"
 #include "src/core/security/security_connector.h"
 #include "src/core/security/security_context.h"
 
+#include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 
 typedef struct call_data {
-  int unused; /* C89 requires at least one struct element */
+  gpr_uint8 got_client_metadata;
+  grpc_stream_op_buffer *recv_ops;
+  /* Closure to call when finished with the auth_on_recv hook. */
+  grpc_iomgr_closure *on_done_recv;
+  /* Receive closures are chained: we inject this closure as the on_done_recv
+     up-call on transport_op, and remember to call our on_done_recv member after
+     handling it. */
+  grpc_iomgr_closure auth_on_recv;
+  grpc_transport_stream_op transport_op;
+  const grpc_metadata *consumed_md;
+  size_t num_consumed_md;
+  grpc_stream_op *md_op;
+  grpc_auth_context *auth_context;
 } call_data;
 
 typedef struct channel_data {
   grpc_security_connector *security_connector;
+  grpc_auth_metadata_processor processor;
+  grpc_mdctx *mdctx;
 } channel_data;
 
+static grpc_metadata_array metadata_batch_to_md_array(
+    const grpc_metadata_batch *batch) {
+  grpc_linked_mdelem *l;
+  grpc_metadata_array result;
+  grpc_metadata_array_init(&result);
+  for (l = batch->list.head; l != NULL; l = l->next) {
+    grpc_metadata *usr_md = NULL;
+    grpc_mdelem *md = l->md;
+    grpc_mdstr *key = md->key;
+    grpc_mdstr *value = md->value;
+    if (result.count == result.capacity) {
+      result.capacity = GPR_MAX(result.capacity + 8, result.capacity * 2);
+      result.metadata =
+          gpr_realloc(result.metadata, result.capacity * sizeof(grpc_metadata));
+    }
+    usr_md = &result.metadata[result.count++];
+    usr_md->key = grpc_mdstr_as_c_string(key);
+    usr_md->value = grpc_mdstr_as_c_string(value);
+    usr_md->value_length = GPR_SLICE_LENGTH(value->slice);
+  }
+  return result;
+}
+
+static grpc_mdelem *remove_consumed_md(void *user_data, grpc_mdelem *md) {
+  grpc_call_element *elem = user_data;
+  call_data *calld = elem->call_data;
+  size_t i;
+  for (i = 0; i < calld->num_consumed_md; i++) {
+    /* Maybe we could do a pointer comparison but we do not have any guarantee
+       that the metadata processor used the same pointers for consumed_md in the
+       callback. */
+    if (memcmp(GPR_SLICE_START_PTR(md->key->slice), calld->consumed_md[i].key,
+               GPR_SLICE_LENGTH(md->key->slice)) == 0 &&
+        memcmp(GPR_SLICE_START_PTR(md->value->slice),
+               calld->consumed_md[i].value,
+               GPR_SLICE_LENGTH(md->value->slice)) == 0) {
+      return NULL; /* Delete. */
+    }
+  }
+  return md;
+}
+
+static void on_md_processing_done(void *user_data,
+                                  const grpc_metadata *consumed_md,
+                                  size_t num_consumed_md, int success) {
+  grpc_call_element *elem = user_data;
+  call_data *calld = elem->call_data;
+
+  if (success) {
+    calld->consumed_md = consumed_md;
+    calld->num_consumed_md = num_consumed_md;
+    grpc_metadata_batch_filter(&calld->md_op->data.metadata, remove_consumed_md,
+                               elem);
+    calld->on_done_recv->cb(calld->on_done_recv->cb_arg, success);
+  } else {
+    gpr_slice message = gpr_slice_from_copied_string(
+        "Authentication metadata processing failed.");
+    grpc_sopb_reset(calld->recv_ops);
+    grpc_transport_stream_op_add_close(&calld->transport_op,
+                                       GRPC_STATUS_UNAUTHENTICATED, &message);
+    grpc_call_next_op(elem, &calld->transport_op);
+  }
+}
+
+static void auth_on_recv(void *user_data, int success) {
+  grpc_call_element *elem = user_data;
+  call_data *calld = elem->call_data;
+  channel_data *chand = elem->channel_data;
+  if (success) {
+    size_t i;
+    size_t nops = calld->recv_ops->nops;
+    grpc_stream_op *ops = calld->recv_ops->ops;
+    for (i = 0; i < nops; i++) {
+      grpc_metadata_array md_array;
+      grpc_stream_op *op = &ops[i];
+      if (op->type != GRPC_OP_METADATA || calld->got_client_metadata) continue;
+      calld->got_client_metadata = 1;
+      if (chand->processor.process == NULL) continue;
+      calld->md_op = op;
+      md_array = metadata_batch_to_md_array(&op->data.metadata);
+      chand->processor.process(chand->processor.state, calld->auth_context,
+                               md_array.metadata, md_array.count,
+                               on_md_processing_done, elem);
+      grpc_metadata_array_destroy(&md_array);
+      return;
+    }
+  }
+  calld->on_done_recv->cb(calld->on_done_recv->cb_arg, success);
+}
+
+static void set_recv_ops_md_callbacks(grpc_call_element *elem,
+                                      grpc_transport_stream_op *op) {
+  call_data *calld = elem->call_data;
+
+  if (op->recv_ops && !calld->got_client_metadata) {
+    /* substitute our callback for the higher callback */
+    calld->recv_ops = op->recv_ops;
+    calld->on_done_recv = op->on_done_recv;
+    op->on_done_recv = &calld->auth_on_recv;
+    calld->transport_op = *op;
+  }
+}
+
 /* Called either:
      - in response to an API call (or similar) from above, to send something
      - a network event (or similar) from below, to receive something
@@ -52,9 +172,7 @@ typedef struct channel_data {
    that is being sent or received. */
 static void auth_start_transport_op(grpc_call_element *elem,
                                     grpc_transport_stream_op *op) {
-  /* TODO(jboeuf): Get the metadata and get a new context from it. */
-
-  /* pass control down the stack */
+  set_recv_ops_md_callbacks(elem, op);
   grpc_call_next_op(elem, op);
 }
 
@@ -68,7 +186,8 @@ static void init_call_elem(grpc_call_element *elem,
   grpc_server_security_context *server_ctx = NULL;
 
   /* initialize members */
-  calld->unused = 0;
+  memset(calld, 0, sizeof(*calld));
+  grpc_iomgr_closure_init(&calld->auth_on_recv, auth_on_recv, elem);
 
   GPR_ASSERT(initial_op && initial_op->context != NULL &&
              initial_op->context[GRPC_CONTEXT_SECURITY].value == NULL);
@@ -80,21 +199,29 @@ static void init_call_elem(grpc_call_element *elem,
         initial_op->context[GRPC_CONTEXT_SECURITY].value);
   }
   server_ctx = grpc_server_security_context_create();
-  server_ctx->auth_context = GRPC_AUTH_CONTEXT_REF(
-      chand->security_connector->auth_context, "server_security_context");
+  server_ctx->auth_context =
+      grpc_auth_context_create(chand->security_connector->auth_context);
+  server_ctx->auth_context->pollset = initial_op->bind_pollset;
   initial_op->context[GRPC_CONTEXT_SECURITY].value = server_ctx;
   initial_op->context[GRPC_CONTEXT_SECURITY].destroy =
       grpc_server_security_context_destroy;
+  calld->auth_context = server_ctx->auth_context;
+
+  /* Set the metadata callbacks. */
+  set_recv_ops_md_callbacks(elem, initial_op);
 }
 
 /* Destructor for call_data */
-static void destroy_call_elem(grpc_call_element *elem) {}
+static void destroy_call_elem(grpc_call_element *elem) {
+}
 
 /* Constructor for channel_data */
 static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
                               const grpc_channel_args *args, grpc_mdctx *mdctx,
                               int is_first, int is_last) {
   grpc_security_connector *sc = grpc_find_security_connector_in_args(args);
+  grpc_auth_metadata_processor *processor =
+      grpc_find_auth_metadata_processor_in_args(args);
   /* grab pointers to our data from the channel element */
   channel_data *chand = elem->channel_data;
 
@@ -104,11 +231,14 @@ static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
   GPR_ASSERT(!is_first);
   GPR_ASSERT(!is_last);
   GPR_ASSERT(sc != NULL);
+  GPR_ASSERT(processor != NULL);
 
   /* initialize members */
   GPR_ASSERT(!sc->is_client_side);
   chand->security_connector =
       GRPC_SECURITY_CONNECTOR_REF(sc, "server_auth_filter");
+  chand->mdctx = mdctx;
+  chand->processor = *processor;
 }
 
 /* Destructor for channel data */
diff --git a/src/core/security/server_secure_chttp2.c b/src/core/security/server_secure_chttp2.c
index 3717b8989f..8d9d036d80 100644
--- a/src/core/security/server_secure_chttp2.c
+++ b/src/core/security/server_secure_chttp2.c
@@ -43,6 +43,7 @@
 #include "src/core/security/auth_filters.h"
 #include "src/core/security/credentials.h"
 #include "src/core/security/security_connector.h"
+#include "src/core/security/security_context.h"
 #include "src/core/security/secure_transport_setup.h"
 #include "src/core/surface/server.h"
 #include "src/core/transport/chttp2_transport.h"
@@ -60,6 +61,7 @@ typedef struct grpc_server_secure_state {
   grpc_server *server;
   grpc_tcp_server *tcp;
   grpc_security_connector *sc;
+  grpc_auth_metadata_processor processor;
   tcp_endpoint_list *handshaking_tcp_endpoints;
   int is_shutdown;
   gpr_mu mu;
@@ -86,9 +88,13 @@ static void setup_transport(void *statep, grpc_transport *transport,
   static grpc_channel_filter const *extra_filters[] = {
       &grpc_server_auth_filter, &grpc_http_server_filter};
   grpc_server_secure_state *state = statep;
-  grpc_arg connector_arg = grpc_security_connector_to_arg(state->sc);
-  grpc_channel_args *args_copy = grpc_channel_args_copy_and_add(
-      grpc_server_get_channel_args(state->server), &connector_arg, 1);
+  grpc_channel_args *args_copy;
+  grpc_arg args_to_add[2];
+  args_to_add[0] = grpc_security_connector_to_arg(state->sc);
+  args_to_add[1] = grpc_auth_metadata_processor_to_arg(&state->processor);
+  args_copy = grpc_channel_args_copy_and_add(
+      grpc_server_get_channel_args(state->server), args_to_add,
+      GPR_ARRAY_SIZE(args_to_add));
   grpc_server_setup_transport(state->server, transport, extra_filters,
                               GPR_ARRAY_SIZE(extra_filters), mdctx, args_copy);
   grpc_channel_args_destroy(args_copy);
@@ -252,9 +258,11 @@ int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
   grpc_resolved_addresses_destroy(resolved);
 
   state = gpr_malloc(sizeof(*state));
+  memset(state, 0, sizeof(*state));
   state->server = server;
   state->tcp = tcp;
   state->sc = sc;
+  state->processor = creds->processor;
   state->handshaking_tcp_endpoints = NULL;
   state->is_shutdown = 0;
   gpr_mu_init(&state->mu);
diff --git a/src/core/surface/call.c b/src/core/surface/call.c
index 327a096ffb..5839d3ac2e 100644
--- a/src/core/surface/call.c
+++ b/src/core/surface/call.c
@@ -143,6 +143,8 @@ typedef enum {
 struct grpc_call {
   grpc_completion_queue *cq;
   grpc_channel *channel;
+  grpc_call *parent;
+  grpc_call *first_child;
   grpc_mdctx *metadata_context;
   /* TODO(ctiller): share with cq if possible? */
   gpr_mu mu;
@@ -176,6 +178,8 @@ struct grpc_call {
   gpr_uint8 cancel_alarm;
   /** bitmask of allocated completion events in completions */
   gpr_uint8 allocated_completions;
+  /** flag indicating that cancellation is inherited */
+  gpr_uint8 cancellation_is_inherited;
 
   /* flags with bits corresponding to write states allowing us to determine
      what was sent */
@@ -267,6 +271,11 @@ struct grpc_call {
 
   /** completion events - for completion queue use */
   grpc_cq_completion completions[MAX_CONCURRENT_COMPLETIONS];
+
+  /** siblings: children of the same parent form a list, and this list is protected under
+      parent->mu */
+  grpc_call *sibling_next;
+  grpc_call *sibling_prev;
 };
 
 #define CALL_STACK_FROM_CALL(call) ((grpc_call_stack *)((call) + 1))
@@ -290,7 +299,9 @@ static void finished_loose_op(void *call, int success);
 static void lock(grpc_call *call);
 static void unlock(grpc_call *call);
 
-grpc_call *grpc_call_create(grpc_channel *channel, grpc_completion_queue *cq,
+grpc_call *grpc_call_create(grpc_channel *channel, grpc_call *parent_call,
+                            gpr_uint32 propagation_mask,
+                            grpc_completion_queue *cq,
                             const void *server_transport_data,
                             grpc_mdelem **add_initial_metadata,
                             size_t add_initial_metadata_count,
@@ -306,9 +317,10 @@ grpc_call *grpc_call_create(grpc_channel *channel, grpc_completion_queue *cq,
   gpr_mu_init(&call->completion_mu);
   call->channel = channel;
   call->cq = cq;
-  if (cq) {
+  if (cq != NULL) {
     GRPC_CQ_INTERNAL_REF(cq, "bind");
   }
+  call->parent = parent_call;
   call->is_client = server_transport_data == NULL;
   for (i = 0; i < GRPC_IOREQ_OP_COUNT; i++) {
     call->request_set[i] = REQSET_EMPTY;
@@ -347,6 +359,46 @@ grpc_call *grpc_call_create(grpc_channel *channel, grpc_completion_queue *cq,
   }
   grpc_call_stack_init(channel_stack, server_transport_data, initial_op_ptr,
                        CALL_STACK_FROM_CALL(call));
+  if (parent_call != NULL) {
+    GRPC_CALL_INTERNAL_REF(parent_call, "child");
+    GPR_ASSERT(call->is_client);
+    GPR_ASSERT(!parent_call->is_client);
+
+    gpr_mu_lock(&parent_call->mu);
+
+    if (propagation_mask & GRPC_PROPAGATE_DEADLINE) {
+      send_deadline = gpr_time_min(
+          gpr_convert_clock_type(send_deadline,
+                                 parent_call->send_deadline.clock_type),
+          parent_call->send_deadline);
+    }
+    /* for now GRPC_PROPAGATE_TRACING_CONTEXT *MUST* be passed with
+     * GRPC_PROPAGATE_STATS_CONTEXT */
+    /* TODO(ctiller): This should change to use the appropriate census start_op
+     * call. */
+    if (propagation_mask & GRPC_PROPAGATE_CENSUS_TRACING_CONTEXT) {
+      GPR_ASSERT(propagation_mask & GRPC_PROPAGATE_CENSUS_STATS_CONTEXT);
+      grpc_call_context_set(call, GRPC_CONTEXT_TRACING,
+                            parent_call->context[GRPC_CONTEXT_TRACING].value,
+                            NULL);
+    } else {
+      GPR_ASSERT(propagation_mask & GRPC_PROPAGATE_CENSUS_STATS_CONTEXT);
+    }
+    if (propagation_mask & GRPC_PROPAGATE_CANCELLATION) {
+      call->cancellation_is_inherited = 1;
+    }
+
+    if (parent_call->first_child == NULL) {
+      parent_call->first_child = call;
+      call->sibling_next = call->sibling_prev = call;
+    } else {
+      call->sibling_next = parent_call->first_child;
+      call->sibling_prev = parent_call->first_child->sibling_prev;
+      call->sibling_next->sibling_prev = call->sibling_prev->sibling_next = call;
+    }
+
+    gpr_mu_unlock(&parent_call->mu);
+  }
   if (gpr_time_cmp(send_deadline, gpr_inf_future(send_deadline.clock_type)) !=
       0) {
     set_deadline_alarm(call, send_deadline);
@@ -870,6 +922,8 @@ static int add_slice_to_message(grpc_call *call, gpr_slice slice) {
 
 static void call_on_done_recv(void *pc, int success) {
   grpc_call *call = pc;
+  grpc_call *child_call;
+  grpc_call *next_child_call;
   size_t i;
   GRPC_TIMER_BEGIN(GRPC_PTAG_CALL_ON_DONE_RECV, 0);
   lock(call);
@@ -903,6 +957,19 @@ static void call_on_done_recv(void *pc, int success) {
       GPR_ASSERT(call->read_state <= READ_STATE_STREAM_CLOSED);
       call->read_state = READ_STATE_STREAM_CLOSED;
       call->cancel_alarm |= call->have_alarm;
+      /* propagate cancellation to any interested children */
+      child_call = call->first_child;
+      if (child_call != NULL) {
+        do {
+          next_child_call = child_call->sibling_next;
+          if (child_call->cancellation_is_inherited) {
+            GRPC_CALL_INTERNAL_REF(child_call, "propagate_cancel");
+            grpc_call_cancel(child_call);
+            GRPC_CALL_INTERNAL_UNREF(child_call, "propagate_cancel", 0);
+          }
+          child_call = next_child_call;
+        } while (child_call != call->first_child);
+      }
       GRPC_CALL_INTERNAL_UNREF(call, "closed", 0);
     }
     finish_read_ops(call);
@@ -1176,6 +1243,22 @@ grpc_call_error grpc_call_start_ioreq_and_call_back(
 
 void grpc_call_destroy(grpc_call *c) {
   int cancel;
+  grpc_call *parent = c->parent;
+
+  if (parent) {
+    gpr_mu_lock(&parent->mu);
+    if (c == parent->first_child) {
+      parent->first_child = c->sibling_next;
+      if (c == parent->first_child) {
+        parent->first_child = NULL;
+      }
+      c->sibling_prev->sibling_next = c->sibling_next;
+      c->sibling_next->sibling_prev = c->sibling_prev;
+    }
+    gpr_mu_unlock(&parent->mu);
+    GRPC_CALL_INTERNAL_UNREF(parent, "child", 1);
+  }
+
   lock(c);
   GPR_ASSERT(!c->destroy_called);
   c->destroy_called = 1;
@@ -1283,9 +1366,9 @@ static void set_deadline_alarm(grpc_call *call, gpr_timespec deadline) {
   }
   GRPC_CALL_INTERNAL_REF(call, "alarm");
   call->have_alarm = 1;
-  grpc_alarm_init(&call->alarm,
-                  gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC),
-                  call_alarm, call, gpr_now(GPR_CLOCK_MONOTONIC));
+  call->send_deadline = gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC);
+  grpc_alarm_init(&call->alarm, call->send_deadline, call_alarm, call,
+                  gpr_now(GPR_CLOCK_MONOTONIC));
 }
 
 /* we offset status by a small amount when storing it into transport metadata
@@ -1377,7 +1460,8 @@ static void recv_metadata(grpc_call *call, grpc_metadata_batch *md) {
     }
   }
   if (gpr_time_cmp(md->deadline, gpr_inf_future(md->deadline.clock_type)) !=
-      0) {
+          0 &&
+      !call->is_client) {
     set_deadline_alarm(call, md->deadline);
   }
   if (!is_trailing) {
@@ -1455,6 +1539,7 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
         /* Flag validation: currently allow no flags */
         if (op->flags != 0) return GRPC_CALL_ERROR_INVALID_FLAGS;
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_SEND_INITIAL_METADATA;
         req->data.send_metadata.count = op->data.send_initial_metadata.count;
         req->data.send_metadata.metadata =
@@ -1465,7 +1550,11 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
         if (!are_write_flags_valid(op->flags)) {
           return GRPC_CALL_ERROR_INVALID_FLAGS;
         }
+        if (op->data.send_message == NULL) {
+          return GRPC_CALL_ERROR_INVALID_MESSAGE;
+        }
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_SEND_MESSAGE;
         req->data.send_message = op->data.send_message;
         req->flags = op->flags;
@@ -1477,6 +1566,7 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
           return GRPC_CALL_ERROR_NOT_ON_SERVER;
         }
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_SEND_CLOSE;
         req->flags = op->flags;
         break;
@@ -1487,6 +1577,7 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
           return GRPC_CALL_ERROR_NOT_ON_CLIENT;
         }
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_SEND_TRAILING_METADATA;
         req->flags = op->flags;
         req->data.send_metadata.count =
@@ -1494,6 +1585,7 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
         req->data.send_metadata.metadata =
             op->data.send_status_from_server.trailing_metadata;
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_SEND_STATUS;
         req->data.send_status.code = op->data.send_status_from_server.status;
         req->data.send_status.details =
@@ -1503,6 +1595,7 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
                       op->data.send_status_from_server.status_details, 0)
                 : NULL;
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_SEND_CLOSE;
         break;
       case GRPC_OP_RECV_INITIAL_METADATA:
@@ -1512,14 +1605,17 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
           return GRPC_CALL_ERROR_NOT_ON_SERVER;
         }
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_RECV_INITIAL_METADATA;
         req->data.recv_metadata = op->data.recv_initial_metadata;
+        req->data.recv_metadata->count = 0;
         req->flags = op->flags;
         break;
       case GRPC_OP_RECV_MESSAGE:
         /* Flag validation: currently allow no flags */
         if (op->flags != 0) return GRPC_CALL_ERROR_INVALID_FLAGS;
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_RECV_MESSAGE;
         req->data.recv_message = op->data.recv_message;
         req->flags = op->flags;
@@ -1531,21 +1627,26 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
           return GRPC_CALL_ERROR_NOT_ON_SERVER;
         }
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_RECV_STATUS;
         req->flags = op->flags;
         req->data.recv_status.set_value = set_status_value_directly;
         req->data.recv_status.user_data = op->data.recv_status_on_client.status;
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_RECV_STATUS_DETAILS;
         req->data.recv_status_details.details =
             op->data.recv_status_on_client.status_details;
         req->data.recv_status_details.details_capacity =
             op->data.recv_status_on_client.status_details_capacity;
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_RECV_TRAILING_METADATA;
         req->data.recv_metadata =
             op->data.recv_status_on_client.trailing_metadata;
+        req->data.recv_metadata->count = 0;
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_RECV_CLOSE;
         finish_func = finish_batch_with_close;
         break;
@@ -1553,12 +1654,14 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
         /* Flag validation: currently allow no flags */
         if (op->flags != 0) return GRPC_CALL_ERROR_INVALID_FLAGS;
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_RECV_STATUS;
         req->flags = op->flags;
         req->data.recv_status.set_value = set_cancelled_value;
         req->data.recv_status.user_data =
             op->data.recv_close_on_server.cancelled;
         req = &reqs[out++];
+	if (out > GRPC_IOREQ_OP_COUNT) return GRPC_CALL_ERROR_BATCH_TOO_BIG;
         req->op = GRPC_IOREQ_RECV_CLOSE;
         finish_func = finish_batch_with_close;
         break;
diff --git a/src/core/surface/call.h b/src/core/surface/call.h
index 265638d519..75bdbce980 100644
--- a/src/core/surface/call.h
+++ b/src/core/surface/call.h
@@ -85,7 +85,9 @@ typedef struct {
 typedef void (*grpc_ioreq_completion_func)(grpc_call *call, int success,
                                            void *user_data);
 
-grpc_call *grpc_call_create(grpc_channel *channel, grpc_completion_queue *cq,
+grpc_call *grpc_call_create(grpc_channel *channel, grpc_call *parent_call,
+                            gpr_uint32 propagation_mask,
+                            grpc_completion_queue *cq,
                             const void *server_transport_data,
                             grpc_mdelem **add_initial_metadata,
                             size_t add_initial_metadata_count,
diff --git a/src/core/surface/channel.c b/src/core/surface/channel.c
index 81f673f856..8692aa3903 100644
--- a/src/core/surface/channel.c
+++ b/src/core/surface/channel.c
@@ -146,7 +146,8 @@ char *grpc_channel_get_target(grpc_channel *channel) {
 }
 
 static grpc_call *grpc_channel_create_call_internal(
-    grpc_channel *channel, grpc_completion_queue *cq, grpc_mdelem *path_mdelem,
+    grpc_channel *channel, grpc_call *parent_call, gpr_uint32 propagation_mask,
+    grpc_completion_queue *cq, grpc_mdelem *path_mdelem,
     grpc_mdelem *authority_mdelem, gpr_timespec deadline) {
   grpc_mdelem *send_metadata[2];
   int num_metadata = 0;
@@ -158,16 +159,18 @@ static grpc_call *grpc_channel_create_call_internal(
     send_metadata[num_metadata++] = authority_mdelem;
   }
 
-  return grpc_call_create(channel, cq, NULL, send_metadata,
-                          num_metadata, deadline);
+  return grpc_call_create(channel, parent_call, propagation_mask, cq, NULL, 
+                          send_metadata, num_metadata, deadline);
 }
 
 grpc_call *grpc_channel_create_call(grpc_channel *channel,
+                                    grpc_call *parent_call,
+                                    gpr_uint32 propagation_mask,
                                     grpc_completion_queue *cq,
                                     const char *method, const char *host,
                                     gpr_timespec deadline) {
   return grpc_channel_create_call_internal(
-      channel, cq,
+      channel, parent_call, propagation_mask, cq,
       grpc_mdelem_from_metadata_strings(
           channel->metadata_context, GRPC_MDSTR_REF(channel->path_string),
           grpc_mdstr_from_string(channel->metadata_context, method, 0)),
@@ -195,11 +198,13 @@ void *grpc_channel_register_call(grpc_channel *channel, const char *method,
 }
 
 grpc_call *grpc_channel_create_registered_call(
-    grpc_channel *channel, grpc_completion_queue *completion_queue,
-    void *registered_call_handle, gpr_timespec deadline) {
+    grpc_channel *channel, grpc_call *parent_call, gpr_uint32 propagation_mask,
+    grpc_completion_queue *completion_queue, void *registered_call_handle,
+    gpr_timespec deadline) {
   registered_call *rc = registered_call_handle;
   return grpc_channel_create_call_internal(
-      channel, completion_queue, GRPC_MDELEM_REF(rc->path),
+      channel, parent_call, propagation_mask, completion_queue, 
+      GRPC_MDELEM_REF(rc->path), 
       rc->authority ? GRPC_MDELEM_REF(rc->authority) : NULL, deadline);
 }
 
@@ -229,7 +234,9 @@ static void destroy_channel(void *p, int ok) {
     registered_call *rc = channel->registered_calls;
     channel->registered_calls = rc->next;
     GRPC_MDELEM_UNREF(rc->path);
-    GRPC_MDELEM_UNREF(rc->authority);
+    if (rc->authority) {
+      GRPC_MDELEM_UNREF(rc->authority);
+    }
     gpr_free(rc);
   }
   grpc_mdctx_unref(channel->metadata_context);
diff --git a/src/core/surface/completion_queue.c b/src/core/surface/completion_queue.c
index 3f60b0b0ba..36d69cfe5f 100644
--- a/src/core/surface/completion_queue.c
+++ b/src/core/surface/completion_queue.c
@@ -45,6 +45,11 @@
 #include <grpc/support/atm.h>
 #include <grpc/support/log.h>
 
+typedef struct {
+  grpc_pollset_worker *worker;
+  void *tag;
+} plucker;
+
 /* Completion queue structure */
 struct grpc_completion_queue {
   /** completed events */
@@ -60,6 +65,8 @@ struct grpc_completion_queue {
   int shutdown;
   int shutdown_called;
   int is_server_cq;
+  int num_pluckers;
+  plucker pluckers[GRPC_MAX_COMPLETION_QUEUE_PLUCKERS];
 };
 
 grpc_completion_queue *grpc_completion_queue_create(void) {
@@ -107,6 +114,11 @@ void grpc_cq_internal_unref(grpc_completion_queue *cc) {
 }
 
 void grpc_cq_begin_op(grpc_completion_queue *cc) {
+#ifndef NDEBUG
+  gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
+  GPR_ASSERT(!cc->shutdown_called);
+  gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
+#endif
   gpr_ref(&cc->pending_events);
 }
 
@@ -117,6 +129,8 @@ void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, int success,
                     void (*done)(void *done_arg, grpc_cq_completion *storage),
                     void *done_arg, grpc_cq_completion *storage) {
   int shutdown;
+  int i;
+  grpc_pollset_worker *pluck_worker;
 
   storage->tag = tag;
   storage->done = done;
@@ -130,7 +144,14 @@ void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, int success,
     cc->completed_tail->next =
         ((gpr_uintptr)storage) | (1u & (gpr_uintptr)cc->completed_tail->next);
     cc->completed_tail = storage;
-    grpc_pollset_kick(&cc->pollset);
+    pluck_worker = NULL;
+    for (i = 0; i < cc->num_pluckers; i++) {
+      if (cc->pluckers[i].tag == tag) {
+        pluck_worker = cc->pluckers[i].worker;
+        break;
+      }
+    }
+    grpc_pollset_kick(&cc->pollset, pluck_worker);
     gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
   } else {
     cc->completed_tail->next =
@@ -147,6 +168,7 @@ void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, int success,
 grpc_event grpc_completion_queue_next(grpc_completion_queue *cc,
                                       gpr_timespec deadline) {
   grpc_event ret;
+  grpc_pollset_worker worker;
 
   deadline = gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC);
 
@@ -172,7 +194,7 @@ grpc_event grpc_completion_queue_next(grpc_completion_queue *cc,
       ret.type = GRPC_QUEUE_SHUTDOWN;
       break;
     }
-    if (!grpc_pollset_work(&cc->pollset, deadline)) {
+    if (!grpc_pollset_work(&cc->pollset, &worker, deadline)) {
       gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
       memset(&ret, 0, sizeof(ret));
       ret.type = GRPC_QUEUE_TIMEOUT;
@@ -184,11 +206,37 @@ grpc_event grpc_completion_queue_next(grpc_completion_queue *cc,
   return ret;
 }
 
+static int add_plucker(grpc_completion_queue *cc, void *tag,
+                       grpc_pollset_worker *worker) {
+  if (cc->num_pluckers == GRPC_MAX_COMPLETION_QUEUE_PLUCKERS) {
+    return 0;
+  }
+  cc->pluckers[cc->num_pluckers].tag = tag;
+  cc->pluckers[cc->num_pluckers].worker = worker;
+  cc->num_pluckers++;
+  return 1;
+}
+
+static void del_plucker(grpc_completion_queue *cc, void *tag,
+                        grpc_pollset_worker *worker) {
+  int i;
+  for (i = 0; i < cc->num_pluckers; i++) {
+    if (cc->pluckers[i].tag == tag && cc->pluckers[i].worker == worker) {
+      cc->num_pluckers--;
+      GPR_SWAP(plucker, cc->pluckers[i], cc->pluckers[cc->num_pluckers]);
+      return;
+    }
+  }
+  gpr_log(GPR_ERROR, "should never reach here");
+  abort();
+}
+
 grpc_event grpc_completion_queue_pluck(grpc_completion_queue *cc, void *tag,
                                        gpr_timespec deadline) {
   grpc_event ret;
   grpc_cq_completion *c;
   grpc_cq_completion *prev;
+  grpc_pollset_worker worker;
 
   deadline = gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC);
 
@@ -219,12 +267,24 @@ grpc_event grpc_completion_queue_pluck(grpc_completion_queue *cc, void *tag,
       ret.type = GRPC_QUEUE_SHUTDOWN;
       break;
     }
-    if (!grpc_pollset_work(&cc->pollset, deadline)) {
+    if (!add_plucker(cc, tag, &worker)) {
+      gpr_log(GPR_DEBUG, 
+              "Too many outstanding grpc_completion_queue_pluck calls: maximum is %d",
+              GRPC_MAX_COMPLETION_QUEUE_PLUCKERS);
       gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
       memset(&ret, 0, sizeof(ret));
+      /* TODO(ctiller): should we use a different result here */
       ret.type = GRPC_QUEUE_TIMEOUT;
       break;
     }
+    if (!grpc_pollset_work(&cc->pollset, &worker, deadline)) {
+      del_plucker(cc, tag, &worker);
+      gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
+      memset(&ret, 0, sizeof(ret));
+      ret.type = GRPC_QUEUE_TIMEOUT;
+      break;
+    }
+    del_plucker(cc, tag, &worker);
   }
 done:
   GRPC_SURFACE_TRACE_RETURNED_EVENT(cc, &ret);
@@ -261,15 +321,6 @@ grpc_pollset *grpc_cq_pollset(grpc_completion_queue *cc) {
   return &cc->pollset;
 }
 
-void grpc_cq_hack_spin_pollset(grpc_completion_queue *cc) {
-  gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
-  grpc_pollset_kick(&cc->pollset);
-  grpc_pollset_work(&cc->pollset,
-                    gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
-                                 gpr_time_from_millis(100, GPR_TIMESPAN)));
-  gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
-}
-
 void grpc_cq_mark_server_cq(grpc_completion_queue *cc) { cc->is_server_cq = 1; }
 
 int grpc_cq_is_server_cq(grpc_completion_queue *cc) { return cc->is_server_cq; }
diff --git a/src/core/surface/completion_queue.h b/src/core/surface/completion_queue.h
index f944f48d8e..8de024aaea 100644
--- a/src/core/surface/completion_queue.h
+++ b/src/core/surface/completion_queue.h
@@ -77,8 +77,6 @@ void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, int success,
 
 grpc_pollset *grpc_cq_pollset(grpc_completion_queue *cc);
 
-void grpc_cq_hack_spin_pollset(grpc_completion_queue *cc);
-
 void grpc_cq_mark_server_cq(grpc_completion_queue *cc);
 int grpc_cq_is_server_cq(grpc_completion_queue *cc);
 
diff --git a/src/core/surface/secure_channel_create.c b/src/core/surface/secure_channel_create.c
index 1f89353025..c3150250b8 100644
--- a/src/core/surface/secure_channel_create.c
+++ b/src/core/surface/secure_channel_create.c
@@ -88,8 +88,8 @@ static void on_secure_transport_setup_done(void *arg,
         c->args.channel_args, secure_endpoint, c->args.metadata_context, 1);
     grpc_chttp2_transport_start_reading(c->result->transport, NULL, 0);
     c->result->filters = gpr_malloc(sizeof(grpc_channel_filter *) * 2);
-    c->result->filters[0] = &grpc_client_auth_filter;
-    c->result->filters[1] = &grpc_http_client_filter;
+    c->result->filters[0] = &grpc_http_client_filter;
+    c->result->filters[1] = &grpc_client_auth_filter;
     c->result->num_filters = 2;
   }
   notify = c->notify;
diff --git a/src/core/surface/server.c b/src/core/surface/server.c
index c370a9b8ab..cd1dc589e1 100644
--- a/src/core/surface/server.c
+++ b/src/core/surface/server.c
@@ -327,6 +327,14 @@ static void request_matcher_zombify_all_pending_calls(
   }
 }
 
+static void request_matcher_kill_requests(grpc_server *server,
+                                          request_matcher *rm) {
+  int request_id;
+  while ((request_id = gpr_stack_lockfree_pop(rm->requests)) != -1) {
+    fail_call(server, &server->requested_calls[request_id]);
+  }
+}
+
 /*
  * server proper
  */
@@ -492,12 +500,25 @@ static int num_channels(grpc_server *server) {
   return n;
 }
 
+static void kill_pending_work_locked(grpc_server *server) {
+  registered_method *rm;
+  request_matcher_kill_requests(server, &server->unregistered_request_matcher);
+  request_matcher_zombify_all_pending_calls(
+      &server->unregistered_request_matcher);
+  for (rm = server->registered_methods; rm; rm = rm->next) {
+    request_matcher_kill_requests(server, &rm->request_matcher);
+    request_matcher_zombify_all_pending_calls(&rm->request_matcher);
+  }
+}
+
 static void maybe_finish_shutdown(grpc_server *server) {
   size_t i;
   if (!gpr_atm_acq_load(&server->shutdown_flag) || server->shutdown_published) {
     return;
   }
 
+  kill_pending_work_locked(server);
+
   if (server->root_channel_data.next != &server->root_channel_data ||
       server->listeners_destroyed < num_listeners(server)) {
     if (gpr_time_cmp(gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME),
@@ -623,8 +644,8 @@ static void accept_stream(void *cd, grpc_transport *transport,
                           const void *transport_server_data) {
   channel_data *chand = cd;
   /* create a call */
-  grpc_call_create(chand->channel, NULL, transport_server_data, NULL, 0,
-                   gpr_inf_future(GPR_CLOCK_REALTIME));
+  grpc_call_create(chand->channel, NULL, 0, NULL, transport_server_data, NULL,
+                   0, gpr_inf_future(GPR_CLOCK_MONOTONIC));
 }
 
 static void channel_connectivity_changed(void *cd, int iomgr_status_ignored) {
@@ -947,52 +968,15 @@ void grpc_server_setup_transport(grpc_server *s, grpc_transport *transport,
   op.set_accept_stream_user_data = chand;
   op.on_connectivity_state_change = &chand->channel_connectivity_changed;
   op.connectivity_state = &chand->connectivity_state;
+  op.disconnect = gpr_atm_acq_load(&s->shutdown_flag);
   grpc_transport_perform_op(transport, &op);
 }
 
-typedef struct {
-  requested_call **requests;
-  size_t count;
-  size_t capacity;
-} request_killer;
-
-static void request_killer_init(request_killer *rk) {
-  memset(rk, 0, sizeof(*rk));
-}
-
-static void request_killer_add(request_killer *rk, requested_call *rc) {
-  if (rk->capacity == rk->count) {
-    rk->capacity = GPR_MAX(8, rk->capacity * 2);
-    rk->requests =
-        gpr_realloc(rk->requests, rk->capacity * sizeof(*rk->requests));
-  }
-  rk->requests[rk->count++] = rc;
-}
-
-static void request_killer_add_request_matcher(request_killer *rk,
-                                               grpc_server *server,
-                                               request_matcher *rm) {
-  int request_id;
-  while ((request_id = gpr_stack_lockfree_pop(rm->requests)) != -1) {
-    request_killer_add(rk, &server->requested_calls[request_id]);
-  }
-}
-
-static void request_killer_run(request_killer *rk, grpc_server *server) {
-  size_t i;
-  for (i = 0; i < rk->count; i++) {
-    fail_call(server, rk->requests[i]);
-  }
-  gpr_free(rk->requests);
-}
-
 void grpc_server_shutdown_and_notify(grpc_server *server,
                                      grpc_completion_queue *cq, void *tag) {
   listener *l;
-  registered_method *rm;
   shutdown_tag *sdt;
   channel_broadcaster broadcaster;
-  request_killer reqkill;
 
   GRPC_SERVER_LOG_SHUTDOWN(GPR_INFO, server, cq, tag);
 
@@ -1013,27 +997,16 @@ void grpc_server_shutdown_and_notify(grpc_server *server,
   server->last_shutdown_message_time = gpr_now(GPR_CLOCK_REALTIME);
 
   channel_broadcaster_init(server, &broadcaster);
-  request_killer_init(&reqkill);
 
   /* collect all unregistered then registered calls */
   gpr_mu_lock(&server->mu_call);
-  request_killer_add_request_matcher(&reqkill, server,
-                                     &server->unregistered_request_matcher);
-  request_matcher_zombify_all_pending_calls(
-      &server->unregistered_request_matcher);
-  for (rm = server->registered_methods; rm; rm = rm->next) {
-    request_killer_add_request_matcher(&reqkill, server, &rm->request_matcher);
-    request_matcher_zombify_all_pending_calls(&rm->request_matcher);
-  }
+  kill_pending_work_locked(server);
   gpr_mu_unlock(&server->mu_call);
 
   gpr_atm_rel_store(&server->shutdown_flag, 1);
   maybe_finish_shutdown(server);
   gpr_mu_unlock(&server->mu_global);
 
-  /* terminate all the requested calls */
-  request_killer_run(&reqkill, server);
-
   /* Shutdown listeners */
   for (l = server->listeners; l; l = l->next) {
     l->destroy(server, l->arg);
diff --git a/src/core/surface/server_chttp2.c b/src/core/surface/server_chttp2.c
index 78c53466b3..4ab845bc00 100644
--- a/src/core/surface/server_chttp2.c
+++ b/src/core/surface/server_chttp2.c
@@ -80,7 +80,7 @@ static void destroy(grpc_server *server, void *tcpp) {
   grpc_tcp_server_destroy(tcp, grpc_server_listener_destroy_done, server);
 }
 
-int grpc_server_add_http2_port(grpc_server *server, const char *addr) {
+int grpc_server_add_insecure_http2_port(grpc_server *server, const char *addr) {
   grpc_resolved_addresses *resolved = NULL;
   grpc_tcp_server *tcp = NULL;
   size_t i;
diff --git a/src/core/surface/version.c b/src/core/surface/version.c
index 4f5d648371..d7aaba3868 100644
--- a/src/core/surface/version.c
+++ b/src/core/surface/version.c
@@ -37,5 +37,5 @@
 #include <grpc/grpc.h>
 
 const char *grpc_version_string(void) {
-	return "0.10.0.0";
+	return "0.10.1.0";
 }
diff --git a/src/core/transport/chttp2/internal.h b/src/core/transport/chttp2/internal.h
index f0eeb6de50..42cf0ecd5b 100644
--- a/src/core/transport/chttp2/internal.h
+++ b/src/core/transport/chttp2/internal.h
@@ -119,6 +119,10 @@ typedef enum {
   GRPC_WRITE_STATE_SENT_CLOSE
 } grpc_chttp2_write_state;
 
+/* flags that can be or'd into stream_global::writing_now */
+#define GRPC_CHTTP2_WRITING_DATA 1
+#define GRPC_CHTTP2_WRITING_WINDOW 2
+
 typedef enum {
   GRPC_DONT_SEND_CLOSED = 0,
   GRPC_SEND_CLOSED,
@@ -382,8 +386,10 @@ typedef struct {
   gpr_uint8 published_cancelled;
   /** is this stream in the stream map? (boolean) */
   gpr_uint8 in_stream_map;
-  /** is this stream actively being written? */
+  /** bitmask of GRPC_CHTTP2_WRITING_xxx above */
   gpr_uint8 writing_now;
+  /** has anything been written to this stream? */
+  gpr_uint8 written_anything;
 
   /** stream state already published to the upper layer */
   grpc_stream_state published_state;
diff --git a/src/core/transport/chttp2/stream_lists.c b/src/core/transport/chttp2/stream_lists.c
index 9e68c1e146..9c3ad7a777 100644
--- a/src/core/transport/chttp2/stream_lists.c
+++ b/src/core/transport/chttp2/stream_lists.c
@@ -164,9 +164,6 @@ void grpc_chttp2_list_add_first_writable_stream(
     grpc_chttp2_transport_global *transport_global,
     grpc_chttp2_stream_global *stream_global) {
   GPR_ASSERT(stream_global->id != 0);
-  gpr_log(GPR_DEBUG, "add:%d:%d:%d:%d", stream_global->id,
-          stream_global->write_state, stream_global->in_stream_map,
-          stream_global->read_closed);
   stream_list_add_head(TRANSPORT_FROM_GLOBAL(transport_global),
                        STREAM_FROM_GLOBAL(stream_global),
                        GRPC_CHTTP2_LIST_WRITABLE);
diff --git a/src/core/transport/chttp2/writing.c b/src/core/transport/chttp2/writing.c
index d39b0c42f7..b55e81fdca 100644
--- a/src/core/transport/chttp2/writing.c
+++ b/src/core/transport/chttp2/writing.c
@@ -77,7 +77,6 @@ int grpc_chttp2_unlocking_check_writes(
 
     stream_writing->id = stream_global->id;
     stream_writing->send_closed = GRPC_DONT_SEND_CLOSED;
-    GPR_ASSERT(!stream_global->writing_now);
 
     if (stream_global->outgoing_sopb) {
       window_delta =
@@ -123,11 +122,13 @@ int grpc_chttp2_unlocking_check_writes(
       stream_global->unannounced_incoming_window = 0;
       grpc_chttp2_list_add_incoming_window_updated(transport_global,
                                                    stream_global);
-      stream_global->writing_now = 1;
-      grpc_chttp2_list_add_writing_stream(transport_writing, stream_writing);
-    } else if (stream_writing->sopb.nops > 0 ||
-               stream_writing->send_closed != GRPC_DONT_SEND_CLOSED) {
-      stream_global->writing_now = 1;
+      stream_global->writing_now |= GRPC_CHTTP2_WRITING_WINDOW;
+    }
+    if (stream_writing->sopb.nops > 0 ||
+        stream_writing->send_closed != GRPC_DONT_SEND_CLOSED) {
+      stream_global->writing_now |= GRPC_CHTTP2_WRITING_DATA;
+    }
+    if (stream_global->writing_now != 0) {
       grpc_chttp2_list_add_writing_stream(transport_writing, stream_writing);
     }
   }
@@ -183,6 +184,7 @@ static void finalize_outbuf(grpc_chttp2_transport_writing *transport_writing) {
                          stream_writing->send_closed != GRPC_DONT_SEND_CLOSED,
                          stream_writing->id, &transport_writing->hpack_compressor,
                          &transport_writing->outbuf);
+      stream_writing->sopb.nops = 0;
     }
     if (stream_writing->announce_window > 0) {
       gpr_slice_buffer_add(
@@ -191,7 +193,6 @@ static void finalize_outbuf(grpc_chttp2_transport_writing *transport_writing) {
               stream_writing->id, stream_writing->announce_window));
       stream_writing->announce_window = 0;
     }
-    stream_writing->sopb.nops = 0;
     if (stream_writing->send_closed == GRPC_SEND_CLOSED_WITH_RST_STREAM) {
       gpr_slice_buffer_add(&transport_writing->outbuf,
                            grpc_chttp2_rst_stream_create(stream_writing->id,
@@ -215,20 +216,23 @@ void grpc_chttp2_cleanup_writing(
 
   while (grpc_chttp2_list_pop_written_stream(
       transport_global, transport_writing, &stream_global, &stream_writing)) {
-    GPR_ASSERT(stream_global->writing_now);
-    stream_global->writing_now = 0;
-    if (stream_global->outgoing_sopb != NULL &&
-        stream_global->outgoing_sopb->nops == 0) {
-      stream_global->outgoing_sopb = NULL;
-      grpc_chttp2_schedule_closure(transport_global,
-                                   stream_global->send_done_closure, 1);
-    }
+    GPR_ASSERT(stream_global->writing_now != 0);
     if (stream_writing->send_closed != GRPC_DONT_SEND_CLOSED) {
       stream_global->write_state = GRPC_WRITE_STATE_SENT_CLOSE;
       if (!transport_global->is_client) {
         stream_global->read_closed = 1;
       }
     }
+    if (stream_global->writing_now & GRPC_CHTTP2_WRITING_DATA) {
+      if (stream_global->outgoing_sopb != NULL &&
+          stream_global->outgoing_sopb->nops == 0) {
+        GPR_ASSERT(stream_global->write_state != GRPC_WRITE_STATE_QUEUED_CLOSE);
+        stream_global->outgoing_sopb = NULL;
+        grpc_chttp2_schedule_closure(transport_global,
+                                     stream_global->send_done_closure, 1);
+      }
+    }
+    stream_global->writing_now = 0;
     grpc_chttp2_list_add_read_write_state_changed(transport_global,
                                                   stream_global);
   }
diff --git a/src/core/transport/chttp2_transport.c b/src/core/transport/chttp2_transport.c
index 1ea4a82c16..a9f91b64d5 100644
--- a/src/core/transport/chttp2_transport.c
+++ b/src/core/transport/chttp2_transport.c
@@ -107,6 +107,11 @@ static void cancel_from_api(grpc_chttp2_transport_global *transport_global,
                             grpc_chttp2_stream_global *stream_global,
                             grpc_status_code status);
 
+static void close_from_api(grpc_chttp2_transport_global *transport_global,
+                           grpc_chttp2_stream_global *stream_global,
+                           grpc_status_code status,
+                           gpr_slice *optional_message);
+
 /** Add endpoint from this transport to pollset */
 static void add_to_pollset_locked(grpc_chttp2_transport *t,
                                   grpc_pollset *pollset);
@@ -602,10 +607,16 @@ static void perform_stream_op_locked(
     cancel_from_api(transport_global, stream_global, op->cancel_with_status);
   }
 
+  if (op->close_with_status != GRPC_STATUS_OK) {
+    close_from_api(transport_global, stream_global, op->close_with_status,
+                   op->optional_close_message);
+  }
+
   if (op->send_ops) {
     GPR_ASSERT(stream_global->outgoing_sopb == NULL);
     stream_global->send_done_closure = op->on_done_send;
     if (!stream_global->cancelled) {
+      stream_global->written_anything = 1;
       stream_global->outgoing_sopb = op->send_ops;
       if (op->is_last_send &&
           stream_global->write_state == GRPC_WRITE_STATE_OPEN) {
@@ -823,6 +834,12 @@ static void unlock_check_read_write_state(grpc_chttp2_transport *t) {
                                                            stream_global);
       } else {
         stream_global->write_state = GRPC_WRITE_STATE_SENT_CLOSE;
+        if (stream_global->outgoing_sopb != NULL) {
+          grpc_sopb_reset(stream_global->outgoing_sopb);
+          stream_global->outgoing_sopb = NULL;
+          grpc_chttp2_schedule_closure(transport_global,
+                                       stream_global->send_done_closure, 1);
+        }
         stream_global->read_closed = 1;
         if (!stream_global->published_cancelled) {
           char buffer[GPR_LTOA_MIN_BUFSIZE];
@@ -849,7 +866,7 @@ static void unlock_check_read_write_state(grpc_chttp2_transport *t) {
     if (!stream_global->publish_sopb) {
       continue;
     }
-    if (stream_global->writing_now) {
+    if (stream_global->writing_now != 0) {
       continue;
     }
     /* FIXME(ctiller): we include in_stream_map in our computation of
@@ -894,6 +911,108 @@ static void cancel_from_api(grpc_chttp2_transport_global *transport_global,
                                                 stream_global);
 }
 
+static void close_from_api(grpc_chttp2_transport_global *transport_global,
+                           grpc_chttp2_stream_global *stream_global,
+                           grpc_status_code status,
+                           gpr_slice *optional_message) {
+  gpr_slice hdr;
+  gpr_slice status_hdr;
+  gpr_slice message_pfx;
+  gpr_uint8 *p;
+  gpr_uint32 len = 0;
+
+  GPR_ASSERT(status >= 0 && (int)status < 100);
+
+  stream_global->cancelled = 1;
+  stream_global->cancelled_status = status;
+  GPR_ASSERT(stream_global->id != 0);
+  GPR_ASSERT(!stream_global->written_anything);
+
+  /* Hand roll a header block.
+     This is unnecessarily ugly - at some point we should find a more elegant
+     solution.
+     It's complicated by the fact that our send machinery would be dead by the
+     time we got around to sending this, so instead we ignore HPACK compression
+     and just write the uncompressed bytes onto the wire. */
+  status_hdr = gpr_slice_malloc(15 + (status >= 10));
+  p = GPR_SLICE_START_PTR(status_hdr);
+  *p++ = 0x40; /* literal header */
+  *p++ = 11;   /* len(grpc-status) */
+  *p++ = 'g';
+  *p++ = 'r';
+  *p++ = 'p';
+  *p++ = 'c';
+  *p++ = '-';
+  *p++ = 's';
+  *p++ = 't';
+  *p++ = 'a';
+  *p++ = 't';
+  *p++ = 'u';
+  *p++ = 's';
+  if (status < 10) {
+    *p++ = 1;
+    *p++ = '0' + status;
+  } else {
+    *p++ = 2;
+    *p++ = '0' + (status / 10);
+    *p++ = '0' + (status % 10);
+  }
+  GPR_ASSERT(p == GPR_SLICE_END_PTR(status_hdr));
+  len += GPR_SLICE_LENGTH(status_hdr);
+
+  if (optional_message) {
+    GPR_ASSERT(GPR_SLICE_LENGTH(*optional_message) < 127);
+    message_pfx = gpr_slice_malloc(15);
+    p = GPR_SLICE_START_PTR(message_pfx);
+    *p++ = 0x40;
+    *p++ = 12; /* len(grpc-message) */
+    *p++ = 'g';
+    *p++ = 'r';
+    *p++ = 'p';
+    *p++ = 'c';
+    *p++ = '-';
+    *p++ = 'm';
+    *p++ = 'e';
+    *p++ = 's';
+    *p++ = 's';
+    *p++ = 'a';
+    *p++ = 'g';
+    *p++ = 'e';
+    *p++ = GPR_SLICE_LENGTH(*optional_message);
+    GPR_ASSERT(p == GPR_SLICE_END_PTR(message_pfx));
+    len += GPR_SLICE_LENGTH(message_pfx);
+    len += GPR_SLICE_LENGTH(*optional_message);
+  }
+
+  hdr = gpr_slice_malloc(9);
+  p = GPR_SLICE_START_PTR(hdr);
+  *p++ = len >> 16;
+  *p++ = len >> 8;
+  *p++ = len;
+  *p++ = GRPC_CHTTP2_FRAME_HEADER;
+  *p++ = GRPC_CHTTP2_DATA_FLAG_END_STREAM | GRPC_CHTTP2_DATA_FLAG_END_HEADERS;
+  *p++ = stream_global->id >> 24;
+  *p++ = stream_global->id >> 16;
+  *p++ = stream_global->id >> 8;
+  *p++ = stream_global->id;
+  GPR_ASSERT(p == GPR_SLICE_END_PTR(hdr));
+
+  gpr_slice_buffer_add(&transport_global->qbuf, hdr);
+  gpr_slice_buffer_add(&transport_global->qbuf, status_hdr);
+  if (optional_message) {
+    gpr_slice_buffer_add(&transport_global->qbuf, message_pfx);
+    gpr_slice_buffer_add(&transport_global->qbuf,
+                         gpr_slice_ref(*optional_message));
+  }
+
+  gpr_slice_buffer_add(
+      &transport_global->qbuf,
+      grpc_chttp2_rst_stream_create(stream_global->id, GRPC_CHTTP2_NO_ERROR));
+
+  grpc_chttp2_list_add_read_write_state_changed(transport_global,
+                                                stream_global);
+}
+
 static void cancel_stream_cb(grpc_chttp2_transport_global *transport_global,
                              void *user_data,
                              grpc_chttp2_stream_global *stream_global) {
diff --git a/src/core/transport/metadata.c b/src/core/transport/metadata.c
index 967fd4898c..44d32b6cb2 100644
--- a/src/core/transport/metadata.c
+++ b/src/core/transport/metadata.c
@@ -135,7 +135,9 @@ static void unlock(grpc_mdctx *ctx) {
   if (ctx->refs == 0) {
     /* uncomment if you're having trouble diagnosing an mdelem leak to make
        things clearer (slows down destruction a lot, however) */
+#ifdef GRPC_METADATA_REFCOUNT_DEBUG
     gc_mdtab(ctx);
+#endif
     if (ctx->mdtab_count && ctx->mdtab_count == ctx->mdtab_free) {
       discard_metadata(ctx);
     }
diff --git a/src/core/transport/stream_op.h b/src/core/transport/stream_op.h
index f27ef1b66b..227320cf2a 100644
--- a/src/core/transport/stream_op.h
+++ b/src/core/transport/stream_op.h
@@ -108,7 +108,7 @@ void grpc_metadata_batch_move(grpc_metadata_batch *dst,
                               grpc_metadata_batch *src);
 
 /** Add \a storage to the beginning of \a batch. storage->md is
-    assumed to be valid. 
+    assumed to be valid.
     \a storage is owned by the caller and must survive for the
     lifetime of batch. This usually means it should be around
     for the lifetime of the call. */
diff --git a/src/core/transport/transport.c b/src/core/transport/transport.c
index 69c00b6a4f..c0d92cf93f 100644
--- a/src/core/transport/transport.c
+++ b/src/core/transport/transport.c
@@ -32,6 +32,8 @@
  */
 
 #include "src/core/transport/transport.h"
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
 #include "src/core/transport/transport_impl.h"
 
 size_t grpc_transport_stream_size(grpc_transport *transport) {
@@ -83,12 +85,54 @@ void grpc_transport_stream_op_finish_with_failure(
 }
 
 void grpc_transport_stream_op_add_cancellation(grpc_transport_stream_op *op,
-                                               grpc_status_code status,
-                                               grpc_mdstr *message) {
+                                               grpc_status_code status) {
+  GPR_ASSERT(status != GRPC_STATUS_OK);
   if (op->cancel_with_status == GRPC_STATUS_OK) {
     op->cancel_with_status = status;
   }
-  if (message) {
-    GRPC_MDSTR_UNREF(message);
+  if (op->close_with_status != GRPC_STATUS_OK) {
+    op->close_with_status = GRPC_STATUS_OK;
+    if (op->optional_close_message != NULL) {
+      gpr_slice_unref(*op->optional_close_message);
+      op->optional_close_message = NULL;
+    }
   }
 }
+
+typedef struct {
+  gpr_slice message;
+  grpc_iomgr_closure *then_call;
+  grpc_iomgr_closure closure;
+} close_message_data;
+
+static void free_message(void *p, int iomgr_success) {
+  close_message_data *cmd = p;
+  gpr_slice_unref(cmd->message);
+  if (cmd->then_call != NULL) {
+    cmd->then_call->cb(cmd->then_call->cb_arg, iomgr_success);
+  }
+  gpr_free(cmd);
+}
+
+void grpc_transport_stream_op_add_close(grpc_transport_stream_op *op,
+                                        grpc_status_code status,
+                                        gpr_slice *optional_message) {
+  close_message_data *cmd;
+  GPR_ASSERT(status != GRPC_STATUS_OK);
+  if (op->cancel_with_status != GRPC_STATUS_OK ||
+      op->close_with_status != GRPC_STATUS_OK) {
+    if (optional_message) {
+      gpr_slice_unref(*optional_message);
+    }
+    return;
+  }
+  if (optional_message) {
+    cmd = gpr_malloc(sizeof(*cmd));
+    cmd->message = *optional_message;
+    cmd->then_call = op->on_consumed;
+    grpc_iomgr_closure_init(&cmd->closure, free_message, cmd);
+    op->on_consumed = &cmd->closure;
+    op->optional_close_message = &cmd->message;
+  }
+  op->close_with_status = status;
+}
diff --git a/src/core/transport/transport.h b/src/core/transport/transport.h
index 7efcfcf970..92c1f38c5e 100644
--- a/src/core/transport/transport.h
+++ b/src/core/transport/transport.h
@@ -80,8 +80,14 @@ typedef struct grpc_transport_stream_op {
 
   grpc_pollset *bind_pollset;
 
+  /** If != GRPC_STATUS_OK, cancel this stream */
   grpc_status_code cancel_with_status;
 
+  /** If != GRPC_STATUS_OK, send grpc-status, grpc-message, and close this
+      stream for both reading and writing */
+  grpc_status_code close_with_status;
+  gpr_slice *optional_close_message;
+
   /* Indexes correspond to grpc_context_index enum values */
   grpc_call_context_element *context;
 } grpc_transport_stream_op;
@@ -148,8 +154,11 @@ void grpc_transport_destroy_stream(grpc_transport *transport,
 void grpc_transport_stream_op_finish_with_failure(grpc_transport_stream_op *op);
 
 void grpc_transport_stream_op_add_cancellation(grpc_transport_stream_op *op,
-                                               grpc_status_code status,
-                                               grpc_mdstr *message);
+                                               grpc_status_code status);
+
+void grpc_transport_stream_op_add_close(grpc_transport_stream_op *op,
+                                        grpc_status_code status,
+                                        gpr_slice *optional_message);
 
 char *grpc_transport_stream_op_string(grpc_transport_stream_op *op);
 
diff --git a/src/core/tsi/transport_security_interface.h b/src/core/tsi/transport_security_interface.h
index 936b0c25b0..e27e6b9fc9 100644
--- a/src/core/tsi/transport_security_interface.h
+++ b/src/core/tsi/transport_security_interface.h
@@ -158,6 +158,8 @@ tsi_result tsi_frame_protector_protect_flush(
      value is expected to be at most max_protected_frame_size minus overhead
      which means that max_protected_frame_size is a safe bet. The output value
      is the number of bytes actually written.
+     If *unprotected_bytes_size is unchanged, there may be more data remaining
+     to unprotect, and the caller should call this function again.
 
    - This method returns TSI_OK in case of success. Success includes cases where
      there is not enough data to output a frame in which case
diff --git a/src/cpp/client/channel.cc b/src/cpp/client/channel.cc
index 5df81e641e..af7366eb01 100644
--- a/src/cpp/client/channel.cc
+++ b/src/cpp/client/channel.cc
@@ -48,26 +48,32 @@
 #include <grpc++/impl/call.h>
 #include <grpc++/impl/rpc_method.h>
 #include <grpc++/status.h>
+#include <grpc++/time.h>
 
 namespace grpc {
 
-Channel::Channel(const grpc::string& target, grpc_channel* channel)
-    : target_(target), c_channel_(channel) {}
+Channel::Channel(grpc_channel* channel) : c_channel_(channel) {}
+
+Channel::Channel(const grpc::string& host, grpc_channel* channel)
+    : host_(host), c_channel_(channel) {}
 
 Channel::~Channel() { grpc_channel_destroy(c_channel_); }
 
 Call Channel::CreateCall(const RpcMethod& method, ClientContext* context,
                          CompletionQueue* cq) {
-  auto c_call =
-      method.channel_tag() && context->authority().empty()
-          ? grpc_channel_create_registered_call(c_channel_, cq->cq(),
-                                                method.channel_tag(),
-                                                context->raw_deadline())
-          : grpc_channel_create_call(c_channel_, cq->cq(), method.name(),
-                                     context->authority().empty()
-                                         ? target_.c_str()
-                                         : context->authority().c_str(),
-                                     context->raw_deadline());
+  const char* host_str = host_.empty() ? NULL : host_.c_str();
+  auto c_call = method.channel_tag() && context->authority().empty()
+                    ? grpc_channel_create_registered_call(
+                          c_channel_, context->propagate_from_call_,
+                          context->propagation_options_.c_bitmask(), cq->cq(),
+                          method.channel_tag(), context->raw_deadline())
+                    : grpc_channel_create_call(
+                          c_channel_, context->propagate_from_call_,
+                          context->propagation_options_.c_bitmask(), cq->cq(),
+                          method.name(), context->authority().empty()
+                                             ? host_str
+                                             : context->authority().c_str(),
+                          context->raw_deadline());
   grpc_census_call_set_context(c_call, context->census_context());
   GRPC_TIMER_MARK(GRPC_PTAG_CPP_CALL_CREATED, c_call);
   context->set_call(c_call, shared_from_this());
@@ -86,7 +92,47 @@ void Channel::PerformOpsOnCall(CallOpSetInterface* ops, Call* call) {
 }
 
 void* Channel::RegisterMethod(const char* method) {
-  return grpc_channel_register_call(c_channel_, method, target_.c_str());
+  return grpc_channel_register_call(c_channel_, method,
+                                    host_.empty() ? NULL : host_.c_str());
+}
+
+grpc_connectivity_state Channel::GetState(bool try_to_connect) {
+  return grpc_channel_check_connectivity_state(c_channel_, try_to_connect);
+}
+
+namespace {
+class TagSaver GRPC_FINAL : public CompletionQueueTag {
+ public:
+  explicit TagSaver(void* tag) : tag_(tag) {}
+  ~TagSaver() GRPC_OVERRIDE {}
+  bool FinalizeResult(void** tag, bool* status) GRPC_OVERRIDE {
+    *tag = tag_;
+    delete this;
+    return true;
+  }
+ private:
+  void* tag_;
+};
+
+}  // namespace
+
+void Channel::NotifyOnStateChangeImpl(grpc_connectivity_state last_observed,
+                                      gpr_timespec deadline,
+                                      CompletionQueue* cq, void* tag) {
+  TagSaver* tag_saver = new TagSaver(tag);
+  grpc_channel_watch_connectivity_state(c_channel_, last_observed, deadline,
+                                        cq->cq(), tag_saver);
+}
+
+bool Channel::WaitForStateChangeImpl(grpc_connectivity_state last_observed,
+                                     gpr_timespec deadline) {
+  CompletionQueue cq;
+  bool ok = false;
+  void* tag = NULL;
+  NotifyOnStateChangeImpl(last_observed, deadline, &cq, NULL);
+  cq.Next(&tag, &ok);
+  GPR_ASSERT(tag == NULL);
+  return ok;
 }
 
 }  // namespace grpc
diff --git a/src/cpp/client/channel.h b/src/cpp/client/channel.h
index 9108713c58..cb8e8d98d2 100644
--- a/src/cpp/client/channel.h
+++ b/src/cpp/client/channel.h
@@ -52,17 +52,27 @@ class StreamContextInterface;
 
 class Channel GRPC_FINAL : public GrpcLibrary, public ChannelInterface {
  public:
-  Channel(const grpc::string& target, grpc_channel* c_channel);
+  explicit Channel(grpc_channel* c_channel);
+  Channel(const grpc::string& host, grpc_channel* c_channel);
   ~Channel() GRPC_OVERRIDE;
 
-  virtual void* RegisterMethod(const char* method) GRPC_OVERRIDE;
-  virtual Call CreateCall(const RpcMethod& method, ClientContext* context,
+  void* RegisterMethod(const char* method) GRPC_OVERRIDE;
+  Call CreateCall(const RpcMethod& method, ClientContext* context,
                           CompletionQueue* cq) GRPC_OVERRIDE;
-  virtual void PerformOpsOnCall(CallOpSetInterface* ops,
+  void PerformOpsOnCall(CallOpSetInterface* ops,
                                 Call* call) GRPC_OVERRIDE;
 
+  grpc_connectivity_state GetState(bool try_to_connect) GRPC_OVERRIDE;
+
  private:
-  const grpc::string target_;
+  void NotifyOnStateChangeImpl(grpc_connectivity_state last_observed,
+                               gpr_timespec deadline, CompletionQueue* cq,
+                               void* tag) GRPC_OVERRIDE;
+
+  bool WaitForStateChangeImpl(grpc_connectivity_state last_observed,
+                              gpr_timespec deadline) GRPC_OVERRIDE;
+
+  const grpc::string host_;
   grpc_channel* const c_channel_;  // owned
 };
 
diff --git a/src/cpp/client/client_context.cc b/src/cpp/client/client_context.cc
index c38d0c1df6..1ed2d38961 100644
--- a/src/cpp/client/client_context.cc
+++ b/src/cpp/client/client_context.cc
@@ -37,6 +37,7 @@
 #include <grpc/support/alloc.h>
 #include <grpc/support/string_util.h>
 #include <grpc++/credentials.h>
+#include <grpc++/server_context.h>
 #include <grpc++/time.h>
 
 #include "src/core/channel/compress_filter.h"
@@ -48,7 +49,8 @@ ClientContext::ClientContext()
     : initial_metadata_received_(false),
       call_(nullptr),
       cq_(nullptr),
-      deadline_(gpr_inf_future(GPR_CLOCK_REALTIME)) {}
+      deadline_(gpr_inf_future(GPR_CLOCK_REALTIME)),
+      propagate_from_call_(nullptr) {}
 
 ClientContext::~ClientContext() {
   if (call_) {
@@ -64,6 +66,14 @@ ClientContext::~ClientContext() {
   }
 }
 
+std::unique_ptr<ClientContext> ClientContext::FromServerContext(
+    const ServerContext& context, PropagationOptions options) {
+  std::unique_ptr<ClientContext> ctx(new ClientContext);
+  ctx->propagate_from_call_ = context.call_;
+  ctx->propagation_options_ = options;
+  return ctx;
+}
+
 void ClientContext::AddMetadata(const grpc::string& meta_key,
                                 const grpc::string& meta_value) {
   send_initial_metadata_.insert(std::make_pair(meta_key, meta_value));
diff --git a/src/cpp/client/create_channel.cc b/src/cpp/client/create_channel.cc
index dbe2694a78..21d01b739d 100644
--- a/src/cpp/client/create_channel.cc
+++ b/src/cpp/client/create_channel.cc
@@ -51,7 +51,7 @@ std::shared_ptr<ChannelInterface> CreateChannel(
   cp_args.SetString(GRPC_ARG_PRIMARY_USER_AGENT_STRING,
                     user_agent_prefix.str());
   return creds ? creds->CreateChannel(target, cp_args)
-               : std::shared_ptr<ChannelInterface>(new Channel(
-                     target, grpc_lame_client_channel_create(NULL)));
+               : std::shared_ptr<ChannelInterface>(
+                     new Channel(grpc_lame_client_channel_create(NULL)));
 }
 }  // namespace grpc
diff --git a/src/cpp/client/insecure_credentials.cc b/src/cpp/client/insecure_credentials.cc
index e802fa8034..d8dcaa1436 100644
--- a/src/cpp/client/insecure_credentials.cc
+++ b/src/cpp/client/insecure_credentials.cc
@@ -49,7 +49,7 @@ class InsecureCredentialsImpl GRPC_FINAL : public Credentials {
     grpc_channel_args channel_args;
     args.SetChannelArgs(&channel_args);
     return std::shared_ptr<ChannelInterface>(new Channel(
-        target, grpc_insecure_channel_create(target.c_str(), &channel_args)));
+        grpc_insecure_channel_create(target.c_str(), &channel_args)));
   }
 
   // InsecureCredentials should not be applied to a call.
diff --git a/src/cpp/client/secure_credentials.cc b/src/cpp/client/secure_credentials.cc
index abf0cb387e..2d6114e06b 100644
--- a/src/cpp/client/secure_credentials.cc
+++ b/src/cpp/client/secure_credentials.cc
@@ -44,8 +44,7 @@ std::shared_ptr<grpc::ChannelInterface> SecureCredentials::CreateChannel(
   grpc_channel_args channel_args;
   args.SetChannelArgs(&channel_args);
   return std::shared_ptr<ChannelInterface>(new Channel(
-      args.GetSslTargetNameOverride().empty() ? target
-                                              : args.GetSslTargetNameOverride(),
+      args.GetSslTargetNameOverride(),
       grpc_secure_channel_create(c_creds_, target.c_str(), &channel_args)));
 }
 
diff --git a/src/cpp/common/auth_property_iterator.cc b/src/cpp/common/auth_property_iterator.cc
index e706c6c921..ba88983515 100644
--- a/src/cpp/common/auth_property_iterator.cc
+++ b/src/cpp/common/auth_property_iterator.cc
@@ -31,7 +31,7 @@
  *
  */
 
-#include <grpc++/auth_property_iterator.h>
+#include <grpc++/auth_context.h>
 
 #include <grpc/grpc_security.h>
 
diff --git a/src/cpp/server/insecure_server_credentials.cc b/src/cpp/server/insecure_server_credentials.cc
index aca3568e59..800cd36caa 100644
--- a/src/cpp/server/insecure_server_credentials.cc
+++ b/src/cpp/server/insecure_server_credentials.cc
@@ -41,7 +41,7 @@ class InsecureServerCredentialsImpl GRPC_FINAL : public ServerCredentials {
  public:
   int AddPortToServer(const grpc::string& addr,
                       grpc_server* server) GRPC_OVERRIDE {
-    return grpc_server_add_http2_port(server, addr.c_str());
+    return grpc_server_add_insecure_http2_port(server, addr.c_str());
   }
 };
 }  // namespace
diff --git a/src/cpp/server/server_context.cc b/src/cpp/server/server_context.cc
index cf19556e7a..04373397f9 100644
--- a/src/cpp/server/server_context.cc
+++ b/src/cpp/server/server_context.cc
@@ -50,16 +50,23 @@ namespace grpc {
 class ServerContext::CompletionOp GRPC_FINAL : public CallOpSetInterface {
  public:
   // initial refs: one in the server context, one in the cq
-  CompletionOp() : refs_(2), finalized_(false), cancelled_(0) {}
+  CompletionOp() : has_tag_(false), tag_(nullptr), refs_(2), finalized_(false), cancelled_(0) {}
 
   void FillOps(grpc_op* ops, size_t* nops) GRPC_OVERRIDE;
   bool FinalizeResult(void** tag, bool* status) GRPC_OVERRIDE;
 
   bool CheckCancelled(CompletionQueue* cq);
 
+  void set_tag(void* tag) {
+    has_tag_ = true;
+    tag_ = tag;
+  }
+
   void Unref();
 
  private:
+  bool has_tag_;
+  void* tag_;
   grpc::mutex mu_;
   int refs_;
   bool finalized_;
@@ -90,18 +97,25 @@ void ServerContext::CompletionOp::FillOps(grpc_op* ops, size_t* nops) {
 bool ServerContext::CompletionOp::FinalizeResult(void** tag, bool* status) {
   grpc::unique_lock<grpc::mutex> lock(mu_);
   finalized_ = true;
+  bool ret = false;
+  if (has_tag_) {
+    *tag = tag_;
+    ret = true;
+  }
   if (!*status) cancelled_ = 1;
   if (--refs_ == 0) {
     lock.unlock();
     delete this;
   }
-  return false;
+  return ret;
 }
 
 // ServerContext body
 
 ServerContext::ServerContext()
     : completion_op_(nullptr),
+      has_notify_when_done_tag_(false),
+      async_notify_when_done_tag_(nullptr),
       call_(nullptr),
       cq_(nullptr),
       sent_initial_metadata_(false) {}
@@ -109,6 +123,8 @@ ServerContext::ServerContext()
 ServerContext::ServerContext(gpr_timespec deadline, grpc_metadata* metadata,
                              size_t metadata_count)
     : completion_op_(nullptr),
+      has_notify_when_done_tag_(false),
+      async_notify_when_done_tag_(nullptr),
       deadline_(deadline),
       call_(nullptr),
       cq_(nullptr),
@@ -133,6 +149,9 @@ ServerContext::~ServerContext() {
 void ServerContext::BeginCompletionOp(Call* call) {
   GPR_ASSERT(!completion_op_);
   completion_op_ = new CompletionOp();
+  if (has_notify_when_done_tag_) {
+    completion_op_->set_tag(async_notify_when_done_tag_);
+  }
   call->PerformOps(completion_op_);
 }
 
diff --git a/src/csharp/Grpc.Auth/OAuth2Interceptors.cs b/src/csharp/Grpc.Auth/OAuth2Interceptors.cs
index c785ca5a16..cc9d2c175f 100644
--- a/src/csharp/Grpc.Auth/OAuth2Interceptors.cs
+++ b/src/csharp/Grpc.Auth/OAuth2Interceptors.cs
@@ -119,7 +119,5 @@ namespace Grpc.Auth
                 return new Metadata.Entry(AuthorizationHeader, Schema + " " + accessToken);
             }
         }
-
-
     }
 }
diff --git a/src/csharp/Grpc.Core.Tests/ChannelTest.cs b/src/csharp/Grpc.Core.Tests/ChannelTest.cs
new file mode 100644
index 0000000000..60b45176e5
--- /dev/null
+++ b/src/csharp/Grpc.Core.Tests/ChannelTest.cs
@@ -0,0 +1,91 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using Grpc.Core;
+using Grpc.Core.Internal;
+using Grpc.Core.Utils;
+using NUnit.Framework;
+
+namespace Grpc.Core.Tests
+{
+    public class ChannelTest
+    {
+        [TestFixtureTearDown]
+        public void CleanupClass()
+        {
+            GrpcEnvironment.Shutdown();
+        }
+
+        [Test]
+        public void Constructor_RejectsInvalidParams()
+        {
+            Assert.Throws(typeof(NullReferenceException), () => new Channel(null, Credentials.Insecure));
+        }
+
+        [Test]
+        public void State_IdleAfterCreation()
+        {
+            using (var channel = new Channel("localhost", Credentials.Insecure))
+            {
+                Assert.AreEqual(ChannelState.Idle, channel.State);
+            }
+        }
+
+        [Test]
+        public void WaitForStateChangedAsync_InvalidArgument()
+        {
+            using (var channel = new Channel("localhost", Credentials.Insecure))
+            {
+                Assert.Throws(typeof(ArgumentException), () => channel.WaitForStateChangedAsync(ChannelState.FatalFailure));
+            }
+        }
+
+        [Test]
+        public void Target()
+        {
+            using (var channel = new Channel("127.0.0.1", Credentials.Insecure))
+            {
+                Assert.IsTrue(channel.Target.Contains("127.0.0.1"));
+            }
+        }
+
+        [Test]
+        public void Dispose_IsIdempotent()
+        {
+            var channel = new Channel("localhost", Credentials.Insecure);
+            channel.Dispose();
+            channel.Dispose();
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core.Tests/ClientServerTest.cs b/src/csharp/Grpc.Core.Tests/ClientServerTest.cs
index 540fe756c0..c5fc85b3fe 100644
--- a/src/csharp/Grpc.Core.Tests/ClientServerTest.cs
+++ b/src/csharp/Grpc.Core.Tests/ClientServerTest.cs
@@ -46,42 +46,18 @@ namespace Grpc.Core.Tests
     public class ClientServerTest
     {
         const string Host = "127.0.0.1";
-        const string ServiceName = "/tests.Test";
-
-        static readonly Method<string, string> EchoMethod = new Method<string, string>(
-            MethodType.Unary,
-            "/tests.Test/Echo",
-            Marshallers.StringMarshaller,
-            Marshallers.StringMarshaller);
-
-        static readonly Method<string, string> ConcatAndEchoMethod = new Method<string, string>(
-            MethodType.ClientStreaming,
-            "/tests.Test/ConcatAndEcho",
-            Marshallers.StringMarshaller,
-            Marshallers.StringMarshaller);
-
-        static readonly Method<string, string> NonexistentMethod = new Method<string, string>(
-            MethodType.Unary,
-            "/tests.Test/NonexistentMethod",
-            Marshallers.StringMarshaller,
-            Marshallers.StringMarshaller);
-
-        static readonly ServerServiceDefinition ServiceDefinition = ServerServiceDefinition.CreateBuilder(ServiceName)
-            .AddMethod(EchoMethod, EchoHandler)
-            .AddMethod(ConcatAndEchoMethod, ConcatAndEchoHandler)
-            .Build();
 
+        MockServiceHelper helper;
         Server server;
         Channel channel;
 
         [SetUp]
         public void Init()
         {
-            server = new Server();
-            server.AddServiceDefinition(ServiceDefinition);
-            int port = server.AddPort(Host, Server.PickUnusedPort, ServerCredentials.Insecure);
+            helper = new MockServiceHelper(Host);
+            server = helper.GetServer();
             server.Start();
-            channel = new Channel(Host, port, Credentials.Insecure);
+            channel = helper.GetChannel();
         }
 
         [TearDown]
@@ -98,86 +74,79 @@ namespace Grpc.Core.Tests
         }
 
         [Test]
-        public void UnaryCall()
+        public async Task UnaryCall()
         {
-            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
-            Assert.AreEqual("ABC", Calls.BlockingUnaryCall(internalCall, "ABC", CancellationToken.None));
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                return request;
+            });
+
+            Assert.AreEqual("ABC", Calls.BlockingUnaryCall(helper.CreateUnaryCall(), "ABC"));
+
+            Assert.AreEqual("ABC", await Calls.AsyncUnaryCall(helper.CreateUnaryCall(), "ABC"));
         }
 
         [Test]
         public void UnaryCall_ServerHandlerThrows()
         {
-            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
-            try
-            {
-                Calls.BlockingUnaryCall(internalCall, "THROW", CancellationToken.None);
-                Assert.Fail();
-            }
-            catch (RpcException e)
+            helper.UnaryHandler = new UnaryServerMethod<string, string>((request, context) =>
             {
-                Assert.AreEqual(StatusCode.Unknown, e.Status.StatusCode); 
-            }
+                throw new Exception("This was thrown on purpose by a test");
+            });
+                
+            var ex = Assert.Throws<RpcException>(() => Calls.BlockingUnaryCall(helper.CreateUnaryCall(), "abc"));
+            Assert.AreEqual(StatusCode.Unknown, ex.Status.StatusCode); 
+
+            var ex2 = Assert.Throws<RpcException>(async () => await Calls.AsyncUnaryCall(helper.CreateUnaryCall(), "abc"));
+            Assert.AreEqual(StatusCode.Unknown, ex2.Status.StatusCode);
         }
 
         [Test]
         public void UnaryCall_ServerHandlerThrowsRpcException()
         {
-            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
-            try
+            helper.UnaryHandler = new UnaryServerMethod<string, string>((request, context) =>
             {
-                Calls.BlockingUnaryCall(internalCall, "THROW_UNAUTHENTICATED", CancellationToken.None);
-                Assert.Fail();
-            }
-            catch (RpcException e)
-            {
-                Assert.AreEqual(StatusCode.Unauthenticated, e.Status.StatusCode);
-            }
+                throw new RpcException(new Status(StatusCode.Unauthenticated, ""));
+            });
+
+            var ex = Assert.Throws<RpcException>(() => Calls.BlockingUnaryCall(helper.CreateUnaryCall(), "abc"));
+            Assert.AreEqual(StatusCode.Unauthenticated, ex.Status.StatusCode);
+
+            var ex2 = Assert.Throws<RpcException>(async () => await Calls.AsyncUnaryCall(helper.CreateUnaryCall(), "abc"));
+            Assert.AreEqual(StatusCode.Unauthenticated, ex2.Status.StatusCode);
         }
 
         [Test]
         public void UnaryCall_ServerHandlerSetsStatus()
         {
-            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
-            try
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
             {
-                Calls.BlockingUnaryCall(internalCall, "SET_UNAUTHENTICATED", CancellationToken.None);
-                Assert.Fail();
-            }
-            catch (RpcException e)
-            {
-                Assert.AreEqual(StatusCode.Unauthenticated, e.Status.StatusCode); 
-            }
-        }
+                context.Status = new Status(StatusCode.Unauthenticated, "");
+                return "";
+            });
 
-        [Test]
-        public void AsyncUnaryCall()
-        {
-            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
-            var result = Calls.AsyncUnaryCall(internalCall, "ABC", CancellationToken.None).ResponseAsync.Result;
-            Assert.AreEqual("ABC", result);
-        }
+            var ex = Assert.Throws<RpcException>(() => Calls.BlockingUnaryCall(helper.CreateUnaryCall(), "abc"));
+            Assert.AreEqual(StatusCode.Unauthenticated, ex.Status.StatusCode);
 
-        [Test]
-        public async Task AsyncUnaryCall_ServerHandlerThrows()
-        {
-            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
-            try
-            {
-                await Calls.AsyncUnaryCall(internalCall, "THROW", CancellationToken.None);
-                Assert.Fail();
-            }
-            catch (RpcException e)
-            {
-                Assert.AreEqual(StatusCode.Unknown, e.Status.StatusCode);
-            }
+            var ex2 = Assert.Throws<RpcException>(async () => await Calls.AsyncUnaryCall(helper.CreateUnaryCall(), "abc"));
+            Assert.AreEqual(StatusCode.Unauthenticated, ex2.Status.StatusCode);
         }
 
         [Test]
         public async Task ClientStreamingCall()
         {
-            var internalCall = new Call<string, string>(ServiceName, ConcatAndEchoMethod, channel, Metadata.Empty);
-            var call = Calls.AsyncClientStreamingCall(internalCall, CancellationToken.None);
+            helper.ClientStreamingHandler = new ClientStreamingServerMethod<string, string>(async (requestStream, context) =>
+            {
+                string result = "";
+                await requestStream.ForEach(async (request) =>
+                {
+                    result += request;
+                });
+                await Task.Delay(100);
+                return result;
+            });
 
+            var call = Calls.AsyncClientStreamingCall(helper.CreateClientStreamingCall());
             await call.RequestStream.WriteAll(new string[] { "A", "B", "C" });
             Assert.AreEqual("ABC", await call.ResponseAsync);
         }
@@ -185,37 +154,47 @@ namespace Grpc.Core.Tests
         [Test]
         public async Task ClientStreamingCall_CancelAfterBegin()
         {
-            var internalCall = new Call<string, string>(ServiceName, ConcatAndEchoMethod, channel, Metadata.Empty);
+            var barrier = new TaskCompletionSource<object>();
+
+            helper.ClientStreamingHandler = new ClientStreamingServerMethod<string, string>(async (requestStream, context) =>
+            {
+                barrier.SetResult(null);
+                await requestStream.ToList();
+                return "";
+            });
 
             var cts = new CancellationTokenSource();
-            var call = Calls.AsyncClientStreamingCall(internalCall, cts.Token);
+            var call = Calls.AsyncClientStreamingCall(helper.CreateClientStreamingCall(new CallOptions(cancellationToken: cts.Token)));
 
-            // TODO(jtattermusch): we need this to ensure call has been initiated once we cancel it.
-            await Task.Delay(1000);
+            await barrier.Task;  // make sure the handler has started.
             cts.Cancel();
 
-            try
-            {
-                await call.ResponseAsync;
-            }
-            catch (RpcException e)
-            {
-                Assert.AreEqual(StatusCode.Cancelled, e.Status.StatusCode);
-            }
+            var ex = Assert.Throws<RpcException>(async () => await call.ResponseAsync);
+            Assert.AreEqual(StatusCode.Cancelled, ex.Status.StatusCode);
         }
 
         [Test]
-        public void AsyncUnaryCall_EchoMetadata()
+        public async Task AsyncUnaryCall_EchoMetadata()
         {
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                foreach (Metadata.Entry metadataEntry in context.RequestHeaders)
+                {
+                    if (metadataEntry.Key != "user-agent")
+                    {
+                        context.ResponseTrailers.Add(metadataEntry);
+                    }
+                }
+                return "";
+            });
+
             var headers = new Metadata
             {
-                new Metadata.Entry("ascii-header", "abcdefg"),
-                new Metadata.Entry("binary-header-bin", new byte[] { 1, 2, 3, 0, 0xff }),
+                { "ascii-header", "abcdefg" },
+                { "binary-header-bin", new byte[] { 1, 2, 3, 0, 0xff } }
             };
-            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, headers);
-            var call = Calls.AsyncUnaryCall(internalCall, "ABC", CancellationToken.None);
-
-            Assert.AreEqual("ABC", call.ResponseAsync.Result);
+            var call = Calls.AsyncUnaryCall(helper.CreateUnaryCall(new CallOptions(headers: headers)), "ABC");
+            await call;
 
             Assert.AreEqual(StatusCode.OK, call.GetStatus().StatusCode);
 
@@ -232,102 +211,89 @@ namespace Grpc.Core.Tests
         public void UnaryCall_DisposedChannel()
         {
             channel.Dispose();
-
-            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
-            Assert.Throws(typeof(ObjectDisposedException), () => Calls.BlockingUnaryCall(internalCall, "ABC", CancellationToken.None));
+            Assert.Throws(typeof(ObjectDisposedException), () => Calls.BlockingUnaryCall(helper.CreateUnaryCall(), "ABC"));
         }
 
         [Test]
         public void UnaryCallPerformance()
         {
-            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                return request;
+            });
+
+            var callDetails = helper.CreateUnaryCall();
             BenchmarkUtil.RunBenchmark(100, 100,
-                                       () => { Calls.BlockingUnaryCall(internalCall, "ABC", default(CancellationToken)); });
+                                       () => { Calls.BlockingUnaryCall(callDetails, "ABC"); });
         }
             
         [Test]
         public void UnknownMethodHandler()
         {
-            var internalCall = new Call<string, string>(ServiceName, NonexistentMethod, channel, Metadata.Empty);
-            try
-            {
-                Calls.BlockingUnaryCall(internalCall, "ABC", default(CancellationToken));
-                Assert.Fail();
-            }
-            catch (RpcException e)
-            {
-                Assert.AreEqual(StatusCode.Unimplemented, e.Status.StatusCode);
-            }
+            var nonexistentMethod = new Method<string, string>(
+                MethodType.Unary,
+                MockServiceHelper.ServiceName,
+                "NonExistentMethod",
+                Marshallers.StringMarshaller,
+                Marshallers.StringMarshaller);
+
+            var callDetails = new CallInvocationDetails<string, string>(channel, nonexistentMethod, new CallOptions());
+
+            var ex = Assert.Throws<RpcException>(() => Calls.BlockingUnaryCall(callDetails, "abc"));
+            Assert.AreEqual(StatusCode.Unimplemented, ex.Status.StatusCode);
         }
 
         [Test]
         public void UserAgentStringPresent()
         {
-            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
-            string userAgent = Calls.BlockingUnaryCall(internalCall, "RETURN-USER-AGENT", CancellationToken.None);
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                return context.RequestHeaders.Where(entry => entry.Key == "user-agent").Single().Value;
+            });
+
+            string userAgent = Calls.BlockingUnaryCall(helper.CreateUnaryCall(), "abc");
             Assert.IsTrue(userAgent.StartsWith("grpc-csharp/"));
         }
 
         [Test]
         public void PeerInfoPresent()
         {
-            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
-            string peer = Calls.BlockingUnaryCall(internalCall, "RETURN-PEER", CancellationToken.None);
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                return context.Peer;
+            });
+
+            string peer = Calls.BlockingUnaryCall(helper.CreateUnaryCall(), "abc");
             Assert.IsTrue(peer.Contains(Host));
         }
 
-        private static async Task<string> EchoHandler(string request, ServerCallContext context)
+        [Test]
+        public async Task Channel_WaitForStateChangedAsync()
         {
-            foreach (Metadata.Entry metadataEntry in context.RequestHeaders)
-            {
-                if (metadataEntry.Key != "user-agent")
-                {
-                    context.ResponseTrailers.Add(metadataEntry);
-                }
-            }
-
-            if (request == "RETURN-USER-AGENT")
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
             {
-                return context.RequestHeaders.Where(entry => entry.Key == "user-agent").Single().Value;
-            }
+                return request;
+            });
 
-            if (request == "RETURN-PEER")
-            {
-                return context.Peer;
-            }
+            Assert.Throws(typeof(TaskCanceledException), 
+                async () => await channel.WaitForStateChangedAsync(channel.State, DateTime.UtcNow.AddMilliseconds(10)));
 
-            if (request == "THROW")
-            {
-                throw new Exception("This was thrown on purpose by a test");
-            }
+            var stateChangedTask = channel.WaitForStateChangedAsync(channel.State);
 
-            if (request == "THROW_UNAUTHENTICATED")
-            {
-                throw new RpcException(new Status(StatusCode.Unauthenticated, ""));
-            }
+            await Calls.AsyncUnaryCall(helper.CreateUnaryCall(), "abc");
 
-            if (request == "SET_UNAUTHENTICATED")
-            {
-                context.Status = new Status(StatusCode.Unauthenticated, "");
-            }
-
-            return request;
+            await stateChangedTask;
+            Assert.AreEqual(ChannelState.Ready, channel.State);
         }
 
-        private static async Task<string> ConcatAndEchoHandler(IAsyncStreamReader<string> requestStream, ServerCallContext context)
+        [Test]
+        public async Task Channel_ConnectAsync()
         {
-            string result = "";
-            await requestStream.ForEach(async (request) =>
-            {
-                if (request == "THROW")
-                {
-                    throw new Exception("This was thrown on purpose by a test");
-                }
-                result += request;
-            });
-            // simulate processing takes some time.
-            await Task.Delay(250);
-            return result;
+            await channel.ConnectAsync();
+            Assert.AreEqual(ChannelState.Ready, channel.State);
+
+            await channel.ConnectAsync(DateTime.UtcNow.AddMilliseconds(1000));
+            Assert.AreEqual(ChannelState.Ready, channel.State);
         }
     }
 }
diff --git a/src/csharp/Grpc.Core.Tests/CompressionTest.cs b/src/csharp/Grpc.Core.Tests/CompressionTest.cs
new file mode 100644
index 0000000000..ac0c3d6b5f
--- /dev/null
+++ b/src/csharp/Grpc.Core.Tests/CompressionTest.cs
@@ -0,0 +1,128 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Diagnostics;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Grpc.Core;
+using Grpc.Core.Internal;
+using Grpc.Core.Utils;
+using NUnit.Framework;
+
+namespace Grpc.Core.Tests
+{
+    public class CompressionTest
+    {
+        MockServiceHelper helper;
+        Server server;
+        Channel channel;
+
+        [SetUp]
+        public void Init()
+        {
+            helper = new MockServiceHelper();
+
+            server = helper.GetServer();
+            server.Start();
+            channel = helper.GetChannel();
+        }
+
+        [TearDown]
+        public void Cleanup()
+        {
+            channel.Dispose();
+            server.ShutdownAsync().Wait();
+        }
+
+        [TestFixtureTearDown]
+        public void CleanupClass()
+        {
+            GrpcEnvironment.Shutdown();
+        }
+
+        [Test]
+        public void WriteOptions_Unary()
+        {
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                context.WriteOptions = new WriteOptions(WriteFlags.NoCompress);
+                return request;
+            });
+
+            var callOptions = new CallOptions(writeOptions: new WriteOptions(WriteFlags.NoCompress));
+            Calls.BlockingUnaryCall(helper.CreateUnaryCall(callOptions), "abc");
+        }
+
+        [Test]
+        public async Task WriteOptions_DuplexStreaming()
+        {
+            helper.DuplexStreamingHandler = new DuplexStreamingServerMethod<string, string>(async (requestStream, responseStream, context) =>
+            {
+                await requestStream.ToList();
+
+                context.WriteOptions = new WriteOptions(WriteFlags.NoCompress);
+
+                await context.WriteResponseHeadersAsync(new Metadata { { "ascii-header", "abcdefg" } });
+
+                await responseStream.WriteAsync("X");
+
+                responseStream.WriteOptions = null;
+                await responseStream.WriteAsync("Y");
+
+                responseStream.WriteOptions = new WriteOptions(WriteFlags.NoCompress);
+                await responseStream.WriteAsync("Z");
+            });
+
+            var callOptions = new CallOptions(writeOptions: new WriteOptions(WriteFlags.NoCompress));
+            var call = Calls.AsyncDuplexStreamingCall(helper.CreateDuplexStreamingCall(callOptions));
+
+            // check that write options from call options are propagated to request stream.
+            Assert.IsTrue((call.RequestStream.WriteOptions.Flags & WriteFlags.NoCompress) != 0);
+
+            call.RequestStream.WriteOptions = new WriteOptions();
+            await call.RequestStream.WriteAsync("A");
+
+            call.RequestStream.WriteOptions = null;
+            await call.RequestStream.WriteAsync("B");
+
+            call.RequestStream.WriteOptions = new WriteOptions(WriteFlags.NoCompress);
+            await call.RequestStream.WriteAsync("C");
+
+            await call.RequestStream.CompleteAsync();
+
+            await call.ResponseStream.ToList();
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core.Tests/ContextPropagationTest.cs b/src/csharp/Grpc.Core.Tests/ContextPropagationTest.cs
new file mode 100644
index 0000000000..a7f5075874
--- /dev/null
+++ b/src/csharp/Grpc.Core.Tests/ContextPropagationTest.cs
@@ -0,0 +1,122 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Diagnostics;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Grpc.Core;
+using Grpc.Core.Internal;
+using Grpc.Core.Utils;
+using NUnit.Framework;
+
+namespace Grpc.Core.Tests
+{
+    public class ContextPropagationTest
+    {
+        MockServiceHelper helper;
+        Server server;
+        Channel channel;
+
+        [SetUp]
+        public void Init()
+        {
+            helper = new MockServiceHelper();
+
+            server = helper.GetServer();
+            server.Start();
+            channel = helper.GetChannel();
+        }
+
+        [TearDown]
+        public void Cleanup()
+        {
+            channel.Dispose();
+            server.ShutdownAsync().Wait();
+        }
+
+        [TestFixtureTearDown]
+        public void CleanupClass()
+        {
+            GrpcEnvironment.Shutdown();
+        }
+
+        [Test]
+        public async Task PropagateCancellation()
+        {
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                // check that we didn't obtain the default cancellation token.
+                Assert.IsTrue(context.CancellationToken.CanBeCanceled);
+                return "PASS";
+            });
+
+            helper.ClientStreamingHandler = new ClientStreamingServerMethod<string, string>(async (requestStream, context) =>
+            {
+                var propagationToken = context.CreatePropagationToken();
+                Assert.IsNotNull(propagationToken.ParentCall);
+
+                var callOptions = new CallOptions(propagationToken: propagationToken);
+                return await Calls.AsyncUnaryCall(helper.CreateUnaryCall(callOptions), "xyz");
+            });
+                
+            var cts = new CancellationTokenSource();
+            var call = Calls.AsyncClientStreamingCall(helper.CreateClientStreamingCall(new CallOptions(cancellationToken: cts.Token)));
+            await call.RequestStream.CompleteAsync();
+            Assert.AreEqual("PASS", await call);
+        }
+
+        [Test]
+        public async Task PropagateDeadline()
+        {
+            var deadline = DateTime.UtcNow.AddDays(7);
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                Assert.IsTrue(context.Deadline < deadline.AddMinutes(1));
+                Assert.IsTrue(context.Deadline > deadline.AddMinutes(-1));
+                return "PASS";
+            });
+
+            helper.ClientStreamingHandler = new ClientStreamingServerMethod<string, string>(async (requestStream, context) =>
+            {
+                var callOptions = new CallOptions(propagationToken: context.CreatePropagationToken());
+                return await Calls.AsyncUnaryCall(helper.CreateUnaryCall(callOptions), "xyz");
+            });
+                
+            var call = Calls.AsyncClientStreamingCall(helper.CreateClientStreamingCall(new CallOptions(deadline: deadline)));
+            await call.RequestStream.CompleteAsync();
+            Assert.AreEqual("PASS", await call);
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj b/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
index 242a60d098..97ee0454bb 100644
--- a/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
+++ b/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
@@ -76,6 +76,11 @@
     <Compile Include="Internal\TimespecTest.cs" />
     <Compile Include="TimeoutsTest.cs" />
     <Compile Include="NUnitVersionTest.cs" />
+    <Compile Include="ChannelTest.cs" />
+    <Compile Include="MockServiceHelper.cs" />
+    <Compile Include="ResponseHeadersTest.cs" />
+    <Compile Include="CompressionTest.cs" />
+    <Compile Include="ContextPropagationTest.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <ItemGroup>
diff --git a/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs b/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs
index 9ae12776f3..4ed93c7eca 100644
--- a/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs
+++ b/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs
@@ -69,5 +69,13 @@ namespace Grpc.Core.Tests
 
             Assert.IsFalse(object.ReferenceEquals(env1, env2));
         }
+
+        [Test]
+        public void GetCoreVersionString()
+        {
+            var coreVersion = GrpcEnvironment.GetCoreVersionString();
+            var parts = coreVersion.Split('.');
+            Assert.AreEqual(4, parts.Length);
+        }
     }
 }
diff --git a/src/csharp/Grpc.Core.Tests/Internal/MetadataArraySafeHandleTest.cs b/src/csharp/Grpc.Core.Tests/Internal/MetadataArraySafeHandleTest.cs
index 46469113c5..33534fdd3c 100644
--- a/src/csharp/Grpc.Core.Tests/Internal/MetadataArraySafeHandleTest.cs
+++ b/src/csharp/Grpc.Core.Tests/Internal/MetadataArraySafeHandleTest.cs
@@ -53,8 +53,8 @@ namespace Grpc.Core.Internal.Tests
         {
             var metadata = new Metadata
             {
-                new Metadata.Entry("host", "somehost"),
-                new Metadata.Entry("header2", "header value"),
+                { "host", "somehost" },
+                { "header2", "header value" },
             };
             var nativeMetadata = MetadataArraySafeHandle.Create(metadata);
             nativeMetadata.Dispose();
@@ -65,8 +65,8 @@ namespace Grpc.Core.Internal.Tests
         {
             var metadata = new Metadata
             {
-                new Metadata.Entry("host", "somehost"),
-                new Metadata.Entry("header2", "header value"),
+                { "host", "somehost" },
+                { "header2", "header value" }
             };
             var nativeMetadata = MetadataArraySafeHandle.Create(metadata);
 
diff --git a/src/csharp/Grpc.Core.Tests/MockServiceHelper.cs b/src/csharp/Grpc.Core.Tests/MockServiceHelper.cs
new file mode 100644
index 0000000000..b642286b11
--- /dev/null
+++ b/src/csharp/Grpc.Core.Tests/MockServiceHelper.cs
@@ -0,0 +1,248 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Diagnostics;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Grpc.Core;
+using Grpc.Core.Internal;
+using Grpc.Core.Utils;
+using NUnit.Framework;
+
+namespace Grpc.Core.Tests
+{
+    /// <summary>
+    /// Allows setting up a mock service in the client-server tests easily.
+    /// </summary>
+    public class MockServiceHelper
+    {
+        public const string ServiceName = "tests.Test";
+
+        public static readonly Method<string, string> UnaryMethod = new Method<string, string>(
+            MethodType.Unary,
+            ServiceName,
+            "Unary",
+            Marshallers.StringMarshaller,
+            Marshallers.StringMarshaller);
+
+        public static readonly Method<string, string> ClientStreamingMethod = new Method<string, string>(
+            MethodType.ClientStreaming,
+            ServiceName,
+            "ClientStreaming",
+            Marshallers.StringMarshaller,
+            Marshallers.StringMarshaller);
+
+        public static readonly Method<string, string> ServerStreamingMethod = new Method<string, string>(
+            MethodType.ServerStreaming,
+            ServiceName,
+            "ServerStreaming",
+            Marshallers.StringMarshaller,
+            Marshallers.StringMarshaller);
+
+        public static readonly Method<string, string> DuplexStreamingMethod = new Method<string, string>(
+            MethodType.DuplexStreaming,
+            ServiceName,
+            "DuplexStreaming",
+            Marshallers.StringMarshaller,
+            Marshallers.StringMarshaller);
+
+        readonly string host;
+        readonly ServerServiceDefinition serviceDefinition;
+
+        UnaryServerMethod<string, string> unaryHandler;
+        ClientStreamingServerMethod<string, string> clientStreamingHandler;
+        ServerStreamingServerMethod<string, string> serverStreamingHandler;
+        DuplexStreamingServerMethod<string, string> duplexStreamingHandler;
+
+        Server server;
+        Channel channel;
+
+        public MockServiceHelper(string host = null)
+        {
+            this.host = host ?? "localhost";
+
+            serviceDefinition = ServerServiceDefinition.CreateBuilder(ServiceName)
+                .AddMethod(UnaryMethod, (request, context) => unaryHandler(request, context))
+                .AddMethod(ClientStreamingMethod, (requestStream, context) => clientStreamingHandler(requestStream, context))
+                .AddMethod(ServerStreamingMethod, (request, responseStream, context) => serverStreamingHandler(request, responseStream, context))
+                .AddMethod(DuplexStreamingMethod, (requestStream, responseStream, context) => duplexStreamingHandler(requestStream, responseStream, context))
+                .Build();
+
+            var defaultStatus = new Status(StatusCode.Unknown, "Default mock implementation. Please provide your own.");
+
+            unaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                context.Status = defaultStatus;
+                return "";
+            });
+
+            clientStreamingHandler = new ClientStreamingServerMethod<string, string>(async (requestStream, context) =>
+            {
+                context.Status = defaultStatus;
+                return "";
+            });
+
+            serverStreamingHandler = new ServerStreamingServerMethod<string, string>(async (request, responseStream, context) =>
+            {
+                context.Status = defaultStatus;
+            });
+
+            duplexStreamingHandler = new DuplexStreamingServerMethod<string, string>(async (requestStream, responseStream, context) =>
+            {
+                context.Status = defaultStatus;
+            });
+        }
+
+        /// <summary>
+        /// Returns the default server for this service and creates one if not yet created.
+        /// </summary>
+        public Server GetServer()
+        {
+            if (server == null)
+            {
+                server = new Server
+                {
+                    Services = { serviceDefinition },
+                    Ports = { { Host, ServerPort.PickUnused, ServerCredentials.Insecure } }
+                };
+            }
+            return server;
+        }
+
+        /// <summary>
+        /// Returns the default channel for this service and creates one if not yet created.
+        /// </summary>
+        public Channel GetChannel()
+        {
+            if (channel == null)
+            {
+                channel = new Channel(Host, GetServer().Ports.Single().BoundPort, Credentials.Insecure);
+            }
+            return channel;
+        }
+
+        public CallInvocationDetails<string, string> CreateUnaryCall(CallOptions options = null)
+        {
+            options = options ?? new CallOptions();
+            return new CallInvocationDetails<string, string>(channel, UnaryMethod, options);
+        }
+
+        public CallInvocationDetails<string, string> CreateClientStreamingCall(CallOptions options = null)
+        {
+            options = options ?? new CallOptions();
+            return new CallInvocationDetails<string, string>(channel, ClientStreamingMethod, options);
+        }
+
+        public CallInvocationDetails<string, string> CreateServerStreamingCall(CallOptions options = null)
+        {
+            options = options ?? new CallOptions();
+            return new CallInvocationDetails<string, string>(channel, ServerStreamingMethod, options);
+        }
+
+        public CallInvocationDetails<string, string> CreateDuplexStreamingCall(CallOptions options = null)
+        {
+            options = options ?? new CallOptions();
+            return new CallInvocationDetails<string, string>(channel, DuplexStreamingMethod, options);
+        }
+
+        public string Host
+        {
+            get
+            {
+                return this.host;
+            }
+        }
+
+        public ServerServiceDefinition ServiceDefinition
+        {
+            get
+            {
+                return this.serviceDefinition;
+            }
+        }
+      
+        public UnaryServerMethod<string, string> UnaryHandler
+        {
+            get
+            {
+                return this.unaryHandler;
+            }
+
+            set
+            {
+                unaryHandler = value;
+            }
+        }
+
+        public ClientStreamingServerMethod<string, string> ClientStreamingHandler
+        {
+            get
+            {
+                return this.clientStreamingHandler;
+            }
+
+            set
+            {
+                clientStreamingHandler = value;
+            }
+        }
+
+        public ServerStreamingServerMethod<string, string> ServerStreamingHandler
+        {
+            get
+            {
+                return this.serverStreamingHandler;
+            }
+
+            set
+            {
+                serverStreamingHandler = value;
+            }
+        }
+
+        public DuplexStreamingServerMethod<string, string> DuplexStreamingHandler
+        {
+            get
+            {
+                return this.duplexStreamingHandler;
+            }
+
+            set
+            {
+                duplexStreamingHandler = value;
+            }
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core.Tests/NUnitVersionTest.cs b/src/csharp/Grpc.Core.Tests/NUnitVersionTest.cs
index 600df1a18d..3fa6ad09c0 100644
--- a/src/csharp/Grpc.Core.Tests/NUnitVersionTest.cs
+++ b/src/csharp/Grpc.Core.Tests/NUnitVersionTest.cs
@@ -70,10 +70,8 @@ namespace Grpc.Core.Tests
         [Test]
         public async Task NUnitVersionTest2()
         {
-            testRunCount ++;
+            testRunCount++;
             await Task.Delay(10);
         }
-
-
     }
 }
diff --git a/src/csharp/Grpc.Core.Tests/ResponseHeadersTest.cs b/src/csharp/Grpc.Core.Tests/ResponseHeadersTest.cs
new file mode 100644
index 0000000000..8925041ba4
--- /dev/null
+++ b/src/csharp/Grpc.Core.Tests/ResponseHeadersTest.cs
@@ -0,0 +1,136 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Diagnostics;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Grpc.Core;
+using Grpc.Core.Internal;
+using Grpc.Core.Utils;
+using NUnit.Framework;
+
+namespace Grpc.Core.Tests
+{
+    /// <summary>
+    /// Tests for response headers support.
+    /// </summary>
+    public class ResponseHeadersTest
+    {
+        MockServiceHelper helper;
+        Server server;
+        Channel channel;
+
+        Metadata headers;
+
+        [SetUp]
+        public void Init()
+        {
+            helper = new MockServiceHelper();
+
+            server = helper.GetServer();
+            server.Start();
+            channel = helper.GetChannel();
+
+            headers = new Metadata { { "ascii-header", "abcdefg" } };
+        }
+
+        [TearDown]
+        public void Cleanup()
+        {
+            channel.Dispose();
+            server.ShutdownAsync().Wait();
+        }
+
+        [TestFixtureTearDown]
+        public void CleanupClass()
+        {
+            GrpcEnvironment.Shutdown();
+        }
+
+        [Test]
+        public void WriteResponseHeaders_NullNotAllowed()
+        {
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                Assert.Throws(typeof(NullReferenceException), async () => await context.WriteResponseHeadersAsync(null));
+                return "PASS";
+            });
+
+            Assert.AreEqual("PASS", Calls.BlockingUnaryCall(helper.CreateUnaryCall(), ""));
+        }
+
+        [Test]
+        public void WriteResponseHeaders_AllowedOnlyOnce()
+        {
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                await context.WriteResponseHeadersAsync(headers);
+                try
+                {
+                    await context.WriteResponseHeadersAsync(headers);
+                    Assert.Fail();
+                }
+                catch (InvalidOperationException expected)
+                {
+                }
+                return "PASS";
+            });
+                
+            Assert.AreEqual("PASS", Calls.BlockingUnaryCall(helper.CreateUnaryCall(), ""));
+        }
+
+        [Test]
+        public async Task WriteResponseHeaders_NotAllowedAfterWrite()
+        {
+            helper.ServerStreamingHandler = new ServerStreamingServerMethod<string, string>(async (request, responseStream, context) =>
+            {
+                await responseStream.WriteAsync("A");
+                try
+                {
+                    await context.WriteResponseHeadersAsync(headers);
+                    Assert.Fail();
+                }
+                catch (InvalidOperationException expected)
+                {
+                }
+                await responseStream.WriteAsync("B");
+            });
+
+            var call = Calls.AsyncServerStreamingCall(helper.CreateServerStreamingCall(), "");
+            var responses = await call.ResponseStream.ToList();
+            CollectionAssert.AreEqual(new[] { "A", "B" }, responses);
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core.Tests/ServerTest.cs b/src/csharp/Grpc.Core.Tests/ServerTest.cs
index ba9efae871..485006ebac 100644
--- a/src/csharp/Grpc.Core.Tests/ServerTest.cs
+++ b/src/csharp/Grpc.Core.Tests/ServerTest.cs
@@ -32,6 +32,7 @@
 #endregion
 
 using System;
+using System.Linq;
 using Grpc.Core;
 using Grpc.Core.Internal;
 using Grpc.Core.Utils;
@@ -44,11 +45,45 @@ namespace Grpc.Core.Tests
         [Test]
         public void StartAndShutdownServer()
         {
-            Server server = new Server();
-            server.AddPort("localhost", Server.PickUnusedPort, ServerCredentials.Insecure);
+            Server server = new Server
+            {
+                Ports = { new ServerPort("localhost", ServerPort.PickUnused, ServerCredentials.Insecure) }
+            };
             server.Start();
             server.ShutdownAsync().Wait();
             GrpcEnvironment.Shutdown();
         }
+
+        [Test]
+        public void PickUnusedPort()
+        {
+            Server server = new Server
+            {
+                Ports = { new ServerPort("localhost", ServerPort.PickUnused, ServerCredentials.Insecure) }
+            };
+
+            var boundPort = server.Ports.Single();
+            Assert.AreEqual(0, boundPort.Port);
+            Assert.Greater(boundPort.BoundPort, 0);
+
+            server.Start();
+            server.ShutdownAsync();
+            GrpcEnvironment.Shutdown();
+        }
+
+        [Test]
+        public void CannotModifyAfterStarted()
+        {
+            Server server = new Server
+            {
+                Ports = { new ServerPort("localhost", ServerPort.PickUnused, ServerCredentials.Insecure) }
+            };
+            server.Start();
+            Assert.Throws(typeof(InvalidOperationException), () => server.Ports.Add("localhost", 9999, ServerCredentials.Insecure));
+            Assert.Throws(typeof(InvalidOperationException), () => server.Services.Add(ServerServiceDefinition.CreateBuilder("serviceName").Build()));
+
+            server.ShutdownAsync().Wait();
+            GrpcEnvironment.Shutdown();
+        }
     }
 }
diff --git a/src/csharp/Grpc.Core.Tests/TimeoutsTest.cs b/src/csharp/Grpc.Core.Tests/TimeoutsTest.cs
index 010ffd898a..d875d601b9 100644
--- a/src/csharp/Grpc.Core.Tests/TimeoutsTest.cs
+++ b/src/csharp/Grpc.Core.Tests/TimeoutsTest.cs
@@ -48,35 +48,18 @@ namespace Grpc.Core.Tests
     /// </summary>
     public class TimeoutsTest
     {
-        const string Host = "localhost";
-        const string ServiceName = "/tests.Test";
-
-        static readonly Method<string, string> TestMethod = new Method<string, string>(
-            MethodType.Unary,
-            "/tests.Test/Test",
-            Marshallers.StringMarshaller,
-            Marshallers.StringMarshaller);
-
-        static readonly ServerServiceDefinition ServiceDefinition = ServerServiceDefinition.CreateBuilder(ServiceName)
-            .AddMethod(TestMethod, TestMethodHandler)
-            .Build();
-
-        // provides a way how to retrieve an out-of-band result value from server handler
-        static TaskCompletionSource<string> stringFromServerHandlerTcs;
-
+        MockServiceHelper helper;
         Server server;
         Channel channel;
 
         [SetUp]
         public void Init()
         {
-            server = new Server();
-            server.AddServiceDefinition(ServiceDefinition);
-            int port = server.AddPort(Host, Server.PickUnusedPort, ServerCredentials.Insecure);
-            server.Start();
-            channel = new Channel(Host, port, Credentials.Insecure);
+            helper = new MockServiceHelper();
 
-            stringFromServerHandlerTcs = new TaskCompletionSource<string>();
+            server = helper.GetServer();
+            server.Start();
+            channel = helper.GetChannel();
         }
 
         [TearDown]
@@ -95,113 +78,83 @@ namespace Grpc.Core.Tests
         [Test]
         public void InfiniteDeadline()
         {
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                Assert.AreEqual(DateTime.MaxValue, context.Deadline);
+                return "PASS";
+            });
+
             // no deadline specified, check server sees infinite deadline
-            var internalCall = new Call<string, string>(ServiceName, TestMethod, channel, Metadata.Empty);
-            Assert.AreEqual("DATETIME_MAXVALUE", Calls.BlockingUnaryCall(internalCall, "RETURN_DEADLINE", CancellationToken.None));
+            Assert.AreEqual("PASS", Calls.BlockingUnaryCall(helper.CreateUnaryCall(), "abc"));
 
             // DateTime.MaxValue deadline specified, check server sees infinite deadline
-            var internalCall2 = new Call<string, string>(ServiceName, TestMethod, channel, Metadata.Empty, DateTime.MaxValue);
-            Assert.AreEqual("DATETIME_MAXVALUE", Calls.BlockingUnaryCall(internalCall2, "RETURN_DEADLINE", CancellationToken.None));
+            Assert.AreEqual("PASS", Calls.BlockingUnaryCall(helper.CreateUnaryCall(new CallOptions(deadline: DateTime.MaxValue)), "abc"));
         }
 
         [Test]
         public void DeadlineTransferredToServer()
         {
-            var remainingTimeClient = TimeSpan.FromDays(7);
-            var deadline = DateTime.UtcNow + remainingTimeClient;
-            Thread.Sleep(1000);
-            var internalCall = new Call<string, string>(ServiceName, TestMethod, channel, Metadata.Empty, deadline);
-
-            var serverDeadlineTicksString = Calls.BlockingUnaryCall(internalCall, "RETURN_DEADLINE", CancellationToken.None);
-            var serverDeadline = new DateTime(long.Parse(serverDeadlineTicksString), DateTimeKind.Utc);
-
-            // A fairly relaxed check that the deadline set by client and deadline seen by server
-            // are in agreement. C core takes care of the work with transferring deadline over the wire,
-            // so we don't need an exact check here.
-            Assert.IsTrue(Math.Abs((deadline - serverDeadline).TotalMilliseconds) < 5000);
+            var clientDeadline = DateTime.UtcNow + TimeSpan.FromDays(7);
+
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                // A fairly relaxed check that the deadline set by client and deadline seen by server
+                // are in agreement. C core takes care of the work with transferring deadline over the wire,
+                // so we don't need an exact check here.
+                Assert.IsTrue(Math.Abs((clientDeadline - context.Deadline).TotalMilliseconds) < 5000);
+                return "PASS";
+            });
+            Calls.BlockingUnaryCall(helper.CreateUnaryCall(new CallOptions(deadline: clientDeadline)), "abc");
         }
 
         [Test]
         public void DeadlineInThePast()
         {
-            var deadline = DateTime.MinValue;
-            var internalCall = new Call<string, string>(ServiceName, TestMethod, channel, Metadata.Empty, deadline);
-
-            try
-            {
-                Calls.BlockingUnaryCall(internalCall, "TIMEOUT", CancellationToken.None);
-                Assert.Fail();
-            }
-            catch (RpcException e)
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
             {
-                Assert.AreEqual(StatusCode.DeadlineExceeded, e.Status.StatusCode);
-            }
+                await Task.Delay(60000);
+                return "FAIL";
+            });
+
+            var ex = Assert.Throws<RpcException>(() => Calls.BlockingUnaryCall(helper.CreateUnaryCall(new CallOptions(deadline: DateTime.MinValue)), "abc"));
+            // We can't guarantee the status code always DeadlineExceeded. See issue #2685.
+            Assert.Contains(ex.Status.StatusCode, new[] { StatusCode.DeadlineExceeded, StatusCode.Internal });
         }
 
         [Test]
         public void DeadlineExceededStatusOnTimeout()
         {
-            var deadline = DateTime.UtcNow.Add(TimeSpan.FromSeconds(5));
-            var internalCall = new Call<string, string>(ServiceName, TestMethod, channel, Metadata.Empty, deadline);
-
-            try
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
             {
-                Calls.BlockingUnaryCall(internalCall, "TIMEOUT", CancellationToken.None);
-                Assert.Fail();
-            }
-            catch (RpcException e)
-            {
-                Assert.AreEqual(StatusCode.DeadlineExceeded, e.Status.StatusCode);
-            }
+                await Task.Delay(60000);
+                return "FAIL";
+            });
+
+            var ex = Assert.Throws<RpcException>(() => Calls.BlockingUnaryCall(helper.CreateUnaryCall(new CallOptions(deadline: DateTime.UtcNow.Add(TimeSpan.FromSeconds(5)))), "abc"));
+            // We can't guarantee the status code always DeadlineExceeded. See issue #2685.
+            Assert.Contains(ex.Status.StatusCode, new[] { StatusCode.DeadlineExceeded, StatusCode.Internal });
         }
 
         [Test]
-        public void ServerReceivesCancellationOnTimeout()
+        public async Task ServerReceivesCancellationOnTimeout()
         {
-            var deadline = DateTime.UtcNow.Add(TimeSpan.FromSeconds(5));
-            var internalCall = new Call<string, string>(ServiceName, TestMethod, channel, Metadata.Empty, deadline);
+            var serverReceivedCancellationTcs = new TaskCompletionSource<bool>();
 
-            try
-            {
-                Calls.BlockingUnaryCall(internalCall, "CHECK_CANCELLATION_RECEIVED", CancellationToken.None);
-                Assert.Fail();
-            }
-            catch (RpcException e)
-            {
-                Assert.AreEqual(StatusCode.DeadlineExceeded, e.Status.StatusCode);
-            }
-            Assert.AreEqual("CANCELLED", stringFromServerHandlerTcs.Task.Result);
-        }
-            
-        private static async Task<string> TestMethodHandler(string request, ServerCallContext context)
-        {
-            if (request == "TIMEOUT")
-            {
-                await Task.Delay(60000);
-                return "";
-            }
-
-            if (request == "RETURN_DEADLINE")
-            {
-                if (context.Deadline == DateTime.MaxValue)
-                {
-                    return "DATETIME_MAXVALUE";
-                }
-
-                return context.Deadline.Ticks.ToString();
-            }
-
-            if (request == "CHECK_CANCELLATION_RECEIVED")
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) => 
             {
                 // wait until cancellation token is fired.
                 var tcs = new TaskCompletionSource<object>();
                 context.CancellationToken.Register(() => { tcs.SetResult(null); });
                 await tcs.Task;
-                stringFromServerHandlerTcs.SetResult("CANCELLED");
+                serverReceivedCancellationTcs.SetResult(true);
                 return "";
-            }
+            });
+
+            var ex = Assert.Throws<RpcException>(() => Calls.BlockingUnaryCall(helper.CreateUnaryCall(new CallOptions(deadline: DateTime.UtcNow.Add(TimeSpan.FromSeconds(5)))), "abc"));
+            // We can't guarantee the status code always DeadlineExceeded. See issue #2685.
+            Assert.Contains(ex.Status.StatusCode, new[] { StatusCode.DeadlineExceeded, StatusCode.Internal });
 
-            return "";
+            Assert.IsTrue(await serverReceivedCancellationTcs.Task);
         }
     }
 }
diff --git a/src/csharp/Grpc.Core/Call.cs b/src/csharp/Grpc.Core/CallInvocationDetails.cs
index 94c5e26082..eb23a3a209 100644
--- a/src/csharp/Grpc.Core/Call.cs
+++ b/src/csharp/Grpc.Core/CallInvocationDetails.cs
@@ -38,30 +38,30 @@ using Grpc.Core.Utils;
 namespace Grpc.Core
 {
     /// <summary>
-    /// Abstraction of a call to be invoked on a client.
+    /// Details about a client-side call to be invoked.
     /// </summary>
-    public class Call<TRequest, TResponse>
+    public class CallInvocationDetails<TRequest, TResponse>
     {
-        readonly string name;
+        readonly Channel channel;
+        readonly string method;
+        readonly string host;
         readonly Marshaller<TRequest> requestMarshaller;
         readonly Marshaller<TResponse> responseMarshaller;
-        readonly Channel channel;
-        readonly Metadata headers;
-        readonly DateTime deadline;
+        readonly CallOptions options;
 
-        public Call(string serviceName, Method<TRequest, TResponse> method, Channel channel, Metadata headers)
-            : this(serviceName, method, channel, headers, DateTime.MaxValue)
+        public CallInvocationDetails(Channel channel, Method<TRequest, TResponse> method, CallOptions options) :
+            this(channel, method.FullName, null, method.RequestMarshaller, method.ResponseMarshaller, options)
         {
         }
 
-        public Call(string serviceName, Method<TRequest, TResponse> method, Channel channel, Metadata headers, DateTime deadline)
+        public CallInvocationDetails(Channel channel, string method, string host, Marshaller<TRequest> requestMarshaller, Marshaller<TResponse> responseMarshaller, CallOptions options)
         {
-            this.name = method.GetFullName(serviceName);
-            this.requestMarshaller = method.RequestMarshaller;
-            this.responseMarshaller = method.ResponseMarshaller;
             this.channel = Preconditions.CheckNotNull(channel);
-            this.headers = Preconditions.CheckNotNull(headers);
-            this.deadline = deadline;
+            this.method = Preconditions.CheckNotNull(method);
+            this.host = host;
+            this.requestMarshaller = Preconditions.CheckNotNull(requestMarshaller);
+            this.responseMarshaller = Preconditions.CheckNotNull(responseMarshaller);
+            this.options = Preconditions.CheckNotNull(options);
         }
 
         public Channel Channel
@@ -72,49 +72,43 @@ namespace Grpc.Core
             }
         }
 
-        /// <summary>
-        /// Full methods name including the service name.
-        /// </summary>
-        public string Name
+        public string Method
         {
             get
             {
-                return name;
+                return this.method;
             }
         }
 
-        /// <summary>
-        /// Headers to send at the beginning of the call.
-        /// </summary>
-        public Metadata Headers
+        public string Host
         {
             get
             {
-                return headers;
+                return this.host;
             }
         }
 
-        public DateTime Deadline
+        public Marshaller<TRequest> RequestMarshaller
         {
             get
             {
-                return this.deadline;
+                return this.requestMarshaller;
             }
         }
 
-        public Marshaller<TRequest> RequestMarshaller
+        public Marshaller<TResponse> ResponseMarshaller
         {
             get
             {
-                return requestMarshaller;
+                return this.responseMarshaller;
             }
         }
-
-        public Marshaller<TResponse> ResponseMarshaller
+            
+        public CallOptions Options
         {
             get
             {
-                return responseMarshaller;
+                return options;
             }
         }
     }
diff --git a/src/csharp/Grpc.Core/CallOptions.cs b/src/csharp/Grpc.Core/CallOptions.cs
new file mode 100644
index 0000000000..0d82b5a28e
--- /dev/null
+++ b/src/csharp/Grpc.Core/CallOptions.cs
@@ -0,0 +1,118 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Threading;
+
+using Grpc.Core.Internal;
+using Grpc.Core.Utils;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// Options for calls made by client.
+    /// </summary>
+    public class CallOptions
+    {
+        readonly Metadata headers;
+        readonly DateTime deadline;
+        readonly CancellationToken cancellationToken;
+        readonly WriteOptions writeOptions;
+        readonly ContextPropagationToken propagationToken;
+
+        /// <summary>
+        /// Creates a new instance of <c>CallOptions</c>.
+        /// </summary>
+        /// <param name="headers">Headers to be sent with the call.</param>
+        /// <param name="deadline">Deadline for the call to finish. null means no deadline.</param>
+        /// <param name="cancellationToken">Can be used to request cancellation of the call.</param>
+        /// <param name="writeOptions">Write options that will be used for this call.</param>
+        /// <param name="propagationToken">Context propagation token obtained from <see cref="ServerCallContext"/>.</param>
+        public CallOptions(Metadata headers = null, DateTime? deadline = null, CancellationToken? cancellationToken = null,
+                           WriteOptions writeOptions = null, ContextPropagationToken propagationToken = null)
+        {
+            // TODO(jtattermusch): consider only creating metadata object once it's really needed.
+            this.headers = headers ?? new Metadata();
+            this.deadline = deadline ?? (propagationToken != null ? propagationToken.Deadline : DateTime.MaxValue);
+            this.cancellationToken = cancellationToken ?? (propagationToken != null ? propagationToken.CancellationToken : CancellationToken.None);
+            this.writeOptions = writeOptions;
+            this.propagationToken = propagationToken;
+        }
+
+        /// <summary>
+        /// Headers to send at the beginning of the call.
+        /// </summary>
+        public Metadata Headers
+        {
+            get { return headers; }
+        }
+
+        /// <summary>
+        /// Call deadline.
+        /// </summary>
+        public DateTime Deadline
+        {
+            get { return deadline; }
+        }
+
+        /// <summary>
+        /// Token that can be used for cancelling the call.
+        /// </summary>
+        public CancellationToken CancellationToken
+        {
+            get { return cancellationToken; }
+        }
+
+        /// <summary>
+        /// Write options that will be used for this call.
+        /// </summary>
+        public WriteOptions WriteOptions
+        {
+            get
+            {
+                return this.writeOptions;
+            }
+        }
+
+        /// <summary>
+        /// Token for propagating parent call context.
+        /// </summary>
+        public ContextPropagationToken PropagationToken
+        {
+            get
+            {
+                return this.propagationToken;
+            }
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core/Calls.cs b/src/csharp/Grpc.Core/Calls.cs
index 054fc27491..00a8cabf82 100644
--- a/src/csharp/Grpc.Core/Calls.cs
+++ b/src/csharp/Grpc.Core/Calls.cs
@@ -43,70 +43,52 @@ namespace Grpc.Core
     /// </summary>
     public static class Calls
     {
-        public static TResponse BlockingUnaryCall<TRequest, TResponse>(Call<TRequest, TResponse> call, TRequest req, CancellationToken token)
+        public static TResponse BlockingUnaryCall<TRequest, TResponse>(CallInvocationDetails<TRequest, TResponse> call, TRequest req)
             where TRequest : class
             where TResponse : class
         {
-            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            // TODO(jtattermusch): this gives a race that cancellation can be requested before the call even starts.
-            RegisterCancellationCallback(asyncCall, token);
-            return asyncCall.UnaryCall(call.Channel, call.Name, req, call.Headers, call.Deadline);
+            var asyncCall = new AsyncCall<TRequest, TResponse>(call);
+            return asyncCall.UnaryCall(req);
         }
 
-        public static AsyncUnaryCall<TResponse> AsyncUnaryCall<TRequest, TResponse>(Call<TRequest, TResponse> call, TRequest req, CancellationToken token)
+        public static AsyncUnaryCall<TResponse> AsyncUnaryCall<TRequest, TResponse>(CallInvocationDetails<TRequest, TResponse> call, TRequest req)
             where TRequest : class
             where TResponse : class
         {
-            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name, Timespec.FromDateTime(call.Deadline));
-            var asyncResult = asyncCall.UnaryCallAsync(req, call.Headers, call.Deadline);
-            RegisterCancellationCallback(asyncCall, token);
+            var asyncCall = new AsyncCall<TRequest, TResponse>(call);
+            var asyncResult = asyncCall.UnaryCallAsync(req);
             return new AsyncUnaryCall<TResponse>(asyncResult, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
         }
 
-        public static AsyncServerStreamingCall<TResponse> AsyncServerStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, TRequest req, CancellationToken token)
+        public static AsyncServerStreamingCall<TResponse> AsyncServerStreamingCall<TRequest, TResponse>(CallInvocationDetails<TRequest, TResponse> call, TRequest req)
             where TRequest : class
             where TResponse : class
         {
-            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name, Timespec.FromDateTime(call.Deadline));
-            asyncCall.StartServerStreamingCall(req, call.Headers, call.Deadline);
-            RegisterCancellationCallback(asyncCall, token);
+            var asyncCall = new AsyncCall<TRequest, TResponse>(call);
+            asyncCall.StartServerStreamingCall(req);
             var responseStream = new ClientResponseStream<TRequest, TResponse>(asyncCall);
             return new AsyncServerStreamingCall<TResponse>(responseStream, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
         }
 
-        public static AsyncClientStreamingCall<TRequest, TResponse> AsyncClientStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, CancellationToken token)
+        public static AsyncClientStreamingCall<TRequest, TResponse> AsyncClientStreamingCall<TRequest, TResponse>(CallInvocationDetails<TRequest, TResponse> call)
             where TRequest : class
             where TResponse : class
         {
-            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name, Timespec.FromDateTime(call.Deadline));
-            var resultTask = asyncCall.ClientStreamingCallAsync(call.Headers, call.Deadline);
-            RegisterCancellationCallback(asyncCall, token);
+            var asyncCall = new AsyncCall<TRequest, TResponse>(call);
+            var resultTask = asyncCall.ClientStreamingCallAsync();
             var requestStream = new ClientRequestStream<TRequest, TResponse>(asyncCall);
             return new AsyncClientStreamingCall<TRequest, TResponse>(requestStream, resultTask, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
         }
 
-        public static AsyncDuplexStreamingCall<TRequest, TResponse> AsyncDuplexStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, CancellationToken token)
+        public static AsyncDuplexStreamingCall<TRequest, TResponse> AsyncDuplexStreamingCall<TRequest, TResponse>(CallInvocationDetails<TRequest, TResponse> call)
             where TRequest : class
             where TResponse : class
         {
-            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name, Timespec.FromDateTime(call.Deadline));
-            asyncCall.StartDuplexStreamingCall(call.Headers, call.Deadline);
-            RegisterCancellationCallback(asyncCall, token);
+            var asyncCall = new AsyncCall<TRequest, TResponse>(call);
+            asyncCall.StartDuplexStreamingCall();
             var requestStream = new ClientRequestStream<TRequest, TResponse>(asyncCall);
             var responseStream = new ClientResponseStream<TRequest, TResponse>(asyncCall);
             return new AsyncDuplexStreamingCall<TRequest, TResponse>(requestStream, responseStream, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
         }
-
-        private static void RegisterCancellationCallback<TRequest, TResponse>(AsyncCall<TRequest, TResponse> asyncCall, CancellationToken token)
-        {
-            if (token.CanBeCanceled)
-            {
-                token.Register(() => asyncCall.Cancel());
-            }
-        }
     }
 }
diff --git a/src/csharp/Grpc.Core/Channel.cs b/src/csharp/Grpc.Core/Channel.cs
index 18e6f2fda5..9273ea4582 100644
--- a/src/csharp/Grpc.Core/Channel.cs
+++ b/src/csharp/Grpc.Core/Channel.cs
@@ -37,6 +37,8 @@ using System.Threading;
 using System.Threading.Tasks;
 
 using Grpc.Core.Internal;
+using Grpc.Core.Logging;
+using Grpc.Core.Utils;
 
 namespace Grpc.Core
 {
@@ -45,21 +47,23 @@ namespace Grpc.Core
     /// </summary>
     public class Channel : IDisposable
     {
+        static readonly ILogger Logger = GrpcEnvironment.Logger.ForType<Channel>();
+
         readonly GrpcEnvironment environment;
         readonly ChannelSafeHandle handle;
         readonly List<ChannelOption> options;
-        readonly string target;
         bool disposed;
 
         /// <summary>
         /// Creates a channel that connects to a specific host.
-        /// Port will default to 80 for an unsecure channel and to 443 a secure channel.
+        /// Port will default to 80 for an unsecure channel and to 443 for a secure channel.
         /// </summary>
-        /// <param name="host">The DNS name of IP address of the host.</param>
+        /// <param name="host">The name or IP address of the host.</param>
         /// <param name="credentials">Credentials to secure the channel.</param>
         /// <param name="options">Channel options.</param>
         public Channel(string host, Credentials credentials, IEnumerable<ChannelOption> options = null)
         {
+            Preconditions.CheckNotNull(host);
             this.environment = GrpcEnvironment.GetInstance();
             this.options = options != null ? new List<ChannelOption>(options) : new List<ChannelOption>();
 
@@ -76,14 +80,13 @@ namespace Grpc.Core
                     this.handle = ChannelSafeHandle.CreateInsecure(host, nativeChannelArgs);
                 }
             }
-            this.target = GetOverridenTarget(host, this.options);
         }
 
         /// <summary>
         /// Creates a channel that connects to a specific host and port.
         /// </summary>
-        /// <param name="host">DNS name or IP address</param>
-        /// <param name="port">the port</param>
+        /// <param name="host">The name or IP address of the host.</param>
+        /// <param name="port">The port.</param>
         /// <param name="credentials">Credentials to secure the channel.</param>
         /// <param name="options">Channel options.</param>
         public Channel(string host, int port, Credentials credentials, IEnumerable<ChannelOption> options = null) :
@@ -91,41 +94,87 @@ namespace Grpc.Core
         {
         }
 
-        public void Dispose()
+        /// <summary>
+        /// Gets current connectivity state of this channel.
+        /// </summary>
+        public ChannelState State
         {
-            Dispose(true);
-            GC.SuppressFinalize(this);
+            get
+            {
+                return handle.CheckConnectivityState(false);        
+            }
         }
 
-        internal string Target
+        /// <summary>
+        /// Returned tasks completes once channel state has become different from 
+        /// given lastObservedState. 
+        /// If deadline is reached or and error occurs, returned task is cancelled.
+        /// </summary>
+        public Task WaitForStateChangedAsync(ChannelState lastObservedState, DateTime? deadline = null)
         {
-            get
+            Preconditions.CheckArgument(lastObservedState != ChannelState.FatalFailure,
+                "FatalFailure is a terminal state. No further state changes can occur.");
+            var tcs = new TaskCompletionSource<object>();
+            var deadlineTimespec = deadline.HasValue ? Timespec.FromDateTime(deadline.Value) : Timespec.InfFuture;
+            var handler = new BatchCompletionDelegate((success, ctx) =>
             {
-                return target;
-            }
+                if (success)
+                {
+                    tcs.SetResult(null);
+                }
+                else
+                {
+                    tcs.SetCanceled();
+                }
+            });
+            handle.WatchConnectivityState(lastObservedState, deadlineTimespec, environment.CompletionQueue, environment.CompletionRegistry, handler);
+            return tcs.Task;
         }
 
-        internal ChannelSafeHandle Handle
+        /// <summary> Address of the remote endpoint in URI format.</summary>
+        public string Target
         {
             get
             {
-                return this.handle;
+                return handle.GetTarget();
             }
         }
 
-        internal CompletionQueueSafeHandle CompletionQueue
+        /// <summary>
+        /// Allows explicitly requesting channel to connect without starting an RPC.
+        /// Returned task completes once state Ready was seen. If the deadline is reached,
+        /// or channel enters the FatalFailure state, the task is cancelled.
+        /// There is no need to call this explicitly unless your use case requires that.
+        /// Starting an RPC on a new channel will request connection implicitly.
+        /// </summary>
+        public async Task ConnectAsync(DateTime? deadline = null)
         {
-            get
+            var currentState = handle.CheckConnectivityState(true);
+            while (currentState != ChannelState.Ready)
             {
-                return this.environment.CompletionQueue;
+                if (currentState == ChannelState.FatalFailure)
+                {
+                    throw new OperationCanceledException("Channel has reached FatalFailure state.");
+                }
+                await WaitForStateChangedAsync(currentState, deadline);
+                currentState = handle.CheckConnectivityState(false);
             }
         }
 
-        internal CompletionRegistry CompletionRegistry
+        /// <summary>
+        /// Destroys the underlying channel.
+        /// </summary>
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        internal ChannelSafeHandle Handle
         {
             get
             {
-                return this.environment.CompletionRegistry;
+                return this.handle;
             }
         }
 
@@ -159,26 +208,5 @@ namespace Grpc.Core
             // TODO(jtattermusch): it would be useful to also provide .NET/mono version.
             return string.Format("grpc-csharp/{0}", VersionInfo.CurrentVersion);
         }
-
-        /// <summary>
-        /// Look for SslTargetNameOverride option and return its value instead of originalTarget
-        /// if found.
-        /// </summary>
-        private static string GetOverridenTarget(string originalTarget, IEnumerable<ChannelOption> options)
-        {
-            if (options == null)
-            {
-                return originalTarget;
-            }
-            foreach (var option in options)
-            {
-                if (option.Type == ChannelOption.OptionType.String
-                    && option.Name == ChannelOptions.SslTargetNameOverride)
-                {
-                    return option.StringValue;
-                }
-            }
-            return originalTarget;
-        }
     }
 }
diff --git a/src/csharp/Grpc.Core/ChannelOptions.cs b/src/csharp/Grpc.Core/ChannelOptions.cs
index 9fe03d2805..1e0f90287a 100644
--- a/src/csharp/Grpc.Core/ChannelOptions.cs
+++ b/src/csharp/Grpc.Core/ChannelOptions.cs
@@ -30,7 +30,6 @@
 #endregion
 using System;
 using System.Collections.Generic;
-using System.Collections.Immutable;
 using System.Runtime.InteropServices;
 using System.Threading;
 using System.Threading.Tasks;
@@ -135,6 +134,9 @@ namespace Grpc.Core
         /// <summary>Initial sequence number for http2 transports</summary>
         public const string Http2InitialSequenceNumber = "grpc.http2.initial_sequence_number";
 
+        /// <summary>Default authority for calls.</summary>
+        public const string DefaultAuthority = "grpc.default_authority";
+
         /// <summary>Primary user agent: goes at the start of the user-agent metadata</summary>
         public const string PrimaryUserAgentString = "grpc.primary_user_agent";
 
diff --git a/src/csharp/Grpc.Core/ChannelState.cs b/src/csharp/Grpc.Core/ChannelState.cs
new file mode 100644
index 0000000000..d293b98f75
--- /dev/null
+++ b/src/csharp/Grpc.Core/ChannelState.cs
@@ -0,0 +1,69 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// Connectivity state of a channel.
+    /// Based on grpc_connectivity_state from grpc/grpc.h
+    /// </summary>
+    public enum ChannelState
+    {
+        /// <summary>
+        /// Channel is idle
+        /// </summary>
+        Idle,
+
+        /// <summary>
+        /// Channel is connecting
+        /// </summary>
+        Connecting,
+
+        /// <summary>
+        /// Channel is ready for work
+        /// </summary>
+        Ready,
+
+        /// <summary>
+        /// Channel has seen a failure but expects to recover
+        /// </summary>
+        TransientFailure,
+
+        /// <summary>
+        /// Channel has seen a failure that it cannot recover from
+        /// </summary>
+        FatalFailure
+    }
+}
diff --git a/src/csharp/Grpc.Core/ClientBase.cs b/src/csharp/Grpc.Core/ClientBase.cs
index fd3473128a..88494bb4ac 100644
--- a/src/csharp/Grpc.Core/ClientBase.cs
+++ b/src/csharp/Grpc.Core/ClientBase.cs
@@ -76,19 +76,17 @@ namespace Grpc.Core
         /// <summary>
         /// Creates a new call to given method.
         /// </summary>
-        protected Call<TRequest, TResponse> CreateCall<TRequest, TResponse>(string serviceName, Method<TRequest, TResponse> method, Metadata metadata, DateTime? deadline)
+        protected CallInvocationDetails<TRequest, TResponse> CreateCall<TRequest, TResponse>(Method<TRequest, TResponse> method, CallOptions options)
             where TRequest : class
             where TResponse : class
         {
             var interceptor = HeaderInterceptor;
             if (interceptor != null)
             {
-                metadata = metadata ?? new Metadata();
-                interceptor(metadata);
-                metadata.Freeze();
+                interceptor(options.Headers);
+                options.Headers.Freeze();
             }
-            return new Call<TRequest, TResponse>(serviceName, method, channel,
-                    metadata ?? Metadata.Empty, deadline ?? DateTime.MaxValue);
+            return new CallInvocationDetails<TRequest, TResponse>(channel, method, options);
         }
     }
 }
diff --git a/src/csharp/Grpc.Core/CompressionLevel.cs b/src/csharp/Grpc.Core/CompressionLevel.cs
new file mode 100644
index 0000000000..399652b85e
--- /dev/null
+++ b/src/csharp/Grpc.Core/CompressionLevel.cs
@@ -0,0 +1,63 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// Compression level based on grpc_compression_level from grpc/compression.h
+    /// </summary>
+    public enum CompressionLevel
+    {
+        /// <summary>
+        /// No compression.
+        /// </summary>
+        None = 0,
+
+        /// <summary>
+        /// Low compression.
+        /// </summary>
+        Low,
+
+        /// <summary>
+        /// Medium compression.
+        /// </summary>
+        Medium,
+
+        /// <summary>
+        /// High compression.
+        /// </summary>
+        High,
+    }
+}
diff --git a/src/csharp/Grpc.Core/ContextPropagationToken.cs b/src/csharp/Grpc.Core/ContextPropagationToken.cs
new file mode 100644
index 0000000000..b6ea5115a4
--- /dev/null
+++ b/src/csharp/Grpc.Core/ContextPropagationToken.cs
@@ -0,0 +1,139 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Threading;
+
+using Grpc.Core.Internal;
+using Grpc.Core.Utils;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// Token for propagating context of server side handlers to child calls.
+    /// In situations when a backend is making calls to another backend,
+    /// it makes sense to propagate properties like deadline and cancellation 
+    /// token of the server call to the child call.
+    /// C core provides some other contexts (like tracing context) that
+    /// are not accessible to C# layer, but this token still allows propagating them.
+    /// </summary>
+    public class ContextPropagationToken
+    {
+        /// <summary>
+        /// Default propagation mask used by C core.
+        /// </summary>
+        const ContextPropagationFlags DefaultCoreMask = (ContextPropagationFlags)0xffff;
+
+        /// <summary>
+        /// Default propagation mask used by C# - we want to propagate deadline 
+        /// and cancellation token by our own means.
+        /// </summary>
+        internal const ContextPropagationFlags DefaultMask = DefaultCoreMask
+            & ~ContextPropagationFlags.Deadline & ~ContextPropagationFlags.Cancellation;
+
+        readonly CallSafeHandle parentCall;
+        readonly DateTime deadline;
+        readonly CancellationToken cancellationToken;
+        readonly ContextPropagationOptions options;
+
+        internal ContextPropagationToken(CallSafeHandle parentCall, DateTime deadline, CancellationToken cancellationToken, ContextPropagationOptions options)
+        {
+            this.parentCall = Preconditions.CheckNotNull(parentCall);
+            this.deadline = deadline;
+            this.cancellationToken = cancellationToken;
+            this.options = options ?? ContextPropagationOptions.Default;
+        }
+
+        internal CallSafeHandle ParentCall
+        {
+            get
+            {
+                return this.parentCall;
+            }
+        }
+
+        internal DateTime Deadline
+        {
+            get
+            {
+                return this.deadline;
+            }
+        }
+
+        internal CancellationToken CancellationToken
+        {
+            get
+            {
+                return this.cancellationToken;
+            }
+        }
+
+        internal ContextPropagationOptions Options
+        {
+            get
+            {
+                return this.options;
+            }
+        }
+
+        internal bool IsPropagateDeadline
+        {
+            get { return false; }
+        }
+
+        internal bool IsPropagateCancellation
+        {
+            get { return false; }
+        }
+    }
+
+    /// <summary>
+    /// Options for <see cref="ContextPropagationToken"/>.
+    /// </summary>
+    public class ContextPropagationOptions
+    {
+        public static readonly ContextPropagationOptions Default = new ContextPropagationOptions();
+    }
+
+    /// <summary>
+    /// Context propagation flags from grpc/grpc.h.
+    /// </summary>
+    [Flags]
+    internal enum ContextPropagationFlags
+    {
+        Deadline = 1,
+        CensusStatsContext = 2,
+        CensusTracingContext = 4,
+        Cancellation = 8
+    }
+}
diff --git a/src/csharp/Grpc.Core/Grpc.Core.csproj b/src/csharp/Grpc.Core/Grpc.Core.csproj
index 940a6b8ac0..e535c47f55 100644
--- a/src/csharp/Grpc.Core/Grpc.Core.csproj
+++ b/src/csharp/Grpc.Core/Grpc.Core.csproj
@@ -44,9 +44,6 @@
     <Reference Include="System.Interactive.Async">
       <HintPath>..\packages\Ix-Async.1.2.3\lib\net45\System.Interactive.Async.dll</HintPath>
     </Reference>
-    <Reference Include="System.Collections.Immutable">
-      <HintPath>..\packages\System.Collections.Immutable.1.1.36\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
-    </Reference>
   </ItemGroup>
   <ItemGroup>
     <Compile Include="AsyncDuplexStreamingCall.cs" />
@@ -55,11 +52,11 @@
     <Compile Include="IServerStreamWriter.cs" />
     <Compile Include="IAsyncStreamWriter.cs" />
     <Compile Include="IAsyncStreamReader.cs" />
+    <Compile Include="ServerPort.cs" />
     <Compile Include="Version.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="RpcException.cs" />
     <Compile Include="Calls.cs" />
-    <Compile Include="Call.cs" />
     <Compile Include="AsyncClientStreamingCall.cs" />
     <Compile Include="GrpcEnvironment.cs" />
     <Compile Include="Status.cs" />
@@ -115,6 +112,12 @@
     <Compile Include="Logging\ILogger.cs" />
     <Compile Include="Logging\ConsoleLogger.cs" />
     <Compile Include="Internal\NativeLogRedirector.cs" />
+    <Compile Include="ChannelState.cs" />
+    <Compile Include="CallInvocationDetails.cs" />
+    <Compile Include="CallOptions.cs" />
+    <Compile Include="CompressionLevel.cs" />
+    <Compile Include="WriteOptions.cs" />
+    <Compile Include="ContextPropagationToken.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="Grpc.Core.nuspec" />
@@ -145,7 +148,5 @@
   </Target>
   <Import Project="..\packages\grpc.dependencies.openssl.redist.1.0.2.2\build\portable-net45\grpc.dependencies.openssl.redist.targets" Condition="Exists('..\packages\grpc.dependencies.openssl.redist.1.0.2.2\build\portable-net45\grpc.dependencies.openssl.redist.targets')" />
   <Import Project="..\packages\grpc.dependencies.zlib.redist.1.2.8.9\build\portable-net45\grpc.dependencies.zlib.redist.targets" Condition="Exists('..\packages\grpc.dependencies.zlib.redist.1.2.8.9\build\portable-net45\grpc.dependencies.zlib.redist.targets')" />
-  <ItemGroup>
-    <Folder Include="Logging\" />
-  </ItemGroup>
+  <ItemGroup />
 </Project>
\ No newline at end of file
diff --git a/src/csharp/Grpc.Core/Grpc.Core.nuspec b/src/csharp/Grpc.Core/Grpc.Core.nuspec
index 086776f69d..fe49efc7ec 100644
--- a/src/csharp/Grpc.Core/Grpc.Core.nuspec
+++ b/src/csharp/Grpc.Core/Grpc.Core.nuspec
@@ -15,7 +15,6 @@
     <copyright>Copyright 2015, Google Inc.</copyright>
     <tags>gRPC RPC Protocol HTTP/2</tags>
 	<dependencies>
-	  <dependency id="System.Collections.Immutable" version="1.1.36" />
 	  <dependency id="Ix-Async" version="1.2.3" />
 	  <dependency id="grpc.native.csharp_ext" version="$GrpcNativeCsharpExtVersion$" />
     </dependencies>
diff --git a/src/csharp/Grpc.Core/GrpcEnvironment.cs b/src/csharp/Grpc.Core/GrpcEnvironment.cs
index 034a66be3c..1bb83c9962 100644
--- a/src/csharp/Grpc.Core/GrpcEnvironment.cs
+++ b/src/csharp/Grpc.Core/GrpcEnvironment.cs
@@ -53,6 +53,9 @@ namespace Grpc.Core
         [DllImport("grpc_csharp_ext.dll")]
         static extern void grpcsharp_shutdown();
 
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern IntPtr grpcsharp_version_string();  // returns not-owned const char*
+
         static object staticLock = new object();
         static GrpcEnvironment instance;
 
@@ -164,6 +167,15 @@ namespace Grpc.Core
         }
 
         /// <summary>
+        /// Gets version of gRPC C core.
+        /// </summary>
+        internal static string GetCoreVersionString()
+        {
+            var ptr = grpcsharp_version_string();  // the pointer is not owned
+            return Marshal.PtrToStringAnsi(ptr);
+        }
+
+        /// <summary>
         /// Shuts down this environment.
         /// </summary>
         private void Close()
diff --git a/src/csharp/Grpc.Core/IAsyncStreamReader.cs b/src/csharp/Grpc.Core/IAsyncStreamReader.cs
index 371fbf27ce..c0a0674e50 100644
--- a/src/csharp/Grpc.Core/IAsyncStreamReader.cs
+++ b/src/csharp/Grpc.Core/IAsyncStreamReader.cs
@@ -43,7 +43,7 @@ namespace Grpc.Core
     /// A stream of messages to be read.
     /// </summary>
     /// <typeparam name="T"></typeparam>
-    public interface IAsyncStreamReader<TResponse> : IAsyncEnumerator<TResponse>
+    public interface IAsyncStreamReader<T> : IAsyncEnumerator<T>
     {
         // TODO(jtattermusch): consider just using IAsyncEnumerator instead of this interface.
     }
diff --git a/src/csharp/Grpc.Core/IAsyncStreamWriter.cs b/src/csharp/Grpc.Core/IAsyncStreamWriter.cs
index 2000210252..4e2acb9c71 100644
--- a/src/csharp/Grpc.Core/IAsyncStreamWriter.cs
+++ b/src/csharp/Grpc.Core/IAsyncStreamWriter.cs
@@ -50,5 +50,13 @@ namespace Grpc.Core
         /// </summary>
         /// <param name="message">the message to be written. Cannot be null.</param>
         Task WriteAsync(T message);
+
+        /// <summary>
+        /// Write options that will be used for the next write.
+        /// If null, default options will be used.
+        /// Once set, this property maintains its value across subsequent
+        /// writes.
+        /// <value>The write options.</value>
+        WriteOptions WriteOptions { get; set; }
     }
 }
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCall.cs b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
index bfcb9366a1..0db9d2a515 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCall.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
@@ -50,7 +50,7 @@ namespace Grpc.Core.Internal
     {
         static readonly ILogger Logger = GrpcEnvironment.Logger.ForType<AsyncCall<TRequest, TResponse>>();
 
-        Channel channel;
+        readonly CallInvocationDetails<TRequest, TResponse> details;
 
         // Completion of a pending unary response if not null.
         TaskCompletionSource<TResponse> unaryResponseTcs;
@@ -60,26 +60,19 @@ namespace Grpc.Core.Internal
 
         bool readObserverCompleted;  // True if readObserver has already been completed.
 
-        public AsyncCall(Func<TRequest, byte[]> serializer, Func<byte[], TResponse> deserializer) : base(serializer, deserializer)
+        public AsyncCall(CallInvocationDetails<TRequest, TResponse> callDetails)
+            : base(callDetails.RequestMarshaller.Serializer, callDetails.ResponseMarshaller.Deserializer)
         {
-        }
-
-        public void Initialize(Channel channel, CompletionQueueSafeHandle cq, string methodName, Timespec deadline)
-        {
-            this.channel = channel;
-            var call = channel.Handle.CreateCall(channel.CompletionRegistry, cq, methodName, channel.Target, deadline);
-            channel.Environment.DebugStats.ActiveClientCalls.Increment();
-            InitializeInternal(call);
+            this.details = callDetails;
+            this.initialMetadataSent = true;  // we always send metadata at the very beginning of the call.
         }
 
         // TODO: this method is not Async, so it shouldn't be in AsyncCall class, but 
         // it is reusing fair amount of code in this class, so we are leaving it here.
-        // TODO: for other calls, you need to call Initialize, this methods calls initialize 
-        // on its own, so there's a usage inconsistency.
         /// <summary>
         /// Blocking unary request - unary response call.
         /// </summary>
-        public TResponse UnaryCall(Channel channel, string methodName, TRequest msg, Metadata headers, DateTime deadline)
+        public TResponse UnaryCall(TRequest msg)
         {
             using (CompletionQueueSafeHandle cq = CompletionQueueSafeHandle.Create())
             {
@@ -89,17 +82,19 @@ namespace Grpc.Core.Internal
 
                 lock (myLock)
                 {
-                    Initialize(channel, cq, methodName, Timespec.FromDateTime(deadline));
+                    Preconditions.CheckState(!started);
                     started = true;
+                    Initialize(cq);
+
                     halfcloseRequested = true;
                     readingDone = true;
                 }
 
-                using (var metadataArray = MetadataArraySafeHandle.Create(headers))
+                using (var metadataArray = MetadataArraySafeHandle.Create(details.Options.Headers))
                 {
                     using (var ctx = BatchContextSafeHandle.Create())
                     {
-                        call.StartUnary(payload, ctx, metadataArray);
+                        call.StartUnary(ctx, payload, metadataArray, GetWriteFlagsForCall());
                         var ev = cq.Pluck(ctx.Handle);
 
                         bool success = (ev.success != 0);
@@ -129,22 +124,24 @@ namespace Grpc.Core.Internal
         /// <summary>
         /// Starts a unary request - unary response call.
         /// </summary>
-        public Task<TResponse> UnaryCallAsync(TRequest msg, Metadata headers, DateTime deadline)
+        public Task<TResponse> UnaryCallAsync(TRequest msg)
         {
             lock (myLock)
             {
-                Preconditions.CheckNotNull(call);
-
+                Preconditions.CheckState(!started);
                 started = true;
+
+                Initialize(details.Channel.Environment.CompletionQueue);
+
                 halfcloseRequested = true;
                 readingDone = true;
 
                 byte[] payload = UnsafeSerialize(msg);
 
                 unaryResponseTcs = new TaskCompletionSource<TResponse>();
-                using (var metadataArray = MetadataArraySafeHandle.Create(headers))
+                using (var metadataArray = MetadataArraySafeHandle.Create(details.Options.Headers))
                 {
-                    call.StartUnary(payload, HandleUnaryResponse, metadataArray);
+                    call.StartUnary(HandleUnaryResponse, payload, metadataArray, GetWriteFlagsForCall());
                 }
                 return unaryResponseTcs.Task;
             }
@@ -154,17 +151,19 @@ namespace Grpc.Core.Internal
         /// Starts a streamed request - unary response call.
         /// Use StartSendMessage and StartSendCloseFromClient to stream requests.
         /// </summary>
-        public Task<TResponse> ClientStreamingCallAsync(Metadata headers, DateTime deadline)
+        public Task<TResponse> ClientStreamingCallAsync()
         {
             lock (myLock)
             {
-                Preconditions.CheckNotNull(call);
-
+                Preconditions.CheckState(!started);
                 started = true;
+
+                Initialize(details.Channel.Environment.CompletionQueue);
+
                 readingDone = true;
 
                 unaryResponseTcs = new TaskCompletionSource<TResponse>();
-                using (var metadataArray = MetadataArraySafeHandle.Create(headers))
+                using (var metadataArray = MetadataArraySafeHandle.Create(details.Options.Headers))
                 {
                     call.StartClientStreaming(HandleUnaryResponse, metadataArray);
                 }
@@ -176,21 +175,23 @@ namespace Grpc.Core.Internal
         /// <summary>
         /// Starts a unary request - streamed response call.
         /// </summary>
-        public void StartServerStreamingCall(TRequest msg, Metadata headers, DateTime deadline)
+        public void StartServerStreamingCall(TRequest msg)
         {
             lock (myLock)
             {
-                Preconditions.CheckNotNull(call);
-
+                Preconditions.CheckState(!started);
                 started = true;
+
+                Initialize(details.Channel.Environment.CompletionQueue);
+
                 halfcloseRequested = true;
                 halfclosed = true;  // halfclose not confirmed yet, but it will be once finishedHandler is called.
 
                 byte[] payload = UnsafeSerialize(msg);
 
-                using (var metadataArray = MetadataArraySafeHandle.Create(headers))
+                using (var metadataArray = MetadataArraySafeHandle.Create(details.Options.Headers))
                 {
-                    call.StartServerStreaming(payload, HandleFinished, metadataArray);
+                    call.StartServerStreaming(HandleFinished, payload, metadataArray, GetWriteFlagsForCall());
                 }
             }
         }
@@ -199,15 +200,16 @@ namespace Grpc.Core.Internal
         /// Starts a streaming request - streaming response call.
         /// Use StartSendMessage and StartSendCloseFromClient to stream requests.
         /// </summary>
-        public void StartDuplexStreamingCall(Metadata headers, DateTime deadline)
+        public void StartDuplexStreamingCall()
         {
             lock (myLock)
             {
-                Preconditions.CheckNotNull(call);
-
+                Preconditions.CheckState(!started);
                 started = true;
 
-                using (var metadataArray = MetadataArraySafeHandle.Create(headers))
+                Initialize(details.Channel.Environment.CompletionQueue);
+
+                using (var metadataArray = MetadataArraySafeHandle.Create(details.Options.Headers))
                 {
                     call.StartDuplexStreaming(HandleFinished, metadataArray);
                 }
@@ -218,9 +220,9 @@ namespace Grpc.Core.Internal
         /// Sends a streaming request. Only one pending send action is allowed at any given time.
         /// completionDelegate is called when the operation finishes.
         /// </summary>
-        public void StartSendMessage(TRequest msg, AsyncCompletionDelegate<object> completionDelegate)
+        public void StartSendMessage(TRequest msg, WriteFlags writeFlags, AsyncCompletionDelegate<object> completionDelegate)
         {
-            StartSendMessageInternal(msg, completionDelegate);
+            StartSendMessageInternal(msg, writeFlags, completionDelegate);
         }
 
         /// <summary>
@@ -277,6 +279,14 @@ namespace Grpc.Core.Internal
             }
         }
 
+        public CallInvocationDetails<TRequest, TResponse> Details
+        {
+            get
+            {
+                return this.details;
+            }
+        }
+
         /// <summary>
         /// On client-side, we only fire readCompletionDelegate once all messages have been read 
         /// and status has been received.
@@ -309,7 +319,39 @@ namespace Grpc.Core.Internal
 
         protected override void OnReleaseResources()
         {
-            channel.Environment.DebugStats.ActiveClientCalls.Decrement();
+            details.Channel.Environment.DebugStats.ActiveClientCalls.Decrement();
+        }
+
+        private void Initialize(CompletionQueueSafeHandle cq)
+        {
+            var propagationToken = details.Options.PropagationToken;
+            var parentCall = propagationToken != null ? propagationToken.ParentCall : CallSafeHandle.NullInstance;
+
+            var call = details.Channel.Handle.CreateCall(details.Channel.Environment.CompletionRegistry,
+                parentCall, ContextPropagationToken.DefaultMask, cq,
+                details.Method, details.Host, Timespec.FromDateTime(details.Options.Deadline));
+            details.Channel.Environment.DebugStats.ActiveClientCalls.Increment();
+            InitializeInternal(call);
+            RegisterCancellationCallback();
+        }
+
+        // Make sure that once cancellationToken for this call is cancelled, Cancel() will be called.
+        private void RegisterCancellationCallback()
+        {
+            var token = details.Options.CancellationToken;
+            if (token.CanBeCanceled)
+            {
+                token.Register(() => this.Cancel());
+            }
+        }
+
+        /// <summary>
+        /// Gets WriteFlags set in callDetails.Options.WriteOptions
+        /// </summary>
+        private WriteFlags GetWriteFlagsForCall()
+        {
+            var writeOptions = details.Options.WriteOptions;
+            return writeOptions != null ? writeOptions.Flags : default(WriteFlags);
         }
 
         /// <summary>
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs b/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
index 38f2a5baeb..9fa0baca87 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
@@ -71,6 +71,9 @@ namespace Grpc.Core.Internal
         protected bool halfclosed;
         protected bool finished;  // True if close has been received from the peer.
 
+        protected bool initialMetadataSent;
+        protected long streamingWritesCounter;
+
         public AsyncCallBase(Func<TWrite, byte[]> serializer, Func<byte[], TRead> deserializer)
         {
             this.serializer = Preconditions.CheckNotNull(serializer);
@@ -123,7 +126,7 @@ namespace Grpc.Core.Internal
         /// Initiates sending a message. Only one send operation can be active at a time.
         /// completionDelegate is invoked upon completion.
         /// </summary>
-        protected void StartSendMessageInternal(TWrite msg, AsyncCompletionDelegate<object> completionDelegate)
+        protected void StartSendMessageInternal(TWrite msg, WriteFlags writeFlags, AsyncCompletionDelegate<object> completionDelegate)
         {
             byte[] payload = UnsafeSerialize(msg);
 
@@ -132,8 +135,11 @@ namespace Grpc.Core.Internal
                 Preconditions.CheckNotNull(completionDelegate, "Completion delegate cannot be null");
                 CheckSendingAllowed();
 
-                call.StartSendMessage(payload, HandleSendFinished);
+                call.StartSendMessage(HandleSendFinished, payload, writeFlags, !initialMetadataSent);
+
                 sendCompletionDelegate = completionDelegate;
+                initialMetadataSent = true;
+                streamingWritesCounter++;
             }
         }
 
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs b/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
index 513902ee36..3710a65d6b 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
@@ -83,9 +83,9 @@ namespace Grpc.Core.Internal
         /// Sends a streaming response. Only one pending send action is allowed at any given time.
         /// completionDelegate is called when the operation finishes.
         /// </summary>
-        public void StartSendMessage(TResponse msg, AsyncCompletionDelegate<object> completionDelegate)
+        public void StartSendMessage(TResponse msg, WriteFlags writeFlags, AsyncCompletionDelegate<object> completionDelegate)
         {
-            StartSendMessageInternal(msg, completionDelegate);
+            StartSendMessageInternal(msg, writeFlags, completionDelegate);
         }
 
         /// <summary>
@@ -98,6 +98,35 @@ namespace Grpc.Core.Internal
         }
 
         /// <summary>
+        /// Initiates sending a initial metadata. 
+        /// Even though C-core allows sending metadata in parallel to sending messages, we will treat sending metadata as a send message operation
+        /// to make things simpler.
+        /// completionDelegate is invoked upon completion.
+        /// </summary>
+        public void StartSendInitialMetadata(Metadata headers, AsyncCompletionDelegate<object> completionDelegate)
+        {
+            lock (myLock)
+            {
+                Preconditions.CheckNotNull(headers, "metadata");
+                Preconditions.CheckNotNull(completionDelegate, "Completion delegate cannot be null");
+
+                Preconditions.CheckState(!initialMetadataSent, "Response headers can only be sent once per call.");
+                Preconditions.CheckState(streamingWritesCounter == 0, "Response headers can only be sent before the first write starts.");
+                CheckSendingAllowed();
+
+                Preconditions.CheckNotNull(completionDelegate, "Completion delegate cannot be null");
+
+                using (var metadataArray = MetadataArraySafeHandle.Create(headers))
+                {
+                    call.StartSendInitialMetadata(HandleSendFinished, metadataArray);
+                }
+
+                this.initialMetadataSent = true;
+                sendCompletionDelegate = completionDelegate;
+            }
+        }
+
+        /// <summary>
         /// Sends call result status, also indicating server is done with streaming responses.
         /// Only one pending send action is allowed at any given time.
         /// completionDelegate is called when the operation finishes.
@@ -111,7 +140,7 @@ namespace Grpc.Core.Internal
 
                 using (var metadataArray = MetadataArraySafeHandle.Create(trailers))
                 {
-                    call.StartSendStatusFromServer(status, HandleHalfclosed, metadataArray);
+                    call.StartSendStatusFromServer(HandleHalfclosed, status, metadataArray, !initialMetadataSent);
                 }
                 halfcloseRequested = true;
                 readingDone = true;
diff --git a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
index 714749b171..3cb01e29bd 100644
--- a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
@@ -42,6 +42,8 @@ namespace Grpc.Core.Internal
     /// </summary>
     internal class CallSafeHandle : SafeHandleZeroIsInvalid
     {
+        public static readonly CallSafeHandle NullInstance = new CallSafeHandle();
+
         const uint GRPC_WRITE_BUFFER_HINT = 1;
         CompletionRegistry completionRegistry;
 
@@ -53,7 +55,7 @@ namespace Grpc.Core.Internal
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern GRPCCallError grpcsharp_call_start_unary(CallSafeHandle call,
-            BatchContextSafeHandle ctx, byte[] send_buffer, UIntPtr send_buffer_len, MetadataArraySafeHandle metadataArray);
+            BatchContextSafeHandle ctx, byte[] send_buffer, UIntPtr send_buffer_len, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags);
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern GRPCCallError grpcsharp_call_start_client_streaming(CallSafeHandle call,
@@ -62,7 +64,7 @@ namespace Grpc.Core.Internal
         [DllImport("grpc_csharp_ext.dll")]
         static extern GRPCCallError grpcsharp_call_start_server_streaming(CallSafeHandle call,
             BatchContextSafeHandle ctx, byte[] send_buffer, UIntPtr send_buffer_len,
-            MetadataArraySafeHandle metadataArray);
+            MetadataArraySafeHandle metadataArray, WriteFlags writeFlags);
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern GRPCCallError grpcsharp_call_start_duplex_streaming(CallSafeHandle call,
@@ -70,7 +72,7 @@ namespace Grpc.Core.Internal
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern GRPCCallError grpcsharp_call_send_message(CallSafeHandle call,
-            BatchContextSafeHandle ctx, byte[] send_buffer, UIntPtr send_buffer_len);
+            BatchContextSafeHandle ctx, byte[] send_buffer, UIntPtr send_buffer_len, WriteFlags writeFlags, bool sendEmptyInitialMetadata);
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern GRPCCallError grpcsharp_call_send_close_from_client(CallSafeHandle call,
@@ -78,7 +80,7 @@ namespace Grpc.Core.Internal
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern GRPCCallError grpcsharp_call_send_status_from_server(CallSafeHandle call, 
-            BatchContextSafeHandle ctx, StatusCode statusCode, string statusMessage, MetadataArraySafeHandle metadataArray);
+            BatchContextSafeHandle ctx, StatusCode statusCode, string statusMessage, MetadataArraySafeHandle metadataArray, bool sendEmptyInitialMetadata);
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern GRPCCallError grpcsharp_call_recv_message(CallSafeHandle call,
@@ -89,6 +91,10 @@ namespace Grpc.Core.Internal
             BatchContextSafeHandle ctx);
 
         [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_send_initial_metadata(CallSafeHandle call,
+            BatchContextSafeHandle ctx, MetadataArraySafeHandle metadataArray);
+
+        [DllImport("grpc_csharp_ext.dll")]
         static extern CStringSafeHandle grpcsharp_call_get_peer(CallSafeHandle call);
 
         [DllImport("grpc_csharp_ext.dll")]
@@ -103,17 +109,17 @@ namespace Grpc.Core.Internal
             this.completionRegistry = completionRegistry;
         }
 
-        public void StartUnary(byte[] payload, BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
+        public void StartUnary(BatchCompletionDelegate callback, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
         {
             var ctx = BatchContextSafeHandle.Create();
             completionRegistry.RegisterBatchCompletion(ctx, callback);
-            grpcsharp_call_start_unary(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray)
+            grpcsharp_call_start_unary(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray, writeFlags)
                 .CheckOk();
         }
 
-        public void StartUnary(byte[] payload, BatchContextSafeHandle ctx, MetadataArraySafeHandle metadataArray)
+        public void StartUnary(BatchContextSafeHandle ctx, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
         {
-            grpcsharp_call_start_unary(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray)
+            grpcsharp_call_start_unary(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray, writeFlags)
                 .CheckOk();
         }
 
@@ -124,11 +130,11 @@ namespace Grpc.Core.Internal
             grpcsharp_call_start_client_streaming(this, ctx, metadataArray).CheckOk();
         }
 
-        public void StartServerStreaming(byte[] payload, BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
+        public void StartServerStreaming(BatchCompletionDelegate callback, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
         {
             var ctx = BatchContextSafeHandle.Create();
             completionRegistry.RegisterBatchCompletion(ctx, callback);
-            grpcsharp_call_start_server_streaming(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray).CheckOk();
+            grpcsharp_call_start_server_streaming(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray, writeFlags).CheckOk();
         }
 
         public void StartDuplexStreaming(BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
@@ -138,11 +144,11 @@ namespace Grpc.Core.Internal
             grpcsharp_call_start_duplex_streaming(this, ctx, metadataArray).CheckOk();
         }
 
-        public void StartSendMessage(byte[] payload, BatchCompletionDelegate callback)
+        public void StartSendMessage(BatchCompletionDelegate callback, byte[] payload, WriteFlags writeFlags, bool sendEmptyInitialMetadata)
         {
             var ctx = BatchContextSafeHandle.Create();
             completionRegistry.RegisterBatchCompletion(ctx, callback);
-            grpcsharp_call_send_message(this, ctx, payload, new UIntPtr((ulong)payload.Length)).CheckOk();
+            grpcsharp_call_send_message(this, ctx, payload, new UIntPtr((ulong)payload.Length), writeFlags, sendEmptyInitialMetadata).CheckOk();
         }
 
         public void StartSendCloseFromClient(BatchCompletionDelegate callback)
@@ -152,11 +158,11 @@ namespace Grpc.Core.Internal
             grpcsharp_call_send_close_from_client(this, ctx).CheckOk();
         }
 
-        public void StartSendStatusFromServer(Status status, BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
+        public void StartSendStatusFromServer(BatchCompletionDelegate callback, Status status, MetadataArraySafeHandle metadataArray, bool sendEmptyInitialMetadata)
         {
             var ctx = BatchContextSafeHandle.Create();
             completionRegistry.RegisterBatchCompletion(ctx, callback);
-            grpcsharp_call_send_status_from_server(this, ctx, status.StatusCode, status.Detail, metadataArray).CheckOk();
+            grpcsharp_call_send_status_from_server(this, ctx, status.StatusCode, status.Detail, metadataArray, sendEmptyInitialMetadata).CheckOk();
         }
 
         public void StartReceiveMessage(BatchCompletionDelegate callback)
@@ -173,6 +179,13 @@ namespace Grpc.Core.Internal
             grpcsharp_call_start_serverside(this, ctx).CheckOk();
         }
 
+        public void StartSendInitialMetadata(BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
+        {
+            var ctx = BatchContextSafeHandle.Create();
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            grpcsharp_call_send_initial_metadata(this, ctx, metadataArray).CheckOk();
+        }
+
         public void Cancel()
         {
             grpcsharp_call_cancel(this).CheckOk();
diff --git a/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs b/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
index 20815efbd3..7f03bf4ea5 100644
--- a/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
@@ -47,7 +47,17 @@ namespace Grpc.Core.Internal
         static extern ChannelSafeHandle grpcsharp_secure_channel_create(CredentialsSafeHandle credentials, string target, ChannelArgsSafeHandle channelArgs);
 
         [DllImport("grpc_csharp_ext.dll")]
-        static extern CallSafeHandle grpcsharp_channel_create_call(ChannelSafeHandle channel, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline);
+        static extern CallSafeHandle grpcsharp_channel_create_call(ChannelSafeHandle channel, CallSafeHandle parentCall, ContextPropagationFlags propagationMask, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern ChannelState grpcsharp_channel_check_connectivity_state(ChannelSafeHandle channel, int tryToConnect);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern void grpcsharp_channel_watch_connectivity_state(ChannelSafeHandle channel, ChannelState lastObservedState,
+            Timespec deadline, CompletionQueueSafeHandle cq, BatchContextSafeHandle ctx);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern CStringSafeHandle grpcsharp_channel_get_target(ChannelSafeHandle call);
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern void grpcsharp_channel_destroy(IntPtr channel);
@@ -66,13 +76,34 @@ namespace Grpc.Core.Internal
             return grpcsharp_secure_channel_create(credentials, target, channelArgs);
         }
 
-        public CallSafeHandle CreateCall(CompletionRegistry registry, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline)
+        public CallSafeHandle CreateCall(CompletionRegistry registry, CallSafeHandle parentCall, ContextPropagationFlags propagationMask, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline)
         {
-            var result = grpcsharp_channel_create_call(this, cq, method, host, deadline);
+            var result = grpcsharp_channel_create_call(this, parentCall, propagationMask, cq, method, host, deadline);
             result.SetCompletionRegistry(registry);
             return result;
         }
 
+        public ChannelState CheckConnectivityState(bool tryToConnect)
+        {
+            return grpcsharp_channel_check_connectivity_state(this, tryToConnect ? 1 : 0);
+        }
+
+        public void WatchConnectivityState(ChannelState lastObservedState, Timespec deadline, CompletionQueueSafeHandle cq,
+            CompletionRegistry completionRegistry, BatchCompletionDelegate callback)
+        {
+            var ctx = BatchContextSafeHandle.Create();
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            grpcsharp_channel_watch_connectivity_state(this, lastObservedState, deadline, cq, ctx);
+        }
+
+        public string GetTarget()
+        {
+            using (var cstring = grpcsharp_channel_get_target(this))
+            {
+                return cstring.GetValue();
+            }
+        }
+
         protected override bool ReleaseHandle()
         {
             grpcsharp_channel_destroy(handle);
diff --git a/src/csharp/Grpc.Core/Internal/ClientRequestStream.cs b/src/csharp/Grpc.Core/Internal/ClientRequestStream.cs
index 58f493463b..013f00ff6f 100644
--- a/src/csharp/Grpc.Core/Internal/ClientRequestStream.cs
+++ b/src/csharp/Grpc.Core/Internal/ClientRequestStream.cs
@@ -40,16 +40,18 @@ namespace Grpc.Core.Internal
     internal class ClientRequestStream<TRequest, TResponse> : IClientStreamWriter<TRequest>
     {
         readonly AsyncCall<TRequest, TResponse> call;
+        WriteOptions writeOptions;
 
         public ClientRequestStream(AsyncCall<TRequest, TResponse> call)
         {
             this.call = call;
+            this.writeOptions = call.Details.Options.WriteOptions;
         }
 
         public Task WriteAsync(TRequest message)
         {
             var taskSource = new AsyncCompletionTaskSource<object>();
-            call.StartSendMessage(message, taskSource.CompletionDelegate);
+            call.StartSendMessage(message, GetWriteFlags(), taskSource.CompletionDelegate);
             return taskSource.Task;
         }
 
@@ -59,5 +61,24 @@ namespace Grpc.Core.Internal
             call.StartSendCloseFromClient(taskSource.CompletionDelegate);
             return taskSource.Task;
         }
+
+        public WriteOptions WriteOptions
+        {
+            get
+            {
+                return this.writeOptions;
+            }
+
+            set
+            {
+                writeOptions = value;
+            }
+        }
+
+        private WriteFlags GetWriteFlags()
+        {
+            var options = writeOptions;
+            return options != null ? options.Flags : default(WriteFlags);
+        }
     }
 }
diff --git a/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs b/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
index 19f0e3c57f..688f9f6fec 100644
--- a/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
@@ -75,7 +75,7 @@ namespace Grpc.Core.Internal
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
 
             Status status;
-            var context = HandlerUtils.NewContext(newRpc, asyncCall.Peer, asyncCall.CancellationToken);
+            var context = HandlerUtils.NewContext(newRpc, asyncCall.Peer, responseStream, asyncCall.CancellationToken);
             try
             {
                 Preconditions.CheckArgument(await requestStream.MoveNext());
@@ -131,7 +131,7 @@ namespace Grpc.Core.Internal
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
 
             Status status;
-            var context = HandlerUtils.NewContext(newRpc, asyncCall.Peer, asyncCall.CancellationToken);
+            var context = HandlerUtils.NewContext(newRpc, asyncCall.Peer, responseStream, asyncCall.CancellationToken);
             try
             {
                 Preconditions.CheckArgument(await requestStream.MoveNext());
@@ -187,7 +187,7 @@ namespace Grpc.Core.Internal
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
 
             Status status;
-            var context = HandlerUtils.NewContext(newRpc, asyncCall.Peer, asyncCall.CancellationToken);
+            var context = HandlerUtils.NewContext(newRpc, asyncCall.Peer, responseStream, asyncCall.CancellationToken);
             try
             {
                 var result = await handler(requestStream, context);
@@ -247,7 +247,7 @@ namespace Grpc.Core.Internal
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
 
             Status status;
-            var context = HandlerUtils.NewContext(newRpc, asyncCall.Peer, asyncCall.CancellationToken);
+            var context = HandlerUtils.NewContext(newRpc, asyncCall.Peer, responseStream, asyncCall.CancellationToken);
             try
             {
                 await handler(requestStream, responseStream, context);
@@ -304,13 +304,14 @@ namespace Grpc.Core.Internal
             return new Status(StatusCode.Unknown, "Exception was thrown by handler.");
         }
 
-        public static ServerCallContext NewContext(ServerRpcNew newRpc, string peer, CancellationToken cancellationToken)
+        public static ServerCallContext NewContext<TRequest, TResponse>(ServerRpcNew newRpc, string peer, ServerResponseStream<TRequest, TResponse> serverResponseStream, CancellationToken cancellationToken)
+            where TRequest : class
+            where TResponse : class
         {
             DateTime realtimeDeadline = newRpc.Deadline.ToClockType(GPRClockType.Realtime).ToDateTime();
 
-            return new ServerCallContext(
-                newRpc.Method, newRpc.Host, peer, realtimeDeadline,
-                newRpc.RequestMetadata, cancellationToken);
+            return new ServerCallContext(newRpc.Call, newRpc.Method, newRpc.Host, peer, realtimeDeadline,
+                newRpc.RequestMetadata, cancellationToken, serverResponseStream.WriteResponseHeadersAsync, serverResponseStream);
         }
     }
 }
diff --git a/src/csharp/Grpc.Core/Internal/ServerCredentialsSafeHandle.cs b/src/csharp/Grpc.Core/Internal/ServerCredentialsSafeHandle.cs
index 59238a452c..37a4f5256b 100644
--- a/src/csharp/Grpc.Core/Internal/ServerCredentialsSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerCredentialsSafeHandle.cs
@@ -42,7 +42,7 @@ namespace Grpc.Core.Internal
     internal class ServerCredentialsSafeHandle : SafeHandleZeroIsInvalid
     {
         [DllImport("grpc_csharp_ext.dll", CharSet = CharSet.Ansi)]
-        static extern ServerCredentialsSafeHandle grpcsharp_ssl_server_credentials_create(string pemRootCerts, string[] keyCertPairCertChainArray, string[] keyCertPairPrivateKeyArray, UIntPtr numKeyCertPairs);
+        static extern ServerCredentialsSafeHandle grpcsharp_ssl_server_credentials_create(string pemRootCerts, string[] keyCertPairCertChainArray, string[] keyCertPairPrivateKeyArray, UIntPtr numKeyCertPairs, bool forceClientAuth);
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern void grpcsharp_server_credentials_release(IntPtr credentials);
@@ -51,12 +51,13 @@ namespace Grpc.Core.Internal
         {
         }
 
-        public static ServerCredentialsSafeHandle CreateSslCredentials(string pemRootCerts, string[] keyCertPairCertChainArray, string[] keyCertPairPrivateKeyArray)
+        public static ServerCredentialsSafeHandle CreateSslCredentials(string pemRootCerts, string[] keyCertPairCertChainArray, string[] keyCertPairPrivateKeyArray, bool forceClientAuth)
         {
             Preconditions.CheckArgument(keyCertPairCertChainArray.Length == keyCertPairPrivateKeyArray.Length);
             return grpcsharp_ssl_server_credentials_create(pemRootCerts,
                                                            keyCertPairCertChainArray, keyCertPairPrivateKeyArray,
-                                                           new UIntPtr((ulong)keyCertPairCertChainArray.Length));
+                                                           new UIntPtr((ulong)keyCertPairCertChainArray.Length),
+                                                           forceClientAuth);
         }
 
         protected override bool ReleaseHandle()
diff --git a/src/csharp/Grpc.Core/Internal/ServerResponseStream.cs b/src/csharp/Grpc.Core/Internal/ServerResponseStream.cs
index 756dcee87f..03e39efc02 100644
--- a/src/csharp/Grpc.Core/Internal/ServerResponseStream.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerResponseStream.cs
@@ -38,11 +38,12 @@ namespace Grpc.Core.Internal
     /// <summary>
     /// Writes responses asynchronously to an underlying AsyncCallServer object.
     /// </summary>
-    internal class ServerResponseStream<TRequest, TResponse> : IServerStreamWriter<TResponse>
+    internal class ServerResponseStream<TRequest, TResponse> : IServerStreamWriter<TResponse>, IHasWriteOptions
         where TRequest : class
         where TResponse : class
     {
         readonly AsyncCallServer<TRequest, TResponse> call;
+        WriteOptions writeOptions;
 
         public ServerResponseStream(AsyncCallServer<TRequest, TResponse> call)
         {
@@ -52,7 +53,7 @@ namespace Grpc.Core.Internal
         public Task WriteAsync(TResponse message)
         {
             var taskSource = new AsyncCompletionTaskSource<object>();
-            call.StartSendMessage(message, taskSource.CompletionDelegate);
+            call.StartSendMessage(message, GetWriteFlags(), taskSource.CompletionDelegate);
             return taskSource.Task;
         }
 
@@ -62,5 +63,31 @@ namespace Grpc.Core.Internal
             call.StartSendStatusFromServer(status, trailers, taskSource.CompletionDelegate);
             return taskSource.Task;
         }
+
+        public Task WriteResponseHeadersAsync(Metadata responseHeaders)
+        {
+            var taskSource = new AsyncCompletionTaskSource<object>();
+            call.StartSendInitialMetadata(responseHeaders, taskSource.CompletionDelegate);
+            return taskSource.Task;
+        }
+
+        public WriteOptions WriteOptions
+        {
+            get
+            {
+                return writeOptions;
+            }
+
+            set
+            {
+                writeOptions = value;
+            }
+        }
+
+        private WriteFlags GetWriteFlags()
+        {
+            var options = writeOptions;
+            return options != null ? options.Flags : default(WriteFlags);
+        }
     }
 }
diff --git a/src/csharp/Grpc.Core/KeyCertificatePair.cs b/src/csharp/Grpc.Core/KeyCertificatePair.cs
index 7cea18618e..5def15a656 100644
--- a/src/csharp/Grpc.Core/KeyCertificatePair.cs
+++ b/src/csharp/Grpc.Core/KeyCertificatePair.cs
@@ -33,7 +33,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Collections.Immutable;
 
 using Grpc.Core.Internal;
 using Grpc.Core.Utils;
diff --git a/src/csharp/Grpc.Core/Metadata.cs b/src/csharp/Grpc.Core/Metadata.cs
index 2f308cbb11..a58dbdbc93 100644
--- a/src/csharp/Grpc.Core/Metadata.cs
+++ b/src/csharp/Grpc.Core/Metadata.cs
@@ -32,7 +32,6 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.Collections.Immutable;
 using System.Collections.Specialized;
 using System.Runtime.InteropServices;
 using System.Text;
@@ -115,6 +114,16 @@ namespace Grpc.Core
             entries.Add(item);
         }
 
+        public void Add(string key, string value)
+        {
+            Add(new Entry(key, value));
+        }
+
+        public void Add(string key, byte[] valueBytes)
+        {
+            Add(new Entry(key, valueBytes));
+        }
+
         public void Clear()
         {
             CheckWriteable();
diff --git a/src/csharp/Grpc.Core/Method.cs b/src/csharp/Grpc.Core/Method.cs
index 77d36191c3..cc047ac9f8 100644
--- a/src/csharp/Grpc.Core/Method.cs
+++ b/src/csharp/Grpc.Core/Method.cs
@@ -53,16 +53,20 @@ namespace Grpc.Core
     public class Method<TRequest, TResponse>
     {
         readonly MethodType type;
+        readonly string serviceName;
         readonly string name;
         readonly Marshaller<TRequest> requestMarshaller;
         readonly Marshaller<TResponse> responseMarshaller;
+        readonly string fullName;
 
-        public Method(MethodType type, string name, Marshaller<TRequest> requestMarshaller, Marshaller<TResponse> responseMarshaller)
+        public Method(MethodType type, string serviceName, string name, Marshaller<TRequest> requestMarshaller, Marshaller<TResponse> responseMarshaller)
         {
             this.type = type;
-            this.name = name;
-            this.requestMarshaller = requestMarshaller;
-            this.responseMarshaller = responseMarshaller;
+            this.serviceName = Preconditions.CheckNotNull(serviceName);
+            this.name = Preconditions.CheckNotNull(name);
+            this.requestMarshaller = Preconditions.CheckNotNull(requestMarshaller);
+            this.responseMarshaller = Preconditions.CheckNotNull(responseMarshaller);
+            this.fullName = GetFullName(serviceName);
         }
 
         public MethodType Type
@@ -72,6 +76,14 @@ namespace Grpc.Core
                 return this.type;
             }
         }
+            
+        public string ServiceName
+        {
+            get
+            {
+                return this.serviceName;
+            }
+        }
 
         public string Name
         {
@@ -97,6 +109,14 @@ namespace Grpc.Core
             }
         }
 
+        public string FullName
+        {
+            get
+            {
+                return this.fullName;
+            }
+        }
+
         /// <summary>
         /// Gets full name of the method including the service name.
         /// </summary>
diff --git a/src/csharp/Grpc.Core/Server.cs b/src/csharp/Grpc.Core/Server.cs
index 3217547cc4..eb5b043d1c 100644
--- a/src/csharp/Grpc.Core/Server.cs
+++ b/src/csharp/Grpc.Core/Server.cs
@@ -32,7 +32,7 @@
 #endregion
 
 using System;
-using System.Collections.Concurrent;
+using System.Collections;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
@@ -48,18 +48,17 @@ namespace Grpc.Core
     /// </summary>
     public class Server
     {
-        /// <summary>
-        /// Pass this value as port to have the server choose an unused listening port for you.
-        /// </summary>
-        public const int PickUnusedPort = 0;
-
         static readonly ILogger Logger = GrpcEnvironment.Logger.ForType<Server>();
 
+        readonly ServiceDefinitionCollection serviceDefinitions;
+        readonly ServerPortCollection ports;
         readonly GrpcEnvironment environment;
         readonly List<ChannelOption> options;
         readonly ServerSafeHandle handle;
         readonly object myLock = new object();
 
+        readonly List<ServerServiceDefinition> serviceDefinitionsList = new List<ServerServiceDefinition>();
+        readonly List<ServerPort> serverPortList = new List<ServerPort>();
         readonly Dictionary<string, IServerCallHandler> callHandlers = new Dictionary<string, IServerCallHandler>();
         readonly TaskCompletionSource<object> shutdownTcs = new TaskCompletionSource<object>();
 
@@ -72,6 +71,8 @@ namespace Grpc.Core
         /// <param name="options">Channel options.</param>
         public Server(IEnumerable<ChannelOption> options = null)
         {
+            this.serviceDefinitions = new ServiceDefinitionCollection(this);
+            this.ports = new ServerPortCollection(this);
             this.environment = GrpcEnvironment.GetInstance();
             this.options = options != null ? new List<ChannelOption>(options) : new List<ChannelOption>();
             using (var channelArgs = ChannelOptions.CreateChannelArgs(this.options))
@@ -81,47 +82,26 @@ namespace Grpc.Core
         }
 
         /// <summary>
-        /// Adds a service definition to the server. This is how you register
-        /// handlers for a service with the server.
-        /// Only call this before Start().
+        /// Services that will be exported by the server once started. Register a service with this
+        /// server by adding its definition to this collection.
         /// </summary>
-        public void AddServiceDefinition(ServerServiceDefinition serviceDefinition)
+        public ServiceDefinitionCollection Services
         {
-            lock (myLock)
+            get
             {
-                Preconditions.CheckState(!startRequested);
-                foreach (var entry in serviceDefinition.CallHandlers)
-                {
-                    callHandlers.Add(entry.Key, entry.Value);
-                }
+                return serviceDefinitions;
             }
         }
 
         /// <summary>
-        /// Add a port on which server should listen.
-        /// Only call this before Start().
+        /// Ports on which the server will listen once started. Register a port with this
+        /// server by adding its definition to this collection.
         /// </summary>
-        /// <returns>The port on which server will be listening.</returns>
-        /// <param name="host">the host</param>
-        /// <param name="port">the port. If zero, an unused port is chosen automatically.</param>
-        public int AddPort(string host, int port, ServerCredentials credentials)
+        public ServerPortCollection Ports
         {
-            lock (myLock)
+            get
             {
-                Preconditions.CheckNotNull(credentials);
-                Preconditions.CheckState(!startRequested);
-                var address = string.Format("{0}:{1}", host, port);
-                using (var nativeCredentials = credentials.ToNativeCredentials())
-                {
-                    if (nativeCredentials != null)
-                    {
-                        return handle.AddSecurePort(address, nativeCredentials);
-                    }
-                    else
-                    {
-                        return handle.AddInsecurePort(address);
-                    }
-                }
+                return ports;
             }
         }
 
@@ -190,6 +170,50 @@ namespace Grpc.Core
         }
 
         /// <summary>
+        /// Adds a service definition.
+        /// </summary>
+        private void AddServiceDefinitionInternal(ServerServiceDefinition serviceDefinition)
+        {
+            lock (myLock)
+            {
+                Preconditions.CheckState(!startRequested);
+                foreach (var entry in serviceDefinition.CallHandlers)
+                {
+                    callHandlers.Add(entry.Key, entry.Value);
+                }
+                serviceDefinitionsList.Add(serviceDefinition);
+            }
+        }
+
+        /// <summary>
+        /// Adds a listening port.
+        /// </summary>
+        private int AddPortInternal(ServerPort serverPort)
+        {
+            lock (myLock)
+            {
+                Preconditions.CheckNotNull(serverPort.Credentials);
+                Preconditions.CheckState(!startRequested);
+                var address = string.Format("{0}:{1}", serverPort.Host, serverPort.Port);
+                int boundPort;
+                using (var nativeCredentials = serverPort.Credentials.ToNativeCredentials())
+                {
+                    if (nativeCredentials != null)
+                    {
+                        boundPort = handle.AddSecurePort(address, nativeCredentials);
+                    }
+                    else
+                    {
+                        boundPort = handle.AddInsecurePort(address);
+                    }
+                }
+                var newServerPort = new ServerPort(serverPort, boundPort);
+                this.serverPortList.Add(newServerPort);
+                return boundPort;
+            }
+        }
+
+        /// <summary>
         /// Allows one new RPC call to be received by server.
         /// </summary>
         private void AllowOneRpc()
@@ -249,5 +273,82 @@ namespace Grpc.Core
         {
             shutdownTcs.SetResult(null);
         }
+
+        /// <summary>
+        /// Collection of service definitions.
+        /// </summary>
+        public class ServiceDefinitionCollection : IEnumerable<ServerServiceDefinition>
+        {
+            readonly Server server;
+
+            internal ServiceDefinitionCollection(Server server)
+            {
+                this.server = server;
+            }
+
+            /// <summary>
+            /// Adds a service definition to the server. This is how you register
+            /// handlers for a service with the server. Only call this before Start().
+            /// </summary>
+            public void Add(ServerServiceDefinition serviceDefinition)
+            {
+                server.AddServiceDefinitionInternal(serviceDefinition);
+            }
+
+            public IEnumerator<ServerServiceDefinition> GetEnumerator()
+            {
+                return server.serviceDefinitionsList.GetEnumerator();
+            }
+
+            IEnumerator IEnumerable.GetEnumerator()
+            {
+                return server.serviceDefinitionsList.GetEnumerator();
+            }
+        }
+
+        /// <summary>
+        /// Collection of server ports.
+        /// </summary>
+        public class ServerPortCollection : IEnumerable<ServerPort>
+        {
+            readonly Server server;
+
+            internal ServerPortCollection(Server server)
+            {
+                this.server = server;
+            }
+
+            /// <summary>
+            /// Adds a new port on which server should listen.
+            /// Only call this before Start().
+            /// <returns>The port on which server will be listening.</returns>
+            /// </summary>
+            public int Add(ServerPort serverPort)
+            {
+                return server.AddPortInternal(serverPort);
+            }
+
+            /// <summary>
+            /// Adds a new port on which server should listen.
+            /// <returns>The port on which server will be listening.</returns>
+            /// </summary>
+            /// <param name="host">the host</param>
+            /// <param name="port">the port. If zero, an unused port is chosen automatically.</param>
+            /// <param name="credentials">credentials to use to secure this port.</param>
+            public int Add(string host, int port, ServerCredentials credentials)
+            {
+                return Add(new ServerPort(host, port, credentials));
+            }
+
+            public IEnumerator<ServerPort> GetEnumerator()
+            {
+                return server.serverPortList.GetEnumerator();
+            }
+
+            IEnumerator IEnumerable.GetEnumerator()
+            {
+                return server.serverPortList.GetEnumerator();
+            }
+        }
     }
 }
diff --git a/src/csharp/Grpc.Core/ServerCallContext.cs b/src/csharp/Grpc.Core/ServerCallContext.cs
index 0c48adaea5..75d81c64f3 100644
--- a/src/csharp/Grpc.Core/ServerCallContext.cs
+++ b/src/csharp/Grpc.Core/ServerCallContext.cs
@@ -36,15 +36,16 @@ using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Threading.Tasks;
 
+using Grpc.Core.Internal;
+
 namespace Grpc.Core
 {
     /// <summary>
     /// Context for a server-side call.
     /// </summary>
-    public sealed class ServerCallContext
+    public class ServerCallContext
     {
-        // TODO(jtattermusch): expose method to send initial metadata back to client
-
+        private readonly CallSafeHandle callHandle;
         private readonly string method;
         private readonly string host;
         private readonly string peer;
@@ -54,18 +55,37 @@ namespace Grpc.Core
         private readonly Metadata responseTrailers = new Metadata();
 
         private Status status = Status.DefaultSuccess;
+        private Func<Metadata, Task> writeHeadersFunc;
+        private IHasWriteOptions writeOptionsHolder;
 
-        public ServerCallContext(string method, string host, string peer, DateTime deadline, Metadata requestHeaders, CancellationToken cancellationToken)
+        internal ServerCallContext(CallSafeHandle callHandle, string method, string host, string peer, DateTime deadline, Metadata requestHeaders, CancellationToken cancellationToken,
+            Func<Metadata, Task> writeHeadersFunc, IHasWriteOptions writeOptionsHolder)
         {
+            this.callHandle = callHandle;
             this.method = method;
             this.host = host;
             this.peer = peer;
             this.deadline = deadline;
             this.requestHeaders = requestHeaders;
             this.cancellationToken = cancellationToken;
+            this.writeHeadersFunc = writeHeadersFunc;
+            this.writeOptionsHolder = writeOptionsHolder;
+        }
+
+        public Task WriteResponseHeadersAsync(Metadata responseHeaders)
+        {
+            return writeHeadersFunc(responseHeaders);
+        }
+
+        /// <summary>
+        /// Creates a propagation token to be used to propagate call context to a child call.
+        /// </summary>
+        public ContextPropagationToken CreatePropagationToken(ContextPropagationOptions options = null)
+        {
+            return new ContextPropagationToken(callHandle, deadline, cancellationToken, options);
         }
             
-        /// <summary> Name of method called in this RPC. </summary>
+        /// <summary>Name of method called in this RPC.</summary>
         public string Method
         {
             get
@@ -74,7 +94,7 @@ namespace Grpc.Core
             }
         }
 
-        /// <summary> Name of host called in this RPC. </summary>
+        /// <summary>Name of host called in this RPC.</summary>
         public string Host
         {
             get
@@ -83,7 +103,7 @@ namespace Grpc.Core
             }
         }
 
-        /// <summary> Address of the remote endpoint in URI format. </summary>
+        /// <summary>Address of the remote endpoint in URI format.</summary>
         public string Peer
         {
             get
@@ -92,7 +112,7 @@ namespace Grpc.Core
             }
         }
 
-        /// <summary> Deadline for this RPC. </summary>
+        /// <summary>Deadline for this RPC.</summary>
         public DateTime Deadline
         {
             get
@@ -101,7 +121,7 @@ namespace Grpc.Core
             }
         }
 
-        /// <summary> Initial metadata sent by client. </summary>
+        /// <summary>Initial metadata sent by client.</summary>
         public Metadata RequestHeaders
         {
             get
@@ -110,8 +130,7 @@ namespace Grpc.Core
             }
         }
 
-        // TODO(jtattermusch): support signalling cancellation.
-        /// <summary> Cancellation token signals when call is cancelled. </summary>
+        /// <summary>Cancellation token signals when call is cancelled.</summary>
         public CancellationToken CancellationToken
         {
             get
@@ -120,7 +139,7 @@ namespace Grpc.Core
             }
         }
 
-        /// <summary> Trailers to send back to client after RPC finishes.</summary>
+        /// <summary>Trailers to send back to client after RPC finishes.</summary>
         public Metadata ResponseTrailers
         {
             get
@@ -142,5 +161,31 @@ namespace Grpc.Core
                 status = value;
             }
         }
+
+        /// <summary>
+        /// Allows setting write options for the following write.
+        /// For streaming response calls, this property is also exposed as on IServerStreamWriter for convenience.
+        /// Both properties are backed by the same underlying value.
+        /// </summary>
+        public WriteOptions WriteOptions
+        {
+            get
+            {
+                return writeOptionsHolder.WriteOptions;
+            }
+
+            set
+            {
+                writeOptionsHolder.WriteOptions = value;
+            }
+        }
+    }
+
+    /// <summary>
+    /// Allows sharing write options between ServerCallContext and other objects.
+    /// </summary>
+    public interface IHasWriteOptions
+    {
+        WriteOptions WriteOptions { get; set; }
     }
 }
diff --git a/src/csharp/Grpc.Core/ServerCredentials.cs b/src/csharp/Grpc.Core/ServerCredentials.cs
index 32ed4b78a1..c11a1ede08 100644
--- a/src/csharp/Grpc.Core/ServerCredentials.cs
+++ b/src/csharp/Grpc.Core/ServerCredentials.cs
@@ -33,7 +33,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Collections.Immutable;
 using Grpc.Core.Internal;
 using Grpc.Core.Utils;
 
@@ -80,18 +79,26 @@ namespace Grpc.Core
     {
         readonly IList<KeyCertificatePair> keyCertificatePairs;
         readonly string rootCertificates;
+        readonly bool forceClientAuth;
 
         /// <summary>
         /// Creates server-side SSL credentials.
         /// </summary>
-        /// <param name="rootCertificates">PEM encoded client root certificates used to authenticate client.</param>
         /// <param name="keyCertificatePairs">Key-certificates to use.</param>
-        public SslServerCredentials(IEnumerable<KeyCertificatePair> keyCertificatePairs, string rootCertificates)
+        /// <param name="rootCertificates">PEM encoded client root certificates used to authenticate client.</param>
+        /// <param name="forceClientAuth">If true, client will be rejected unless it proves its unthenticity using against rootCertificates.</param>
+        public SslServerCredentials(IEnumerable<KeyCertificatePair> keyCertificatePairs, string rootCertificates, bool forceClientAuth)
         {
             this.keyCertificatePairs = new List<KeyCertificatePair>(keyCertificatePairs).AsReadOnly();
             Preconditions.CheckArgument(this.keyCertificatePairs.Count > 0,
                 "At least one KeyCertificatePair needs to be provided");
+            if (forceClientAuth)
+            {
+                Preconditions.CheckNotNull(rootCertificates,
+                    "Cannot force client authentication unless you provide rootCertificates.");
+            }
             this.rootCertificates = rootCertificates;
+            this.forceClientAuth = forceClientAuth;
         }
 
         /// <summary>
@@ -100,7 +107,7 @@ namespace Grpc.Core
         /// using client root certificates.
         /// </summary>
         /// <param name="keyCertificatePairs">Key-certificates to use.</param>
-        public SslServerCredentials(IEnumerable<KeyCertificatePair> keyCertificatePairs) : this(keyCertificatePairs, null)
+        public SslServerCredentials(IEnumerable<KeyCertificatePair> keyCertificatePairs) : this(keyCertificatePairs, null, false)
         {
         }
 
@@ -126,6 +133,17 @@ namespace Grpc.Core
             }
         }
 
+        /// <summary>
+        /// If true, the authenticity of client check will be enforced.
+        /// </summary>
+        public bool ForceClientAuthentication
+        {
+            get
+            {
+                return this.forceClientAuth;
+            }
+        }
+
         internal override ServerCredentialsSafeHandle ToNativeCredentials()
         {
             int count = keyCertificatePairs.Count;
@@ -136,7 +154,7 @@ namespace Grpc.Core
                 certChains[i] = keyCertificatePairs[i].CertificateChain;
                 keys[i] = keyCertificatePairs[i].PrivateKey;
             }
-            return ServerCredentialsSafeHandle.CreateSslCredentials(rootCertificates, certChains, keys);
+            return ServerCredentialsSafeHandle.CreateSslCredentials(rootCertificates, certChains, keys, forceClientAuth);
         }
     }
 }
diff --git a/src/csharp/Grpc.Core/ServerPort.cs b/src/csharp/Grpc.Core/ServerPort.cs
new file mode 100644
index 0000000000..55e4bd0062
--- /dev/null
+++ b/src/csharp/Grpc.Core/ServerPort.cs
@@ -0,0 +1,120 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+
+using Grpc.Core.Utils;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// A port exposed by a server.
+    /// </summary>
+    public class ServerPort
+    {
+        /// <summary>
+        /// Pass this value as port to have the server choose an unused listening port for you.
+        /// Ports added to a server will contain the bound port in their <see cref="BoundPort"/> property.
+        /// </summary>
+        public const int PickUnused = 0;
+
+        readonly string host;
+        readonly int port;
+        readonly ServerCredentials credentials;
+        readonly int boundPort;
+
+        /// <summary>
+        /// Creates a new port on which server should listen.
+        /// </summary>
+        /// <returns>The port on which server will be listening.</returns>
+        /// <param name="host">the host</param>
+        /// <param name="port">the port. If zero, an unused port is chosen automatically.</param>
+        /// <param name="credentials">credentials to use to secure this port.</param>
+        public ServerPort(string host, int port, ServerCredentials credentials)
+        {
+            this.host = Preconditions.CheckNotNull(host);
+            this.port = port;
+            this.credentials = Preconditions.CheckNotNull(credentials);
+        }
+
+        /// <summary>
+        /// Creates a port from an existing <c>ServerPort</c> instance and boundPort value.
+        /// </summary>
+        internal ServerPort(ServerPort serverPort, int boundPort)
+        {
+            this.host = serverPort.host;
+            this.port = serverPort.port;
+            this.credentials = serverPort.credentials;
+            this.boundPort = boundPort;
+        }
+
+        /// <value>The host.</value>
+        public string Host
+        {
+            get
+            {
+                return host;
+            }
+        }
+
+        /// <value>The port.</value>
+        public int Port
+        {
+            get
+            {
+                return port;
+            }
+        }
+
+        /// <value>The server credentials.</value>
+        public ServerCredentials Credentials
+        {
+            get
+            {
+                return credentials;
+            }
+        }
+
+        /// <value>
+        /// The port actually bound by the server. This is useful if you let server
+        /// pick port automatically. <see cref="PickUnused"/>
+        /// </value>
+        public int BoundPort
+        {
+            get
+            {
+                return boundPort;
+            }
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core/ServerServiceDefinition.cs b/src/csharp/Grpc.Core/ServerServiceDefinition.cs
index b180186c12..a00d156e52 100644
--- a/src/csharp/Grpc.Core/ServerServiceDefinition.cs
+++ b/src/csharp/Grpc.Core/ServerServiceDefinition.cs
@@ -33,7 +33,7 @@
 
 using System;
 using System.Collections.Generic;
-using System.Collections.Immutable;
+using System.Collections.ObjectModel;
 using Grpc.Core.Internal;
 
 namespace Grpc.Core
@@ -43,14 +43,14 @@ namespace Grpc.Core
     /// </summary>
     public class ServerServiceDefinition
     {
-        readonly ImmutableDictionary<string, IServerCallHandler> callHandlers;
+        readonly ReadOnlyDictionary<string, IServerCallHandler> callHandlers;
 
-        private ServerServiceDefinition(ImmutableDictionary<string, IServerCallHandler> callHandlers)
+        private ServerServiceDefinition(Dictionary<string, IServerCallHandler> callHandlers)
         {
-            this.callHandlers = callHandlers;
+            this.callHandlers = new ReadOnlyDictionary<string, IServerCallHandler>(callHandlers);
         }
 
-        internal ImmutableDictionary<string, IServerCallHandler> CallHandlers
+        internal IDictionary<string, IServerCallHandler> CallHandlers
         {
             get
             {
@@ -115,7 +115,7 @@ namespace Grpc.Core
 
             public ServerServiceDefinition Build()
             {
-                return new ServerServiceDefinition(callHandlers.ToImmutableDictionary());
+                return new ServerServiceDefinition(callHandlers);
             }
         }
     }
diff --git a/src/csharp/Grpc.Core/Version.cs b/src/csharp/Grpc.Core/Version.cs
index b5cb652945..d2a029fbb4 100644
--- a/src/csharp/Grpc.Core/Version.cs
+++ b/src/csharp/Grpc.Core/Version.cs
@@ -2,4 +2,4 @@ using System.Reflection;
 using System.Runtime.CompilerServices;
 
 // The current version of gRPC C#.
-[assembly: AssemblyVersion(Grpc.Core.VersionInfo.CurrentVersion + ".*")]
+[assembly: AssemblyVersion(Grpc.Core.VersionInfo.CurrentVersion + ".0")]
diff --git a/src/csharp/Grpc.Core/VersionInfo.cs b/src/csharp/Grpc.Core/VersionInfo.cs
index 656a3d47bb..939372e237 100644
--- a/src/csharp/Grpc.Core/VersionInfo.cs
+++ b/src/csharp/Grpc.Core/VersionInfo.cs
@@ -8,6 +8,6 @@ namespace Grpc.Core
         /// <summary>
         /// Current version of gRPC
         /// </summary>
-        public const string CurrentVersion = "0.6.0";
+        public const string CurrentVersion = "0.6.1";
     }
 }
diff --git a/src/csharp/Grpc.Core/WriteOptions.cs b/src/csharp/Grpc.Core/WriteOptions.cs
new file mode 100644
index 0000000000..7ef3189d76
--- /dev/null
+++ b/src/csharp/Grpc.Core/WriteOptions.cs
@@ -0,0 +1,82 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// Flags for write operations.
+    /// </summary>
+    [Flags]
+    public enum WriteFlags
+    {
+        /// <summary>
+        /// Hint that the write may be buffered and need not go out on the wire immediately.
+        /// gRPC is free to buffer the message until the next non-buffered
+        /// write, or until write stream completion, but it need not buffer completely or at all.
+        /// </summary>
+        BufferHint = 0x1,
+
+        /// <summary>
+        /// Force compression to be disabled for a particular write.
+        /// </summary>
+        NoCompress = 0x2
+    }
+
+    /// <summary>
+    /// Options for write operations.
+    /// </summary>
+    public class WriteOptions
+    {
+        /// <summary>
+        /// Default write options.
+        /// </summary>
+        public static readonly WriteOptions Default = new WriteOptions();
+            
+        private WriteFlags flags;
+
+        public WriteOptions(WriteFlags flags = default(WriteFlags))
+        {
+            this.flags = flags;
+        }
+
+        public WriteFlags Flags
+        {
+            get
+            {
+                return this.flags;
+            }
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core/packages.config b/src/csharp/Grpc.Core/packages.config
index 6cdcdf2656..9b12b9b096 100644
--- a/src/csharp/Grpc.Core/packages.config
+++ b/src/csharp/Grpc.Core/packages.config
@@ -3,5 +3,4 @@
   <package id="grpc.dependencies.openssl.redist" version="1.0.2.2" targetFramework="net45" />
   <package id="grpc.dependencies.zlib.redist" version="1.2.8.9" targetFramework="net45" />
   <package id="Ix-Async" version="1.2.3" targetFramework="net45" />
-  <package id="System.Collections.Immutable" version="1.1.36" targetFramework="net45" />
 </packages>
\ No newline at end of file
diff --git a/src/csharp/Grpc.Examples.MathServer/MathServer.cs b/src/csharp/Grpc.Examples.MathServer/MathServer.cs
index 468eefbe3e..5f7e717b0c 100644
--- a/src/csharp/Grpc.Examples.MathServer/MathServer.cs
+++ b/src/csharp/Grpc.Examples.MathServer/MathServer.cs
@@ -38,16 +38,19 @@ namespace math
 {
     class MainClass
     {
+        const string Host = "0.0.0.0";
+        const int Port = 23456;
+
         public static void Main(string[] args)
         {
-            string host = "0.0.0.0";
-
-            Server server = new Server();
-            server.AddServiceDefinition(Math.BindService(new MathServiceImpl()));
-            int port = server.AddPort(host, 23456, ServerCredentials.Insecure);
+            Server server = new Server
+            {
+                Services = { Math.BindService(new MathServiceImpl()) },
+                Ports = { { Host, Port, ServerCredentials.Insecure } }
+            };
             server.Start();
 
-            Console.WriteLine("MathServer listening on port " + port);
+            Console.WriteLine("MathServer listening on port " + Port);
 
             Console.WriteLine("Press any key to stop the server...");
             Console.ReadKey();
diff --git a/src/csharp/Grpc.Examples.Tests/MathClientServerTests.cs b/src/csharp/Grpc.Examples.Tests/MathClientServerTests.cs
index 242d29a9a5..73d2a1ca9b 100644
--- a/src/csharp/Grpc.Examples.Tests/MathClientServerTests.cs
+++ b/src/csharp/Grpc.Examples.Tests/MathClientServerTests.cs
@@ -33,6 +33,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Grpc.Core;
@@ -46,7 +47,7 @@ namespace math.Tests
     /// </summary>
     public class MathClientServerTest
     {
-        string host = "localhost";
+        const string Host = "localhost";
         Server server;
         Channel channel;
         Math.MathClient client;
@@ -54,19 +55,14 @@ namespace math.Tests
         [TestFixtureSetUp]
         public void Init()
         {
-            server = new Server();
-            server.AddServiceDefinition(Math.BindService(new MathServiceImpl()));
-            int port = server.AddPort(host, Server.PickUnusedPort, ServerCredentials.Insecure);
-            server.Start();
-            channel = new Channel(host, port, Credentials.Insecure);
-            client = Math.NewClient(channel);
-
-            // TODO(jtattermusch): get rid of the custom header here once we have dedicated tests
-            // for header support.
-            client.HeaderInterceptor = (metadata) =>
+            server = new Server
             {
-                metadata.Add(new Metadata.Entry("custom-header", "abcdef"));
+                Services = { Math.BindService(new MathServiceImpl()) },
+                Ports = { { Host, ServerPort.PickUnused, ServerCredentials.Insecure } }
             };
+            server.Start();
+            channel = new Channel(Host, server.Ports.Single().BoundPort, Credentials.Insecure);
+            client = Math.NewClient(channel);
         }
 
         [TestFixtureTearDown]
@@ -96,15 +92,8 @@ namespace math.Tests
         [Test]
         public void DivByZero()
         {
-            try
-            {
-                DivReply response = client.Div(new DivArgs.Builder { Dividend = 0, Divisor = 0 }.Build());
-                Assert.Fail();
-            }
-            catch (RpcException e)
-            {
-                Assert.AreEqual(StatusCode.Unknown, e.Status.StatusCode);
-            }   
+            var ex = Assert.Throws<RpcException>(() => client.Div(new DivArgs.Builder { Dividend = 0, Divisor = 0 }.Build()));
+            Assert.AreEqual(StatusCode.Unknown, ex.Status.StatusCode);
         }
 
         [Test]
@@ -162,15 +151,10 @@ namespace math.Tests
             using (var call = client.Fib(new FibArgs.Builder { Limit = 0 }.Build(), 
                 deadline: DateTime.UtcNow.AddMilliseconds(500)))
             {
-                try
-                {
-                    await call.ResponseStream.ToList();
-                    Assert.Fail();
-                }
-                catch (RpcException e)
-                {
-                    Assert.AreEqual(StatusCode.DeadlineExceeded, e.Status.StatusCode);
-                }
+                var ex = Assert.Throws<RpcException>(async () => await call.ResponseStream.ToList());
+
+                // We can't guarantee the status code always DeadlineExceeded. See issue #2685.
+                Assert.Contains(ex.Status.StatusCode, new[] { StatusCode.DeadlineExceeded, StatusCode.Internal });
             }
         }
 
diff --git a/src/csharp/Grpc.Examples/MathGrpc.cs b/src/csharp/Grpc.Examples/MathGrpc.cs
index 67827e7b4f..4941ff35f7 100644
--- a/src/csharp/Grpc.Examples/MathGrpc.cs
+++ b/src/csharp/Grpc.Examples/MathGrpc.cs
@@ -19,24 +19,28 @@ namespace math {
 
     static readonly Method<global::math.DivArgs, global::math.DivReply> __Method_Div = new Method<global::math.DivArgs, global::math.DivReply>(
         MethodType.Unary,
+        __ServiceName,
         "Div",
         __Marshaller_DivArgs,
         __Marshaller_DivReply);
 
     static readonly Method<global::math.DivArgs, global::math.DivReply> __Method_DivMany = new Method<global::math.DivArgs, global::math.DivReply>(
         MethodType.DuplexStreaming,
+        __ServiceName,
         "DivMany",
         __Marshaller_DivArgs,
         __Marshaller_DivReply);
 
     static readonly Method<global::math.FibArgs, global::math.Num> __Method_Fib = new Method<global::math.FibArgs, global::math.Num>(
         MethodType.ServerStreaming,
+        __ServiceName,
         "Fib",
         __Marshaller_FibArgs,
         __Marshaller_Num);
 
     static readonly Method<global::math.Num, global::math.Num> __Method_Sum = new Method<global::math.Num, global::math.Num>(
         MethodType.ClientStreaming,
+        __ServiceName,
         "Sum",
         __Marshaller_Num,
         __Marshaller_Num);
@@ -45,10 +49,15 @@ namespace math {
     public interface IMathClient
     {
       global::math.DivReply Div(global::math.DivArgs request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      global::math.DivReply Div(global::math.DivArgs request, CallOptions options);
       AsyncUnaryCall<global::math.DivReply> DivAsync(global::math.DivArgs request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncUnaryCall<global::math.DivReply> DivAsync(global::math.DivArgs request, CallOptions options);
       AsyncDuplexStreamingCall<global::math.DivArgs, global::math.DivReply> DivMany(Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncDuplexStreamingCall<global::math.DivArgs, global::math.DivReply> DivMany(CallOptions options);
       AsyncServerStreamingCall<global::math.Num> Fib(global::math.FibArgs request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncServerStreamingCall<global::math.Num> Fib(global::math.FibArgs request, CallOptions options);
       AsyncClientStreamingCall<global::math.Num, global::math.Num> Sum(Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncClientStreamingCall<global::math.Num, global::math.Num> Sum(CallOptions options);
     }
 
     // server-side interface
@@ -68,28 +77,53 @@ namespace math {
       }
       public global::math.DivReply Div(global::math.DivArgs request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_Div, headers, deadline);
-        return Calls.BlockingUnaryCall(call, request, cancellationToken);
+        var call = CreateCall(__Method_Div, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.BlockingUnaryCall(call, request);
+      }
+      public global::math.DivReply Div(global::math.DivArgs request, CallOptions options)
+      {
+        var call = CreateCall(__Method_Div, options);
+        return Calls.BlockingUnaryCall(call, request);
       }
       public AsyncUnaryCall<global::math.DivReply> DivAsync(global::math.DivArgs request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_Div, headers, deadline);
-        return Calls.AsyncUnaryCall(call, request, cancellationToken);
+        var call = CreateCall(__Method_Div, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.AsyncUnaryCall(call, request);
+      }
+      public AsyncUnaryCall<global::math.DivReply> DivAsync(global::math.DivArgs request, CallOptions options)
+      {
+        var call = CreateCall(__Method_Div, options);
+        return Calls.AsyncUnaryCall(call, request);
       }
       public AsyncDuplexStreamingCall<global::math.DivArgs, global::math.DivReply> DivMany(Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_DivMany, headers, deadline);
-        return Calls.AsyncDuplexStreamingCall(call, cancellationToken);
+        var call = CreateCall(__Method_DivMany, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.AsyncDuplexStreamingCall(call);
+      }
+      public AsyncDuplexStreamingCall<global::math.DivArgs, global::math.DivReply> DivMany(CallOptions options)
+      {
+        var call = CreateCall(__Method_DivMany, options);
+        return Calls.AsyncDuplexStreamingCall(call);
       }
       public AsyncServerStreamingCall<global::math.Num> Fib(global::math.FibArgs request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_Fib, headers, deadline);
-        return Calls.AsyncServerStreamingCall(call, request, cancellationToken);
+        var call = CreateCall(__Method_Fib, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.AsyncServerStreamingCall(call, request);
+      }
+      public AsyncServerStreamingCall<global::math.Num> Fib(global::math.FibArgs request, CallOptions options)
+      {
+        var call = CreateCall(__Method_Fib, options);
+        return Calls.AsyncServerStreamingCall(call, request);
       }
       public AsyncClientStreamingCall<global::math.Num, global::math.Num> Sum(Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_Sum, headers, deadline);
-        return Calls.AsyncClientStreamingCall(call, cancellationToken);
+        var call = CreateCall(__Method_Sum, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.AsyncClientStreamingCall(call);
+      }
+      public AsyncClientStreamingCall<global::math.Num, global::math.Num> Sum(CallOptions options)
+      {
+        var call = CreateCall(__Method_Sum, options);
+        return Calls.AsyncClientStreamingCall(call);
       }
     }
 
diff --git a/src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs b/src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs
index 9d89698a8f..024377e216 100644
--- a/src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs
+++ b/src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs
@@ -57,11 +57,13 @@ namespace Grpc.HealthCheck.Tests
         {
             serviceImpl = new HealthServiceImpl();
 
-            server = new Server();
-            server.AddServiceDefinition(Grpc.Health.V1Alpha.Health.BindService(serviceImpl));
-            int port = server.AddPort(Host, Server.PickUnusedPort, ServerCredentials.Insecure);
+            server = new Server
+            {
+                Services = { Grpc.Health.V1Alpha.Health.BindService(serviceImpl) },
+                Ports = { { Host, ServerPort.PickUnused, ServerCredentials.Insecure } }
+            };
             server.Start();
-            channel = new Channel(Host, port, Credentials.Insecure);
+            channel = new Channel(Host, server.Ports.Single().BoundPort, Credentials.Insecure);
 
             client = Grpc.Health.V1Alpha.Health.NewClient(channel);
         }
diff --git a/src/csharp/Grpc.HealthCheck/HealthGrpc.cs b/src/csharp/Grpc.HealthCheck/HealthGrpc.cs
index 892cdb3f04..0dabc91f7c 100644
--- a/src/csharp/Grpc.HealthCheck/HealthGrpc.cs
+++ b/src/csharp/Grpc.HealthCheck/HealthGrpc.cs
@@ -17,6 +17,7 @@ namespace Grpc.Health.V1Alpha {
 
     static readonly Method<global::Grpc.Health.V1Alpha.HealthCheckRequest, global::Grpc.Health.V1Alpha.HealthCheckResponse> __Method_Check = new Method<global::Grpc.Health.V1Alpha.HealthCheckRequest, global::Grpc.Health.V1Alpha.HealthCheckResponse>(
         MethodType.Unary,
+        __ServiceName,
         "Check",
         __Marshaller_HealthCheckRequest,
         __Marshaller_HealthCheckResponse);
@@ -25,7 +26,9 @@ namespace Grpc.Health.V1Alpha {
     public interface IHealthClient
     {
       global::Grpc.Health.V1Alpha.HealthCheckResponse Check(global::Grpc.Health.V1Alpha.HealthCheckRequest request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      global::Grpc.Health.V1Alpha.HealthCheckResponse Check(global::Grpc.Health.V1Alpha.HealthCheckRequest request, CallOptions options);
       AsyncUnaryCall<global::Grpc.Health.V1Alpha.HealthCheckResponse> CheckAsync(global::Grpc.Health.V1Alpha.HealthCheckRequest request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncUnaryCall<global::Grpc.Health.V1Alpha.HealthCheckResponse> CheckAsync(global::Grpc.Health.V1Alpha.HealthCheckRequest request, CallOptions options);
     }
 
     // server-side interface
@@ -42,13 +45,23 @@ namespace Grpc.Health.V1Alpha {
       }
       public global::Grpc.Health.V1Alpha.HealthCheckResponse Check(global::Grpc.Health.V1Alpha.HealthCheckRequest request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_Check, headers, deadline);
-        return Calls.BlockingUnaryCall(call, request, cancellationToken);
+        var call = CreateCall(__Method_Check, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.BlockingUnaryCall(call, request);
+      }
+      public global::Grpc.Health.V1Alpha.HealthCheckResponse Check(global::Grpc.Health.V1Alpha.HealthCheckRequest request, CallOptions options)
+      {
+        var call = CreateCall(__Method_Check, options);
+        return Calls.BlockingUnaryCall(call, request);
       }
       public AsyncUnaryCall<global::Grpc.Health.V1Alpha.HealthCheckResponse> CheckAsync(global::Grpc.Health.V1Alpha.HealthCheckRequest request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_Check, headers, deadline);
-        return Calls.AsyncUnaryCall(call, request, cancellationToken);
+        var call = CreateCall(__Method_Check, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.AsyncUnaryCall(call, request);
+      }
+      public AsyncUnaryCall<global::Grpc.Health.V1Alpha.HealthCheckResponse> CheckAsync(global::Grpc.Health.V1Alpha.HealthCheckRequest request, CallOptions options)
+      {
+        var call = CreateCall(__Method_Check, options);
+        return Calls.AsyncUnaryCall(call, request);
       }
     }
 
diff --git a/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj b/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
index abc27f811e..06a75a3351 100644
--- a/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
+++ b/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
@@ -87,9 +87,6 @@
     <Reference Include="Microsoft.Threading.Tasks.Extensions.Desktop">
       <HintPath>..\packages\Microsoft.Bcl.Async.1.0.168\lib\net40\Microsoft.Threading.Tasks.Extensions.Desktop.dll</HintPath>
     </Reference>
-    <Reference Include="System.Collections.Immutable">
-      <HintPath>..\packages\System.Collections.Immutable.1.1.36\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
-    </Reference>
   </ItemGroup>
   <ItemGroup>
     <Compile Include="..\Grpc.Core\Version.cs">
diff --git a/src/csharp/Grpc.IntegrationTesting/InteropClient.cs b/src/csharp/Grpc.IntegrationTesting/InteropClient.cs
index 7411d91d5a..6802de489d 100644
--- a/src/csharp/Grpc.IntegrationTesting/InteropClient.cs
+++ b/src/csharp/Grpc.IntegrationTesting/InteropClient.cs
@@ -404,15 +404,8 @@ namespace Grpc.IntegrationTesting
                 await Task.Delay(1000);
                 cts.Cancel();
 
-                try
-                {
-                    var response = await call.ResponseAsync;
-                    Assert.Fail();
-                }
-                catch (RpcException e)
-                {
-                    Assert.AreEqual(StatusCode.Cancelled, e.Status.StatusCode);
-                }
+                var ex = Assert.Throws<RpcException>(async () => await call.ResponseAsync);
+                Assert.AreEqual(StatusCode.Cancelled, ex.Status.StatusCode);
             }
             Console.WriteLine("Passed!");
         }
@@ -435,15 +428,8 @@ namespace Grpc.IntegrationTesting
 
                 cts.Cancel();
 
-                try
-                {
-                    await call.ResponseStream.MoveNext();
-                    Assert.Fail();
-                }
-                catch (RpcException e)
-                {
-                    Assert.AreEqual(StatusCode.Cancelled, e.Status.StatusCode);
-                }
+                var ex = Assert.Throws<RpcException>(async () => await call.ResponseStream.MoveNext());
+                Assert.AreEqual(StatusCode.Cancelled, ex.Status.StatusCode);
             }
             Console.WriteLine("Passed!");
         }
diff --git a/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs b/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs
index 2756ce97aa..6fa721bc1c 100644
--- a/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs
+++ b/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs
@@ -33,6 +33,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using grpc.testing;
@@ -47,7 +48,7 @@ namespace Grpc.IntegrationTesting
     /// </summary>
     public class InteropClientServerTest
     {
-        string host = "localhost";
+        const string Host = "localhost";
         Server server;
         Channel channel;
         TestService.ITestServiceClient client;
@@ -55,16 +56,19 @@ namespace Grpc.IntegrationTesting
         [TestFixtureSetUp]
         public void Init()
         {
-            server = new Server();
-            server.AddServiceDefinition(TestService.BindService(new TestServiceImpl()));
-            int port = server.AddPort(host, Server.PickUnusedPort, TestCredentials.CreateTestServerCredentials());
+            server = new Server
+            {
+                Services = { TestService.BindService(new TestServiceImpl()) },
+                Ports = { { Host, ServerPort.PickUnused, TestCredentials.CreateTestServerCredentials() } }
+            };
             server.Start();
 
             var options = new List<ChannelOption>
             {
                 new ChannelOption(ChannelOptions.SslTargetNameOverride, TestCredentials.DefaultHostOverride)
             };
-            channel = new Channel(host, port, TestCredentials.CreateTestClientCredentials(true), options);
+            int port = server.Ports.Single().BoundPort;
+            channel = new Channel(Host, port, TestCredentials.CreateTestClientCredentials(true), options);
             client = TestService.NewClient(channel);
         }
 
diff --git a/src/csharp/Grpc.IntegrationTesting/InteropServer.cs b/src/csharp/Grpc.IntegrationTesting/InteropServer.cs
index bf6947e09d..504fd11857 100644
--- a/src/csharp/Grpc.IntegrationTesting/InteropServer.cs
+++ b/src/csharp/Grpc.IntegrationTesting/InteropServer.cs
@@ -88,18 +88,20 @@ namespace Grpc.IntegrationTesting
 
         private void Run()
         {
-            var server = new Server();
-            server.AddServiceDefinition(TestService.BindService(new TestServiceImpl()));
+            var server = new Server
+            {
+                Services = { TestService.BindService(new TestServiceImpl()) }
+            };
 
             string host = "0.0.0.0";
             int port = options.port.Value;
             if (options.useTls)
             {
-                server.AddPort(host, port, TestCredentials.CreateTestServerCredentials());
+                server.Ports.Add(host, port, TestCredentials.CreateTestServerCredentials());
             }
             else
             {
-                server.AddPort(host, options.port.Value, ServerCredentials.Insecure);
+                server.Ports.Add(host, options.port.Value, ServerCredentials.Insecure);
             }
             Console.WriteLine("Running server on " + string.Format("{0}:{1}", host, port));
             server.Start();
diff --git a/src/csharp/Grpc.IntegrationTesting/SslCredentialsTest.cs b/src/csharp/Grpc.IntegrationTesting/SslCredentialsTest.cs
index 1baf40eea2..1c398eb84e 100644
--- a/src/csharp/Grpc.IntegrationTesting/SslCredentialsTest.cs
+++ b/src/csharp/Grpc.IntegrationTesting/SslCredentialsTest.cs
@@ -34,6 +34,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using grpc.testing;
@@ -49,7 +50,7 @@ namespace Grpc.IntegrationTesting
     /// </summary>
     public class SslCredentialsTest
     {
-        string host = "localhost";
+        const string Host = "localhost";
         Server server;
         Channel channel;
         TestService.ITestServiceClient client;
@@ -62,12 +63,14 @@ namespace Grpc.IntegrationTesting
                 File.ReadAllText(TestCredentials.ServerCertChainPath),
                 File.ReadAllText(TestCredentials.ServerPrivateKeyPath));
 
-            var serverCredentials = new SslServerCredentials(new[] { keyCertPair }, rootCert);
+            var serverCredentials = new SslServerCredentials(new[] { keyCertPair }, rootCert, true);
             var clientCredentials = new SslCredentials(rootCert, keyCertPair);
 
-            server = new Server();
-            server.AddServiceDefinition(TestService.BindService(new TestServiceImpl()));
-            int port = server.AddPort(host, Server.PickUnusedPort, serverCredentials);
+            server = new Server
+            {
+                Services = { TestService.BindService(new TestServiceImpl()) },
+                Ports = { { Host, ServerPort.PickUnused, serverCredentials } }
+            };
             server.Start();
 
             var options = new List<ChannelOption>
@@ -75,7 +78,7 @@ namespace Grpc.IntegrationTesting
                 new ChannelOption(ChannelOptions.SslTargetNameOverride, TestCredentials.DefaultHostOverride)
             };
 
-            channel = new Channel(host, port, clientCredentials, options);
+            channel = new Channel(Host, server.Ports.Single().BoundPort, clientCredentials, options);
             client = TestService.NewClient(channel);
         }
 
diff --git a/src/csharp/Grpc.IntegrationTesting/TestCredentials.cs b/src/csharp/Grpc.IntegrationTesting/TestCredentials.cs
index 54d8587713..da0b7fb910 100644
--- a/src/csharp/Grpc.IntegrationTesting/TestCredentials.cs
+++ b/src/csharp/Grpc.IntegrationTesting/TestCredentials.cs
@@ -33,7 +33,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Collections.Immutable;
 using System.Diagnostics;
 using System.IO;
 using System.Text.RegularExpressions;
diff --git a/src/csharp/Grpc.IntegrationTesting/TestGrpc.cs b/src/csharp/Grpc.IntegrationTesting/TestGrpc.cs
index ddcd0c2958..697acb53d8 100644
--- a/src/csharp/Grpc.IntegrationTesting/TestGrpc.cs
+++ b/src/csharp/Grpc.IntegrationTesting/TestGrpc.cs
@@ -22,36 +22,42 @@ namespace grpc.testing {
 
     static readonly Method<global::grpc.testing.Empty, global::grpc.testing.Empty> __Method_EmptyCall = new Method<global::grpc.testing.Empty, global::grpc.testing.Empty>(
         MethodType.Unary,
+        __ServiceName,
         "EmptyCall",
         __Marshaller_Empty,
         __Marshaller_Empty);
 
     static readonly Method<global::grpc.testing.SimpleRequest, global::grpc.testing.SimpleResponse> __Method_UnaryCall = new Method<global::grpc.testing.SimpleRequest, global::grpc.testing.SimpleResponse>(
         MethodType.Unary,
+        __ServiceName,
         "UnaryCall",
         __Marshaller_SimpleRequest,
         __Marshaller_SimpleResponse);
 
     static readonly Method<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse> __Method_StreamingOutputCall = new Method<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse>(
         MethodType.ServerStreaming,
+        __ServiceName,
         "StreamingOutputCall",
         __Marshaller_StreamingOutputCallRequest,
         __Marshaller_StreamingOutputCallResponse);
 
     static readonly Method<global::grpc.testing.StreamingInputCallRequest, global::grpc.testing.StreamingInputCallResponse> __Method_StreamingInputCall = new Method<global::grpc.testing.StreamingInputCallRequest, global::grpc.testing.StreamingInputCallResponse>(
         MethodType.ClientStreaming,
+        __ServiceName,
         "StreamingInputCall",
         __Marshaller_StreamingInputCallRequest,
         __Marshaller_StreamingInputCallResponse);
 
     static readonly Method<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse> __Method_FullDuplexCall = new Method<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse>(
         MethodType.DuplexStreaming,
+        __ServiceName,
         "FullDuplexCall",
         __Marshaller_StreamingOutputCallRequest,
         __Marshaller_StreamingOutputCallResponse);
 
     static readonly Method<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse> __Method_HalfDuplexCall = new Method<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse>(
         MethodType.DuplexStreaming,
+        __ServiceName,
         "HalfDuplexCall",
         __Marshaller_StreamingOutputCallRequest,
         __Marshaller_StreamingOutputCallResponse);
@@ -60,13 +66,21 @@ namespace grpc.testing {
     public interface ITestServiceClient
     {
       global::grpc.testing.Empty EmptyCall(global::grpc.testing.Empty request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      global::grpc.testing.Empty EmptyCall(global::grpc.testing.Empty request, CallOptions options);
       AsyncUnaryCall<global::grpc.testing.Empty> EmptyCallAsync(global::grpc.testing.Empty request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncUnaryCall<global::grpc.testing.Empty> EmptyCallAsync(global::grpc.testing.Empty request, CallOptions options);
       global::grpc.testing.SimpleResponse UnaryCall(global::grpc.testing.SimpleRequest request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      global::grpc.testing.SimpleResponse UnaryCall(global::grpc.testing.SimpleRequest request, CallOptions options);
       AsyncUnaryCall<global::grpc.testing.SimpleResponse> UnaryCallAsync(global::grpc.testing.SimpleRequest request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncUnaryCall<global::grpc.testing.SimpleResponse> UnaryCallAsync(global::grpc.testing.SimpleRequest request, CallOptions options);
       AsyncServerStreamingCall<global::grpc.testing.StreamingOutputCallResponse> StreamingOutputCall(global::grpc.testing.StreamingOutputCallRequest request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncServerStreamingCall<global::grpc.testing.StreamingOutputCallResponse> StreamingOutputCall(global::grpc.testing.StreamingOutputCallRequest request, CallOptions options);
       AsyncClientStreamingCall<global::grpc.testing.StreamingInputCallRequest, global::grpc.testing.StreamingInputCallResponse> StreamingInputCall(Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncClientStreamingCall<global::grpc.testing.StreamingInputCallRequest, global::grpc.testing.StreamingInputCallResponse> StreamingInputCall(CallOptions options);
       AsyncDuplexStreamingCall<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse> FullDuplexCall(Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncDuplexStreamingCall<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse> FullDuplexCall(CallOptions options);
       AsyncDuplexStreamingCall<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse> HalfDuplexCall(Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncDuplexStreamingCall<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse> HalfDuplexCall(CallOptions options);
     }
 
     // server-side interface
@@ -88,43 +102,83 @@ namespace grpc.testing {
       }
       public global::grpc.testing.Empty EmptyCall(global::grpc.testing.Empty request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_EmptyCall, headers, deadline);
-        return Calls.BlockingUnaryCall(call, request, cancellationToken);
+        var call = CreateCall(__Method_EmptyCall, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.BlockingUnaryCall(call, request);
+      }
+      public global::grpc.testing.Empty EmptyCall(global::grpc.testing.Empty request, CallOptions options)
+      {
+        var call = CreateCall(__Method_EmptyCall, options);
+        return Calls.BlockingUnaryCall(call, request);
       }
       public AsyncUnaryCall<global::grpc.testing.Empty> EmptyCallAsync(global::grpc.testing.Empty request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_EmptyCall, headers, deadline);
-        return Calls.AsyncUnaryCall(call, request, cancellationToken);
+        var call = CreateCall(__Method_EmptyCall, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.AsyncUnaryCall(call, request);
+      }
+      public AsyncUnaryCall<global::grpc.testing.Empty> EmptyCallAsync(global::grpc.testing.Empty request, CallOptions options)
+      {
+        var call = CreateCall(__Method_EmptyCall, options);
+        return Calls.AsyncUnaryCall(call, request);
       }
       public global::grpc.testing.SimpleResponse UnaryCall(global::grpc.testing.SimpleRequest request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_UnaryCall, headers, deadline);
-        return Calls.BlockingUnaryCall(call, request, cancellationToken);
+        var call = CreateCall(__Method_UnaryCall, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.BlockingUnaryCall(call, request);
+      }
+      public global::grpc.testing.SimpleResponse UnaryCall(global::grpc.testing.SimpleRequest request, CallOptions options)
+      {
+        var call = CreateCall(__Method_UnaryCall, options);
+        return Calls.BlockingUnaryCall(call, request);
       }
       public AsyncUnaryCall<global::grpc.testing.SimpleResponse> UnaryCallAsync(global::grpc.testing.SimpleRequest request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_UnaryCall, headers, deadline);
-        return Calls.AsyncUnaryCall(call, request, cancellationToken);
+        var call = CreateCall(__Method_UnaryCall, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.AsyncUnaryCall(call, request);
+      }
+      public AsyncUnaryCall<global::grpc.testing.SimpleResponse> UnaryCallAsync(global::grpc.testing.SimpleRequest request, CallOptions options)
+      {
+        var call = CreateCall(__Method_UnaryCall, options);
+        return Calls.AsyncUnaryCall(call, request);
       }
       public AsyncServerStreamingCall<global::grpc.testing.StreamingOutputCallResponse> StreamingOutputCall(global::grpc.testing.StreamingOutputCallRequest request, Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_StreamingOutputCall, headers, deadline);
-        return Calls.AsyncServerStreamingCall(call, request, cancellationToken);
+        var call = CreateCall(__Method_StreamingOutputCall, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.AsyncServerStreamingCall(call, request);
+      }
+      public AsyncServerStreamingCall<global::grpc.testing.StreamingOutputCallResponse> StreamingOutputCall(global::grpc.testing.StreamingOutputCallRequest request, CallOptions options)
+      {
+        var call = CreateCall(__Method_StreamingOutputCall, options);
+        return Calls.AsyncServerStreamingCall(call, request);
       }
       public AsyncClientStreamingCall<global::grpc.testing.StreamingInputCallRequest, global::grpc.testing.StreamingInputCallResponse> StreamingInputCall(Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_StreamingInputCall, headers, deadline);
-        return Calls.AsyncClientStreamingCall(call, cancellationToken);
+        var call = CreateCall(__Method_StreamingInputCall, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.AsyncClientStreamingCall(call);
+      }
+      public AsyncClientStreamingCall<global::grpc.testing.StreamingInputCallRequest, global::grpc.testing.StreamingInputCallResponse> StreamingInputCall(CallOptions options)
+      {
+        var call = CreateCall(__Method_StreamingInputCall, options);
+        return Calls.AsyncClientStreamingCall(call);
       }
       public AsyncDuplexStreamingCall<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse> FullDuplexCall(Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_FullDuplexCall, headers, deadline);
-        return Calls.AsyncDuplexStreamingCall(call, cancellationToken);
+        var call = CreateCall(__Method_FullDuplexCall, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.AsyncDuplexStreamingCall(call);
+      }
+      public AsyncDuplexStreamingCall<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse> FullDuplexCall(CallOptions options)
+      {
+        var call = CreateCall(__Method_FullDuplexCall, options);
+        return Calls.AsyncDuplexStreamingCall(call);
       }
       public AsyncDuplexStreamingCall<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse> HalfDuplexCall(Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken))
       {
-        var call = CreateCall(__ServiceName, __Method_HalfDuplexCall, headers, deadline);
-        return Calls.AsyncDuplexStreamingCall(call, cancellationToken);
+        var call = CreateCall(__Method_HalfDuplexCall, new CallOptions(headers, deadline, cancellationToken));
+        return Calls.AsyncDuplexStreamingCall(call);
+      }
+      public AsyncDuplexStreamingCall<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse> HalfDuplexCall(CallOptions options)
+      {
+        var call = CreateCall(__Method_HalfDuplexCall, options);
+        return Calls.AsyncDuplexStreamingCall(call);
       }
     }
 
diff --git a/src/csharp/Grpc.IntegrationTesting/packages.config b/src/csharp/Grpc.IntegrationTesting/packages.config
index 746133a7a5..7d1f84f303 100644
--- a/src/csharp/Grpc.IntegrationTesting/packages.config
+++ b/src/csharp/Grpc.IntegrationTesting/packages.config
@@ -11,5 +11,4 @@
   <package id="Microsoft.Net.Http" version="2.2.29" targetFramework="net45" />
   <package id="Newtonsoft.Json" version="7.0.1" targetFramework="net45" />
   <package id="NUnit" version="2.6.4" targetFramework="net45" />
-  <package id="System.Collections.Immutable" version="1.1.36" targetFramework="net45" />
 </packages>
\ No newline at end of file
diff --git a/src/csharp/build_packages.bat b/src/csharp/build_packages.bat
index 9e1253bf0b..8a11d01430 100644
--- a/src/csharp/build_packages.bat
+++ b/src/csharp/build_packages.bat
@@ -1,8 +1,8 @@
 @rem Builds gRPC NuGet packages
 
 @rem Current package versions
-set VERSION=0.6.0
-set CORE_VERSION=0.10.0
+set VERSION=0.6.1
+set CORE_VERSION=0.10.1
 
 @rem Adjust the location of nuget.exe
 set NUGET=C:\nuget\nuget.exe
diff --git a/src/csharp/doc/README.md b/src/csharp/doc/README.md
new file mode 100644
index 0000000000..585500b5ca
--- /dev/null
+++ b/src/csharp/doc/README.md
@@ -0,0 +1,2 @@
+
+SandCastle project files to generate HTML reference documentation.
\ No newline at end of file
diff --git a/src/csharp/doc/grpc_csharp_public.shfbproj b/src/csharp/doc/grpc_csharp_public.shfbproj
new file mode 100644
index 0000000000..05c93f4a13
--- /dev/null
+++ b/src/csharp/doc/grpc_csharp_public.shfbproj
@@ -0,0 +1,70 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <!-- The configuration and platform will be used to determine which assemblies to include from solution and
+				 project documentation sources -->
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <SchemaVersion>2.0</SchemaVersion>
+    <ProjectGuid>{77e3da09-fc92-486f-a90a-99ca788e8b59}</ProjectGuid>
+    <SHFBSchemaVersion>2015.6.5.0</SHFBSchemaVersion>
+    <!-- AssemblyName, Name, and RootNamespace are not used by SHFB but Visual Studio adds them anyway -->
+    <AssemblyName>Documentation</AssemblyName>
+    <RootNamespace>Documentation</RootNamespace>
+    <Name>Documentation</Name>
+    <!-- SHFB properties -->
+    <FrameworkVersion>.NET Framework 4.5</FrameworkVersion>
+    <OutputPath>..\..\..\doc\ref\csharp\html</OutputPath>
+    <Language>en-US</Language>
+    <DocumentationSources>
+      <DocumentationSource sourceFile="..\Grpc.Auth\Grpc.Auth.csproj" />
+<DocumentationSource sourceFile="..\Grpc.Core\Grpc.Core.csproj" /></DocumentationSources>
+    <BuildAssemblerVerbosity>OnlyWarningsAndErrors</BuildAssemblerVerbosity>
+    <HelpFileFormat>Website</HelpFileFormat>
+    <IndentHtml>False</IndentHtml>
+    <KeepLogFile>True</KeepLogFile>
+    <DisableCodeBlockComponent>False</DisableCodeBlockComponent>
+    <CleanIntermediates>True</CleanIntermediates>
+    <HelpFileVersion>1.0.0.0</HelpFileVersion>
+    <MaximumGroupParts>2</MaximumGroupParts>
+    <NamespaceGrouping>False</NamespaceGrouping>
+    <SyntaxFilters>Standard</SyntaxFilters>
+    <SdkLinkTarget>Blank</SdkLinkTarget>
+    <RootNamespaceContainer>True</RootNamespaceContainer>
+    <PresentationStyle>VS2013</PresentationStyle>
+    <Preliminary>False</Preliminary>
+    <NamingMethod>MemberName</NamingMethod>
+    <HelpTitle>gRPC C#</HelpTitle>
+    <ContentPlacement>AboveNamespaces</ContentPlacement>
+    <HtmlHelpName>Documentation</HtmlHelpName>
+  </PropertyGroup>
+  <!-- There are no properties for these groups.  AnyCPU needs to appear in order for Visual Studio to perform
+			 the build.  The others are optional common platform types that may appear. -->
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|x86' ">
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x86' ">
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|x64' ">
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x64' ">
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|Win32' ">
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|Win32' ">
+  </PropertyGroup>
+  <!-- Import the SHFB build targets -->
+  <Import Project="$(SHFBROOT)\SandcastleHelpFileBuilder.targets" />
+  <!-- The pre-build and post-build event properties must appear *after* the targets file import in order to be
+			 evaluated correctly. -->
+  <PropertyGroup>
+    <PreBuildEvent>
+    </PreBuildEvent>
+    <PostBuildEvent>
+    </PostBuildEvent>
+    <RunPostBuildEvent>OnBuildSuccess</RunPostBuildEvent>
+  </PropertyGroup>
+</Project>
\ No newline at end of file
diff --git a/src/csharp/ext/grpc_csharp_ext.c b/src/csharp/ext/grpc_csharp_ext.c
index 49a0471042..9379ae01f1 100644
--- a/src/csharp/ext/grpc_csharp_ext.c
+++ b/src/csharp/ext/grpc_csharp_ext.c
@@ -376,10 +376,29 @@ GPR_EXPORT void GPR_CALLTYPE grpcsharp_channel_destroy(grpc_channel *channel) {
 }
 
 GPR_EXPORT grpc_call *GPR_CALLTYPE
-grpcsharp_channel_create_call(grpc_channel *channel, grpc_completion_queue *cq,
+grpcsharp_channel_create_call(grpc_channel *channel, grpc_call *parent_call,
+                              gpr_uint32 propagation_mask,
+                              grpc_completion_queue *cq,
                               const char *method, const char *host,
                               gpr_timespec deadline) {
-  return grpc_channel_create_call(channel, cq, method, host, deadline);
+  return grpc_channel_create_call(channel, parent_call, propagation_mask, cq,
+                                  method, host, deadline);
+}
+
+GPR_EXPORT grpc_connectivity_state GPR_CALLTYPE
+grpcsharp_channel_check_connectivity_state(grpc_channel *channel, gpr_int32 try_to_connect) {
+  return grpc_channel_check_connectivity_state(channel, try_to_connect);
+}
+
+GPR_EXPORT void GPR_CALLTYPE grpcsharp_channel_watch_connectivity_state(
+    grpc_channel *channel, grpc_connectivity_state last_observed_state,
+    gpr_timespec deadline, grpc_completion_queue *cq, grpcsharp_batch_context *ctx) {
+  grpc_channel_watch_connectivity_state(channel, last_observed_state,
+                                        deadline, cq, ctx);
+}
+
+GPR_EXPORT char *GPR_CALLTYPE grpcsharp_channel_get_target(grpc_channel *channel) {
+  return grpc_channel_get_target(channel);
 }
 
 /* Channel args */
@@ -480,7 +499,7 @@ GPR_EXPORT void GPR_CALLTYPE grpcsharp_call_destroy(grpc_call *call) {
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
 grpcsharp_call_start_unary(grpc_call *call, grpcsharp_batch_context *ctx,
                            const char *send_buffer, size_t send_buffer_len,
-                           grpc_metadata_array *initial_metadata) {
+                           grpc_metadata_array *initial_metadata, gpr_uint32 write_flags) {
   /* TODO: don't use magic number */
   grpc_op ops[6];
   ops[0].op = GRPC_OP_SEND_INITIAL_METADATA;
@@ -494,7 +513,7 @@ grpcsharp_call_start_unary(grpc_call *call, grpcsharp_batch_context *ctx,
   ops[1].op = GRPC_OP_SEND_MESSAGE;
   ctx->send_message = string_to_byte_buffer(send_buffer, send_buffer_len);
   ops[1].data.send_message = ctx->send_message;
-  ops[1].flags = 0;
+  ops[1].flags = write_flags;
 
   ops[2].op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   ops[2].flags = 0;
@@ -561,7 +580,7 @@ grpcsharp_call_start_client_streaming(grpc_call *call,
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_start_server_streaming(
     grpc_call *call, grpcsharp_batch_context *ctx, const char *send_buffer,
-    size_t send_buffer_len, grpc_metadata_array *initial_metadata) {
+    size_t send_buffer_len, grpc_metadata_array *initial_metadata, gpr_uint32 write_flags) {
   /* TODO: don't use magic number */
   grpc_op ops[5];
   ops[0].op = GRPC_OP_SEND_INITIAL_METADATA;
@@ -575,7 +594,7 @@ GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_start_server_streaming(
   ops[1].op = GRPC_OP_SEND_MESSAGE;
   ctx->send_message = string_to_byte_buffer(send_buffer, send_buffer_len);
   ops[1].data.send_message = ctx->send_message;
-  ops[1].flags = 0;
+  ops[1].flags = write_flags;
 
   ops[2].op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   ops[2].flags = 0;
@@ -634,15 +653,22 @@ grpcsharp_call_start_duplex_streaming(grpc_call *call,
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
 grpcsharp_call_send_message(grpc_call *call, grpcsharp_batch_context *ctx,
-                            const char *send_buffer, size_t send_buffer_len) {
+                            const char *send_buffer, size_t send_buffer_len,
+                            gpr_uint32 write_flags,
+                            gpr_int32 send_empty_initial_metadata) {
   /* TODO: don't use magic number */
-  grpc_op ops[1];
+  grpc_op ops[2];
+  size_t nops = send_empty_initial_metadata ? 2 : 1;
   ops[0].op = GRPC_OP_SEND_MESSAGE;
   ctx->send_message = string_to_byte_buffer(send_buffer, send_buffer_len);
   ops[0].data.send_message = ctx->send_message;
-  ops[0].flags = 0;
+  ops[0].flags = write_flags;
+  ops[1].op = GRPC_OP_SEND_INITIAL_METADATA;
+  ops[1].data.send_initial_metadata.count = 0;
+  ops[1].data.send_initial_metadata.metadata = NULL;
+  ops[1].flags = 0;
 
-  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);
+  return grpc_call_start_batch(call, ops, nops, ctx);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
@@ -658,9 +684,11 @@ grpcsharp_call_send_close_from_client(grpc_call *call,
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_send_status_from_server(
     grpc_call *call, grpcsharp_batch_context *ctx, grpc_status_code status_code,
-    const char *status_details, grpc_metadata_array *trailing_metadata) {
+    const char *status_details, grpc_metadata_array *trailing_metadata,
+    gpr_int32 send_empty_initial_metadata) {
   /* TODO: don't use magic number */
-  grpc_op ops[1];
+  grpc_op ops[2];
+  size_t nops = send_empty_initial_metadata ? 2 : 1;
   ops[0].op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   ops[0].data.send_status_from_server.status = status_code;
   ops[0].data.send_status_from_server.status_details =
@@ -672,8 +700,12 @@ GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_send_status_from_server(
   ops[0].data.send_status_from_server.trailing_metadata =
       ctx->send_status_from_server.trailing_metadata.metadata;
   ops[0].flags = 0;
+  ops[1].op = GRPC_OP_SEND_INITIAL_METADATA;
+  ops[1].data.send_initial_metadata.count = 0;
+  ops[1].data.send_initial_metadata.metadata = NULL;
+  ops[1].flags = 0;
 
-  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);
+  return grpc_call_start_batch(call, ops, nops, ctx);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
@@ -689,16 +721,28 @@ grpcsharp_call_recv_message(grpc_call *call, grpcsharp_batch_context *ctx) {
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
 grpcsharp_call_start_serverside(grpc_call *call, grpcsharp_batch_context *ctx) {
   /* TODO: don't use magic number */
-  grpc_op ops[2];
-  ops[0].op = GRPC_OP_SEND_INITIAL_METADATA;
-  ops[0].data.send_initial_metadata.count = 0;
-  ops[0].data.send_initial_metadata.metadata = NULL;
+  grpc_op ops[1];
+  ops[0].op = GRPC_OP_RECV_CLOSE_ON_SERVER;
+  ops[0].data.recv_close_on_server.cancelled =
+      (&ctx->recv_close_on_server_cancelled);
   ops[0].flags = 0;
 
-  ops[1].op = GRPC_OP_RECV_CLOSE_ON_SERVER;
-  ops[1].data.recv_close_on_server.cancelled =
-      (&ctx->recv_close_on_server_cancelled);
-  ops[1].flags = 0;
+  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);
+}
+
+GPR_EXPORT grpc_call_error GPR_CALLTYPE
+grpcsharp_call_send_initial_metadata(grpc_call *call,
+                                     grpcsharp_batch_context *ctx,
+                                     grpc_metadata_array *initial_metadata) {
+  /* TODO: don't use magic number */
+  grpc_op ops[1];
+  ops[0].op = GRPC_OP_SEND_INITIAL_METADATA;
+  grpcsharp_metadata_array_move(&(ctx->send_initial_metadata),
+                                initial_metadata);
+  ops[0].data.send_initial_metadata.count = ctx->send_initial_metadata.count;
+  ops[0].data.send_initial_metadata.metadata =
+      ctx->send_initial_metadata.metadata;
+  ops[0].flags = 0;
 
   return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);
 }
@@ -715,7 +759,7 @@ grpcsharp_server_create(grpc_completion_queue *cq,
 
 GPR_EXPORT gpr_int32 GPR_CALLTYPE
 grpcsharp_server_add_insecure_http2_port(grpc_server *server, const char *addr) {
-  return grpc_server_add_http2_port(server, addr);
+  return grpc_server_add_insecure_http2_port(server, addr);
 }
 
 GPR_EXPORT void GPR_CALLTYPE grpcsharp_server_start(grpc_server *server) {
@@ -776,7 +820,8 @@ grpcsharp_secure_channel_create(grpc_credentials *creds, const char *target,
 GPR_EXPORT grpc_server_credentials *GPR_CALLTYPE
 grpcsharp_ssl_server_credentials_create(
     const char *pem_root_certs, const char **key_cert_pair_cert_chain_array,
-    const char **key_cert_pair_private_key_array, size_t num_key_cert_pairs) {
+    const char **key_cert_pair_private_key_array, size_t num_key_cert_pairs,
+    int force_client_auth) {
   size_t i;
   grpc_server_credentials *creds;
   grpc_ssl_pem_key_cert_pair *key_cert_pairs =
@@ -791,9 +836,9 @@ grpcsharp_ssl_server_credentials_create(
       key_cert_pairs[i].private_key = key_cert_pair_private_key_array[i];
     }
   }
-  /* TODO: Add a force_client_auth parameter and pass it here. */
   creds = grpc_ssl_server_credentials_create(pem_root_certs, key_cert_pairs,
-                                             num_key_cert_pairs, 0);
+                                             num_key_cert_pairs,
+                                             force_client_auth);
   gpr_free(key_cert_pairs);
   return creds;
 }
@@ -831,6 +876,11 @@ GPR_EXPORT void GPR_CALLTYPE grpcsharp_redirect_log(grpcsharp_log_func func) {
 
 typedef void(GPR_CALLTYPE *test_callback_funcptr)(gpr_int32 success);
 
+/* Version info */
+GPR_EXPORT const char *GPR_CALLTYPE grpcsharp_version_string() {
+  return grpc_version_string();
+}
+
 /* For testing */
 GPR_EXPORT void GPR_CALLTYPE
 grpcsharp_test_callback(test_callback_funcptr callback) {
diff --git a/src/node/ext/call.cc b/src/node/ext/call.cc
index ab177e8513..c5c8313385 100644
--- a/src/node/ext/call.cc
+++ b/src/node/ext/call.cc
@@ -514,12 +514,14 @@ NAN_METHOD(Call::New) {
       if (args[3]->IsString()) {
         NanUtf8String host_override(args[3]);
         wrapped_call = grpc_channel_create_call(
-          wrapped_channel, CompletionQueueAsyncWorker::GetQueue(), *method,
-          *host_override, MillisecondsToTimespec(deadline));
+            wrapped_channel, NULL, GRPC_PROPAGATE_DEFAULTS,
+            CompletionQueueAsyncWorker::GetQueue(), *method,
+            *host_override, MillisecondsToTimespec(deadline));
       } else if (args[3]->IsUndefined() || args[3]->IsNull()) {
         wrapped_call = grpc_channel_create_call(
-          wrapped_channel, CompletionQueueAsyncWorker::GetQueue(), *method,
-          NULL, MillisecondsToTimespec(deadline));
+            wrapped_channel, NULL, GRPC_PROPAGATE_DEFAULTS,
+            CompletionQueueAsyncWorker::GetQueue(), *method,
+            NULL, MillisecondsToTimespec(deadline));
       } else {
         return NanThrowTypeError("Call's fourth argument must be a string");
       }
diff --git a/src/node/ext/server.cc b/src/node/ext/server.cc
index 04fabc871d..1dc179db3d 100644
--- a/src/node/ext/server.cc
+++ b/src/node/ext/server.cc
@@ -265,8 +265,8 @@ NAN_METHOD(Server::AddHttp2Port) {
   grpc_server_credentials *creds = creds_object->GetWrappedServerCredentials();
   int port;
   if (creds == NULL) {
-    port = grpc_server_add_http2_port(server->wrapped_server,
-                                      *NanUtf8String(args[0]));
+    port = grpc_server_add_insecure_http2_port(server->wrapped_server,
+                                               *NanUtf8String(args[0]));
   } else {
     port = grpc_server_add_secure_http2_port(server->wrapped_server,
                                              *NanUtf8String(args[0]),
diff --git a/src/node/interop/interop_client.js b/src/node/interop/interop_client.js
index 68f474777d..55d243ca1a 100644
--- a/src/node/interop/interop_client.js
+++ b/src/node/interop/interop_client.js
@@ -69,9 +69,6 @@ function zeroBuffer(size) {
 function emptyUnary(client, done) {
   var call = client.emptyCall({}, function(err, resp) {
     assert.ifError(err);
-  });
-  call.on('status', function(status) {
-    assert.strictEqual(status.code, grpc.status.OK);
     if (done) {
       done();
     }
@@ -96,9 +93,6 @@ function largeUnary(client, done) {
     assert.ifError(err);
     assert.strictEqual(resp.payload.type, 'COMPRESSABLE');
     assert.strictEqual(resp.payload.body.length, 314159);
-  });
-  call.on('status', function(status) {
-    assert.strictEqual(status.code, grpc.status.OK);
     if (done) {
       done();
     }
@@ -115,9 +109,6 @@ function clientStreaming(client, done) {
   var call = client.streamingInputCall(function(err, resp) {
     assert.ifError(err);
     assert.strictEqual(resp.aggregated_payload_size, 74922);
-  });
-  call.on('status', function(status) {
-    assert.strictEqual(status.code, grpc.status.OK);
     if (done) {
       done();
     }
@@ -308,9 +299,6 @@ function authTest(expected_user, scope, client, done) {
       assert.strictEqual(resp.payload.body.length, 314159);
       assert.strictEqual(resp.username, expected_user);
       assert.strictEqual(resp.oauth_scope, AUTH_SCOPE_RESPONSE);
-    });
-    call.on('status', function(status) {
-      assert.strictEqual(status.code, grpc.status.OK);
       if (done) {
         done();
       }
@@ -344,9 +332,6 @@ function oauth2Test(expected_user, scope, per_rpc, client, done) {
           assert.ifError(err);
           assert.strictEqual(resp.username, expected_user);
           assert.strictEqual(resp.oauth_scope, AUTH_SCOPE_RESPONSE);
-        });
-        call.on('status', function(status) {
-          assert.strictEqual(status.code, grpc.status.OK);
           if (done) {
             done();
           }
@@ -358,7 +343,6 @@ function oauth2Test(expected_user, scope, per_rpc, client, done) {
         client.updateMetadata = updateMetadata;
         makeTestCall(null, {});
       }
-
     });
   });
 }
diff --git a/src/objective-c/GRPCClient/GRPCCall+OAuth2.h b/src/objective-c/GRPCClient/GRPCCall+OAuth2.h
new file mode 100644
index 0000000000..2e379a7157
--- /dev/null
+++ b/src/objective-c/GRPCClient/GRPCCall+OAuth2.h
@@ -0,0 +1,49 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#import "GRPCCall.h"
+
+// Helpers for setting and reading headers compatible with OAuth2.
+@interface GRPCCall (OAuth2)
+
+// Setting this property is equivalent to setting "Bearer <passed token>" as the value of the
+// request header with key "authorization" (the authorization header). Setting it to nil removes the
+// authorization header from the request.
+// The value obtained by getting the property is the OAuth2 bearer token if the authorization header
+// of the request has the form "Bearer <token>", or nil otherwise.
+@property(atomic, copy) NSString *oauth2AccessToken;
+
+// Returns the value (if any) of the "www-authenticate" response header (the challenge header).
+@property(atomic, readonly) NSString *oauth2ChallengeHeader;
+
+@end
diff --git a/src/objective-c/GRPCClient/GRPCCall+OAuth2.m b/src/objective-c/GRPCClient/GRPCCall+OAuth2.m
new file mode 100644
index 0000000000..ed39d4b0f7
--- /dev/null
+++ b/src/objective-c/GRPCClient/GRPCCall+OAuth2.m
@@ -0,0 +1,63 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#import "GRPCCall+OAuth2.h"
+
+static NSString * const kAuthorizationHeader = @"authorization";
+static NSString * const kBearerPrefix = @"Bearer ";
+static NSString * const kChallengeHeader = @"www-authenticate";
+
+@implementation GRPCCall (OAuth2)
+
+- (NSString *)oauth2AccessToken {
+  NSString *headerValue = self.requestMetadata[kAuthorizationHeader];
+  if ([headerValue hasPrefix:kBearerPrefix]) {
+    return [headerValue substringFromIndex:kBearerPrefix.length];
+  } else {
+    return nil;
+  }
+}
+
+- (void)setOauth2AccessToken:(NSString *)token {
+  if (token) {
+    self.requestMetadata[kAuthorizationHeader] = [kBearerPrefix stringByAppendingString:token];
+  } else {
+    [self.requestMetadata removeObjectForKey:kAuthorizationHeader];
+  }
+}
+
+- (NSString *)oauth2ChallengeHeader {
+  return self.responseMetadata[kChallengeHeader];
+}
+
+@end
diff --git a/src/objective-c/GRPCClient/GRPCCall+Tests.h b/src/objective-c/GRPCClient/GRPCCall+Tests.h
new file mode 100644
index 0000000000..cca1614606
--- /dev/null
+++ b/src/objective-c/GRPCClient/GRPCCall+Tests.h
@@ -0,0 +1,54 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#import "GRPCCall.h"
+
+// Methods to let tune down the security of gRPC connections for specific hosts. These shouldn't be
+// used in releases, but are sometimes needed for testing.
+@interface GRPCCall (Tests)
+
+// Establish all SSL connections to the provided host using the passed SSL target name and the root
+// certificates found in the file at |certsPath|.
+//
+// Must be called before any gRPC call to that host is made. It's illegal to pass the same host to
+// more than one invocation of the methods of this category.
++ (void)useTestCertsPath:(NSString *)certsPath
+                testName:(NSString *)testName
+                 forHost:(NSString *)host;
+
+// Establish all connections to the provided host using cleartext instead of SSL.
+//
+// Must be called before any gRPC call to that host is made. It's illegal to pass the same host to
+// more than one invocation of the methods of this category.
++ (void)useInsecureConnectionsForHost:(NSString *)host;
+@end
diff --git a/src/objective-c/GRPCClient/GRPCCall+Tests.m b/src/objective-c/GRPCClient/GRPCCall+Tests.m
new file mode 100644
index 0000000000..bade0b2920
--- /dev/null
+++ b/src/objective-c/GRPCClient/GRPCCall+Tests.m
@@ -0,0 +1,53 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#import "GRPCCall+Tests.h"
+
+#import "private/GRPCHost.h"
+
+@implementation GRPCCall (Tests)
+
++ (void)useTestCertsPath:(NSString *)certsPath
+                testName:(NSString *)testName
+                 forHost:(NSString *)host {
+  GRPCHost *hostConfig = [GRPCHost hostWithAddress:host];
+  hostConfig.pathToCertificates = certsPath;
+  hostConfig.hostNameOverride = testName;
+}
+
++ (void)useInsecureConnectionsForHost:(NSString *)host {
+  GRPCHost *hostConfig = [GRPCHost hostWithAddress:host];
+  hostConfig.secure = NO;
+}
+
+@end
diff --git a/src/objective-c/GRPCClient/GRPCCall.m b/src/objective-c/GRPCClient/GRPCCall.m
index 9d9648ae28..0f4c811ce4 100644
--- a/src/objective-c/GRPCClient/GRPCCall.m
+++ b/src/objective-c/GRPCClient/GRPCCall.m
@@ -37,7 +37,6 @@
 #include <grpc/support/time.h>
 #import <RxLibrary/GRXConcurrentWriteable.h>
 
-#import "private/GRPCChannel.h"
 #import "private/GRPCWrappedCall.h"
 #import "private/NSData+GRPC.h"
 #import "private/NSDictionary+GRPC.h"
@@ -70,18 +69,25 @@ NSString * const kGRPCStatusMetadataKey = @"io.grpc.StatusMetadataKey";
   GRPCWrappedCall *_wrappedCall;
   dispatch_once_t _callAlreadyInvoked;
 
-  GRPCChannel *_channel;
-
   // The C gRPC library has less guarantees on the ordering of events than we
   // do. Particularly, in the face of errors, there's no ordering guarantee at
   // all. This wrapper over our actual writeable ensures thread-safety and
   // correct ordering.
   GRXConcurrentWriteable *_responseWriteable;
+
+  // The network thread wants the requestWriter to resume (when the server is ready for more input),
+  // or to stop (on errors), concurrently with user threads that want to start it, pause it or stop
+  // it. Because a writer isn't thread-safe, we'll synchronize those operations on it.
+  // We don't use a dispatch queue for that purpose, because the writer can call writeValue: or
+  // writesFinishedWithError: on this GRPCCall as part of those operations. We want to be able to
+  // pause the writer immediately on writeValue:, so we need our locking to be recursive.
   GRXWriter *_requestWriter;
 
   // To create a retain cycle when a call is started, up until it finishes. See
-  // |startWithWriteable:| and |finishWithError:|.
-  GRPCCall *_self;
+  // |startWithWriteable:| and |finishWithError:|. This saves users from having to retain a
+  // reference to the call object if all they're interested in is the handler being executed when
+  // the response arrives.
+  GRPCCall *_retainSelf;
 
   NSMutableDictionary *_requestMetadata;
   NSMutableDictionary *_responseMetadata;
@@ -105,11 +111,10 @@ NSString * const kGRPCStatusMetadataKey = @"io.grpc.StatusMetadataKey";
                 format:@"The requests writer can't be already started."];
   }
   if ((self = [super init])) {
-    _channel = [GRPCChannel channelToHost:host];
-
-    _wrappedCall = [[GRPCWrappedCall alloc] initWithChannel:_channel
-                                                       path:path
-                                                       host:host];
+    _wrappedCall = [[GRPCWrappedCall alloc] initWithHost:host path:path];
+    if (!_wrappedCall) {
+      return nil;
+    }
 
     // Serial queue to invoke the non-reentrant methods of the grpc_call object.
     _callQueue = dispatch_queue_create("org.grpc.call", NULL);
@@ -140,11 +145,12 @@ NSString * const kGRPCStatusMetadataKey = @"io.grpc.StatusMetadataKey";
 
 - (void)finishWithError:(NSError *)errorOrNil {
   // If the call isn't retained anywhere else, it can be deallocated now.
-  _self = nil;
+  _retainSelf = nil;
 
   // If there were still request messages coming, stop them.
-  _requestWriter.state = GRXWriterStateFinished;
-  _requestWriter = nil;
+  @synchronized(_requestWriter) {
+    _requestWriter.state = GRXWriterStateFinished;
+  }
 
   if (errorOrNil) {
     [_responseWriteable cancelWithError:errorOrNil];
@@ -244,12 +250,14 @@ NSString * const kGRPCStatusMetadataKey = @"io.grpc.StatusMetadataKey";
     // Resume the request writer.
     GRPCCall *strongSelf = weakSelf;
     if (strongSelf) {
-      strongSelf->_requestWriter.state = GRXWriterStateStarted;
+      @synchronized(strongSelf->_requestWriter) {
+        strongSelf->_requestWriter.state = GRXWriterStateStarted;
+      }
     }
   };
-  [_wrappedCall startBatchWithOperations:@[[[GRPCOpSendMessage alloc]
-                                            initWithMessage:message
-                                            handler:resumingHandler]] errorHandler:errorHandler];
+  [_wrappedCall startBatchWithOperations:@[[[GRPCOpSendMessage alloc] initWithMessage:message
+                                                                              handler:resumingHandler]]
+                            errorHandler:errorHandler];
 }
 
 - (void)writeValue:(id)value {
@@ -257,7 +265,9 @@ NSString * const kGRPCStatusMetadataKey = @"io.grpc.StatusMetadataKey";
 
   // Pause the input and only resume it when the C layer notifies us that writes
   // can proceed.
-  _requestWriter.state = GRXWriterStatePaused;
+  @synchronized(_requestWriter) {
+    _requestWriter.state = GRXWriterStatePaused;
+  }
 
   __weak GRPCCall *weakSelf = self;
   dispatch_async(_callQueue, ^{
@@ -277,7 +287,6 @@ NSString * const kGRPCStatusMetadataKey = @"io.grpc.StatusMetadataKey";
 }
 
 - (void)writesFinishedWithError:(NSError *)errorOrNil {
-  _requestWriter = nil;
   if (errorOrNil) {
     [self cancel];
   } else {
@@ -331,7 +340,9 @@ NSString * const kGRPCStatusMetadataKey = @"io.grpc.StatusMetadataKey";
     }
   }];
   // Now that the RPC has been initiated, request writes can start.
-  [_requestWriter startWithWriteable:self];
+  @synchronized(_requestWriter) {
+    [_requestWriter startWithWriteable:self];
+  }
 }
 
 #pragma mark GRXWriter implementation
@@ -342,7 +353,7 @@ NSString * const kGRPCStatusMetadataKey = @"io.grpc.StatusMetadataKey";
   // before being autoreleased).
   // Care is taken not to retain self strongly in any of the blocks used in this implementation, so
   // that the life of the instance is determined by this retain cycle.
-  _self = self;
+  _retainSelf = self;
 
   _responseWriteable = [[GRXConcurrentWriteable alloc] initWithWriteable:writeable];
   [self sendHeaders:_requestMetadata];
diff --git a/src/objective-c/GRPCClient/private/GRPCChannel.h b/src/objective-c/GRPCClient/private/GRPCChannel.h
index bc6a47d469..2a7b701576 100644
--- a/src/objective-c/GRPCClient/private/GRPCChannel.h
+++ b/src/objective-c/GRPCClient/private/GRPCChannel.h
@@ -35,17 +35,12 @@
 
 struct grpc_channel;
 
-// Each separate instance of this class represents at least one TCP
-// connection to the provided host. To create a grpc_call, pass the
-// value of the unmanagedChannel property to grpc_channel_create_call.
-// Release this object when the call is finished.
+// Each separate instance of this class represents at least one TCP connection to the provided host.
+// Create them using one of the subclasses |GRPCSecureChannel| and |GRPCUnsecuredChannel|.
 @interface GRPCChannel : NSObject
 @property(nonatomic, readonly) struct grpc_channel *unmanagedChannel;
 
-// Convenience constructor to allow for reuse of connections.
-+ (instancetype)channelToHost:(NSString *)host;
-
-- (instancetype)initWithHost:(NSString *)host NS_DESIGNATED_INITIALIZER;
-
+// This initializer takes ownership of the passed channel, and will destroy it when this object is
+// deallocated. It's illegal to pass the same grpc_channel to two different GRPCChannel objects.
 - (instancetype)initWithChannel:(struct grpc_channel *)unmanagedChannel NS_DESIGNATED_INITIALIZER;
 @end
diff --git a/src/objective-c/GRPCClient/private/GRPCChannel.m b/src/objective-c/GRPCClient/private/GRPCChannel.m
index af4326332f..4366e63320 100644
--- a/src/objective-c/GRPCClient/private/GRPCChannel.m
+++ b/src/objective-c/GRPCClient/private/GRPCChannel.m
@@ -35,53 +35,17 @@
 
 #include <grpc/grpc.h>
 
-#import "GRPCSecureChannel.h"
-#import "GRPCUnsecuredChannel.h"
-
 @implementation GRPCChannel
 
-+ (instancetype)channelToHost:(NSString *)host {
-  // TODO(mlumish): Investigate whether a cache with strong links is a good idea
-  static NSMutableDictionary *channelCache;
-  static dispatch_once_t cacheInitialization;
-  dispatch_once(&cacheInitialization, ^{
-    channelCache = [NSMutableDictionary dictionary];
-  });
-  GRPCChannel *channel = channelCache[host];
-  if (!channel) {
-    channel = [[self alloc] initWithHost:host];
-    channelCache[host] = channel;
-  }
-  return channel;
-}
-
 - (instancetype)init {
-  return [self initWithHost:nil];
+  return [self initWithChannel:NULL];
 }
 
-- (instancetype)initWithHost:(NSString *)host {
-  if (![host rangeOfString:@"://"].length) {
-    // No scheme provided; assume https.
-    host = [@"https://" stringByAppendingString:host];
-  }
-  NSURL *hostURL = [NSURL URLWithString:host];
-  if (!hostURL) {
-    [NSException raise:NSInvalidArgumentException format:@"Invalid URL: %@", host];
+// Designated initializer
+- (instancetype)initWithChannel:(grpc_channel *)unmanagedChannel {
+  if (!unmanagedChannel) {
+    return nil;
   }
-  if ([hostURL.scheme isEqualToString:@"https"]) {
-    host = [@[hostURL.host, hostURL.port ?: @443] componentsJoinedByString:@":"];
-    return [[GRPCSecureChannel alloc] initWithHost:host];
-  }
-  if ([hostURL.scheme isEqualToString:@"http"]) {
-    host = [@[hostURL.host, hostURL.port ?: @80] componentsJoinedByString:@":"];
-    return [[GRPCUnsecuredChannel alloc] initWithHost:host];
-  }
-  [NSException raise:NSInvalidArgumentException
-              format:@"URL scheme %@ isn't supported.", hostURL.scheme];
-  return nil; // silence warning.
-}
-
-- (instancetype)initWithChannel:(struct grpc_channel *)unmanagedChannel {
   if ((self = [super init])) {
     _unmanagedChannel = unmanagedChannel;
   }
@@ -89,12 +53,8 @@
 }
 
 - (void)dealloc {
-  // _unmanagedChannel is NULL when deallocating an object of the base class (because the
-  // initializer returns a different object).
-  if (_unmanagedChannel) {
-    // TODO(jcanizales): Be sure to add a test with a server that closes the connection prematurely,
-    // as in the past that made this call to crash.
-    grpc_channel_destroy(_unmanagedChannel);
-  }
+  // TODO(jcanizales): Be sure to add a test with a server that closes the connection prematurely,
+  // as in the past that made this call to crash.
+  grpc_channel_destroy(_unmanagedChannel);
 }
 @end
diff --git a/src/objective-c/GRPCClient/private/GRPCCompletionQueue.m b/src/objective-c/GRPCClient/private/GRPCCompletionQueue.m
index 12535c9616..696069c200 100644
--- a/src/objective-c/GRPCClient/private/GRPCCompletionQueue.m
+++ b/src/objective-c/GRPCClient/private/GRPCCompletionQueue.m
@@ -38,8 +38,6 @@
 @implementation GRPCCompletionQueue
 
 + (instancetype)completionQueue {
-  // TODO(jcanizales): Reuse completion queues to consume only one thread,
-  // instead of one per call.
   return [[self alloc] init];
 }
 
diff --git a/src/objective-c/GRPCClient/private/GRPCHost.h b/src/objective-c/GRPCClient/private/GRPCHost.h
new file mode 100644
index 0000000000..f0bbd53023
--- /dev/null
+++ b/src/objective-c/GRPCClient/private/GRPCHost.h
@@ -0,0 +1,58 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#import <Foundation/Foundation.h>
+
+@class GRPCCompletionQueue;
+struct grpc_call;
+
+@interface GRPCHost : NSObject
+
+@property(nonatomic, readonly) NSString *address;
+
+// The following properties should only be modified for testing:
+
+@property(nonatomic, getter=isSecure) BOOL secure;
+
+@property(nonatomic, copy) NSString *pathToCertificates;
+@property(nonatomic, copy) NSString *hostNameOverride;
+
+// Host objects initialized with the same address are the same.
++ (instancetype)hostWithAddress:(NSString *)address;
+- (instancetype)initWithAddress:(NSString *)address NS_DESIGNATED_INITIALIZER;
+
+// Create a grpc_call object to the provided path on this host.
+- (struct grpc_call *)unmanagedCallWithPath:(NSString *)path
+                            completionQueue:(GRPCCompletionQueue *)queue;
+
+@end
diff --git a/src/objective-c/GRPCClient/private/GRPCHost.m b/src/objective-c/GRPCClient/private/GRPCHost.m
new file mode 100644
index 0000000000..d902f95b51
--- /dev/null
+++ b/src/objective-c/GRPCClient/private/GRPCHost.m
@@ -0,0 +1,126 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#import "GRPCHost.h"
+
+#include <grpc/grpc.h>
+
+#import "GRPCChannel.h"
+#import "GRPCCompletionQueue.h"
+#import "GRPCSecureChannel.h"
+#import "GRPCUnsecuredChannel.h"
+
+@interface GRPCHost ()
+// TODO(mlumish): Investigate whether caching channels with strong links is a good idea.
+@property(nonatomic, strong) GRPCChannel *channel;
+@end
+
+@implementation GRPCHost
+
++ (instancetype)hostWithAddress:(NSString *)address {
+  return [[self alloc] initWithAddress:address];
+}
+
+- (instancetype)init {
+  return [self initWithAddress:nil];
+}
+
+// Default initializer.
+- (instancetype)initWithAddress:(NSString *)address {
+
+  // To provide a default port, we try to interpret the address. If it's just a host name without
+  // scheme and without port, we'll use port 443. If it has a scheme, we pass it untouched to the C
+  // gRPC library.
+  // TODO(jcanizales): Add unit tests for the types of addresses we want to let pass untouched.
+  NSURL *hostURL = [NSURL URLWithString:[@"https://" stringByAppendingString:address]];
+  if (hostURL && !hostURL.port) {
+    address = [hostURL.host stringByAppendingString:@":443"];
+  }
+
+  // Look up the GRPCHost in the cache.
+  static NSMutableDictionary *hostCache;
+  static dispatch_once_t cacheInitialization;
+  dispatch_once(&cacheInitialization, ^{
+    hostCache = [NSMutableDictionary dictionary];
+  });
+  @synchronized(hostCache) {
+    GRPCHost *cachedHost = hostCache[address];
+    if (cachedHost) {
+      return cachedHost;
+    }
+
+    if ((self = [super init])) {
+      _address = address;
+      _secure = YES;
+      hostCache[address] = self;
+    }
+  }
+  return self;
+}
+
+- (grpc_call *)unmanagedCallWithPath:(NSString *)path completionQueue:(GRPCCompletionQueue *)queue {
+  if (!queue || !path || !self.channel) {
+    return NULL;
+  }
+  return grpc_channel_create_call(self.channel.unmanagedChannel,
+                                  NULL, GRPC_PROPAGATE_DEFAULTS,
+                                  queue.unmanagedQueue,
+                                  path.UTF8String,
+                                  self.hostName.UTF8String,
+                                  gpr_inf_future(GPR_CLOCK_REALTIME));
+}
+
+- (GRPCChannel *)channel {
+  // Create it lazily, because we don't want to open a connection just because someone is
+  // configuring a host.
+  if (!_channel) {
+    if (_secure) {
+      _channel = [[GRPCSecureChannel alloc] initWithHost:_address
+                                      pathToCertificates:_pathToCertificates
+                                        hostNameOverride:_hostNameOverride];
+    } else {
+      _channel = [[GRPCUnsecuredChannel alloc] initWithHost:_address];
+    }
+  }
+  return _channel;
+}
+
+- (NSString *)hostName {
+  // TODO(jcanizales): Default to nil instead of _address when Issue #2635 is clarified.
+  return _hostNameOverride ?: _address;
+}
+
+// TODO(jcanizales): Don't let set |secure| to |NO| if |pathToCertificates| or |hostNameOverride|
+// have been set. Don't let set either of the latter if |secure| has been set to |NO|.
+
+@end
diff --git a/src/objective-c/GRPCClient/private/GRPCSecureChannel.h b/src/objective-c/GRPCClient/private/GRPCSecureChannel.h
index d34ceaea0c..74257eb058 100644
--- a/src/objective-c/GRPCClient/private/GRPCSecureChannel.h
+++ b/src/objective-c/GRPCClient/private/GRPCSecureChannel.h
@@ -31,8 +31,23 @@
  *
  */
 
+#include <grpc/grpc.h>
+
 #import "GRPCChannel.h"
 
+struct grpc_credentials;
+
 @interface GRPCSecureChannel : GRPCChannel
+- (instancetype)initWithHost:(NSString *)host;
+
+// Only in tests shouldn't pathToCertificates or hostNameOverride be nil. Passing nil for
+// pathToCertificates results in using the default root certificates distributed with the library.
+- (instancetype)initWithHost:(NSString *)host
+          pathToCertificates:(NSString *)path
+            hostNameOverride:(NSString *)hostNameOverride;
 
+// The passed arguments aren't required to be valid beyond the invocation of this initializer.
+- (instancetype)initWithHost:(NSString *)host
+                 credentials:(struct grpc_credentials *)credentials
+                        args:(grpc_channel_args *)args NS_DESIGNATED_INITIALIZER;
 @end
diff --git a/src/objective-c/GRPCClient/private/GRPCSecureChannel.m b/src/objective-c/GRPCClient/private/GRPCSecureChannel.m
index 43a8bd539e..0a54804bb2 100644
--- a/src/objective-c/GRPCClient/private/GRPCSecureChannel.m
+++ b/src/objective-c/GRPCClient/private/GRPCSecureChannel.m
@@ -33,28 +33,83 @@
 
 #import "GRPCSecureChannel.h"
 
-#import <grpc/grpc_security.h>
+#include <grpc/grpc_security.h>
+
+// Returns NULL if the file at path couldn't be read. In that case, if errorPtr isn't NULL,
+// *errorPtr will be an object describing what went wrong.
+static grpc_credentials *CertificatesAtPath(NSString *path, NSError **errorPtr) {
+  // Files in PEM format can have non-ASCII characters in their comments (e.g. for the name of the
+  // issuer). Load them as UTF8 and produce an ASCII equivalent.
+  NSString *contentInUTF8 = [NSString stringWithContentsOfFile:path
+                                                     encoding:NSUTF8StringEncoding
+                                                        error:errorPtr];
+  NSData *contentInASCII = [contentInUTF8 dataUsingEncoding:NSASCIIStringEncoding
+                                       allowLossyConversion:YES];
+  if (!contentInASCII.bytes) {
+    // Passing NULL to grpc_ssl_credentials_create produces behavior we don't want, so return.
+    return NULL;
+  }
+  return grpc_ssl_credentials_create(contentInASCII.bytes, NULL);
+}
 
 @implementation GRPCSecureChannel
 
 - (instancetype)initWithHost:(NSString *)host {
-  static grpc_credentials *kCredentials;
+  return [self initWithHost:host pathToCertificates:nil hostNameOverride:nil];
+}
+
+- (instancetype)initWithHost:(NSString *)host
+          pathToCertificates:(NSString *)path
+            hostNameOverride:(NSString *)hostNameOverride {
+  // Load default SSL certificates once.
+  static grpc_credentials *kDefaultCertificates;
   static dispatch_once_t loading;
   dispatch_once(&loading, ^{
+    NSString *defaultPath = @"gRPCCertificates.bundle/roots"; // .pem
     // Do not use NSBundle.mainBundle, as it's nil for tests of library projects.
     NSBundle *bundle = [NSBundle bundleForClass:self.class];
-    NSString *certsPath = [bundle pathForResource:@"gRPCCertificates.bundle/roots" ofType:@"pem"];
-    NSAssert(certsPath.length,
-             @"gRPCCertificates.bundle/roots.pem not found under %@. This file, with the root "
-             "certificates, is needed to establish TLS (HTTPS) connections.", bundle.bundlePath);
-    NSData *certsData = [NSData dataWithContentsOfFile:certsPath];
-    NSAssert(certsData.length, @"No data read from %@", certsPath);
-    NSString *certsString = [[NSString alloc] initWithData:certsData encoding:NSUTF8StringEncoding];
-    kCredentials = grpc_ssl_credentials_create(certsString.UTF8String, NULL);
+    NSString *path = [bundle pathForResource:defaultPath ofType:@"pem"];
+    NSError *error;
+    kDefaultCertificates = CertificatesAtPath(path, &error);
+    NSAssert(kDefaultCertificates, @"Could not read %@/%@.pem. This file, with the root "
+             "certificates, is needed to establish secure (TLS) connections. Because the file is "
+             "distributed with the gRPC library, this error is usually a sign that the library "
+             "wasn't configured correctly for your project. Error: %@",
+             bundle.bundlePath, defaultPath, error);
   });
-  return (self = [super initWithChannel:grpc_secure_channel_create(kCredentials,
-                                                                   host.UTF8String,
-                                                                   NULL)]);
+
+  //TODO(jcanizales): Add NSError** parameter to the initializer.
+  grpc_credentials *certificates = path ? CertificatesAtPath(path, NULL) : kDefaultCertificates;
+  if (!certificates) {
+    return nil;
+  }
+
+  // Ritual to pass the SSL host name override to the C library.
+  grpc_channel_args channelArgs;
+  grpc_arg nameOverrideArg;
+  channelArgs.num_args = 1;
+  channelArgs.args = &nameOverrideArg;
+  nameOverrideArg.type = GRPC_ARG_STRING;
+  nameOverrideArg.key = GRPC_SSL_TARGET_NAME_OVERRIDE_ARG;
+  // Cast const away. Hope C gRPC doesn't modify it!
+  nameOverrideArg.value.string = (char *) hostNameOverride.UTF8String;
+  grpc_channel_args *args = hostNameOverride ? &channelArgs : NULL;
+
+  return [self initWithHost:host credentials:certificates args:args];
+}
+
+- (instancetype)initWithHost:(NSString *)host
+                 credentials:(grpc_credentials *)credentials
+                        args:(grpc_channel_args *)args {
+  return (self =
+          [super initWithChannel:grpc_secure_channel_create(credentials, host.UTF8String, args)]);
+}
+
+// TODO(jcanizales): GRPCSecureChannel and GRPCUnsecuredChannel are just convenience initializers
+// for GRPCChannel. Move them into GRPCChannel, which will make the following unnecessary.
+- (instancetype)initWithChannel:(grpc_channel *)unmanagedChannel {
+  [NSException raise:NSInternalInconsistencyException format:@"use another initializer"];
+  return [self initWithHost:nil]; // silence warnings
 }
 
 @end
diff --git a/src/objective-c/GRPCClient/private/GRPCUnsecuredChannel.h b/src/objective-c/GRPCClient/private/GRPCUnsecuredChannel.h
index 9d89cfb541..8528be44c0 100644
--- a/src/objective-c/GRPCClient/private/GRPCUnsecuredChannel.h
+++ b/src/objective-c/GRPCClient/private/GRPCUnsecuredChannel.h
@@ -34,5 +34,5 @@
 #import "GRPCChannel.h"
 
 @interface GRPCUnsecuredChannel : GRPCChannel
-
+- (instancetype)initWithHost:(NSString *)host NS_DESIGNATED_INITIALIZER;
 @end
diff --git a/src/objective-c/GRPCClient/private/GRPCUnsecuredChannel.m b/src/objective-c/GRPCClient/private/GRPCUnsecuredChannel.m
index 8518f78c5b..070a529629 100644
--- a/src/objective-c/GRPCClient/private/GRPCUnsecuredChannel.m
+++ b/src/objective-c/GRPCClient/private/GRPCUnsecuredChannel.m
@@ -41,4 +41,10 @@
   return (self = [super initWithChannel:grpc_insecure_channel_create(host.UTF8String, NULL)]);
 }
 
+// TODO(jcanizales): GRPCSecureChannel and GRPCUnsecuredChannel are just convenience initializers
+// for GRPCChannel. Move them into GRPCChannel, which will make the following unnecessary.
+- (instancetype)initWithChannel:(grpc_channel *)unmanagedChannel {
+  [NSException raise:NSInternalInconsistencyException format:@"use the other initializer"];
+  return [self initWithHost:nil]; // silence warnings
+}
 @end
diff --git a/src/objective-c/GRPCClient/private/GRPCWrappedCall.h b/src/objective-c/GRPCClient/private/GRPCWrappedCall.h
index 18f8bb5531..da11cbb761 100644
--- a/src/objective-c/GRPCClient/private/GRPCWrappedCall.h
+++ b/src/objective-c/GRPCClient/private/GRPCWrappedCall.h
@@ -81,11 +81,12 @@
 
 @end
 
+#pragma mark GRPCWrappedCall
+
 @interface GRPCWrappedCall : NSObject
 
-- (instancetype)initWithChannel:(GRPCChannel *)channel
-                           path:(NSString *)path
-                           host:(NSString *)host NS_DESIGNATED_INITIALIZER;
+- (instancetype)initWithHost:(NSString *)host
+                        path:(NSString *)path NS_DESIGNATED_INITIALIZER;
 
 - (void)startBatchWithOperations:(NSArray *)ops errorHandler:(void(^)())errorHandler;
 
diff --git a/src/objective-c/GRPCClient/private/GRPCWrappedCall.m b/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
index 1db63df77f..951c051036 100644
--- a/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
+++ b/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
@@ -32,11 +32,14 @@
  */
 
 #import "GRPCWrappedCall.h"
+
 #import <Foundation/Foundation.h>
 #include <grpc/grpc.h>
 #include <grpc/byte_buffer.h>
 #include <grpc/support/alloc.h>
+
 #import "GRPCCompletionQueue.h"
+#import "GRPCHost.h"
 #import "NSDictionary+GRPC.h"
 #import "NSData+GRPC.h"
 #import "NSError+GRPC.h"
@@ -219,38 +222,36 @@
 
 @end
 
-@implementation GRPCWrappedCall{
-  grpc_call *_call;
+#pragma mark GRPCWrappedCall
+
+@implementation GRPCWrappedCall {
   GRPCCompletionQueue *_queue;
+  grpc_call *_call;
 }
 
 - (instancetype)init {
-  return [self initWithChannel:nil path:nil host:nil];
+  return [self initWithHost:nil path:nil];
 }
 
-- (instancetype)initWithChannel:(GRPCChannel *)channel
-                           path:(NSString *)path
-                           host:(NSString *)host {
-  if (!channel || !path || !host) {
+- (instancetype)initWithHost:(NSString *)host
+                        path:(NSString *)path {
+  if (!path || !host) {
     [NSException raise:NSInvalidArgumentException
-                format:@"channel, method, and host cannot be nil."];
+                format:@"path and host cannot be nil."];
   }
-  
+
   if (self = [super init]) {
     static dispatch_once_t initialization;
     dispatch_once(&initialization, ^{
       grpc_init();
     });
-    
+
+    // Each completion queue consumes one thread. There's a trade to be made between creating and
+    // consuming too many threads and having contention of multiple calls in a single completion
+    // queue. Currently we favor latency and use one per call.
     _queue = [GRPCCompletionQueue completionQueue];
-    if (!_queue) {
-      return nil;
-    }
-    _call = grpc_channel_create_call(channel.unmanagedChannel,
-                                     _queue.unmanagedQueue,
-                                     path.UTF8String,
-                                     host.UTF8String,
-                                     gpr_inf_future(GPR_CLOCK_REALTIME));
+
+    _call = [[GRPCHost hostWithAddress:host] unmanagedCallWithPath:path completionQueue:_queue];
     if (_call == NULL) {
       return nil;
     }
@@ -299,4 +300,4 @@
   grpc_call_destroy(_call);
 }
 
-@end
\ No newline at end of file
+@end
diff --git a/src/objective-c/RxLibrary/GRXBufferedPipe.h b/src/objective-c/RxLibrary/GRXBufferedPipe.h
index b6296e1ed7..ca94ce275f 100644
--- a/src/objective-c/RxLibrary/GRXBufferedPipe.h
+++ b/src/objective-c/RxLibrary/GRXBufferedPipe.h
@@ -36,13 +36,11 @@
 #import "GRXWriteable.h"
 #import "GRXWriter.h"
 
-// A buffered pipe is a Writeable that also acts as a Writer (to whichever other writeable is passed
-// to -startWithWriteable:).
+// A buffered pipe is a Writer that also acts as a Writeable.
 // Once it is started, whatever values are written into it (via -writeValue:) will be propagated
 // immediately, unless flow control prevents it.
 // If it is throttled and keeps receiving values, as well as if it receives values before being
-// started, it will buffer them and propagate them in order as soon as its state becomes
-// GRXWriterStateStarted.
+// started, it will buffer them and propagate them in order as soon as its state becomes Started.
 // If it receives an error (via -writesFinishedWithError:), it will drop any buffered values and
 // propagate the error immediately.
 //
@@ -51,6 +49,9 @@
 // pipe will keep buffering all data written to it, your application could run out of memory and
 // crash. If you want to react to flow control signals to prevent that, instead of using this class
 // you can implement an object that conforms to GRXWriter.
+//
+// Thread-safety:
+// The methods of an object of this class should not be called concurrently from different threads.
 @interface GRXBufferedPipe : GRXWriter<GRXWriteable>
 
 // Convenience constructor.
diff --git a/src/objective-c/RxLibrary/GRXForwardingWriter.h b/src/objective-c/RxLibrary/GRXForwardingWriter.h
index d004333d2b..f310832284 100644
--- a/src/objective-c/RxLibrary/GRXForwardingWriter.h
+++ b/src/objective-c/RxLibrary/GRXForwardingWriter.h
@@ -33,11 +33,17 @@
 
 #import "GRXWriter.h"
 
-// A "proxy" class that simply forwards values, completion, and errors from its
-// input writer to its writeable.
+// A "proxy" class that simply forwards values, completion, and errors from its input writer to its
+// writeable.
 // It is useful as a superclass for pipes that act as a transformation of their
 // input writer, and for classes that represent objects with input and
 // output sequences of values, like an RPC.
+//
+// Thread-safety:
+// All messages sent to this object need to be serialized. When it is started, the writer it wraps
+// is started in the same thread. Manual state changes are propagated to the wrapped writer in the
+// same thread too. Importantly, all messages the wrapped writer sends to its writeable need to be
+// serialized with any message sent to this object.
 @interface GRXForwardingWriter : GRXWriter
 - (instancetype)initWithWriter:(GRXWriter *)writer NS_DESIGNATED_INITIALIZER;
 @end
diff --git a/src/objective-c/RxLibrary/GRXForwardingWriter.m b/src/objective-c/RxLibrary/GRXForwardingWriter.m
index 2342f51ab3..a72be9ace2 100644
--- a/src/objective-c/RxLibrary/GRXForwardingWriter.m
+++ b/src/objective-c/RxLibrary/GRXForwardingWriter.m
@@ -48,7 +48,11 @@
 // Designated initializer
 - (instancetype)initWithWriter:(GRXWriter *)writer {
   if (!writer) {
-    [NSException raise:NSInvalidArgumentException format:@"writer can't be nil."];
+    return nil;
+  }
+  if (writer.state != GRXWriterStateNotStarted) {
+    [NSException raise:NSInvalidArgumentException
+                format:@"The writer argument must not have already started."];
   }
   if ((self = [super init])) {
     _writer = writer;
diff --git a/src/objective-c/RxLibrary/GRXImmediateWriter.h b/src/objective-c/RxLibrary/GRXImmediateWriter.h
index b171f0c760..3fcc259434 100644
--- a/src/objective-c/RxLibrary/GRXImmediateWriter.h
+++ b/src/objective-c/RxLibrary/GRXImmediateWriter.h
@@ -36,10 +36,17 @@
 #import "GRXWriter.h"
 
 // Utility to construct GRXWriter instances from values that are immediately available when
-// required. The returned writers all support pausing and early termination.
+// required.
 //
-// Unless the writeable callback pauses them or stops them early, these writers will do all their
-// interactions with the writeable before the start method returns.
+// Thread-safety:
+//
+// An object of this class shouldn't be messaged concurrently by more than one thread. It will start
+// messaging the writeable before |startWithWriteable:| returns, in the same thread. That is the
+// only place where the writer can be paused or stopped prematurely.
+//
+// If a paused writer of this class is resumed, it will start messaging the writeable, in the same
+// thread, before |setState:| returns. Because the object can't be legally accessed concurrently,
+// that's the only place where it can be paused again (or stopped).
 @interface GRXImmediateWriter : GRXWriter
 
 // Returns a writer that pulls values from the passed NSEnumerator instance and pushes them to
diff --git a/src/objective-c/RxLibrary/GRXWriter.h b/src/objective-c/RxLibrary/GRXWriter.h
index 5d6e1a472a..b1c994aa38 100644
--- a/src/objective-c/RxLibrary/GRXWriter.h
+++ b/src/objective-c/RxLibrary/GRXWriter.h
@@ -35,84 +35,73 @@
 
 #import "GRXWriteable.h"
 
+// States of a writer.
 typedef NS_ENUM(NSInteger, GRXWriterState) {
 
-  // The writer has not yet been given a writeable to which it can push its
-  // values. To have an writer transition to the Started state, send it a
-  // startWithWriteable: message.
+  // The writer has not yet been given a writeable to which it can push its values. To have a writer
+  // transition to the Started state, send it a startWithWriteable: message.
   //
-  // An writer's state cannot be manually set to this value.
+  // A writer's state cannot be manually set to this value.
   GRXWriterStateNotStarted,
 
   // The writer might push values to the writeable at any moment.
   GRXWriterStateStarted,
 
-  // The writer is temporarily paused, and won't send any more values to the
-  // writeable unless its state is set back to Started. The writer might still
-  // transition to the Finished state at any moment, and is allowed to send
-  // writesFinishedWithError: to its writeable.
-  //
-  // Not all implementations of writer have to support pausing, and thus
-  // trying to set an writer's state to this value might have no effect.
+  // The writer is temporarily paused, and won't send any more values to the writeable unless its
+  // state is set back to Started. The writer might still transition to the Finished state at any
+  // moment, and is allowed to send writesFinishedWithError: to its writeable.
   GRXWriterStatePaused,
 
   // The writer has released its writeable and won't interact with it anymore.
   //
-  // One seldomly wants to set an writer's state to this value, as its
-  // writeable isn't notified with a writesFinishedWithError: message. Instead, sending
-  // finishWithError: to the writer will make it notify the writeable and then
-  // transition to this state.
+  // One seldomly wants to set a writer's state to this value, as its writeable isn't notified with
+  // a writesFinishedWithError: message. Instead, sending finishWithError: to the writer will make
+  // it notify the writeable and then transition to this state.
   GRXWriterStateFinished
 };
 
-// An object that conforms to this protocol can produce, on demand, a sequence
-// of values. The sequence may be produced asynchronously, and it may consist of
-// any number of elements, including none or an infinite number.
+// An GRXWriter object can produce, on demand, a sequence of values. The sequence may be produced
+// asynchronously, and it may consist of any number of elements, including none or an infinite
+// number.
+//
+// GRXWriter is the active dual of NSEnumerator. The difference between them is thus whether the
+// object plays an active or passive role during usage: A user of NSEnumerator pulls values off it,
+// and passes the values to a writeable. A user of GRXWriter, though, just gives it a writeable, and
+// the GRXWriter instance pushes values to the writeable. This makes this protocol suitable to
+// represent a sequence of future values, as well as collections with internal iteration.
 //
-// GRXWriter is the active dual of NSEnumerator. The difference between them
-// is thus whether the object plays an active or passive role during usage: A
-// user of NSEnumerator pulls values off it, and passes the values to a writeable.
-// A user of GRXWriter, though, just gives it a writeable, and the
-// GRXWriter instance pushes values to the writeable. This makes this protocol
-// suitable to represent a sequence of future values, as well as collections
-// with internal iteration.
+// An instance of GRXWriter can start producing values after a writeable is passed to it. It can
+// also be commanded to finish the sequence immediately (with an optional error). Finally, it can be
+// asked to pause, and resumed later. All GRXWriter objects support pausing and early termination.
 //
-// An instance of GRXWriter can start producing values after a writeable is
-// passed to it. It can also be commanded to finish the sequence immediately
-// (with an optional error). Finally, it can be asked to pause, but the
-// conforming instance is not required to oblige.
+// Thread-safety:
 //
-// Unless otherwise indicated by a conforming class, no messages should be sent
-// concurrently to a GRXWriter. I.e., conforming classes aren't required to
-// be thread-safe.
+// State transitions take immediate effect if the object is used from a single thread. Subclasses
+// might offer stronger guarantees.
+//
+// Unless otherwise indicated by a conforming subclass, no messages should be sent concurrently to a
+// GRXWriter. I.e., conforming classes aren't required to be thread-safe.
 @interface GRXWriter : NSObject
 
-// This property can be used to query the current state of the writer, which
-// determines how it might currently use its writeable. Some state transitions can
-// be triggered by setting this property to the corresponding value, and that's
-// useful for advanced use cases like pausing an writer. For more details,
-// see the documentation of the enum.
+// This property can be used to query the current state of the writer, which determines how it might
+// currently use its writeable. Some state transitions can be triggered by setting this property to
+// the corresponding value, and that's useful for advanced use cases like pausing an writer. For
+// more details, see the documentation of the enum further down.
 @property(nonatomic) GRXWriterState state;
 
-// Start sending messages to the writeable. Messages may be sent before the method
-// returns, or they may be sent later in the future. See GRXWriteable.h for the
-// different messages a writeable can receive.
+// Transition to the Started state, and start sending messages to the writeable (a reference to it
+// is retained). Messages to the writeable may be sent before the method returns, or they may be
+// sent later in the future. See GRXWriteable.h for the different messages a writeable can receive.
 //
-// If this writer draws its values from an external source (e.g. from the
-// filesystem or from a server), calling this method will commonly trigger side
-// effects (like network connections).
+// If this writer draws its values from an external source (e.g. from the filesystem or from a
+// server), calling this method will commonly trigger side effects (like network connections).
 //
 // This method might only be called on writers in the NotStarted state.
 - (void)startWithWriteable:(id<GRXWriteable>)writeable;
 
-// Send writesFinishedWithError:errorOrNil immediately to the writeable, and don't send
-// any more messages to it.
-//
-// This method might only be called on writers in the Started or Paused
-// state.
+// Send writesFinishedWithError:errorOrNil to the writeable. Then release the reference to it and
+// transition to the Finished state.
 //
-// TODO(jcanizales): Consider adding some guarantee about the immediacy of that
-// stopping. I know I've relied on it in part of the code that uses this, but
-// can't remember the details in the presence of concurrency.
+// This method might only be called on writers in the Started or Paused state.
 - (void)finishWithError:(NSError *)errorOrNil;
 @end
diff --git a/src/objective-c/generated_libraries/RemoteTestClient/RemoteTest.podspec b/src/objective-c/generated_libraries/RemoteTestClient/RemoteTest.podspec
index 6b00efebb8..8710753e59 100644
--- a/src/objective-c/generated_libraries/RemoteTestClient/RemoteTest.podspec
+++ b/src/objective-c/generated_libraries/RemoteTestClient/RemoteTest.podspec
@@ -8,7 +8,10 @@ Pod::Spec.new do |s|
 
   # Run protoc with the Objective-C and gRPC plugins to generate protocol messages and gRPC clients.
   s.prepare_command = <<-CMD
-    protoc --plugin=protoc-gen-grpc=../../../../bins/$CONFIG/grpc_objective_c_plugin --objc_out=. --grpc_out=. *.proto
+    BINDIR=../../../../bins/$CONFIG
+    PROTOC=$BINDIR/protobuf/protoc
+    PLUGIN=$BINDIR/grpc_objective_c_plugin
+    $PROTOC --plugin=protoc-gen-grpc=$PLUGIN --objc_out=. --grpc_out=. *.proto
   CMD
 
   s.subspec "Messages" do |ms|
diff --git a/src/objective-c/generated_libraries/RouteGuideClient/RouteGuide.podspec b/src/objective-c/generated_libraries/RouteGuideClient/RouteGuide.podspec
index 2c9cead7cf..23ccffe69d 100644
--- a/src/objective-c/generated_libraries/RouteGuideClient/RouteGuide.podspec
+++ b/src/objective-c/generated_libraries/RouteGuideClient/RouteGuide.podspec
@@ -8,7 +8,10 @@ Pod::Spec.new do |s|
 
   # Run protoc with the Objective-C and gRPC plugins to generate protocol messages and gRPC clients.
   s.prepare_command = <<-CMD
-    protoc --plugin=protoc-gen-grpc=../../../../bins/$CONFIG/grpc_objective_c_plugin --objc_out=. --grpc_out=. *.proto
+    BINDIR=../../../../bins/$CONFIG
+    PROTOC=$BINDIR/protobuf/protoc
+    PLUGIN=$BINDIR/grpc_objective_c_plugin
+    $PROTOC --plugin=protoc-gen-grpc=$PLUGIN --objc_out=. --grpc_out=. *.proto
   CMD
 
   s.subspec "Messages" do |ms|
diff --git a/src/objective-c/tests/GRPCClientTests.m b/src/objective-c/tests/GRPCClientTests.m
index 103e5ca3d4..f23102988b 100644
--- a/src/objective-c/tests/GRPCClientTests.m
+++ b/src/objective-c/tests/GRPCClientTests.m
@@ -35,6 +35,8 @@
 #import <XCTest/XCTest.h>
 
 #import <GRPCClient/GRPCCall.h>
+#import <GRPCClient/GRPCCall+OAuth2.h>
+#import <GRPCClient/GRPCCall+Tests.h>
 #import <ProtoRPC/ProtoMethod.h>
 #import <RemoteTest/Messages.pbobjc.h>
 #import <RxLibrary/GRXWriteable.h>
@@ -43,8 +45,7 @@
 // These are a few tests similar to InteropTests, but which use the generic gRPC client (GRPCCall)
 // rather than a generated proto library on top of it.
 
-// grpc-test.sandbox.google.com
-static NSString * const kHostAddress = @"http://localhost:5050";
+static NSString * const kHostAddress = @"localhost:5050";
 static NSString * const kPackage = @"grpc.testing";
 static NSString * const kService = @"TestService";
 
@@ -58,6 +59,9 @@ static ProtoMethod *kUnaryCallMethod;
 @implementation GRPCClientTests
 
 - (void)setUp {
+  // Register test server as non-SSL.
+  [GRPCCall useInsecureConnectionsForHost:kHostAddress];
+
   // This method isn't implemented by the remote server.
   kInexistentMethod = [[ProtoMethod alloc] initWithPackage:kPackage
                                                    service:kService
@@ -110,7 +114,7 @@ static ProtoMethod *kUnaryCallMethod;
 
   [call startWithWriteable:responsesWriteable];
 
-  [self waitForExpectationsWithTimeout:4 handler:nil];
+  [self waitForExpectationsWithTimeout:8 handler:nil];
 }
 
 - (void)testSimpleProtoRPC {
@@ -142,7 +146,7 @@ static ProtoMethod *kUnaryCallMethod;
 
   [call startWithWriteable:responsesWriteable];
 
-  [self waitForExpectationsWithTimeout:4 handler:nil];
+  [self waitForExpectationsWithTimeout:8 handler:nil];
 }
 
 - (void)testMetadata {
@@ -157,7 +161,7 @@ static ProtoMethod *kUnaryCallMethod;
                                              path:kUnaryCallMethod.HTTPPath
                                    requestsWriter:requestsWriter];
 
-  call.requestMetadata[@"Authorization"] = @"Bearer bogusToken";
+  call.oauth2AccessToken = @"bogusToken";
 
   id<GRXWriteable> responsesWriteable = [[GRXWriteable alloc] initWithValueHandler:^(NSData *value) {
     XCTFail(@"Received unexpected response: %@", value);
@@ -166,7 +170,7 @@ static ProtoMethod *kUnaryCallMethod;
     XCTAssertEqual(errorOrNil.code, 16, @"Finished with unexpected error: %@", errorOrNil);
     XCTAssertEqualObjects(call.responseMetadata, errorOrNil.userInfo[kGRPCStatusMetadataKey],
                           @"Metadata in the NSError object and call object differ.");
-    NSString *challengeHeader = call.responseMetadata[@"www-authenticate"];
+    NSString *challengeHeader = call.oauth2ChallengeHeader;
     XCTAssertGreaterThan(challengeHeader.length, 0,
                          @"No challenge in response headers %@", call.responseMetadata);
     [expectation fulfill];
diff --git a/src/core/httpcli/httpcli_security_connector.h b/src/objective-c/tests/InteropTests.h
index c50f25905e..1045c3d124 100644
--- a/src/core/httpcli/httpcli_security_connector.h
+++ b/src/objective-c/tests/InteropTests.h
@@ -31,13 +31,13 @@
  *
  */
 
-#ifndef GRPC_INTERNAL_CORE_HTTPCLI_HTTPCLI_SECURITY_CONNECTOR_H
-#define GRPC_INTERNAL_CORE_HTTPCLI_HTTPCLI_SECURITY_CONNECTOR_H
+#import <XCTest/XCTest.h>
 
-#include "src/core/security/security_connector.h"
+// Implements tests as described here:
+// https://github.com/grpc/grpc/blob/master/doc/interop-test-descriptions.md
 
-grpc_security_status grpc_httpcli_ssl_channel_security_connector_create(
-    const unsigned char *pem_root_certs, size_t pem_root_certs_size,
-    const char *secure_peer_name, grpc_channel_security_connector **sc);
-
-#endif  /* GRPC_INTERNAL_CORE_HTTPCLI_HTTPCLI_SECURITY_CONNECTOR_H */
+@interface InteropTests : XCTestCase
+// Returns @"grpc-test.sandbox.google.com".
+// Override in a subclass to perform the same tests against a different address.
++ (NSString *)host;
+@end
diff --git a/src/objective-c/tests/InteropTests.m b/src/objective-c/tests/InteropTests.m
index b473d73422..1b63fe2059 100644
--- a/src/objective-c/tests/InteropTests.m
+++ b/src/objective-c/tests/InteropTests.m
@@ -31,11 +31,11 @@
  *
  */
 
-#include <grpc/status.h>
+#import "InteropTests.h"
 
-#import <UIKit/UIKit.h>
-#import <XCTest/XCTest.h>
+#include <grpc/status.h>
 
+#import <GRPCClient/GRPCCall+Tests.h>
 #import <ProtoRPC/ProtoRPC.h>
 #import <RemoteTest/Empty.pbobjc.h>
 #import <RemoteTest/Messages.pbobjc.h>
@@ -76,21 +76,22 @@
 }
 @end
 
-@interface InteropTests : XCTestCase
-@end
+#pragma mark Tests
+
+static NSString * const kRemoteSSLHost = @"grpc-test.sandbox.google.com";
 
 @implementation InteropTests {
   RMTTestService *_service;
 }
 
-// grpc-test.sandbox.google.com
++ (NSString *)host {
+  return kRemoteSSLHost;
+}
 
 - (void)setUp {
-  _service = [[RMTTestService alloc] initWithHost:@"http://localhost:5050"];
+  _service = [[RMTTestService alloc] initWithHost:self.class.host];
 }
 
-// Tests as described here: https://github.com/grpc/grpc/blob/master/doc/interop-test-descriptions.md
-
 - (void)testEmptyUnaryRPC {
   __weak XCTestExpectation *expectation = [self expectationWithDescription:@"EmptyUnary"];
 
@@ -127,7 +128,7 @@
     [expectation fulfill];
   }];
 
-  [self waitForExpectationsWithTimeout:8 handler:nil];
+  [self waitForExpectationsWithTimeout:16 handler:nil];
 }
 
 - (void)testClientStreamingRPC {
diff --git a/src/objective-c/tests/InteropTestsLocalCleartext.m b/src/objective-c/tests/InteropTestsLocalCleartext.m
new file mode 100644
index 0000000000..2d7d3c4b2c
--- /dev/null
+++ b/src/objective-c/tests/InteropTestsLocalCleartext.m
@@ -0,0 +1,59 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+// Repeat of the tests in InteropTests.m, but sending the RPCs to a local cleartext server instead
+// of the remote SSL one.
+
+#import <GRPCClient/GRPCCall+Tests.h>
+
+#import "InteropTests.h"
+
+static NSString * const kLocalCleartextHost = @"localhost:5050";
+
+@interface InteropTestsLocalCleartext : InteropTests
+@end
+
+@implementation InteropTestsLocalCleartext
+
++ (NSString *)host {
+  return kLocalCleartextHost;
+}
+
+- (void)setUp {
+  // Register test server as non-SSL.
+  [GRPCCall useInsecureConnectionsForHost:kLocalCleartextHost];
+
+  [super setUp];
+}
+
+@end
diff --git a/src/objective-c/tests/InteropTestsLocalSSL.m b/src/objective-c/tests/InteropTestsLocalSSL.m
new file mode 100644
index 0000000000..f69f806dcf
--- /dev/null
+++ b/src/objective-c/tests/InteropTestsLocalSSL.m
@@ -0,0 +1,62 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+// Repeat of the tests in InteropTests.m, but sending the RPCs to a local SSL server instead of the
+// remote one.
+
+#import <GRPCClient/GRPCCall+Tests.h>
+
+#import "InteropTests.h"
+
+static NSString * const kLocalSSLHost = @"localhost:5051";
+
+@interface InteropTestsLocalSSL : InteropTests
+@end
+
+@implementation InteropTestsLocalSSL
+
++ (NSString *)host {
+  return kLocalSSLHost;
+}
+
+- (void)setUp {
+  // Register test server certificates and name.
+  NSBundle *bundle = [NSBundle bundleForClass:self.class];
+  NSString *certsPath = [bundle pathForResource:@"TestCertificates.bundle/test-certificates"
+                                         ofType:@"pem"];
+  [GRPCCall useTestCertsPath:certsPath testName:@"foo.test.google.fr" forHost:kLocalSSLHost];
+
+  [super setUp];
+}
+
+@end
diff --git a/src/objective-c/tests/TestCertificates.bundle/test-certificates.pem b/src/objective-c/tests/TestCertificates.bundle/test-certificates.pem
new file mode 100644
index 0000000000..6c8511a73c
--- /dev/null
+++ b/src/objective-c/tests/TestCertificates.bundle/test-certificates.pem
@@ -0,0 +1,15 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/src/objective-c/tests/Tests.xcodeproj/project.pbxproj b/src/objective-c/tests/Tests.xcodeproj/project.pbxproj
index f13fb8288b..3a1c3d940a 100644
--- a/src/objective-c/tests/Tests.xcodeproj/project.pbxproj
+++ b/src/objective-c/tests/Tests.xcodeproj/project.pbxproj
@@ -13,6 +13,9 @@
 		63423F511B151B77006CF63C /* RxLibraryUnitTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 63423F501B151B77006CF63C /* RxLibraryUnitTests.m */; };
 		635697CD1B14FC11007A7283 /* Tests.m in Sources */ = {isa = PBXBuildFile; fileRef = 635697CC1B14FC11007A7283 /* Tests.m */; };
 		635ED2EC1B1A3BC400FDE5C3 /* InteropTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 635ED2EB1B1A3BC400FDE5C3 /* InteropTests.m */; };
+		63715F561B780C020029CB0B /* InteropTestsLocalCleartext.m in Sources */ = {isa = PBXBuildFile; fileRef = 63715F551B780C020029CB0B /* InteropTestsLocalCleartext.m */; };
+		63E240CE1B6C4E2B005F3B0E /* InteropTestsLocalSSL.m in Sources */ = {isa = PBXBuildFile; fileRef = 63E240CD1B6C4E2B005F3B0E /* InteropTestsLocalSSL.m */; };
+		63E240D01B6C63DC005F3B0E /* TestCertificates.bundle in Resources */ = {isa = PBXBuildFile; fileRef = 63E240CF1B6C63DC005F3B0E /* TestCertificates.bundle */; };
 		7D8A186224D39101F90230F6 /* libPods.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 35F2B6BF3BAE8F0DC4AFD76E /* libPods.a */; };
 /* End PBXBuildFile section */
 
@@ -49,6 +52,10 @@
 		635697CC1B14FC11007A7283 /* Tests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = Tests.m; sourceTree = "<group>"; };
 		635697D81B14FC11007A7283 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		635ED2EB1B1A3BC400FDE5C3 /* InteropTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = InteropTests.m; sourceTree = "<group>"; };
+		63715F551B780C020029CB0B /* InteropTestsLocalCleartext.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = InteropTestsLocalCleartext.m; sourceTree = "<group>"; };
+		63E240CC1B6C4D3A005F3B0E /* InteropTests.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = InteropTests.h; sourceTree = "<group>"; };
+		63E240CD1B6C4E2B005F3B0E /* InteropTestsLocalSSL.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = InteropTestsLocalSSL.m; sourceTree = "<group>"; };
+		63E240CF1B6C63DC005F3B0E /* TestCertificates.bundle */ = {isa = PBXFileReference; lastKnownFileType = "wrapper.plug-in"; path = TestCertificates.bundle; sourceTree = "<group>"; };
 		FF7B5489BCFE40111D768DD0 /* Pods.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = Pods.debug.xcconfig; path = "Pods/Target Support Files/Pods/Pods.debug.xcconfig"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
@@ -93,6 +100,7 @@
 			isa = PBXGroup;
 			children = (
 				635697C91B14FC11007A7283 /* Tests */,
+				63E240CF1B6C63DC005F3B0E /* TestCertificates.bundle */,
 				635697C81B14FC11007A7283 /* Products */,
 				51E4650F34F854F41FF053B3 /* Pods */,
 				136D535E19727099B941D7B1 /* Frameworks */,
@@ -112,9 +120,12 @@
 			isa = PBXGroup;
 			children = (
 				6312AE4D1B1BF49B00341DEE /* GRPCClientTests.m */,
-				63175DFE1B1B9FAF00027841 /* LocalClearTextTests.m */,
+				63E240CC1B6C4D3A005F3B0E /* InteropTests.h */,
 				635ED2EB1B1A3BC400FDE5C3 /* InteropTests.m */,
+				63E240CD1B6C4E2B005F3B0E /* InteropTestsLocalSSL.m */,
+				63715F551B780C020029CB0B /* InteropTestsLocalCleartext.m */,
 				63423F501B151B77006CF63C /* RxLibraryUnitTests.m */,
+				63175DFE1B1B9FAF00027841 /* LocalClearTextTests.m */,
 				635697CC1B14FC11007A7283 /* Tests.m */,
 				635697D71B14FC11007A7283 /* Supporting Files */,
 			);
@@ -209,6 +220,7 @@
 			isa = PBXResourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				63E240D01B6C63DC005F3B0E /* TestCertificates.bundle in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -252,8 +264,10 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				63715F561B780C020029CB0B /* InteropTestsLocalCleartext.m in Sources */,
 				63175DFF1B1B9FAF00027841 /* LocalClearTextTests.m in Sources */,
 				63423F511B151B77006CF63C /* RxLibraryUnitTests.m in Sources */,
+				63E240CE1B6C4E2B005F3B0E /* InteropTestsLocalSSL.m in Sources */,
 				6312AE4E1B1BF49B00341DEE /* GRPCClientTests.m in Sources */,
 				635ED2EC1B1A3BC400FDE5C3 /* InteropTests.m in Sources */,
 			);
diff --git a/src/objective-c/tests/build_tests.sh b/src/objective-c/tests/build_tests.sh
index d98e0a769c..e7ad31e403 100755
--- a/src/objective-c/tests/build_tests.sh
+++ b/src/objective-c/tests/build_tests.sh
@@ -28,12 +28,39 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+# Don't run this script standalone. Instead, run from the repository root:
+# ./tools/run_tests/run_tests.py -l objc
+
 set -e
 
 cd $(dirname $0)
 
-# The local test server needs to be compiled before this because pod install of
-# gRPC renames some C gRPC files and not the server's code references to them.
-#
-# Suppress error output because Cocoapods issue #3823 causes a flooding warning.
-pod install 2>/dev/null
+hash pod 2>/dev/null || { echo >&2 "Cocoapods needs to be installed."; exit 1; }
+hash xcodebuild 2>/dev/null || {
+    echo >&2 "XCode command-line tools need to be installed."
+    exit 1
+}
+
+BINDIR=../../../bins/$CONFIG
+
+if [ ! -f $BINDIR/protobuf/protoc ]; then
+    hash protoc 2>/dev/null || {
+        echo >&2 "Can't find protoc. Make sure run_tests.py is making" \
+                 "grpc_objective_c_plugin before calling this script."
+        exit 1
+    }
+    # When protoc is already installed, make doesn't compile one. Put a link
+    # there so the podspecs can do codegen using that path.
+    mkdir -p $BINDIR/protobuf
+    ln -s `which protoc` $BINDIR/protobuf/protoc
+fi
+
+[ -f $BINDIR/interop_server ] || {
+    echo >&2 "Can't find the test server. Make sure run_tests.py is making" \
+             "interop_server before calling this script. It needs to be done" \
+             "before because pod install of gRPC renames some C gRPC files" \
+             "and not the server's code references to them."
+    exit 1
+}
+
+pod install
diff --git a/src/objective-c/tests/run_tests.sh b/src/objective-c/tests/run_tests.sh
index 9afec687d6..7b133c1782 100755
--- a/src/objective-c/tests/run_tests.sh
+++ b/src/objective-c/tests/run_tests.sh
@@ -28,13 +28,17 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+# Don't run this script standalone. Instead, run from the repository root:
+# ./tools/run_tests/run_tests.py -l objc
+
 set -e
 
 cd $(dirname $0)
 
 # Run the tests server.
 ../../../bins/$CONFIG/interop_server --port=5050 &
-# Kill it when this script exits.
+../../../bins/$CONFIG/interop_server --port=5051 --enable_ssl &
+# Kill them when this script exits.
 trap 'kill -9 `jobs -p`' EXIT
 
 # xcodebuild is very verbose. We filter its output and tell Bash to fail if any
diff --git a/src/php/ext/grpc/call.c b/src/php/ext/grpc/call.c
index 1f76c7359d..01ec909b79 100644
--- a/src/php/ext/grpc/call.c
+++ b/src/php/ext/grpc/call.c
@@ -240,8 +240,8 @@ PHP_METHOD(Call, __construct) {
       (wrapped_grpc_timeval *)zend_object_store_get_object(
           deadline_obj TSRMLS_CC);
   call->wrapped = grpc_channel_create_call(
-      channel->wrapped, completion_queue, method, channel->target,
-      deadline->wrapped);
+      channel->wrapped, NULL, GRPC_PROPAGATE_DEFAULTS, completion_queue, method,
+      channel->target, deadline->wrapped);
 }
 
 /**
diff --git a/src/php/ext/grpc/server.c b/src/php/ext/grpc/server.c
index 8b8d5b2f47..d58aa884ca 100644
--- a/src/php/ext/grpc/server.c
+++ b/src/php/ext/grpc/server.c
@@ -182,7 +182,7 @@ PHP_METHOD(Server, addHttp2Port) {
                          "add_http2_port expects a string", 1 TSRMLS_CC);
     return;
   }
-  RETURN_LONG(grpc_server_add_http2_port(server->wrapped, addr));
+  RETURN_LONG(grpc_server_add_insecure_http2_port(server->wrapped, addr));
 }
 
 PHP_METHOD(Server, addSecureHttp2Port) {
diff --git a/src/python/grpcio/.gitignore b/src/python/grpcio/.gitignore
index efbe1737ba..4c02b8d14d 100644
--- a/src/python/grpcio/.gitignore
+++ b/src/python/grpcio/.gitignore
@@ -6,3 +6,4 @@ dist/
 *.egg/
 *.eggs/
 doc/
+_grpcio_metadata.py
diff --git a/src/python/grpcio/commands.py b/src/python/grpcio/commands.py
index 605d9d5612..89c0fbf0f3 100644
--- a/src/python/grpcio/commands.py
+++ b/src/python/grpcio/commands.py
@@ -34,6 +34,7 @@ import os.path
 import sys
 
 import setuptools
+from setuptools.command import build_py
 
 _CONF_PY_ADDENDUM = """
 extensions.append('sphinx.ext.napoleon')
@@ -74,3 +75,28 @@ class SphinxDocumentation(setuptools.Command):
       conf_file.write(_CONF_PY_ADDENDUM)
     sphinx.main(['', os.path.join('doc', 'src'), os.path.join('doc', 'build')])
 
+
+class BuildProjectMetadata(setuptools.Command):
+  """Command to generate project metadata in a module."""
+
+  description = ''
+  user_options = []
+
+  def initialize_options(self):
+    pass
+
+  def finalize_options(self):
+    pass
+
+  def run(self):
+    with open('grpc/_grpcio_metadata.py', 'w') as module_file:
+      module_file.write('__version__ = """{}"""'.format(
+          self.distribution.get_version()))
+
+
+class BuildPy(build_py.build_py):
+  """Custom project build command."""
+
+  def run(self):
+    self.run_command('build_project_metadata')
+    build_py.build_py.run(self)
diff --git a/src/python/grpcio/grpc/_adapter/_c/module.c b/src/python/grpcio/grpc/_adapter/_c/module.c
index 1f3aedd9d8..9b93b051f6 100644
--- a/src/python/grpcio/grpc/_adapter/_c/module.c
+++ b/src/python/grpcio/grpc/_adapter/_c/module.c
@@ -53,6 +53,12 @@ PyMODINIT_FUNC init_c(void) {
     return;
   }
 
+  if (PyModule_AddStringConstant(
+          module, "PRIMARY_USER_AGENT_KEY",
+          GRPC_ARG_PRIMARY_USER_AGENT_STRING) < 0) {
+    return;
+  }
+
   /* GRPC maintains an internal counter of how many times it has been
      initialized and handles multiple pairs of grpc_init()/grpc_shutdown()
      invocations accordingly. */
diff --git a/src/python/grpcio/grpc/_adapter/_c/types/channel.c b/src/python/grpcio/grpc/_adapter/_c/types/channel.c
index feb256cf00..963104742f 100644
--- a/src/python/grpcio/grpc/_adapter/_c/types/channel.c
+++ b/src/python/grpcio/grpc/_adapter/_c/types/channel.c
@@ -128,7 +128,7 @@ Call *pygrpc_Channel_create_call(
   }
   call = pygrpc_Call_new_empty(cq);
   call->c_call = grpc_channel_create_call(
-      self->c_chan, cq->c_cq, method, host,
+      self->c_chan, NULL, GRPC_PROPAGATE_DEFAULTS, cq->c_cq, method, host,
       pygrpc_cast_double_to_gpr_timespec(deadline));
   return call;
 }
diff --git a/src/python/grpcio/grpc/_adapter/_c/types/server.c b/src/python/grpcio/grpc/_adapter/_c/types/server.c
index 2a00f34039..c2190ea672 100644
--- a/src/python/grpcio/grpc/_adapter/_c/types/server.c
+++ b/src/python/grpcio/grpc/_adapter/_c/types/server.c
@@ -155,7 +155,7 @@ PyObject *pygrpc_Server_add_http2_port(
     port = grpc_server_add_secure_http2_port(
         self->c_serv, addr, creds->c_creds);
   } else {
-    port = grpc_server_add_http2_port(self->c_serv, addr);
+    port = grpc_server_add_insecure_http2_port(self->c_serv, addr);
   }
   return PyInt_FromLong(port);
 
diff --git a/src/python/grpcio/grpc/_adapter/_low.py b/src/python/grpcio/grpc/_adapter/_low.py
index dcf67dbc11..239aac81b2 100644
--- a/src/python/grpcio/grpc/_adapter/_low.py
+++ b/src/python/grpcio/grpc/_adapter/_low.py
@@ -27,9 +27,12 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+from grpc import _grpcio_metadata
 from grpc._adapter import _c
 from grpc._adapter import _types
 
+_USER_AGENT = 'Python-gRPC-{}'.format(_grpcio_metadata.__version__)
+
 ClientCredentials = _c.ClientCredentials
 ServerCredentials = _c.ServerCredentials
 
@@ -76,6 +79,7 @@ class Call(_types.Call):
 class Channel(_types.Channel):
 
   def __init__(self, target, args, creds=None):
+    args = list(args) + [(_c.PRIMARY_USER_AGENT_KEY, _USER_AGENT)]
     if creds is None:
       self.channel = _c.Channel(target, args)
     else:
diff --git a/src/python/grpcio/setup.py b/src/python/grpcio/setup.py
index e408f2ace9..caa71a4f7c 100644
--- a/src/python/grpcio/setup.py
+++ b/src/python/grpcio/setup.py
@@ -98,6 +98,8 @@ _SETUP_REQUIRES = (
 
 _COMMAND_CLASS = {
     'doc': commands.SphinxDocumentation,
+    'build_project_metadata': commands.BuildProjectMetadata,
+    'build_py': commands.BuildPy,
 }
 
 setuptools.setup(
diff --git a/src/python/grpcio_test/grpc_interop/_interop_test_case.py b/src/python/grpcio_test/grpc_interop/_interop_test_case.py
index ed8f7ef009..b6d06b300d 100644
--- a/src/python/grpcio_test/grpc_interop/_interop_test_case.py
+++ b/src/python/grpcio_test/grpc_interop/_interop_test_case.py
@@ -59,3 +59,6 @@ class InteropTestCase(object):
 
   def testCancelAfterFirstResponse(self):
     methods.TestCase.CANCEL_AFTER_FIRST_RESPONSE.test_interoperability(self.stub, None)
+
+  def testTimeoutOnSleepingServer(self):
+    methods.TestCase.TIMEOUT_ON_SLEEPING_SERVER.test_interoperability(self.stub, None)
diff --git a/src/python/grpcio_test/grpc_interop/methods.py b/src/python/grpcio_test/grpc_interop/methods.py
index f4c94685ee..7a831f3cbd 100644
--- a/src/python/grpcio_test/grpc_interop/methods.py
+++ b/src/python/grpcio_test/grpc_interop/methods.py
@@ -33,10 +33,12 @@ import enum
 import json
 import os
 import threading
+import time
 
 from oauth2client import client as oauth2client_client
 
 from grpc.framework.alpha import utilities
+from grpc.framework.alpha import exceptions
 
 from grpc_interop import empty_pb2
 from grpc_interop import messages_pb2
@@ -318,6 +320,24 @@ def _cancel_after_first_response(stub):
       raise ValueError('expected call to be cancelled')
 
 
+def _timeout_on_sleeping_server(stub):
+  request_payload_size = 27182
+  with stub, _Pipe() as pipe:
+    response_iterator = stub.FullDuplexCall(pipe, 0.001)
+
+    request = messages_pb2.StreamingOutputCallRequest(
+        response_type=messages_pb2.COMPRESSABLE,
+        payload=messages_pb2.Payload(body=b'\x00' * request_payload_size))
+    pipe.add(request)
+    time.sleep(0.1)
+    try:
+      next(response_iterator)
+    except exceptions.ExpirationError:
+      pass
+    else:
+      raise ValueError('expected call to exceed deadline')
+
+
 def _compute_engine_creds(stub, args):
   response = _large_unary_common_behavior(stub, True, True)
   if args.default_service_account != response.username:
@@ -351,6 +371,7 @@ class TestCase(enum.Enum):
   CANCEL_AFTER_FIRST_RESPONSE = 'cancel_after_first_response'
   COMPUTE_ENGINE_CREDS = 'compute_engine_creds'
   SERVICE_ACCOUNT_CREDS = 'service_account_creds'
+  TIMEOUT_ON_SLEEPING_SERVER = 'timeout_on_sleeping_server'
 
   def test_interoperability(self, stub, args):
     if self is TestCase.EMPTY_UNARY:
@@ -367,6 +388,8 @@ class TestCase(enum.Enum):
       _cancel_after_begin(stub)
     elif self is TestCase.CANCEL_AFTER_FIRST_RESPONSE:
       _cancel_after_first_response(stub)
+    elif self is TestCase.TIMEOUT_ON_SLEEPING_SERVER:
+      _timeout_on_sleeping_server(stub)
     elif self is TestCase.COMPUTE_ENGINE_CREDS:
       _compute_engine_creds(stub, args)
     elif self is TestCase.SERVICE_ACCOUNT_CREDS:
diff --git a/src/python/grpcio_test/grpc_protoc_plugin/__init__.py b/src/python/grpcio_test/grpc_protoc_plugin/__init__.py
new file mode 100644
index 0000000000..7086519106
--- /dev/null
+++ b/src/python/grpcio_test/grpc_protoc_plugin/__init__.py
@@ -0,0 +1,30 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
diff --git a/src/python/grpcio_test/grpc_protoc_plugin/python_plugin_test.py b/src/python/grpcio_test/grpc_protoc_plugin/python_plugin_test.py
new file mode 100644
index 0000000000..b200d129a9
--- /dev/null
+++ b/src/python/grpcio_test/grpc_protoc_plugin/python_plugin_test.py
@@ -0,0 +1,541 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+import argparse
+import contextlib
+import distutils.spawn
+import errno
+import itertools
+import os
+import pkg_resources
+import shutil
+import subprocess
+import sys
+import tempfile
+import threading
+import time
+import unittest
+
+from grpc.framework.alpha import exceptions
+from grpc.framework.foundation import future
+
+# Identifiers of entities we expect to find in the generated module.
+SERVICER_IDENTIFIER = 'EarlyAdopterTestServiceServicer'
+SERVER_IDENTIFIER = 'EarlyAdopterTestServiceServer'
+STUB_IDENTIFIER = 'EarlyAdopterTestServiceStub'
+SERVER_FACTORY_IDENTIFIER = 'early_adopter_create_TestService_server'
+STUB_FACTORY_IDENTIFIER = 'early_adopter_create_TestService_stub'
+
+# The timeout used in tests of RPCs that are supposed to expire.
+SHORT_TIMEOUT = 2
+# The timeout used in tests of RPCs that are not supposed to expire. The
+# absurdly large value doesn't matter since no passing execution of this test
+# module will ever wait the duration.
+LONG_TIMEOUT = 600
+NO_DELAY = 0
+
+
+class _ServicerMethods(object):
+
+  def __init__(self, test_pb2, delay):
+    self._condition = threading.Condition()
+    self._delay = delay
+    self._paused = False
+    self._fail = False
+    self._test_pb2 = test_pb2
+
+  @contextlib.contextmanager
+  def pause(self):  # pylint: disable=invalid-name
+    with self._condition:
+      self._paused = True
+    yield
+    with self._condition:
+      self._paused = False
+      self._condition.notify_all()
+
+  @contextlib.contextmanager
+  def fail(self):  # pylint: disable=invalid-name
+    with self._condition:
+      self._fail = True
+    yield
+    with self._condition:
+      self._fail = False
+
+  def _control(self):  # pylint: disable=invalid-name
+    with self._condition:
+      if self._fail:
+        raise ValueError()
+      while self._paused:
+        self._condition.wait()
+    time.sleep(self._delay)
+
+  def UnaryCall(self, request, unused_rpc_context):
+    response = self._test_pb2.SimpleResponse()
+    response.payload.payload_type = self._test_pb2.COMPRESSABLE
+    response.payload.payload_compressable = 'a' * request.response_size
+    self._control()
+    return response
+
+  def StreamingOutputCall(self, request, unused_rpc_context):
+    for parameter in request.response_parameters:
+      response = self._test_pb2.StreamingOutputCallResponse()
+      response.payload.payload_type = self._test_pb2.COMPRESSABLE
+      response.payload.payload_compressable = 'a' * parameter.size
+      self._control()
+      yield response
+
+  def StreamingInputCall(self, request_iter, unused_rpc_context):
+    response = self._test_pb2.StreamingInputCallResponse()
+    aggregated_payload_size = 0
+    for request in request_iter:
+      aggregated_payload_size += len(request.payload.payload_compressable)
+    response.aggregated_payload_size = aggregated_payload_size
+    self._control()
+    return response
+
+  def FullDuplexCall(self, request_iter, unused_rpc_context):
+    for request in request_iter:
+      for parameter in request.response_parameters:
+        response = self._test_pb2.StreamingOutputCallResponse()
+        response.payload.payload_type = self._test_pb2.COMPRESSABLE
+        response.payload.payload_compressable = 'a' * parameter.size
+        self._control()
+        yield response
+
+  def HalfDuplexCall(self, request_iter, unused_rpc_context):
+    responses = []
+    for request in request_iter:
+      for parameter in request.response_parameters:
+        response = self._test_pb2.StreamingOutputCallResponse()
+        response.payload.payload_type = self._test_pb2.COMPRESSABLE
+        response.payload.payload_compressable = 'a' * parameter.size
+        self._control()
+        responses.append(response)
+    for response in responses:
+      yield response
+
+
+@contextlib.contextmanager
+def _CreateService(test_pb2, delay):
+  """Provides a servicer backend and a stub.
+
+  The servicer is just the implementation
+  of the actual servicer passed to the face player of the python RPC
+  implementation; the two are detached.
+
+  Non-zero delay puts a delay on each call to the servicer, representative of
+  communication latency. Timeout is the default timeout for the stub while
+  waiting for the service.
+
+  Args:
+    test_pb2: The test_pb2 module generated by this test.
+    delay: Delay in seconds per response from the servicer.
+
+  Yields:
+    A (servicer_methods, servicer, stub) three-tuple where servicer_methods is
+      the back-end of the service bound to the stub and the server and stub
+      are both activated and ready for use.
+  """
+  servicer_methods = _ServicerMethods(test_pb2, delay)
+
+  class Servicer(getattr(test_pb2, SERVICER_IDENTIFIER)):
+
+    def UnaryCall(self, request, context):
+      return servicer_methods.UnaryCall(request, context)
+
+    def StreamingOutputCall(self, request, context):
+      return servicer_methods.StreamingOutputCall(request, context)
+
+    def StreamingInputCall(self, request_iter, context):
+      return servicer_methods.StreamingInputCall(request_iter, context)
+
+    def FullDuplexCall(self, request_iter, context):
+      return servicer_methods.FullDuplexCall(request_iter, context)
+
+    def HalfDuplexCall(self, request_iter, context):
+      return servicer_methods.HalfDuplexCall(request_iter, context)
+
+  servicer = Servicer()
+  server = getattr(
+      test_pb2, SERVER_FACTORY_IDENTIFIER)(servicer, 0)
+  with server:
+    port = server.port()
+    stub = getattr(test_pb2, STUB_FACTORY_IDENTIFIER)('localhost', port)
+    with stub:
+      yield servicer_methods, stub, server
+
+
+def _streaming_input_request_iterator(test_pb2):
+  for _ in range(3):
+    request = test_pb2.StreamingInputCallRequest()
+    request.payload.payload_type = test_pb2.COMPRESSABLE
+    request.payload.payload_compressable = 'a'
+    yield request
+
+
+def _streaming_output_request(test_pb2):
+  request = test_pb2.StreamingOutputCallRequest()
+  sizes = [1, 2, 3]
+  request.response_parameters.add(size=sizes[0], interval_us=0)
+  request.response_parameters.add(size=sizes[1], interval_us=0)
+  request.response_parameters.add(size=sizes[2], interval_us=0)
+  return request
+
+
+def _full_duplex_request_iterator(test_pb2):
+  request = test_pb2.StreamingOutputCallRequest()
+  request.response_parameters.add(size=1, interval_us=0)
+  yield request
+  request = test_pb2.StreamingOutputCallRequest()
+  request.response_parameters.add(size=2, interval_us=0)
+  request.response_parameters.add(size=3, interval_us=0)
+  yield request
+
+
+class PythonPluginTest(unittest.TestCase):
+  """Test case for the gRPC Python protoc-plugin.
+
+  While reading these tests, remember that the futures API
+  (`stub.method.async()`) only gives futures for the *non-streaming* responses,
+  else it behaves like its blocking cousin.
+  """
+
+  def setUp(self):
+    # Assume that the appropriate protoc and grpc_python_plugins are on the
+    # path.
+    protoc_command = 'protoc'
+    protoc_plugin_filename = distutils.spawn.find_executable(
+        'grpc_python_plugin')
+    test_proto_filename = pkg_resources.resource_filename(
+        'grpc_protoc_plugin', 'test.proto')
+    if not os.path.isfile(protoc_command):
+      # Assume that if we haven't built protoc that it's on the system.
+      protoc_command = 'protoc'
+
+    # Ensure that the output directory exists.
+    self.outdir = tempfile.mkdtemp()
+
+    # Invoke protoc with the plugin.
+    cmd = [
+        protoc_command,
+        '--plugin=protoc-gen-python-grpc=%s' % protoc_plugin_filename,
+        '-I .',
+        '--python_out=%s' % self.outdir,
+        '--python-grpc_out=%s' % self.outdir,
+        os.path.basename(test_proto_filename),
+    ]
+    subprocess.check_call(' '.join(cmd), shell=True, env=os.environ,
+                          cwd=os.path.dirname(test_proto_filename))
+    sys.path.append(self.outdir)
+
+  def tearDown(self):
+    try:
+      shutil.rmtree(self.outdir)
+    except OSError as exc:
+      if exc.errno != errno.ENOENT:
+        raise
+
+  # TODO(atash): Figure out which of these tests is hanging flakily with small
+  # probability.
+
+  def testImportAttributes(self):
+    # check that we can access the generated module and its members.
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    self.assertIsNotNone(getattr(test_pb2, SERVICER_IDENTIFIER, None))
+    self.assertIsNotNone(getattr(test_pb2, SERVER_IDENTIFIER, None))
+    self.assertIsNotNone(getattr(test_pb2, STUB_IDENTIFIER, None))
+    self.assertIsNotNone(getattr(test_pb2, SERVER_FACTORY_IDENTIFIER, None))
+    self.assertIsNotNone(getattr(test_pb2, STUB_FACTORY_IDENTIFIER, None))
+
+  def testUpDown(self):
+    import test_pb2
+    with _CreateService(
+        test_pb2, NO_DELAY) as (servicer, stub, unused_server):
+      request = test_pb2.SimpleRequest(response_size=13)
+
+  def testUnaryCall(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    with _CreateService(test_pb2, NO_DELAY) as (methods, stub, unused_server):
+      timeout = 6  # TODO(issue 2039): LONG_TIMEOUT like the other methods.
+      request = test_pb2.SimpleRequest(response_size=13)
+      response = stub.UnaryCall(request, timeout)
+    expected_response = methods.UnaryCall(request, 'not a real RpcContext!')
+    self.assertEqual(expected_response, response)
+
+  def testUnaryCallAsync(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    request = test_pb2.SimpleRequest(response_size=13)
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      # Check that the call does not block waiting for the server to respond.
+      with methods.pause():
+        response_future = stub.UnaryCall.async(request, LONG_TIMEOUT)
+      response = response_future.result()
+    expected_response = methods.UnaryCall(request, 'not a real RpcContext!')
+    self.assertEqual(expected_response, response)
+
+  def testUnaryCallAsyncExpired(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      request = test_pb2.SimpleRequest(response_size=13)
+      with methods.pause():
+        response_future = stub.UnaryCall.async(request, SHORT_TIMEOUT)
+        with self.assertRaises(exceptions.ExpirationError):
+          response_future.result()
+
+  @unittest.skip('TODO(atash,nathaniel): figure out why this flakily hangs '
+                 'forever and fix.')
+  def testUnaryCallAsyncCancelled(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    request = test_pb2.SimpleRequest(response_size=13)
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      with methods.pause():
+        response_future = stub.UnaryCall.async(request, 1)
+        response_future.cancel()
+        self.assertTrue(response_future.cancelled())
+
+  def testUnaryCallAsyncFailed(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    request = test_pb2.SimpleRequest(response_size=13)
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      with methods.fail():
+        response_future = stub.UnaryCall.async(request, LONG_TIMEOUT)
+        self.assertIsNotNone(response_future.exception())
+
+  def testStreamingOutputCall(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    request = _streaming_output_request(test_pb2)
+    with _CreateService(test_pb2, NO_DELAY) as (methods, stub, unused_server):
+      responses = stub.StreamingOutputCall(request, LONG_TIMEOUT)
+      expected_responses = methods.StreamingOutputCall(
+          request, 'not a real RpcContext!')
+      for expected_response, response in itertools.izip_longest(
+          expected_responses, responses):
+        self.assertEqual(expected_response, response)
+
+  @unittest.skip('TODO(atash,nathaniel): figure out why this flakily hangs '
+                 'forever and fix.')
+  def testStreamingOutputCallExpired(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    request = _streaming_output_request(test_pb2)
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      with methods.pause():
+        responses = stub.StreamingOutputCall(request, SHORT_TIMEOUT)
+        with self.assertRaises(exceptions.ExpirationError):
+          list(responses)
+
+  @unittest.skip('TODO(atash,nathaniel): figure out why this flakily hangs '
+                 'forever and fix.')
+  def testStreamingOutputCallCancelled(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    request = _streaming_output_request(test_pb2)
+    with _CreateService(test_pb2, NO_DELAY) as (
+        unused_methods, stub, unused_server):
+      responses = stub.StreamingOutputCall(request, SHORT_TIMEOUT)
+      next(responses)
+      responses.cancel()
+      with self.assertRaises(future.CancelledError):
+        next(responses)
+
+  @unittest.skip('TODO(atash,nathaniel): figure out why this times out '
+                 'instead of raising the proper error.')
+  def testStreamingOutputCallFailed(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    request = _streaming_output_request(test_pb2)
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      with methods.fail():
+        responses = stub.StreamingOutputCall(request, 1)
+        self.assertIsNotNone(responses)
+        with self.assertRaises(exceptions.ServicerError):
+          next(responses)
+
+  @unittest.skip('TODO(atash,nathaniel): figure out why this flakily hangs '
+                 'forever and fix.')
+  def testStreamingInputCall(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    with _CreateService(test_pb2, NO_DELAY) as (methods, stub, unused_server):
+      response = stub.StreamingInputCall(
+          _streaming_input_request_iterator(test_pb2), LONG_TIMEOUT)
+    expected_response = methods.StreamingInputCall(
+        _streaming_input_request_iterator(test_pb2), 'not a real RpcContext!')
+    self.assertEqual(expected_response, response)
+
+  def testStreamingInputCallAsync(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      with methods.pause():
+        response_future = stub.StreamingInputCall.async(
+            _streaming_input_request_iterator(test_pb2), LONG_TIMEOUT)
+      response = response_future.result()
+    expected_response = methods.StreamingInputCall(
+        _streaming_input_request_iterator(test_pb2), 'not a real RpcContext!')
+    self.assertEqual(expected_response, response)
+
+  def testStreamingInputCallAsyncExpired(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      with methods.pause():
+        response_future = stub.StreamingInputCall.async(
+            _streaming_input_request_iterator(test_pb2), SHORT_TIMEOUT)
+        with self.assertRaises(exceptions.ExpirationError):
+          response_future.result()
+        self.assertIsInstance(
+            response_future.exception(), exceptions.ExpirationError)
+
+  def testStreamingInputCallAsyncCancelled(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      with methods.pause():
+        timeout = 6  # TODO(issue 2039): LONG_TIMEOUT like the other methods.
+        response_future = stub.StreamingInputCall.async(
+            _streaming_input_request_iterator(test_pb2), timeout)
+        response_future.cancel()
+        self.assertTrue(response_future.cancelled())
+      with self.assertRaises(future.CancelledError):
+        response_future.result()
+
+  def testStreamingInputCallAsyncFailed(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      with methods.fail():
+        response_future = stub.StreamingInputCall.async(
+            _streaming_input_request_iterator(test_pb2), SHORT_TIMEOUT)
+        self.assertIsNotNone(response_future.exception())
+
+  def testFullDuplexCall(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    with _CreateService(test_pb2, NO_DELAY) as (methods, stub, unused_server):
+      responses = stub.FullDuplexCall(
+          _full_duplex_request_iterator(test_pb2), LONG_TIMEOUT)
+      expected_responses = methods.FullDuplexCall(
+          _full_duplex_request_iterator(test_pb2), 'not a real RpcContext!')
+      for expected_response, response in itertools.izip_longest(
+          expected_responses, responses):
+        self.assertEqual(expected_response, response)
+
+  @unittest.skip('TODO(atash,nathaniel): figure out why this flakily hangs '
+                 'forever and fix.')
+  def testFullDuplexCallExpired(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    request_iterator = _full_duplex_request_iterator(test_pb2)
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      with methods.pause():
+        responses = stub.FullDuplexCall(request_iterator, SHORT_TIMEOUT)
+        with self.assertRaises(exceptions.ExpirationError):
+          list(responses)
+
+  @unittest.skip('TODO(atash,nathaniel): figure out why this flakily hangs '
+                 'forever and fix.')
+  def testFullDuplexCallCancelled(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    with _CreateService(test_pb2, NO_DELAY) as (methods, stub, unused_server):
+      request_iterator = _full_duplex_request_iterator(test_pb2)
+      responses = stub.FullDuplexCall(request_iterator, LONG_TIMEOUT)
+      next(responses)
+      responses.cancel()
+      with self.assertRaises(future.CancelledError):
+        next(responses)
+
+  @unittest.skip('TODO(atash,nathaniel): figure out why this hangs forever '
+                 'and fix.')
+  def testFullDuplexCallFailed(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    request_iterator = _full_duplex_request_iterator(test_pb2)
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      with methods.fail():
+        responses = stub.FullDuplexCall(request_iterator, LONG_TIMEOUT)
+        self.assertIsNotNone(responses)
+        with self.assertRaises(exceptions.ServicerError):
+          next(responses)
+
+  @unittest.skip('TODO(atash,nathaniel): figure out why this flakily hangs '
+                 'forever and fix.')
+  def testHalfDuplexCall(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    with _CreateService(test_pb2, NO_DELAY) as (
+        methods, stub, unused_server):
+      def half_duplex_request_iterator():
+        request = test_pb2.StreamingOutputCallRequest()
+        request.response_parameters.add(size=1, interval_us=0)
+        yield request
+        request = test_pb2.StreamingOutputCallRequest()
+        request.response_parameters.add(size=2, interval_us=0)
+        request.response_parameters.add(size=3, interval_us=0)
+        yield request
+      responses = stub.HalfDuplexCall(
+          half_duplex_request_iterator(), LONG_TIMEOUT)
+      expected_responses = methods.HalfDuplexCall(
+          half_duplex_request_iterator(), 'not a real RpcContext!')
+      for check in itertools.izip_longest(expected_responses, responses):
+        expected_response, response = check
+        self.assertEqual(expected_response, response)
+
+  def testHalfDuplexCallWedged(self):
+    import test_pb2  # pylint: disable=g-import-not-at-top
+    condition = threading.Condition()
+    wait_cell = [False]
+    @contextlib.contextmanager
+    def wait():  # pylint: disable=invalid-name
+      # Where's Python 3's 'nonlocal' statement when you need it?
+      with condition:
+        wait_cell[0] = True
+      yield
+      with condition:
+        wait_cell[0] = False
+        condition.notify_all()
+    def half_duplex_request_iterator():
+      request = test_pb2.StreamingOutputCallRequest()
+      request.response_parameters.add(size=1, interval_us=0)
+      yield request
+      with condition:
+        while wait_cell[0]:
+          condition.wait()
+    with _CreateService(test_pb2, NO_DELAY) as (methods, stub, unused_server):
+      with wait():
+        responses = stub.HalfDuplexCall(
+            half_duplex_request_iterator(), SHORT_TIMEOUT)
+        # half-duplex waits for the client to send all info
+        with self.assertRaises(exceptions.ExpirationError):
+          next(responses)
+
+
+if __name__ == '__main__':
+  os.chdir(os.path.dirname(sys.argv[0]))
+  unittest.main(verbosity=2)
diff --git a/src/python/grpcio_test/grpc_protoc_plugin/test.proto b/src/python/grpcio_test/grpc_protoc_plugin/test.proto
new file mode 100644
index 0000000000..ed7c6a7b79
--- /dev/null
+++ b/src/python/grpcio_test/grpc_protoc_plugin/test.proto
@@ -0,0 +1,139 @@
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// An integration test service that covers all the method signature permutations
+// of unary/streaming requests/responses.
+// This file is duplicated around the code base. See GitHub issue #526.
+syntax = "proto2";
+
+package grpc.testing;
+
+enum PayloadType {
+  // Compressable text format.
+  COMPRESSABLE= 1;
+
+  // Uncompressable binary format.
+  UNCOMPRESSABLE = 2;
+
+  // Randomly chosen from all other formats defined in this enum.
+  RANDOM = 3;
+}
+
+message Payload {
+  required PayloadType payload_type = 1;
+  oneof payload_body {
+    string payload_compressable = 2;
+    bytes payload_uncompressable = 3;
+  }
+}
+
+message SimpleRequest {
+  // Desired payload type in the response from the server.
+  // If response_type is RANDOM, server randomly chooses one from other formats.
+  optional PayloadType response_type = 1 [default=COMPRESSABLE];
+
+  // Desired payload size in the response from the server.
+  // If response_type is COMPRESSABLE, this denotes the size before compression.
+  optional int32 response_size = 2;
+
+  // Optional input payload sent along with the request.
+  optional Payload payload = 3;
+}
+
+message SimpleResponse {
+  optional Payload payload = 1;
+}
+
+message StreamingInputCallRequest {
+  // Optional input payload sent along with the request.
+  optional Payload payload = 1;
+
+  // Not expecting any payload from the response.
+}
+
+message StreamingInputCallResponse {
+  // Aggregated size of payloads received from the client.
+  optional int32 aggregated_payload_size = 1;
+}
+
+message ResponseParameters {
+  // Desired payload sizes in responses from the server.
+  // If response_type is COMPRESSABLE, this denotes the size before compression.
+  required int32 size = 1;
+
+  // Desired interval between consecutive responses in the response stream in
+  // microseconds.
+  required int32 interval_us = 2;
+}
+
+message StreamingOutputCallRequest {
+  // Desired payload type in the response from the server.
+  // If response_type is RANDOM, the payload from each response in the stream
+  // might be of different types. This is to simulate a mixed type of payload
+  // stream.
+  optional PayloadType response_type = 1 [default=COMPRESSABLE];
+
+  repeated ResponseParameters response_parameters = 2;
+
+  // Optional input payload sent along with the request.
+  optional Payload payload = 3;
+}
+
+message StreamingOutputCallResponse {
+  optional Payload payload = 1;
+}
+
+service TestService {
+  // One request followed by one response.
+  // The server returns the client payload as-is.
+  rpc UnaryCall(SimpleRequest) returns (SimpleResponse);
+
+  // One request followed by a sequence of responses (streamed download).
+  // The server returns the payload with client desired type and sizes.
+  rpc StreamingOutputCall(StreamingOutputCallRequest)
+      returns (stream StreamingOutputCallResponse);
+
+  // A sequence of requests followed by one response (streamed upload).
+  // The server returns the aggregated size of client payload as the result.
+  rpc StreamingInputCall(stream StreamingInputCallRequest)
+      returns (StreamingInputCallResponse);
+
+  // A sequence of requests with each request served by the server immediately.
+  // As one request could lead to multiple responses, this interface
+  // demonstrates the idea of full duplexing.
+  rpc FullDuplexCall(stream StreamingOutputCallRequest)
+      returns (stream StreamingOutputCallResponse);
+
+  // A sequence of requests followed by a sequence of responses.
+  // The server buffers all the client requests and then serves them in order. A
+  // stream of responses are returned to the client when the server starts with
+  // first request.
+  rpc HalfDuplexCall(stream StreamingOutputCallRequest)
+      returns (stream StreamingOutputCallResponse);
+}
diff --git a/src/python/grpcio_test/grpc_test/_adapter/_low_test.py b/src/python/grpcio_test/grpc_test/_adapter/_low_test.py
index 9a8edfad0c..b6583662f3 100644
--- a/src/python/grpcio_test/grpc_test/_adapter/_low_test.py
+++ b/src/python/grpcio_test/grpc_test/_adapter/_low_test.py
@@ -31,11 +31,12 @@ import threading
 import time
 import unittest
 
+from grpc import _grpcio_metadata
 from grpc._adapter import _types
 from grpc._adapter import _low
 
 
-def WaitForEvents(completion_queues, deadline):
+def wait_for_events(completion_queues, deadline):
   """
   Args:
     completion_queues: list of completion queues to wait for events on
@@ -62,6 +63,7 @@ def WaitForEvents(completion_queues, deadline):
     thread.join()
   return results
 
+
 class InsecureServerInsecureClient(unittest.TestCase):
 
   def setUp(self):
@@ -123,16 +125,21 @@ class InsecureServerInsecureClient(unittest.TestCase):
     ], client_call_tag)
     self.assertEquals(_types.CallError.OK, client_start_batch_result)
 
-    client_no_event, request_event, = WaitForEvents([self.client_completion_queue, self.server_completion_queue], time.time() + 2)
+    client_no_event, request_event, = wait_for_events([self.client_completion_queue, self.server_completion_queue], time.time() + 2)
     self.assertEquals(client_no_event, None)
     self.assertEquals(_types.EventType.OP_COMPLETE, request_event.type)
     self.assertIsInstance(request_event.call, _low.Call)
     self.assertIs(server_request_tag, request_event.tag)
     self.assertEquals(1, len(request_event.results))
-    got_initial_metadata = dict(request_event.results[0].initial_metadata)
+    received_initial_metadata = dict(request_event.results[0].initial_metadata)
+    # Check that our metadata were transmitted
     self.assertEquals(
         dict(client_initial_metadata),
-        dict((x, got_initial_metadata[x]) for x in zip(*client_initial_metadata)[0]))
+        dict((x, received_initial_metadata[x]) for x in zip(*client_initial_metadata)[0]))
+    # Check that Python's user agent string is a part of the full user agent
+    # string
+    self.assertIn('Python-gRPC-{}'.format(_grpcio_metadata.__version__),
+                  received_initial_metadata['user-agent'])
     self.assertEquals(METHOD, request_event.call_details.method)
     self.assertEquals(HOST, request_event.call_details.host)
     self.assertLess(abs(DEADLINE - request_event.call_details.deadline), DEADLINE_TOLERANCE)
@@ -150,7 +157,7 @@ class InsecureServerInsecureClient(unittest.TestCase):
     ], server_call_tag)
     self.assertEquals(_types.CallError.OK, server_start_batch_result)
 
-    client_event, server_event, = WaitForEvents([self.client_completion_queue, self.server_completion_queue], time.time() + 1)
+    client_event, server_event, = wait_for_events([self.client_completion_queue, self.server_completion_queue], time.time() + 1)
 
     self.assertEquals(6, len(client_event.results))
     found_client_op_types = set()
diff --git a/src/python/grpcio_test/grpc_test/_links/_transmission_test.py b/src/python/grpcio_test/grpc_test/_links/_transmission_test.py
index 0531fa1d33..9cdc9620f0 100644
--- a/src/python/grpcio_test/grpc_test/_links/_transmission_test.py
+++ b/src/python/grpcio_test/grpc_test/_links/_transmission_test.py
@@ -35,6 +35,7 @@ from grpc._adapter import _intermediary_low
 from grpc._links import invocation
 from grpc._links import service
 from grpc.framework.interfaces.links import links
+from grpc_test import test_common
 from grpc_test._links import _proto_scenarios
 from grpc_test.framework.common import test_constants
 from grpc_test.framework.interfaces.links import test_cases
@@ -94,12 +95,11 @@ class TransmissionTest(test_cases.TransmissionTest, unittest.TestCase):
     return _intermediary_low.Code.OK, 'An exuberant test "details" message!'
 
   def assertMetadataTransmitted(self, original_metadata, transmitted_metadata):
-    # we need to filter out any additional metadata added in transmitted_metadata
-    # since implementations are allowed to add to what is sent (in any position)
-    keys, _ = zip(*original_metadata)
-    self.assertSequenceEqual(
-        original_metadata,
-        [x for x in transmitted_metadata if x[0] in keys])
+    self.assertTrue(
+        test_common.metadata_transmitted(
+            original_metadata, transmitted_metadata),
+        '%s erroneously transmitted as %s' % (
+            original_metadata, transmitted_metadata))
 
 
 class RoundTripTest(unittest.TestCase):
diff --git a/src/python/grpcio_test/grpc_test/test_common.py b/src/python/grpcio_test/grpc_test/test_common.py
new file mode 100644
index 0000000000..f8e1f1e43f
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/test_common.py
@@ -0,0 +1,71 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Common code used throughout tests of gRPC."""
+
+import collections
+
+
+def metadata_transmitted(original_metadata, transmitted_metadata):
+  """Judges whether or not metadata was acceptably transmitted.
+
+  gRPC is allowed to insert key-value pairs into the metadata values given by
+  applications and to reorder key-value pairs with different keys but it is not
+  allowed to alter existing key-value pairs or to reorder key-value pairs with
+  the same key.
+
+  Args:
+    original_metadata: A metadata value used in a test of gRPC.
+    transmitted_metadata: A metadata value corresponding to original_metadata
+      after having been transmitted via gRPC.
+
+  Returns:
+     A boolean indicating whether transmitted_metadata accurately reflects
+      original_metadata after having been transmitted via gRPC.
+  """
+  original = collections.defaultdict(list)
+  for key, value in original_metadata:
+    original[key].append(value)
+  transmitted = collections.defaultdict(list)
+  for key, value in transmitted_metadata:
+    transmitted[key].append(value)
+
+  for key, values in original.iteritems():
+    transmitted_values = transmitted[key]
+    transmitted_iterator = iter(transmitted_values)
+    try:
+      for value in values:
+        while True:
+          transmitted_value = next(transmitted_iterator)
+          if value == transmitted_value:
+            break
+    except StopIteration:
+      return False
+  else:
+    return True
diff --git a/src/python/grpcio_test/setup.py b/src/python/grpcio_test/setup.py
index 925c32720f..a6203cae2d 100644
--- a/src/python/grpcio_test/setup.py
+++ b/src/python/grpcio_test/setup.py
@@ -48,8 +48,13 @@ _PACKAGE_DIRECTORIES = {
 
 _PACKAGE_DATA = {
     'grpc_interop': [
-        'credentials/ca.pem', 'credentials/server1.key',
-        'credentials/server1.pem',]
+        'credentials/ca.pem',
+        'credentials/server1.key',
+        'credentials/server1.pem',
+    ],
+    'grpc_protoc_plugin': [
+        'test.proto',
+    ],
 }
 
 _SETUP_REQUIRES = (
@@ -75,5 +80,5 @@ setuptools.setup(
     package_data=_PACKAGE_DATA,
     install_requires=_INSTALL_REQUIRES + _SETUP_REQUIRES,
     setup_requires=_SETUP_REQUIRES,
-    cmdclass=_COMMAND_CLASS
+    cmdclass=_COMMAND_CLASS,
 )
diff --git a/src/ruby/ext/grpc/rb_channel.c b/src/ruby/ext/grpc/rb_channel.c
index 0cb6fa2f80..a0663607c2 100644
--- a/src/ruby/ext/grpc/rb_channel.c
+++ b/src/ruby/ext/grpc/rb_channel.c
@@ -212,10 +212,10 @@ static VALUE grpc_rb_channel_create_call(VALUE self, VALUE cqueue, VALUE method,
     return Qnil;
   }
 
-  call =
-      grpc_channel_create_call(ch, cq, method_chars, host_chars,
-                               grpc_rb_time_timeval(deadline,
-                                                    /* absolute time */ 0));
+  call = grpc_channel_create_call(ch, NULL, GRPC_PROPAGATE_DEFAULTS, cq,
+                                  method_chars, host_chars,
+                                  grpc_rb_time_timeval(deadline,
+                                                       /* absolute time */ 0));
   if (call == NULL) {
     rb_raise(rb_eRuntimeError, "cannot create call with method %s",
              method_chars);
diff --git a/src/ruby/ext/grpc/rb_server.c b/src/ruby/ext/grpc/rb_server.c
index 375a651d24..79a4ae8757 100644
--- a/src/ruby/ext/grpc/rb_server.c
+++ b/src/ruby/ext/grpc/rb_server.c
@@ -357,7 +357,8 @@ static VALUE grpc_rb_server_add_http2_port(int argc, VALUE *argv, VALUE self) {
     rb_raise(rb_eRuntimeError, "destroyed!");
     return Qnil;
   } else if (rb_creds == Qnil) {
-    recvd_port = grpc_server_add_http2_port(s->wrapped, StringValueCStr(port));
+    recvd_port =
+        grpc_server_add_insecure_http2_port(s->wrapped, StringValueCStr(port));
     if (recvd_port == 0) {
       rb_raise(rb_eRuntimeError,
                "could not add port %s to server, not sure why",