Merge branch 'master' of github.com:grpc/grpc into decompression

# Conflicts: # Makefile # include/grpc++/client_context.h # include/grpc++/server_context.h # src/cpp/client/client_context.cc # src/cpp/server/server_context.cc # vsprojects/Grpc.mak
author: David Garcia Quintas <dgq@google.com> 2015-07-15 14:07:18 -0700
committer: David Garcia Quintas <dgq@google.com> 2015-07-15 14:07:18 -0700
commit: e0d581b6ad1023635598d9de95bd951cd04b0354 (patch)
tree: a0601b1315a1dc7b499998a95adba61322825f3c /src
parent: 658b6087cc07f8706d270ee0e31f28bbf732ec3d (diff)
parent: 3e5d61670e23b040ed47b2df1e4c87ee2cfec4aa (diff)
181 files changed, 8519 insertions, 989 deletions
diff --git a/src/compiler/objective_c_generator.cc b/src/compiler/objective_c_generator.cc
index 79a84b4a7a..2a74a3b340 100644
--- a/src/compiler/objective_c_generator.cc
+++ b/src/compiler/objective_c_generator.cc
@@ -57,13 +57,12 @@ void PrintProtoRpcDeclarationAsPragma(Printer *printer,
   vars["server_stream"] = method->server_streaming() ? "stream " : "";
 
   printer->Print(vars,
-      "#pragma mark $method_name$($client_stream$$request_type$)"
-      " returns ($server_stream$$response_type$)\n\n");
+                 "#pragma mark $method_name$($client_stream$$request_type$)"
+                 " returns ($server_stream$$response_type$)\n\n");
 }
 
-void PrintMethodSignature(Printer *printer,
-                          const MethodDescriptor *method,
-                          const map<string, string>& vars) {
+void PrintMethodSignature(Printer *printer, const MethodDescriptor *method,
+                          const map<string, string> &vars) {
   // TODO(jcanizales): Print method comments.
 
   printer->Print(vars, "- ($return_type$)$method_name$With");
@@ -75,16 +74,17 @@ void PrintMethodSignature(Printer *printer,
 
   // TODO(jcanizales): Put this on a new line and align colons.
   if (method->server_streaming()) {
-    printer->Print(vars, " eventHandler:(void(^)(BOOL done, "
-      "$response_class$ *response, NSError *error))eventHandler");
+    printer->Print(vars,
+                   " eventHandler:(void(^)(BOOL done, "
+                   "$response_class$ *response, NSError *error))eventHandler");
   } else {
-    printer->Print(vars, " handler:(void(^)($response_class$ *response, "
-      "NSError *error))handler");
+    printer->Print(vars,
+                   " handler:(void(^)($response_class$ *response, "
+                   "NSError *error))handler");
   }
 }
 
-void PrintSimpleSignature(Printer *printer,
-                          const MethodDescriptor *method,
+void PrintSimpleSignature(Printer *printer, const MethodDescriptor *method,
                           map<string, string> vars) {
   vars["method_name"] =
       grpc_generator::LowercaseFirstLetter(vars["method_name"]);
@@ -92,8 +92,7 @@ void PrintSimpleSignature(Printer *printer,
   PrintMethodSignature(printer, method, vars);
 }
 
-void PrintAdvancedSignature(Printer *printer,
-                            const MethodDescriptor *method,
+void PrintAdvancedSignature(Printer *printer, const MethodDescriptor *method,
                             map<string, string> vars) {
   vars["method_name"] = "RPCTo" + vars["method_name"];
   vars["return_type"] = "ProtoRPC *";
@@ -101,15 +100,16 @@ void PrintAdvancedSignature(Printer *printer,
 }
 
 inline map<string, string> GetMethodVars(const MethodDescriptor *method) {
-  return {{ "method_name", method->name() },
-          { "request_type", method->input_type()->name() },
-          { "response_type", method->output_type()->name() },
-          { "request_class", ClassName(method->input_type()) },
-          { "response_class", ClassName(method->output_type()) }};
+  map<string, string> res;
+  res["method_name"] = method->name();
+  res["request_type"] = method->input_type()->name();
+  res["response_type"] = method->output_type()->name();
+  res["request_class"] = ClassName(method->input_type());
+  res["response_class"] = ClassName(method->output_type());
+  return res;
 }
 
-void PrintMethodDeclarations(Printer *printer,
-                             const MethodDescriptor *method) {
+void PrintMethodDeclarations(Printer *printer, const MethodDescriptor *method) {
   map<string, string> vars = GetMethodVars(method);
 
   PrintProtoRpcDeclarationAsPragma(printer, method, vars);
@@ -120,8 +120,7 @@ void PrintMethodDeclarations(Printer *printer,
   printer->Print(";\n\n\n");
 }
 
-void PrintSimpleImplementation(Printer *printer,
-                               const MethodDescriptor *method,
+void PrintSimpleImplementation(Printer *printer, const MethodDescriptor *method,
                                map<string, string> vars) {
   printer->Print("{\n");
   printer->Print(vars, "  [[self RPCTo$method_name$With");
@@ -178,7 +177,7 @@ void PrintMethodImplementations(Printer *printer,
   PrintAdvancedImplementation(printer, method, vars);
 }
 
-} // namespace
+}  // namespace
 
 string GetHeader(const ServiceDescriptor *service) {
   string output;
@@ -186,7 +185,7 @@ string GetHeader(const ServiceDescriptor *service) {
     // Scope the output stream so it closes and finalizes output to the string.
     grpc::protobuf::io::StringOutputStream output_stream(&output);
     Printer printer(&output_stream, '$');
-  
+
     printer.Print("@protocol GRXWriteable;\n");
     printer.Print("@protocol GRXWriter;\n\n");
 
@@ -199,12 +198,15 @@ string GetHeader(const ServiceDescriptor *service) {
     }
     printer.Print("@end\n\n");
 
-    printer.Print("// Basic service implementation, over gRPC, that only does"
+    printer.Print(
+        "// Basic service implementation, over gRPC, that only does"
         " marshalling and parsing.\n");
-    printer.Print(vars, "@interface $service_class$ :"
-      " ProtoService<$service_class$>\n");
-    printer.Print("- (instancetype)initWithHost:(NSString *)host"
-      " NS_DESIGNATED_INITIALIZER;\n");
+    printer.Print(vars,
+                  "@interface $service_class$ :"
+                  " ProtoService<$service_class$>\n");
+    printer.Print(
+        "- (instancetype)initWithHost:(NSString *)host"
+        " NS_DESIGNATED_INITIALIZER;\n");
     printer.Print("@end\n");
   }
   return output;
@@ -222,18 +224,20 @@ string GetSource(const ServiceDescriptor *service) {
                                 {"package", service->file()->package()}};
 
     printer.Print(vars,
-        "static NSString *const kPackageName = @\"$package$\";\n");
-    printer.Print(vars,
-        "static NSString *const kServiceName = @\"$service_name$\";\n\n");
+                  "static NSString *const kPackageName = @\"$package$\";\n");
+    printer.Print(
+        vars, "static NSString *const kServiceName = @\"$service_name$\";\n\n");
 
     printer.Print(vars, "@implementation $service_class$\n\n");
-  
+
     printer.Print("// Designated initializer\n");
     printer.Print("- (instancetype)initWithHost:(NSString *)host {\n");
-    printer.Print("  return (self = [super initWithHost:host"
+    printer.Print(
+        "  return (self = [super initWithHost:host"
         " packageName:kPackageName serviceName:kServiceName]);\n");
     printer.Print("}\n\n");
-    printer.Print("// Override superclass initializer to disallow different"
+    printer.Print(
+        "// Override superclass initializer to disallow different"
         " package and service names.\n");
     printer.Print("- (instancetype)initWithHost:(NSString *)host\n");
     printer.Print("                 packageName:(NSString *)packageName\n");
@@ -250,4 +254,4 @@ string GetSource(const ServiceDescriptor *service) {
   return output;
 }
 
-} // namespace grpc_objective_c_generator
+}  // namespace grpc_objective_c_generator
diff --git a/src/core/channel/census_filter.c b/src/core/channel/census_filter.c
index 43ef5fb3ff..d996c3475e 100644
--- a/src/core/channel/census_filter.c
+++ b/src/core/channel/census_filter.c
@@ -151,7 +151,7 @@ static void client_init_call_elem(grpc_call_element* elem,
   call_data* d = elem->call_data;
   GPR_ASSERT(d != NULL);
   init_rpc_stats(&d->stats);
-  d->start_ts = gpr_now();
+  d->start_ts = gpr_now(GPR_CLOCK_REALTIME);
   d->op_id = census_tracing_start_op();
   if (initial_op) client_mutate_op(elem, initial_op);
 }
@@ -169,7 +169,7 @@ static void server_init_call_elem(grpc_call_element* elem,
   call_data* d = elem->call_data;
   GPR_ASSERT(d != NULL);
   init_rpc_stats(&d->stats);
-  d->start_ts = gpr_now();
+  d->start_ts = gpr_now(GPR_CLOCK_REALTIME);
   d->op_id = census_tracing_start_op();
   if (initial_op) server_mutate_op(elem, initial_op);
 }
@@ -177,8 +177,8 @@ static void server_init_call_elem(grpc_call_element* elem,
 static void server_destroy_call_elem(grpc_call_element* elem) {
   call_data* d = elem->call_data;
   GPR_ASSERT(d != NULL);
-  d->stats.elapsed_time_ms =
-      gpr_timespec_to_micros(gpr_time_sub(gpr_now(), d->start_ts));
+  d->stats.elapsed_time_ms = gpr_timespec_to_micros(
+      gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME), d->start_ts));
   census_record_rpc_server_stats(d->op_id, &d->stats);
   census_tracing_end_op(d->op_id);
 }
diff --git a/src/core/client_config/subchannel.c b/src/core/client_config/subchannel.c
index 6cf9062ab0..8cdad1015f 100644
--- a/src/core/client_config/subchannel.c
+++ b/src/core/client_config/subchannel.c
@@ -300,7 +300,7 @@ static void continue_connect(grpc_subchannel *c) {
 }
 
 static void start_connect(grpc_subchannel *c) {
-  gpr_timespec now = gpr_now();
+  gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
   c->next_attempt = now;
   c->backoff_delta = gpr_time_from_seconds(1);
 
@@ -585,7 +585,7 @@ static void subchannel_connected(void *arg, int iomgr_success) {
     c->have_alarm = 1;
     c->next_attempt = gpr_time_add(c->next_attempt, c->backoff_delta);
     c->backoff_delta = gpr_time_add(c->backoff_delta, c->backoff_delta);
-    grpc_alarm_init(&c->alarm, c->next_attempt, on_alarm, c, gpr_now());
+    grpc_alarm_init(&c->alarm, c->next_attempt, on_alarm, c, gpr_now(GPR_CLOCK_REALTIME));
     gpr_mu_unlock(&c->mu);
   }
 }
diff --git a/src/core/iomgr/iocp_windows.c b/src/core/iomgr/iocp_windows.c
index 0c62bfccd5..3d3a193d00 100644
--- a/src/core/iomgr/iocp_windows.c
+++ b/src/core/iomgr/iocp_windows.c
@@ -127,7 +127,6 @@ static void iocp_loop(void *p) {
     grpc_maybe_call_delayed_callbacks(NULL, 1);
     do_iocp_work();
   }
-  gpr_log(GPR_DEBUG, "iocp_loop is done");
 
   gpr_event_set(&g_iocp_done, (void *)1);
 }
diff --git a/src/core/iomgr/iomgr.c b/src/core/iomgr/iomgr.c
index c507e7c26a..cca92d3b32 100644
--- a/src/core/iomgr/iomgr.c
+++ b/src/core/iomgr/iomgr.c
@@ -59,7 +59,7 @@ static void background_callback_executor(void *ignored) {
   while (!g_shutdown) {
     gpr_timespec deadline = gpr_inf_future;
     gpr_timespec short_deadline =
-        gpr_time_add(gpr_now(), gpr_time_from_millis(100));
+        gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_millis(100));
     if (g_cbs_head) {
       grpc_iomgr_closure *closure = g_cbs_head;
       g_cbs_head = closure->next;
@@ -67,7 +67,8 @@ static void background_callback_executor(void *ignored) {
       gpr_mu_unlock(&g_mu);
       closure->cb(closure->cb_arg, closure->success);
       gpr_mu_lock(&g_mu);
-    } else if (grpc_alarm_check(&g_mu, gpr_now(), &deadline)) {
+    } else if (grpc_alarm_check(&g_mu, gpr_now(GPR_CLOCK_REALTIME),
+                                &deadline)) {
     } else {
       gpr_mu_unlock(&g_mu);
       gpr_sleep_until(gpr_time_min(short_deadline, deadline));
@@ -89,7 +90,7 @@ void grpc_iomgr_init(void) {
   gpr_thd_id id;
   gpr_mu_init(&g_mu);
   gpr_cv_init(&g_rcv);
-  grpc_alarm_list_init(gpr_now());
+  grpc_alarm_list_init(gpr_now(GPR_CLOCK_REALTIME));
   g_root_object.next = g_root_object.prev = &g_root_object;
   g_root_object.name = "root";
   grpc_iomgr_platform_init();
@@ -110,21 +111,27 @@ void grpc_iomgr_shutdown(void) {
   grpc_iomgr_object *obj;
   grpc_iomgr_closure *closure;
   gpr_timespec shutdown_deadline =
-      gpr_time_add(gpr_now(), gpr_time_from_seconds(10));
+      gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_seconds(10));
+  gpr_timespec last_warning_time = gpr_now(GPR_CLOCK_REALTIME);
 
   gpr_mu_lock(&g_mu);
   g_shutdown = 1;
   while (g_cbs_head != NULL || g_root_object.next != &g_root_object) {
-    if (g_cbs_head != NULL && g_root_object.next != &g_root_object) {
-      gpr_log(GPR_DEBUG,
-              "Waiting for %d iomgr objects to be destroyed and executing "
-              "final callbacks",
-              count_objects());
-    } else if (g_cbs_head != NULL) {
-      gpr_log(GPR_DEBUG, "Executing final iomgr callbacks");
-    } else {
-      gpr_log(GPR_DEBUG, "Waiting for %d iomgr objects to be destroyed",
-              count_objects());
+    if (gpr_time_cmp(
+            gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME), last_warning_time),
+            gpr_time_from_seconds(1)) >= 0) {
+      if (g_cbs_head != NULL && g_root_object.next != &g_root_object) {
+        gpr_log(GPR_DEBUG,
+                "Waiting for %d iomgr objects to be destroyed and executing "
+                "final callbacks",
+                count_objects());
+      } else if (g_cbs_head != NULL) {
+        gpr_log(GPR_DEBUG, "Executing final iomgr callbacks");
+      } else {
+        gpr_log(GPR_DEBUG, "Waiting for %d iomgr objects to be destroyed",
+                count_objects());
+      }
+      last_warning_time = gpr_now(GPR_CLOCK_REALTIME);
     }
     if (g_cbs_head) {
       do {
@@ -145,9 +152,9 @@ void grpc_iomgr_shutdown(void) {
     if (g_root_object.next != &g_root_object) {
       int timeout = 0;
       gpr_timespec short_deadline =
-          gpr_time_add(gpr_now(), gpr_time_from_millis(100));
+          gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_millis(100));
       while (gpr_cv_wait(&g_rcv, &g_mu, short_deadline) && g_cbs_head == NULL) {
-        if (gpr_time_cmp(gpr_now(), shutdown_deadline) > 0) {
+        if (gpr_time_cmp(gpr_now(GPR_CLOCK_REALTIME), shutdown_deadline) > 0) {
           timeout = 1;
           break;
         }
diff --git a/src/core/iomgr/pollset_multipoller_with_epoll.c b/src/core/iomgr/pollset_multipoller_with_epoll.c
index 1900bbf9e1..3746c8edaf 100644
--- a/src/core/iomgr/pollset_multipoller_with_epoll.c
+++ b/src/core/iomgr/pollset_multipoller_with_epoll.c
@@ -105,10 +105,11 @@ static void multipoll_with_epoll_pollset_maybe_work(
    * here.
    */
 
-  timeout_ms = grpc_poll_deadline_to_millis_timeout(deadline, now);
   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) {
diff --git a/src/core/iomgr/pollset_posix.c b/src/core/iomgr/pollset_posix.c
index 12496440de..85101764d2 100644
--- a/src/core/iomgr/pollset_posix.c
+++ b/src/core/iomgr/pollset_posix.c
@@ -122,7 +122,7 @@ static void finish_shutdown(grpc_pollset *pollset) {
 
 int grpc_pollset_work(grpc_pollset *pollset, gpr_timespec deadline) {
   /* pollset->mu already held */
-  gpr_timespec now = gpr_now();
+  gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
   if (gpr_time_cmp(now, deadline) > 0) {
     return 0;
   }
@@ -187,15 +187,16 @@ void grpc_pollset_destroy(grpc_pollset *pollset) {
   gpr_mu_destroy(&pollset->mu);
 }
 
-int grpc_poll_deadline_to_millis_timeout(gpr_timespec deadline, gpr_timespec now) {
+int grpc_poll_deadline_to_millis_timeout(gpr_timespec deadline,
+                                         gpr_timespec now) {
   gpr_timespec timeout;
   static const int max_spin_polling_us = 10;
   if (gpr_time_cmp(deadline, gpr_inf_future) == 0) {
     return -1;
   }
   if (gpr_time_cmp(
-        deadline, 
-        gpr_time_add(now, gpr_time_from_micros(max_spin_polling_us))) <= 0) {
+          deadline,
+          gpr_time_add(now, gpr_time_from_micros(max_spin_polling_us))) <= 0) {
     return 0;
   }
   timeout = gpr_time_sub(deadline, now);
diff --git a/src/core/iomgr/pollset_windows.c b/src/core/iomgr/pollset_windows.c
index 8d6bc79c96..24226cc980 100644
--- a/src/core/iomgr/pollset_windows.c
+++ b/src/core/iomgr/pollset_windows.c
@@ -70,7 +70,7 @@ void grpc_pollset_destroy(grpc_pollset *pollset) {
 
 int grpc_pollset_work(grpc_pollset *pollset, gpr_timespec deadline) {
   gpr_timespec now;
-  now = gpr_now();
+  now = gpr_now(GPR_CLOCK_REALTIME);
   if (gpr_time_cmp(now, deadline) > 0) {
     return 0 /* GPR_FALSE */;
   }
@@ -86,8 +86,6 @@ int grpc_pollset_work(grpc_pollset *pollset, gpr_timespec deadline) {
   return 1 /* GPR_TRUE */;
 }
 
-void grpc_pollset_kick(grpc_pollset *p) {
-  gpr_cv_signal(&p->cv);
-}
+void grpc_pollset_kick(grpc_pollset *p) { gpr_cv_signal(&p->cv); }
 
 #endif /* GPR_WINSOCK_SOCKET */
diff --git a/src/core/iomgr/socket_windows.c b/src/core/iomgr/socket_windows.c
index fbf3fdc949..f6ddfff0ad 100644
--- a/src/core/iomgr/socket_windows.c
+++ b/src/core/iomgr/socket_windows.c
@@ -37,6 +37,7 @@
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
 
 #include "src/core/iomgr/iocp_windows.h"
 #include "src/core/iomgr/iomgr_internal.h"
@@ -45,11 +46,14 @@
 #include "src/core/iomgr/socket_windows.h"
 
 grpc_winsocket *grpc_winsocket_create(SOCKET socket, const char *name) {
+  char *final_name;
   grpc_winsocket *r = gpr_malloc(sizeof(grpc_winsocket));
   memset(r, 0, sizeof(grpc_winsocket));
   r->socket = socket;
   gpr_mu_init(&r->state_mu);
-  grpc_iomgr_register_object(&r->iomgr_object, name);
+  gpr_asprintf(&final_name, "%s:socket=0x%p", name, r);
+  grpc_iomgr_register_object(&r->iomgr_object, final_name);
+  gpr_free(final_name);
   grpc_iocp_add_socket(r);
   return r;
 }
@@ -58,22 +62,27 @@ grpc_winsocket *grpc_winsocket_create(SOCKET socket, const char *name) {
    operations to abort them. We need to do that this way because of the
    various callsites of that function, which happens to be in various
    mutex hold states, and that'd be unsafe to call them directly. */
-int grpc_winsocket_shutdown(grpc_winsocket *socket) {
+int grpc_winsocket_shutdown(grpc_winsocket *winsocket) {
   int callbacks_set = 0;
-  gpr_mu_lock(&socket->state_mu);
-  if (socket->read_info.cb) {
+  SOCKET socket;
+  gpr_mu_lock(&winsocket->state_mu);
+  socket = winsocket->socket;
+  if (winsocket->read_info.cb) {
     callbacks_set++;
-    grpc_iomgr_closure_init(&socket->shutdown_closure, socket->read_info.cb,
-                            socket->read_info.opaque);
-    grpc_iomgr_add_delayed_callback(&socket->shutdown_closure, 0);
+    grpc_iomgr_closure_init(&winsocket->shutdown_closure,
+                            winsocket->read_info.cb,
+                            winsocket->read_info.opaque);
+    grpc_iomgr_add_delayed_callback(&winsocket->shutdown_closure, 0);
   }
-  if (socket->write_info.cb) {
+  if (winsocket->write_info.cb) {
     callbacks_set++;
-    grpc_iomgr_closure_init(&socket->shutdown_closure, socket->write_info.cb,
-                            socket->write_info.opaque);
-    grpc_iomgr_add_delayed_callback(&socket->shutdown_closure, 0);
+    grpc_iomgr_closure_init(&winsocket->shutdown_closure,
+                            winsocket->write_info.cb,
+                            winsocket->write_info.opaque);
+    grpc_iomgr_add_delayed_callback(&winsocket->shutdown_closure, 0);
   }
-  gpr_mu_unlock(&socket->state_mu);
+  gpr_mu_unlock(&winsocket->state_mu);
+  closesocket(socket);
   return callbacks_set;
 }
 
@@ -84,14 +93,12 @@ int grpc_winsocket_shutdown(grpc_winsocket *socket) {
    an "idle" socket which is neither trying to read or write, we'd start leaking
    both memory and sockets. */
 void grpc_winsocket_orphan(grpc_winsocket *winsocket) {
-  SOCKET socket = winsocket->socket;
   grpc_iomgr_unregister_object(&winsocket->iomgr_object);
   if (winsocket->read_info.outstanding || winsocket->write_info.outstanding) {
     grpc_iocp_socket_orphan(winsocket);
   } else {
     grpc_winsocket_destroy(winsocket);
   }
-  closesocket(socket);
 }
 
 void grpc_winsocket_destroy(grpc_winsocket *winsocket) {
diff --git a/src/core/iomgr/tcp_client_posix.c b/src/core/iomgr/tcp_client_posix.c
index d981aaf028..dc0489e64f 100644
--- a/src/core/iomgr/tcp_client_posix.c
+++ b/src/core/iomgr/tcp_client_posix.c
@@ -114,6 +114,7 @@ static void on_writable(void *acp, int success) {
   void (*cb)(void *arg, grpc_endpoint *tcp) = ac->cb;
   void *cb_arg = ac->cb_arg;
 
+  gpr_mu_lock(&ac->mu);
   if (success) {
     do {
       so_error_size = sizeof(so_error);
@@ -139,6 +140,7 @@ static void on_writable(void *acp, int success) {
            opened too many network connections.  The "easy" fix:
            don't do that! */
         gpr_log(GPR_ERROR, "kernel out of buffers");
+        gpr_mu_unlock(&ac->mu);
         grpc_fd_notify_on_write(ac->fd, &ac->write_closure);
         return;
       } else {
@@ -165,10 +167,11 @@ static void on_writable(void *acp, int success) {
   abort();
 
 finish:
-  gpr_mu_lock(&ac->mu);
-  if (!ep) {
+  if (ep == NULL) {
     grpc_pollset_set_del_fd(ac->interested_parties, ac->fd);
     grpc_fd_orphan(ac->fd, NULL, "tcp_client_orphan");
+  } else {
+    ac->fd = NULL;
   }
   done = (--ac->refs == 0);
   gpr_mu_unlock(&ac->mu);
@@ -250,7 +253,8 @@ void grpc_tcp_client_connect(void (*cb)(void *arg, grpc_endpoint *ep),
   ac->write_closure.cb_arg = ac;
 
   gpr_mu_lock(&ac->mu);
-  grpc_alarm_init(&ac->alarm, deadline, on_alarm, ac, gpr_now());
+  grpc_alarm_init(&ac->alarm, deadline, on_alarm, ac,
+                  gpr_now(GPR_CLOCK_REALTIME));
   grpc_fd_notify_on_write(ac->fd, &ac->write_closure);
   gpr_mu_unlock(&ac->mu);
 
diff --git a/src/core/iomgr/tcp_client_windows.c b/src/core/iomgr/tcp_client_windows.c
index b1a169b519..16741452b9 100644
--- a/src/core/iomgr/tcp_client_windows.c
+++ b/src/core/iomgr/tcp_client_windows.c
@@ -215,7 +215,8 @@ void grpc_tcp_client_connect(void (*cb)(void *arg, grpc_endpoint *tcp),
   ac->refs = 2;
   ac->aborted = 0;
 
-  grpc_alarm_init(&ac->alarm, deadline, on_alarm, ac, gpr_now());
+  grpc_alarm_init(&ac->alarm, deadline, on_alarm, ac,
+                  gpr_now(GPR_CLOCK_REALTIME));
   socket->write_info.outstanding = 1;
   grpc_socket_notify_on_write(socket, on_connect, ac);
   return;
diff --git a/src/core/iomgr/tcp_server_windows.c b/src/core/iomgr/tcp_server_windows.c
index d70968de88..e6e1d1499e 100644
--- a/src/core/iomgr/tcp_server_windows.c
+++ b/src/core/iomgr/tcp_server_windows.c
@@ -108,9 +108,10 @@ void grpc_tcp_server_destroy(grpc_tcp_server *s,
   size_t i;
   gpr_mu_lock(&s->mu);
   /* First, shutdown all fd's. This will queue abortion calls for all
-     of the pending accepts. */
+     of the pending accepts due to the normal operation mechanism. */
   for (i = 0; i < s->nports; i++) {
     server_port *sp = &s->ports[i];
+    sp->shutting_down = 1;
     grpc_winsocket_shutdown(sp->socket);
   }
   /* This happens asynchronously. Wait while that happens. */
@@ -242,63 +243,52 @@ static void on_accept(void *arg, int from_iocp) {
   SOCKET sock = sp->new_socket;
   grpc_winsocket_callback_info *info = &sp->socket->read_info;
   grpc_endpoint *ep = NULL;
-
-  /* The shutdown sequence is done in two parts. This is the second
-     part here, acknowledging the IOCP notification, and doing nothing
-     else, especially not queuing a new accept. */
-  if (sp->shutting_down) {
-    GPR_ASSERT(from_iocp);
-    sp->shutting_down = 0;
-    sp->socket->read_info.outstanding = 0;
-    gpr_mu_lock(&sp->server->mu);
-    if (0 == --sp->server->active_ports) {
-      gpr_cv_broadcast(&sp->server->cv);
-    }
-    gpr_mu_unlock(&sp->server->mu);
-    return;
-  }
-
-  if (from_iocp) {
-    /* The IOCP notified us of a completed operation. Let's grab the results,
-       and act accordingly. */
-    DWORD transfered_bytes = 0;
-    DWORD flags;
-    BOOL wsa_success = WSAGetOverlappedResult(sock, &info->overlapped,
-                                              &transfered_bytes, FALSE, &flags);
-    if (!wsa_success) {
+  DWORD transfered_bytes;
+  DWORD flags;
+  BOOL wsa_success;
+
+  /* The general mechanism for shutting down is to queue abortion calls. While
+     this is necessary in the read/write case, it's useless for the accept
+     case. Let's do nothing. */
+  if (!from_iocp) return;
+
+  /* The IOCP notified us of a completed operation. Let's grab the results,
+      and act accordingly. */
+  transfered_bytes = 0;
+  wsa_success = WSAGetOverlappedResult(sock, &info->overlapped,
+                                            &transfered_bytes, FALSE, &flags);
+  if (!wsa_success) {
+    if (sp->shutting_down) {
+      /* During the shutdown case, we ARE expecting an error. So that's swell,
+         and we can wake up the shutdown thread. */
+      sp->shutting_down = 0;
+      sp->socket->read_info.outstanding = 0;
+      gpr_mu_lock(&sp->server->mu);
+      if (0 == --sp->server->active_ports) {
+        gpr_cv_broadcast(&sp->server->cv);
+      }
+      gpr_mu_unlock(&sp->server->mu);
+      return;
+    } else {
       char *utf8_message = gpr_format_message(WSAGetLastError());
       gpr_log(GPR_ERROR, "on_accept error: %s", utf8_message);
       gpr_free(utf8_message);
       closesocket(sock);
-    } else {
-	  /* TODO(ctiller): add sockaddr address to label */
-      ep = grpc_tcp_create(grpc_winsocket_create(sock, "server"));
     }
   } else {
-    /* If we're not notified from the IOCP, it means we are asked to shutdown.
-       This will initiate that shutdown. Calling closesocket will trigger an
-       IOCP notification, that will call this function a second time, from
-       the IOCP thread. Of course, this only works if the socket was, in fact,
-       listening. If that's not the case, we'd wait indefinitely. That's a bit
-       of a degenerate case, but it can happen if you create a server, but
-       don't start it. So let's support that by recursing once. */
-    sp->shutting_down = 1;
-    sp->new_socket = INVALID_SOCKET;
-    if (sock != INVALID_SOCKET) {
-      closesocket(sock);
-    } else {
-      on_accept(sp, 1);
+    if (!sp->shutting_down) {
+      /* TODO(ctiller): add sockaddr address to label */
+      ep = grpc_tcp_create(grpc_winsocket_create(sock, "server"));
     }
-    return;
   }
 
   /* The only time we should call our callback, is where we successfully
      managed to accept a connection, and created an endpoint. */
   if (ep) sp->server->cb(sp->server->cb_arg, ep);
   /* As we were notified from the IOCP of one and exactly one accept,
-      the former socked we created has now either been destroy or assigned
-      to the new connection. We need to create a new one for the next
-      connection. */
+     the former socked we created has now either been destroy or assigned
+     to the new connection. We need to create a new one for the next
+     connection. */
   start_accept(sp);
 }
 
diff --git a/src/core/iomgr/tcp_windows.c b/src/core/iomgr/tcp_windows.c
index 15759c398a..1bf81a73e0 100644
--- a/src/core/iomgr/tcp_windows.c
+++ b/src/core/iomgr/tcp_windows.c
@@ -148,9 +148,11 @@ static void on_read(void *tcpp, int from_iocp) {
   GPR_ASSERT(tcp->socket->read_info.outstanding);
 
   if (socket->read_info.wsa_error != 0) {
-    char *utf8_message = gpr_format_message(info->wsa_error);
-    gpr_log(GPR_ERROR, "ReadFile overlapped error: %s", utf8_message);
-    gpr_free(utf8_message);
+    if (socket->read_info.wsa_error != WSAECONNRESET) {
+      char *utf8_message = gpr_format_message(info->wsa_error);
+      gpr_log(GPR_ERROR, "ReadFile overlapped error: %s", utf8_message);
+      gpr_free(utf8_message);
+    }
     status = GRPC_ENDPOINT_CB_ERROR;
   } else {
     if (info->bytes_transfered != 0) {
@@ -259,9 +261,11 @@ static void on_write(void *tcpp, int from_iocp) {
   GPR_ASSERT(tcp->socket->write_info.outstanding);
 
   if (info->wsa_error != 0) {
-    char *utf8_message = gpr_format_message(info->wsa_error);
-    gpr_log(GPR_ERROR, "WSASend overlapped error: %s", utf8_message);
-    gpr_free(utf8_message);
+    if (info->wsa_error != WSAECONNRESET) {
+      char *utf8_message = gpr_format_message(info->wsa_error);
+      gpr_log(GPR_ERROR, "WSASend overlapped error: %s", utf8_message);
+      gpr_free(utf8_message);
+    }
     status = GRPC_ENDPOINT_CB_ERROR;
   } else {
     GPR_ASSERT(info->bytes_transfered == tcp->write_slices.length);
@@ -325,9 +329,11 @@ static grpc_endpoint_write_status win_write(grpc_endpoint *ep,
       ret = GRPC_ENDPOINT_WRITE_DONE;
       GPR_ASSERT(bytes_sent == tcp->write_slices.length);
     } else {
-      char *utf8_message = gpr_format_message(info->wsa_error);
-      gpr_log(GPR_ERROR, "WSASend error: %s", utf8_message);
-      gpr_free(utf8_message);
+      if (socket->read_info.wsa_error != WSAECONNRESET) {
+        char *utf8_message = gpr_format_message(info->wsa_error);
+        gpr_log(GPR_ERROR, "WSASend error: %s", utf8_message);
+        gpr_free(utf8_message);
+      }
     }
     if (allocated) gpr_free(allocated);
     gpr_slice_buffer_reset_and_unref(&tcp->write_slices);
diff --git a/src/core/profiling/timers_preciseclock.h b/src/core/profiling/timers_preciseclock.h
index 163d52b797..5c251b47e6 100644
--- a/src/core/profiling/timers_preciseclock.h
+++ b/src/core/profiling/timers_preciseclock.h
@@ -82,7 +82,7 @@ struct grpc_precise_clock {
   gpr_timespec clock;
 };
 static void grpc_precise_clock_now(grpc_precise_clock* clk) {
-  clk->clock = gpr_now();
+  clk->clock = gpr_now(GPR_CLOCK_REALTIME);
 }
 #define GRPC_PRECISE_CLOCK_FORMAT "%ld.%09d"
 #define GRPC_PRECISE_CLOCK_PRINTF_ARGS(clk) \
diff --git a/src/core/security/client_auth_filter.c b/src/core/security/client_auth_filter.c
index 16f2abe04b..9e49a807f1 100644
--- a/src/core/security/client_auth_filter.c
+++ b/src/core/security/client_auth_filter.c
@@ -61,6 +61,7 @@ typedef struct {
   grpc_transport_stream_op op;
   size_t op_md_idx;
   int sent_initial_metadata;
+  gpr_uint8 security_context_set;
   grpc_linked_mdelem md_links[MAX_CREDENTIALS_METADATA_COUNT];
 } call_data;
 
@@ -199,8 +200,22 @@ static void auth_start_transport_op(grpc_call_element *elem,
   channel_data *chand = elem->channel_data;
   grpc_linked_mdelem *l;
   size_t i;
+  grpc_client_security_context* sec_ctx = NULL;
 
-  /* TODO(jboeuf): write the call auth context. */
+  if (calld->security_context_set == 0) {
+    calld->security_context_set = 1;
+    GPR_ASSERT(op->context);
+    if (op->context[GRPC_CONTEXT_SECURITY].value == NULL) {
+      op->context[GRPC_CONTEXT_SECURITY].value =
+          grpc_client_security_context_create();
+      op->context[GRPC_CONTEXT_SECURITY].destroy =
+          grpc_client_security_context_destroy;
+    }
+    sec_ctx = op->context[GRPC_CONTEXT_SECURITY].value;
+    GRPC_AUTH_CONTEXT_UNREF(sec_ctx->auth_context, "client auth filter");
+    sec_ctx->auth_context = GRPC_AUTH_CONTEXT_REF(
+        chand->security_connector->base.auth_context, "client_auth_filter");
+  }
 
   if (op->bind_pollset) {
     calld->pollset = op->bind_pollset;
@@ -263,6 +278,7 @@ static void init_call_elem(grpc_call_element *elem,
   calld->method = NULL;
   calld->pollset = NULL;
   calld->sent_initial_metadata = 0;
+  calld->security_context_set = 0;
 
   GPR_ASSERT(!initial_op || !initial_op->send_ops);
 }
diff --git a/src/core/security/credentials.c b/src/core/security/credentials.c
index 8d694c2f79..230f0dfb85 100644
--- a/src/core/security/credentials.c
+++ b/src/core/security/credentials.c
@@ -41,7 +41,6 @@
 #include "src/core/json/json.h"
 #include "src/core/httpcli/httpcli.h"
 #include "src/core/iomgr/iomgr.h"
-#include "src/core/security/json_token.h"
 #include "src/core/support/string.h"
 
 #include <grpc/support/alloc.h>
@@ -52,12 +51,12 @@
 
 /* -- Common. -- */
 
-typedef struct {
+struct grpc_credentials_metadata_request {
   grpc_credentials *creds;
   grpc_credentials_metadata_cb cb;
   grpc_iomgr_closure *on_simulated_token_fetch_done_closure;
   void *user_data;
-} grpc_credentials_metadata_request;
+};
 
 static grpc_credentials_metadata_request *
 grpc_credentials_metadata_request_create(grpc_credentials *creds,
@@ -152,16 +151,6 @@ grpc_security_status grpc_server_credentials_create_security_connector(
 
 /* -- Ssl credentials. -- */
 
-typedef struct {
-  grpc_credentials base;
-  grpc_ssl_config config;
-} grpc_ssl_credentials;
-
-typedef struct {
-  grpc_server_credentials base;
-  grpc_ssl_server_config config;
-} grpc_ssl_server_credentials;
-
 static void ssl_destroy(grpc_credentials *creds) {
   grpc_ssl_credentials *c = (grpc_ssl_credentials *)creds;
   if (c->config.pem_root_certs != NULL) gpr_free(c->config.pem_root_certs);
@@ -326,22 +315,6 @@ grpc_server_credentials *grpc_ssl_server_credentials_create(
 
 /* -- Jwt credentials -- */
 
-typedef struct {
-  grpc_credentials base;
-
-  /* Have a simple cache for now with just 1 entry. We could have a map based on
-     the service_url for a more sophisticated one. */
-  gpr_mu cache_mu;
-  struct {
-    grpc_credentials_md_store *jwt_md;
-    char *service_url;
-    gpr_timespec jwt_expiration;
-  } cached;
-
-  grpc_auth_json_key key;
-  gpr_timespec jwt_lifetime;
-} grpc_jwt_credentials;
-
 static void jwt_reset_cache(grpc_jwt_credentials *c) {
   if (c->cached.jwt_md != NULL) {
     grpc_credentials_md_store_unref(c->cached.jwt_md);
@@ -384,7 +357,8 @@ static void jwt_get_request_metadata(grpc_credentials *creds,
     if (c->cached.service_url != NULL &&
         strcmp(c->cached.service_url, service_url) == 0 &&
         c->cached.jwt_md != NULL &&
-        (gpr_time_cmp(gpr_time_sub(c->cached.jwt_expiration, gpr_now()),
+        (gpr_time_cmp(gpr_time_sub(c->cached.jwt_expiration,
+                                   gpr_now(GPR_CLOCK_REALTIME)),
                       refresh_threshold) > 0)) {
       jwt_md = grpc_credentials_md_store_ref(c->cached.jwt_md);
     }
@@ -401,7 +375,8 @@ static void jwt_get_request_metadata(grpc_credentials *creds,
       char *md_value;
       gpr_asprintf(&md_value, "Bearer %s", jwt);
       gpr_free(jwt);
-      c->cached.jwt_expiration = gpr_time_add(gpr_now(), c->jwt_lifetime);
+      c->cached.jwt_expiration =
+          gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), c->jwt_lifetime);
       c->cached.service_url = gpr_strdup(service_url);
       c->cached.jwt_md = grpc_credentials_md_store_create(1);
       grpc_credentials_md_store_add_cstrings(
@@ -424,10 +399,9 @@ static grpc_credentials_vtable jwt_vtable = {
     jwt_destroy, jwt_has_request_metadata, jwt_has_request_metadata_only,
     jwt_get_request_metadata, NULL};
 
-grpc_credentials *grpc_jwt_credentials_create(const char *json_key,
-                                              gpr_timespec token_lifetime) {
+grpc_credentials *grpc_jwt_credentials_create_from_auth_json_key(
+    grpc_auth_json_key key, gpr_timespec token_lifetime) {
   grpc_jwt_credentials *c;
-  grpc_auth_json_key key = grpc_auth_json_key_create_from_string(json_key);
   if (!grpc_auth_json_key_is_valid(&key)) {
     gpr_log(GPR_ERROR, "Invalid input for jwt credentials creation");
     return NULL;
@@ -444,25 +418,13 @@ grpc_credentials *grpc_jwt_credentials_create(const char *json_key,
   return &c->base;
 }
 
-/* -- Oauth2TokenFetcher credentials -- */
-
-/* This object is a base for credentials that need to acquire an oauth2 token
-   from an http service. */
-
-typedef void (*grpc_fetch_oauth2_func)(grpc_credentials_metadata_request *req,
-                                       grpc_httpcli_context *http_context,
-                                       grpc_pollset *pollset,
-                                       grpc_httpcli_response_cb response_cb,
-                                       gpr_timespec deadline);
+grpc_credentials *grpc_jwt_credentials_create(const char *json_key,
+                                              gpr_timespec token_lifetime) {
+  return grpc_jwt_credentials_create_from_auth_json_key(
+      grpc_auth_json_key_create_from_string(json_key), token_lifetime);
+}
 
-typedef struct {
-  grpc_credentials base;
-  gpr_mu mu;
-  grpc_credentials_md_store *access_token_md;
-  gpr_timespec token_expiration;
-  grpc_httpcli_context httpcli_context;
-  grpc_fetch_oauth2_func fetch_func;
-} grpc_oauth2_token_fetcher_credentials;
+/* -- Oauth2TokenFetcher credentials -- */
 
 static void oauth2_token_fetcher_destroy(grpc_credentials *creds) {
   grpc_oauth2_token_fetcher_credentials *c =
@@ -585,7 +547,8 @@ static void on_oauth2_token_fetcher_http_response(
   status = grpc_oauth2_token_fetcher_credentials_parse_server_response(
       response, &c->access_token_md, &token_lifetime);
   if (status == GRPC_CREDENTIALS_OK) {
-    c->token_expiration = gpr_time_add(gpr_now(), token_lifetime);
+    c->token_expiration =
+        gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), token_lifetime);
     r->cb(r->user_data, c->access_token_md->entries,
           c->access_token_md->num_entries, status);
   } else {
@@ -607,8 +570,9 @@ static void oauth2_token_fetcher_get_request_metadata(
   {
     gpr_mu_lock(&c->mu);
     if (c->access_token_md != NULL &&
-        (gpr_time_cmp(gpr_time_sub(c->token_expiration, gpr_now()),
-                      refresh_threshold) > 0)) {
+        (gpr_time_cmp(
+             gpr_time_sub(c->token_expiration, gpr_now(GPR_CLOCK_REALTIME)),
+             refresh_threshold) > 0)) {
       cached_access_token_md =
           grpc_credentials_md_store_ref(c->access_token_md);
     }
@@ -622,7 +586,7 @@ static void oauth2_token_fetcher_get_request_metadata(
     c->fetch_func(
         grpc_credentials_metadata_request_create(creds, cb, user_data),
         &c->httpcli_context, pollset, on_oauth2_token_fetcher_http_response,
-        gpr_time_add(gpr_now(), refresh_threshold));
+        gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), refresh_threshold));
   }
 }
 
@@ -669,13 +633,6 @@ grpc_credentials *grpc_compute_engine_credentials_create(void) {
 
 /* -- ServiceAccount credentials. -- */
 
-typedef struct {
-  grpc_oauth2_token_fetcher_credentials base;
-  grpc_auth_json_key key;
-  char *scope;
-  gpr_timespec token_lifetime;
-} grpc_service_account_credentials;
-
 static void service_account_destroy(grpc_credentials *creds) {
   grpc_service_account_credentials *c =
       (grpc_service_account_credentials *)creds;
@@ -746,11 +703,6 @@ grpc_credentials *grpc_service_account_credentials_create(
 
 /* -- RefreshToken credentials. -- */
 
-typedef struct {
-  grpc_oauth2_token_fetcher_credentials base;
-  grpc_auth_refresh_token refresh_token;
-} grpc_refresh_token_credentials;
-
 static void refresh_token_destroy(grpc_credentials *creds) {
   grpc_refresh_token_credentials *c = (grpc_refresh_token_credentials *)creds;
   grpc_auth_refresh_token_destruct(&c->refresh_token);
@@ -786,12 +738,9 @@ static void refresh_token_fetch_oauth2(
   gpr_free(body);
 }
 
-grpc_credentials *grpc_refresh_token_credentials_create(
-    const char *json_refresh_token) {
+grpc_credentials *grpc_refresh_token_credentials_create_from_auth_refresh_token(
+    grpc_auth_refresh_token refresh_token) {
   grpc_refresh_token_credentials *c;
-  grpc_auth_refresh_token refresh_token =
-      grpc_auth_refresh_token_create_from_string(json_refresh_token);
-
   if (!grpc_auth_refresh_token_is_valid(&refresh_token)) {
     gpr_log(GPR_ERROR, "Invalid input for refresh token credentials creation");
     return NULL;
@@ -804,13 +753,13 @@ grpc_credentials *grpc_refresh_token_credentials_create(
   return &c->base.base;
 }
 
-/* -- Fake Oauth2 credentials. -- */
+grpc_credentials *grpc_refresh_token_credentials_create(
+    const char *json_refresh_token) {
+  return grpc_refresh_token_credentials_create_from_auth_refresh_token(
+      grpc_auth_refresh_token_create_from_string(json_refresh_token));
+}
 
-typedef struct {
-  grpc_credentials base;
-  grpc_credentials_md_store *access_token_md;
-  int is_async;
-} grpc_fake_oauth2_credentials;
+/* -- Fake Oauth2 credentials. -- */
 
 static void fake_oauth2_destroy(grpc_credentials *creds) {
   grpc_fake_oauth2_credentials *c = (grpc_fake_oauth2_credentials *)creds;
@@ -877,11 +826,6 @@ grpc_credentials *grpc_fake_oauth2_credentials_create(
 
 /* -- Oauth2 Access Token credentials. -- */
 
-typedef struct {
-  grpc_credentials base;
-  grpc_credentials_md_store *access_token_md;
-} grpc_access_token_credentials;
-
 static void access_token_destroy(grpc_credentials *creds) {
   grpc_access_token_credentials *c = (grpc_access_token_credentials *)creds;
   grpc_credentials_md_store_unref(c->access_token_md);
@@ -997,12 +941,6 @@ grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
 /* -- Composite credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
-  grpc_credentials_array inner;
-  grpc_credentials *connector_creds;
-} grpc_composite_credentials;
-
-typedef struct {
   grpc_composite_credentials *composite_creds;
   size_t creds_index;
   grpc_credentials_md_store *md_elems;
@@ -1232,11 +1170,6 @@ grpc_credentials *grpc_credentials_contains_type(
 
 /* -- IAM credentials. -- */
 
-typedef struct {
-  grpc_credentials base;
-  grpc_credentials_md_store *iam_md;
-} grpc_iam_credentials;
-
 static void iam_destroy(grpc_credentials *creds) {
   grpc_iam_credentials *c = (grpc_iam_credentials *)creds;
   grpc_credentials_md_store_unref(c->iam_md);
diff --git a/src/core/security/credentials.h b/src/core/security/credentials.h
index 75af73a0c6..d988901cf7 100644
--- a/src/core/security/credentials.h
+++ b/src/core/security/credentials.h
@@ -39,6 +39,8 @@
 #include <grpc/grpc_security.h>
 #include <grpc/support/sync.h>
 
+#include "src/core/httpcli/httpcli.h"
+#include "src/core/security/json_token.h"
 #include "src/core/security/security_connector.h"
 
 struct grpc_httpcli_response;
@@ -178,11 +180,22 @@ grpc_credentials_status
 grpc_oauth2_token_fetcher_credentials_parse_server_response(
     const struct grpc_httpcli_response *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);
 
+/* Private constructor for jwt credentials from an already parsed json key.
+   Takes ownership of the key. */
+grpc_credentials *grpc_jwt_credentials_create_from_auth_json_key(
+    grpc_auth_json_key key, gpr_timespec token_lifetime);
+
+/* Private constructor for refresh token credentials from an already parsed
+   refresh token. Takes ownership of the refresh token. */
+grpc_credentials *grpc_refresh_token_credentials_create_from_auth_refresh_token(
+    grpc_auth_refresh_token token);
+
 /* --- grpc_server_credentials. --- */
 
 typedef struct {
@@ -199,4 +212,103 @@ struct grpc_server_credentials {
 grpc_security_status grpc_server_credentials_create_security_connector(
     grpc_server_credentials *creds, grpc_security_connector **sc);
 
+/* -- Ssl credentials. -- */
+
+typedef struct {
+  grpc_credentials base;
+  grpc_ssl_config config;
+} grpc_ssl_credentials;
+
+typedef struct {
+  grpc_server_credentials base;
+  grpc_ssl_server_config config;
+} grpc_ssl_server_credentials;
+
+/* -- Jwt credentials -- */
+
+typedef struct {
+  grpc_credentials base;
+
+  /* Have a simple cache for now with just 1 entry. We could have a map based on
+     the service_url for a more sophisticated one. */
+  gpr_mu cache_mu;
+  struct {
+    grpc_credentials_md_store *jwt_md;
+    char *service_url;
+    gpr_timespec jwt_expiration;
+  } cached;
+
+  grpc_auth_json_key key;
+  gpr_timespec jwt_lifetime;
+} grpc_jwt_credentials;
+
+/* -- Oauth2TokenFetcher credentials --
+
+   This object is a base for credentials that need to acquire an oauth2 token
+   from an http service. */
+
+typedef struct grpc_credentials_metadata_request
+    grpc_credentials_metadata_request;
+
+typedef void (*grpc_fetch_oauth2_func)(grpc_credentials_metadata_request *req,
+                                       grpc_httpcli_context *http_context,
+                                       grpc_pollset *pollset,
+                                       grpc_httpcli_response_cb response_cb,
+                                       gpr_timespec deadline);
+
+typedef struct {
+  grpc_credentials base;
+  gpr_mu mu;
+  grpc_credentials_md_store *access_token_md;
+  gpr_timespec token_expiration;
+  grpc_httpcli_context httpcli_context;
+  grpc_fetch_oauth2_func fetch_func;
+} grpc_oauth2_token_fetcher_credentials;
+
+/* -- ServiceAccount credentials. -- */
+
+typedef struct {
+  grpc_oauth2_token_fetcher_credentials base;
+  grpc_auth_json_key key;
+  char *scope;
+  gpr_timespec token_lifetime;
+} grpc_service_account_credentials;
+
+/* -- RefreshToken credentials. -- */
+
+typedef struct {
+  grpc_oauth2_token_fetcher_credentials base;
+  grpc_auth_refresh_token refresh_token;
+} grpc_refresh_token_credentials;
+
+/* -- Oauth2 Access Token credentials. -- */
+
+typedef struct {
+  grpc_credentials base;
+  grpc_credentials_md_store *access_token_md;
+} grpc_access_token_credentials;
+
+/* -- Fake Oauth2 credentials. -- */
+
+typedef struct {
+  grpc_credentials base;
+  grpc_credentials_md_store *access_token_md;
+  int is_async;
+} grpc_fake_oauth2_credentials;
+
+/* -- IAM credentials. -- */
+
+typedef struct {
+  grpc_credentials base;
+  grpc_credentials_md_store *iam_md;
+} grpc_iam_credentials;
+
+/* -- Composite credentials. -- */
+
+typedef struct {
+  grpc_credentials base;
+  grpc_credentials_array inner;
+  grpc_credentials *connector_creds;
+} grpc_composite_credentials;
+
 #endif /* GRPC_INTERNAL_CORE_SECURITY_CREDENTIALS_H */
diff --git a/src/core/security/google_default_credentials.c b/src/core/security/google_default_credentials.c
index 5822ce6337..f622deff42 100644
--- a/src/core/security/google_default_credentials.c
+++ b/src/core/security/google_default_credentials.c
@@ -46,7 +46,6 @@
 /* -- Constants. -- */
 
 #define GRPC_COMPUTE_ENGINE_DETECTION_HOST "metadata.google.internal"
-#define GRPC_GOOGLE_CREDENTIALS_ENV_VAR "GOOGLE_APPLICATION_CREDENTIALS"
 
 /* -- Default credentials. -- */
 
@@ -104,9 +103,10 @@ static int is_stack_running_on_compute_engine(void) {
 
   grpc_httpcli_context_init(&context);
 
-  grpc_httpcli_get(&context, &detector.pollset, &request,
-                   gpr_time_add(gpr_now(), max_detection_delay),
-                   on_compute_engine_detection_http_response, &detector);
+  grpc_httpcli_get(
+      &context, &detector.pollset, &request,
+      gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), max_detection_delay),
+      on_compute_engine_detection_http_response, &detector);
 
   /* Block until we get the response. This is not ideal but this should only be
      called once for the lifetime of the process by the default credentials. */
@@ -123,36 +123,40 @@ static int is_stack_running_on_compute_engine(void) {
 }
 
 /* Takes ownership of creds_path if not NULL. */
-static grpc_credentials *create_jwt_creds_from_path(char *creds_path) {
+static grpc_credentials *create_default_creds_from_path(char *creds_path) {
+  grpc_json *json = NULL;
+  grpc_auth_json_key key;
+  grpc_auth_refresh_token token;
   grpc_credentials *result = NULL;
-  gpr_slice creds_data;
+  gpr_slice creds_data = gpr_empty_slice();
   int file_ok = 0;
-  if (creds_path == NULL) return NULL;
-  creds_data = gpr_load_file(creds_path, 1, &file_ok);
-  gpr_free(creds_path);
-  if (file_ok) {
-    result = grpc_jwt_credentials_create(
-        (const char *)GPR_SLICE_START_PTR(creds_data),
-        grpc_max_auth_token_lifetime);
-    gpr_slice_unref(creds_data);
+  if (creds_path == NULL) goto end;
+  creds_data = gpr_load_file(creds_path, 0, &file_ok);
+  if (!file_ok) goto end;
+  json = grpc_json_parse_string_with_len(
+      (char *)GPR_SLICE_START_PTR(creds_data), GPR_SLICE_LENGTH(creds_data));
+  if (json == NULL) goto end;
+
+  /* First, try an auth json key. */
+  key = grpc_auth_json_key_create_from_json(json);
+  if (grpc_auth_json_key_is_valid(&key)) {
+    result = grpc_jwt_credentials_create_from_auth_json_key(
+        key, grpc_max_auth_token_lifetime);
+    goto end;
   }
-  return result;
-}
 
-/* Takes ownership of creds_path if not NULL. */
-static grpc_credentials *create_refresh_token_creds_from_path(
-    char *creds_path) {
-  grpc_credentials *result = NULL;
-  gpr_slice creds_data;
-  int file_ok = 0;
-  if (creds_path == NULL) return NULL;
-  creds_data = gpr_load_file(creds_path, 1, &file_ok);
-  gpr_free(creds_path);
-  if (file_ok) {
-    result = grpc_refresh_token_credentials_create(
-        (const char *)GPR_SLICE_START_PTR(creds_data));
-    gpr_slice_unref(creds_data);
+  /* Then try a refresh token if the auth json key was invalid. */
+  token = grpc_auth_refresh_token_create_from_json(json);
+  if (grpc_auth_refresh_token_is_valid(&token)) {
+    result =
+        grpc_refresh_token_credentials_create_from_auth_refresh_token(token);
+    goto end;
   }
+
+end:
+  if (creds_path != NULL) gpr_free(creds_path);
+  gpr_slice_unref(creds_data);
+  if (json != NULL) grpc_json_destroy(json);
   return result;
 }
 
@@ -170,12 +174,12 @@ grpc_credentials *grpc_google_default_credentials_create(void) {
   }
 
   /* First, try the environment variable. */
-  result =
-      create_jwt_creds_from_path(gpr_getenv(GRPC_GOOGLE_CREDENTIALS_ENV_VAR));
+  result = create_default_creds_from_path(
+      gpr_getenv(GRPC_GOOGLE_CREDENTIALS_ENV_VAR));
   if (result != NULL) goto end;
 
   /* Then the well-known file. */
-  result = create_refresh_token_creds_from_path(
+  result = create_default_creds_from_path(
       grpc_get_well_known_google_credentials_file_path());
   if (result != NULL) goto end;
 
@@ -193,11 +197,24 @@ end:
   if (!serving_cached_credentials && result != NULL) {
     /* Blend with default ssl credentials and add a global reference so that it
        can be cached and re-served. */
-    result = grpc_composite_credentials_create(
-        grpc_ssl_credentials_create(NULL, NULL), result);
-    GPR_ASSERT(result != NULL);
-    default_credentials = grpc_credentials_ref(result);
+    grpc_credentials *ssl_creds = grpc_ssl_credentials_create(NULL, NULL);
+    default_credentials = grpc_credentials_ref(grpc_composite_credentials_create(
+        ssl_creds, result));
+    GPR_ASSERT(default_credentials != NULL);
+    grpc_credentials_unref(ssl_creds);
+    grpc_credentials_unref(result);
+    result = default_credentials;
   }
   gpr_mu_unlock(&g_mu);
   return result;
 }
+
+void grpc_flush_cached_google_default_credentials(void) {
+  gpr_once_init(&g_once, init_default_credentials);
+  gpr_mu_lock(&g_mu);
+  if (default_credentials != NULL) {
+    grpc_credentials_unref(default_credentials);
+    default_credentials = NULL;
+  }
+  gpr_mu_unlock(&g_mu);
+}
diff --git a/src/core/security/json_token.c b/src/core/security/json_token.c
index 6116f1d767..9b1ea255ae 100644
--- a/src/core/security/json_token.c
+++ b/src/core/security/json_token.c
@@ -46,17 +46,11 @@
 #include <openssl/evp.h>
 #include <openssl/pem.h>
 
-#include "src/core/json/json.h"
-
 /* --- Constants. --- */
 
 /* 1 hour max. */
 const gpr_timespec grpc_max_auth_token_lifetime = {3600, 0};
 
-#define GRPC_AUTH_JSON_TYPE_INVALID "invalid"
-#define GRPC_AUTH_JSON_TYPE_SERVICE_ACCOUNT "service_account"
-#define GRPC_AUTH_JSON_TYPE_AUTHORIZED_USER "authorized_user"
-
 #define GRPC_JWT_RSA_SHA256_ALGORITHM "RS256"
 #define GRPC_JWT_TYPE "JWT"
 
@@ -66,7 +60,7 @@ static grpc_jwt_encode_and_sign_override g_jwt_encode_and_sign_override = NULL;
 
 /* --- grpc_auth_json_key. --- */
 
-static const char *json_get_string_property(grpc_json *json,
+static const char *json_get_string_property(const grpc_json *json,
                                             const char *prop_name) {
   grpc_json *child;
   for (child = json->child; child != NULL; child = child->next) {
@@ -79,7 +73,8 @@ static const char *json_get_string_property(grpc_json *json,
   return child->value;
 }
 
-static int set_json_key_string_property(grpc_json *json, const char *prop_name,
+static int set_json_key_string_property(const grpc_json *json,
+                                        const char *prop_name,
                                         char **json_key_field) {
   const char *prop_value = json_get_string_property(json, prop_name);
   if (prop_value == NULL) return 0;
@@ -92,11 +87,8 @@ int grpc_auth_json_key_is_valid(const grpc_auth_json_key *json_key) {
          strcmp(json_key->type, GRPC_AUTH_JSON_TYPE_INVALID);
 }
 
-grpc_auth_json_key grpc_auth_json_key_create_from_string(
-    const char *json_string) {
+grpc_auth_json_key grpc_auth_json_key_create_from_json(const grpc_json *json) {
   grpc_auth_json_key result;
-  char *scratchpad = gpr_strdup(json_string);
-  grpc_json *json = grpc_json_parse_string(scratchpad);
   BIO *bio = NULL;
   const char *prop_value;
   int success = 0;
@@ -104,7 +96,7 @@ grpc_auth_json_key grpc_auth_json_key_create_from_string(
   memset(&result, 0, sizeof(grpc_auth_json_key));
   result.type = GRPC_AUTH_JSON_TYPE_INVALID;
   if (json == NULL) {
-    gpr_log(GPR_ERROR, "Invalid json string %s", json_string);
+    gpr_log(GPR_ERROR, "Invalid json.");
     goto end;
   }
 
@@ -142,8 +134,16 @@ grpc_auth_json_key grpc_auth_json_key_create_from_string(
 
 end:
   if (bio != NULL) BIO_free(bio);
-  if (json != NULL) grpc_json_destroy(json);
   if (!success) grpc_auth_json_key_destruct(&result);
+  return result;
+}
+
+grpc_auth_json_key grpc_auth_json_key_create_from_string(
+    const char *json_string) {
+  char *scratchpad = gpr_strdup(json_string);
+  grpc_json *json = grpc_json_parse_string(scratchpad);
+  grpc_auth_json_key result = grpc_auth_json_key_create_from_json(json);
+  if (json != NULL) grpc_json_destroy(json);
   gpr_free(scratchpad);
   return result;
 }
@@ -207,7 +207,7 @@ static char *encoded_jwt_claim(const grpc_auth_json_key *json_key,
   grpc_json *child = NULL;
   char *json_str = NULL;
   char *result = NULL;
-  gpr_timespec now = gpr_now();
+  gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
   gpr_timespec expiration = gpr_time_add(now, token_lifetime);
   char now_str[GPR_LTOA_MIN_BUFSIZE];
   char expiration_str[GPR_LTOA_MIN_BUFSIZE];
@@ -218,8 +218,8 @@ static char *encoded_jwt_claim(const grpc_auth_json_key *json_key,
   gpr_ltoa(now.tv_sec, now_str);
   gpr_ltoa(expiration.tv_sec, expiration_str);
 
-  child = create_child(NULL, json, "iss", json_key->client_email,
-                       GRPC_JSON_STRING);
+  child =
+      create_child(NULL, json, "iss", json_key->client_email, GRPC_JSON_STRING);
   if (scope != NULL) {
     child = create_child(child, json, "scope", scope, GRPC_JSON_STRING);
   } else {
@@ -342,18 +342,16 @@ int grpc_auth_refresh_token_is_valid(
          strcmp(refresh_token->type, GRPC_AUTH_JSON_TYPE_INVALID);
 }
 
-grpc_auth_refresh_token grpc_auth_refresh_token_create_from_string(
-    const char *json_string) {
+grpc_auth_refresh_token grpc_auth_refresh_token_create_from_json(
+    const grpc_json *json) {
   grpc_auth_refresh_token result;
-  char *scratchpad = gpr_strdup(json_string);
-  grpc_json *json = grpc_json_parse_string(scratchpad);
   const char *prop_value;
   int success = 0;
 
   memset(&result, 0, sizeof(grpc_auth_refresh_token));
   result.type = GRPC_AUTH_JSON_TYPE_INVALID;
   if (json == NULL) {
-    gpr_log(GPR_ERROR, "Invalid json string %s", json_string);
+    gpr_log(GPR_ERROR, "Invalid json.");
     goto end;
   }
 
@@ -374,8 +372,17 @@ grpc_auth_refresh_token grpc_auth_refresh_token_create_from_string(
   success = 1;
 
 end:
-  if (json != NULL) grpc_json_destroy(json);
   if (!success) grpc_auth_refresh_token_destruct(&result);
+  return result;
+}
+
+grpc_auth_refresh_token grpc_auth_refresh_token_create_from_string(
+    const char *json_string) {
+  char *scratchpad = gpr_strdup(json_string);
+  grpc_json *json = grpc_json_parse_string(scratchpad);
+  grpc_auth_refresh_token result =
+      grpc_auth_refresh_token_create_from_json(json);
+  if (json != NULL) grpc_json_destroy(json);
   gpr_free(scratchpad);
   return result;
 }
@@ -396,4 +403,3 @@ void grpc_auth_refresh_token_destruct(grpc_auth_refresh_token *refresh_token) {
     refresh_token->refresh_token = NULL;
   }
 }
-
diff --git a/src/core/security/json_token.h b/src/core/security/json_token.h
index 197796ab4c..091dfefb6e 100644
--- a/src/core/security/json_token.h
+++ b/src/core/security/json_token.h
@@ -37,10 +37,16 @@
 #include <grpc/support/slice.h>
 #include <openssl/rsa.h>
 
+#include "src/core/json/json.h"
+
 /* --- Constants. --- */
 
 #define GRPC_JWT_OAUTH2_AUDIENCE "https://www.googleapis.com/oauth2/v3/token"
 
+#define GRPC_AUTH_JSON_TYPE_INVALID "invalid"
+#define GRPC_AUTH_JSON_TYPE_SERVICE_ACCOUNT "service_account"
+#define GRPC_AUTH_JSON_TYPE_AUTHORIZED_USER "authorized_user"
+
 /* --- auth_json_key parsing. --- */
 
 typedef struct {
@@ -59,6 +65,10 @@ int grpc_auth_json_key_is_valid(const grpc_auth_json_key *json_key);
 grpc_auth_json_key grpc_auth_json_key_create_from_string(
     const char *json_string);
 
+/* Creates a json_key object from parsed json. Returns an invalid object if a
+   parsing error has been encountered. */
+grpc_auth_json_key grpc_auth_json_key_create_from_json(const grpc_json *json);
+
 /* Destructs the object. */
 void grpc_auth_json_key_destruct(grpc_auth_json_key *json_key);
 
@@ -97,6 +107,11 @@ int grpc_auth_refresh_token_is_valid(
 grpc_auth_refresh_token grpc_auth_refresh_token_create_from_string(
     const char *json_string);
 
+/* Creates a refresh token object from parsed json. Returns an invalid object if
+   a parsing error has been encountered. */
+grpc_auth_refresh_token grpc_auth_refresh_token_create_from_json(
+    const grpc_json *json);
+
 /* Destructs the object. */
 void grpc_auth_refresh_token_destruct(grpc_auth_refresh_token *refresh_token);
 
diff --git a/src/core/security/jwt_verifier.c b/src/core/security/jwt_verifier.c
index 01007a1a84..9140eb2ef7 100644
--- a/src/core/security/jwt_verifier.c
+++ b/src/core/security/jwt_verifier.c
@@ -189,7 +189,6 @@ struct grpc_jwt_claims {
   gpr_slice buffer;
 };
 
-
 void grpc_jwt_claims_destroy(grpc_jwt_claims *claims) {
   grpc_json_destroy(claims->json);
   gpr_slice_unref(claims->buffer);
@@ -286,12 +285,14 @@ grpc_jwt_verifier_status grpc_jwt_claims_check(const grpc_jwt_claims *claims,
 
   GPR_ASSERT(claims != NULL);
 
-  skewed_now = gpr_time_add(gpr_now(), grpc_jwt_verifier_clock_skew);
+  skewed_now =
+      gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), grpc_jwt_verifier_clock_skew);
   if (gpr_time_cmp(skewed_now, claims->nbf) < 0) {
     gpr_log(GPR_ERROR, "JWT is not valid yet.");
     return GRPC_JWT_VERIFIER_TIME_CONSTRAINT_FAILURE;
   }
-  skewed_now = gpr_time_sub(gpr_now(), grpc_jwt_verifier_clock_skew);
+  skewed_now =
+      gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME), grpc_jwt_verifier_clock_skew);
   if (gpr_time_cmp(skewed_now, claims->exp) > 0) {
     gpr_log(GPR_ERROR, "JWT is expired.");
     return GRPC_JWT_VERIFIER_TIME_CONSTRAINT_FAILURE;
@@ -327,10 +328,10 @@ typedef struct {
 
 /* Takes ownership of the header, claims and signature. */
 static verifier_cb_ctx *verifier_cb_ctx_create(
-    grpc_jwt_verifier *verifier, grpc_pollset *pollset,
-    jose_header * header, grpc_jwt_claims *claims, const char *audience,
-    gpr_slice signature, const char *signed_jwt, size_t signed_jwt_len,
-    void *user_data, grpc_jwt_verification_done_cb cb) {
+    grpc_jwt_verifier *verifier, grpc_pollset *pollset, jose_header *header,
+    grpc_jwt_claims *claims, const char *audience, gpr_slice signature,
+    const char *signed_jwt, size_t signed_jwt_len, void *user_data,
+    grpc_jwt_verification_done_cb cb) {
   verifier_cb_ctx *ctx = gpr_malloc(sizeof(verifier_cb_ctx));
   memset(ctx, 0, sizeof(verifier_cb_ctx));
   ctx->verifier = verifier;
@@ -604,7 +605,7 @@ end:
 
 static void on_openid_config_retrieved(void *user_data,
                                        const grpc_httpcli_response *response) {
-  const grpc_json* cur;
+  const grpc_json *cur;
   grpc_json *json = json_from_http(response);
   verifier_cb_ctx *ctx = (verifier_cb_ctx *)user_data;
   grpc_httpcli_request req;
@@ -632,9 +633,10 @@ static void on_openid_config_retrieved(void *user_data,
   } else {
     *(req.host + (req.path - jwks_uri)) = '\0';
   }
-  grpc_httpcli_get(&ctx->verifier->http_ctx, ctx->pollset, &req,
-                   gpr_time_add(gpr_now(), grpc_jwt_verifier_max_delay),
-                   on_keys_retrieved, ctx);
+  grpc_httpcli_get(
+      &ctx->verifier->http_ctx, ctx->pollset, &req,
+      gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), grpc_jwt_verifier_max_delay),
+      on_keys_retrieved, ctx);
   grpc_json_destroy(json);
   gpr_free(req.host);
   return;
@@ -645,8 +647,8 @@ error:
   verifier_cb_ctx_destroy(ctx);
 }
 
-static email_key_mapping *verifier_get_mapping(
-    grpc_jwt_verifier *v, const char *email_domain) {
+static email_key_mapping *verifier_get_mapping(grpc_jwt_verifier *v,
+                                               const char *email_domain) {
   size_t i;
   if (v->mappings == NULL) return NULL;
   for (i = 0; i < v->num_mappings; i++) {
@@ -733,9 +735,10 @@ static void retrieve_key_and_verify(verifier_cb_ctx *ctx) {
     http_cb = on_openid_config_retrieved;
   }
 
-  grpc_httpcli_get(&ctx->verifier->http_ctx, ctx->pollset, &req,
-                   gpr_time_add(gpr_now(), grpc_jwt_verifier_max_delay),
-                   http_cb, ctx);
+  grpc_httpcli_get(
+      &ctx->verifier->http_ctx, ctx->pollset, &req,
+      gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), grpc_jwt_verifier_max_delay),
+      http_cb, ctx);
   gpr_free(req.host);
   gpr_free(req.path);
   return;
@@ -764,7 +767,7 @@ void grpc_jwt_verifier_verify(grpc_jwt_verifier *verifier,
   dot = strchr(cur, '.');
   if (dot == NULL) goto error;
   json = parse_json_part_from_jwt(cur, dot - cur, &header_buffer);
-  if (json == NULL)  goto error;
+  if (json == NULL) goto error;
   header = jose_header_from_json(json, header_buffer);
   if (header == NULL) goto error;
 
@@ -772,7 +775,7 @@ void grpc_jwt_verifier_verify(grpc_jwt_verifier *verifier,
   dot = strchr(cur, '.');
   if (dot == NULL) goto error;
   json = parse_json_part_from_jwt(cur, dot - cur, &claims_buffer);
-  if (json == NULL)  goto error;
+  if (json == NULL) goto error;
   claims = grpc_jwt_claims_from_json(json, claims_buffer);
   if (claims == NULL) goto error;
 
@@ -827,4 +830,3 @@ void grpc_jwt_verifier_destroy(grpc_jwt_verifier *v) {
   }
   gpr_free(v);
 }
-
diff --git a/src/core/security/security_context.c b/src/core/security/security_context.c
index 4d56549f9b..8ce7876bd8 100644
--- a/src/core/security/security_context.c
+++ b/src/core/security/security_context.c
@@ -69,12 +69,20 @@ grpc_call_error grpc_call_set_credentials(grpc_call *call,
   return GRPC_CALL_OK;
 }
 
-const grpc_auth_context *grpc_call_auth_context(grpc_call *call) {
+grpc_auth_context *grpc_call_auth_context(grpc_call *call) {
   void *sec_ctx = grpc_call_context_get(call, GRPC_CONTEXT_SECURITY);
   if (sec_ctx == NULL) return NULL;
   return grpc_call_is_client(call)
-             ? ((grpc_client_security_context *)sec_ctx)->auth_context
-             : ((grpc_server_security_context *)sec_ctx)->auth_context;
+             ? GRPC_AUTH_CONTEXT_REF(
+                   ((grpc_client_security_context *)sec_ctx)->auth_context,
+                   "grpc_call_auth_context client")
+             : GRPC_AUTH_CONTEXT_REF(
+                   ((grpc_server_security_context *)sec_ctx)->auth_context,
+                   "grpc_call_auth_context server");
+}
+
+void grpc_auth_context_release(grpc_auth_context *context) {
+  GRPC_AUTH_CONTEXT_UNREF(context, "grpc_auth_context_unref");
 }
 
 /* --- grpc_client_security_context --- */
diff --git a/src/core/security/security_context.h b/src/core/security/security_context.h
index 20c4390898..76a45910bb 100644
--- a/src/core/security/security_context.h
+++ b/src/core/security/security_context.h
@@ -36,6 +36,10 @@
 
 #include "src/core/security/credentials.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* --- grpc_auth_context ---
 
    High level authentication context object. Can optionally be chained. */
@@ -103,5 +107,9 @@ typedef struct {
 grpc_server_security_context *grpc_server_security_context_create(void);
 void grpc_server_security_context_destroy(void *ctx);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif  /* GRPC_INTERNAL_CORE_SECURITY_SECURITY_CONTEXT_H */
 
diff --git a/src/core/statistics/census_rpc_stats.c b/src/core/statistics/census_rpc_stats.c
index 0491c91947..3e571b1143 100644
--- a/src/core/statistics/census_rpc_stats.c
+++ b/src/core/statistics/census_rpc_stats.c
@@ -157,7 +157,7 @@ static void record_stats(census_ht* store, census_op_id op_id,
         key.ptr = gpr_strdup(key.ptr);
         census_ht_insert(store, key, (void*)window_stats);
       }
-      census_window_stats_add(window_stats, gpr_now(), stats);
+      census_window_stats_add(window_stats, gpr_now(GPR_CLOCK_REALTIME), stats);
     } else {
       census_internal_unlock_trace_store();
     }
@@ -185,7 +185,7 @@ static void get_stats(census_ht* store, census_aggregated_rpc_stats* data) {
   if (store != NULL) {
     size_t n;
     unsigned i, j;
-    gpr_timespec now = gpr_now();
+    gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
     census_ht_kv* kv = census_ht_get_all_elements(store, &n);
     if (kv != NULL) {
       data->num_entries = n;
diff --git a/src/core/statistics/census_tracing.c b/src/core/statistics/census_tracing.c
index 05e72b99c0..3036ba5407 100644
--- a/src/core/statistics/census_tracing.c
+++ b/src/core/statistics/census_tracing.c
@@ -94,7 +94,7 @@ census_op_id census_tracing_start_op(void) {
     g_id++;
     memcpy(&ret->id, &g_id, sizeof(census_op_id));
     ret->rpc_stats.cnt = 1;
-    ret->ts = gpr_now();
+    ret->ts = gpr_now(GPR_CLOCK_REALTIME);
     census_ht_insert(g_trace_store, op_id_as_key(&ret->id), (void*)ret);
     gpr_log(GPR_DEBUG, "Start tracing for id %lu", g_id);
     gpr_mu_unlock(&g_mu);
@@ -122,7 +122,7 @@ void census_tracing_print(census_op_id op_id, const char* anno_txt) {
   trace = census_ht_find(g_trace_store, op_id_as_key(&op_id));
   if (trace != NULL) {
     census_trace_annotation* anno = gpr_malloc(sizeof(census_trace_annotation));
-    anno->ts = gpr_now();
+    anno->ts = gpr_now(GPR_CLOCK_REALTIME);
     {
       char* d = anno->txt;
       const char* s = anno_txt;
@@ -143,8 +143,8 @@ void census_tracing_end_op(census_op_id op_id) {
   gpr_mu_lock(&g_mu);
   trace = census_ht_find(g_trace_store, op_id_as_key(&op_id));
   if (trace != NULL) {
-    trace->rpc_stats.elapsed_time_ms =
-        gpr_timespec_to_micros(gpr_time_sub(gpr_now(), trace->ts));
+    trace->rpc_stats.elapsed_time_ms = gpr_timespec_to_micros(
+        gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME), trace->ts));
     gpr_log(GPR_DEBUG, "End tracing for id %lu, method %s, latency %f us",
             op_id_2_uint64(&op_id), trace->method,
             trace->rpc_stats.elapsed_time_ms);
@@ -194,8 +194,8 @@ const char* census_get_trace_method_name(const census_trace_obj* trace) {
 
 static census_trace_annotation* dup_annotation_chain(
     census_trace_annotation* from) {
-  census_trace_annotation *ret = NULL;
-  census_trace_annotation **to = &ret;
+  census_trace_annotation* ret = NULL;
+  census_trace_annotation** to = &ret;
   for (; from != NULL; from = from->next) {
     *to = gpr_malloc(sizeof(census_trace_annotation));
     memcpy(*to, from, sizeof(census_trace_annotation));
@@ -223,9 +223,9 @@ census_trace_obj** census_get_active_ops(int* num_active_ops) {
     size_t n = 0;
     census_ht_kv* all_kvs = census_ht_get_all_elements(g_trace_store, &n);
     *num_active_ops = (int)n;
-    if (n != 0 ) {
+    if (n != 0) {
       size_t i = 0;
-      ret = gpr_malloc(sizeof(census_trace_obj *) * n);
+      ret = gpr_malloc(sizeof(census_trace_obj*) * n);
       for (i = 0; i < n; i++) {
         ret[i] = trace_obj_dup((census_trace_obj*)all_kvs[i].v);
       }
diff --git a/src/core/statistics/window_stats.h b/src/core/statistics/window_stats.h
index d733d8d247..0020f6b44c 100644
--- a/src/core/statistics/window_stats.h
+++ b/src/core/statistics/window_stats.h
@@ -90,11 +90,11 @@
     // Record a new event, taking 15.3ms, transferring 1784 bytes.
     stat.latency = 0.153;
     stat.bytes = 1784;
-    census_window_stats_add(stats, gpr_now(), &stat);
+    census_window_stats_add(stats, gpr_now(GPR_CLOCK_REALTIME), &stat);
     // Get sums and print them out
     result[kMinInterval].statistic = &sums[kMinInterval];
     result[kHourInterval].statistic = &sums[kHourInterval];
-    census_window_stats_get_sums(stats, gpr_now(), result);
+    census_window_stats_get_sums(stats, gpr_now(GPR_CLOCK_REALTIME), result);
     printf("%d events/min, average time %gs, average bytes %g\n",
            result[kMinInterval].count,
            (my_stat*)result[kMinInterval].statistic->latency /
@@ -170,4 +170,4 @@ void census_window_stats_get_sums(const struct census_window_stats* wstats,
    assertion failure). This function is thread-compatible. */
 void census_window_stats_destroy(struct census_window_stats* wstats);
 
-#endif  /* GRPC_INTERNAL_CORE_STATISTICS_WINDOW_STATS_H */
+#endif /* GRPC_INTERNAL_CORE_STATISTICS_WINDOW_STATS_H */
diff --git a/src/core/support/cancellable.c b/src/core/support/cancellable.c
index 5a4d488dd3..3cbb318ab6 100644
--- a/src/core/support/cancellable.c
+++ b/src/core/support/cancellable.c
@@ -121,8 +121,8 @@ void gpr_cancellable_cancel(gpr_cancellable *c) {
         } else {
           gpr_event ev;
           gpr_event_init(&ev);
-          gpr_event_wait(&ev,
-                         gpr_time_add(gpr_now(), gpr_time_from_micros(1000)));
+          gpr_event_wait(&ev, gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
+                                           gpr_time_from_micros(1000)));
         }
       }
     } while (failures != 0);
diff --git a/src/core/support/log_linux.c b/src/core/support/log_linux.c
index 7937466b79..5ac36e7b95 100644
--- a/src/core/support/log_linux.c
+++ b/src/core/support/log_linux.c
@@ -76,7 +76,7 @@ void gpr_default_log(gpr_log_func_args *args) {
   char *prefix;
   const char *display_file;
   char time_buffer[64];
-  gpr_timespec now = gpr_now();
+  gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
   struct tm tm;
 
   final_slash = strrchr(args->file, '/');
diff --git a/src/core/support/log_posix.c b/src/core/support/log_posix.c
index afca792c40..940ee20f15 100644
--- a/src/core/support/log_posix.c
+++ b/src/core/support/log_posix.c
@@ -75,7 +75,7 @@ void gpr_default_log(gpr_log_func_args *args) {
   char *final_slash;
   const char *display_file;
   char time_buffer[64];
-  gpr_timespec now = gpr_now();
+  gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
   struct tm tm;
 
   final_slash = strrchr(args->file, '/');
diff --git a/src/core/support/log_win32.c b/src/core/support/log_win32.c
index d249be7d2e..629781da8a 100644
--- a/src/core/support/log_win32.c
+++ b/src/core/support/log_win32.c
@@ -82,7 +82,7 @@ void gpr_log(const char *file, int line, gpr_log_severity severity,
 /* Simple starter implementation */
 void gpr_default_log(gpr_log_func_args *args) {
   char time_buffer[64];
-  gpr_timespec now = gpr_now();
+  gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
   struct tm tm;
 
   if (localtime_s(&tm, &now.tv_sec)) {
diff --git a/src/core/support/stack_lockfree.c b/src/core/support/stack_lockfree.c
new file mode 100644
index 0000000000..9497efbfb5
--- /dev/null
+++ b/src/core/support/stack_lockfree.c
@@ -0,0 +1,130 @@
+/*
+ *
+ * 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 "src/core/support/stack_lockfree.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <grpc/support/port_platform.h>
+#include <grpc/support/alloc.h>
+#include <grpc/support/atm.h>
+#include <grpc/support/log.h>
+
+/* The lockfree node structure is a single architecture-level
+   word that allows for an atomic CAS to set it up. */
+struct lockfree_node_contents {
+  /* next thing to look at. Actual index for head, next index otherwise */
+  gpr_uint16 index;
+#ifdef GPR_ARCH_64
+  gpr_uint16 pad;
+  gpr_uint32 aba_ctr;
+#else
+#ifdef GPR_ARCH_32
+  gpr_uint16 aba_ctr;
+#else
+#error Unsupported bit width architecture
+#endif
+#endif
+};
+
+/* Use a union to make sure that these are in the same bits as an atm word */
+typedef union lockfree_node {
+  gpr_atm atm;
+  struct lockfree_node_contents contents;
+} lockfree_node;
+
+#define ENTRY_ALIGNMENT_BITS 3 /* make sure that entries aligned to 8-bytes */
+#define INVALID_ENTRY_INDEX ((1 << 16) - 1) /* reserve this entry as invalid \
+                                               */
+
+struct gpr_stack_lockfree {
+  lockfree_node *entries;
+  lockfree_node head; /* An atomic entry describing curr head */
+};
+
+gpr_stack_lockfree *gpr_stack_lockfree_create(int entries) {
+  gpr_stack_lockfree *stack;
+  stack = gpr_malloc(sizeof(*stack));
+  /* Since we only allocate 16 bits to represent an entry number,
+   * make sure that we are within the desired range */
+  /* Reserve the highest entry number as a dummy */
+  GPR_ASSERT(entries < INVALID_ENTRY_INDEX);
+  stack->entries = gpr_malloc_aligned(entries * sizeof(stack->entries[0]),
+                                      ENTRY_ALIGNMENT_BITS);
+  /* Clear out all entries */
+  memset(stack->entries, 0, entries * sizeof(stack->entries[0]));
+  memset(&stack->head, 0, sizeof(stack->head));
+
+  /* Point the head at reserved dummy entry */
+  stack->head.contents.index = INVALID_ENTRY_INDEX;
+  return stack;
+}
+
+void gpr_stack_lockfree_destroy(gpr_stack_lockfree *stack) {
+  gpr_free_aligned(stack->entries);
+  gpr_free(stack);
+}
+
+void gpr_stack_lockfree_push(gpr_stack_lockfree *stack, int entry) {
+  lockfree_node head;
+  lockfree_node newhead;
+
+  /* First fill in the entry's index and aba ctr for new head */
+  newhead.contents.index = (gpr_uint16)entry;
+  /* Also post-increment the aba_ctr */
+  newhead.contents.aba_ctr = stack->entries[entry].contents.aba_ctr++;
+
+  do {
+    /* Atomically get the existing head value for use */
+    head.atm = gpr_atm_no_barrier_load(&(stack->head.atm));
+    /* Point to it */
+    stack->entries[entry].contents.index = head.contents.index;
+  } while (!gpr_atm_rel_cas(&(stack->head.atm), head.atm, newhead.atm));
+  /* Use rel_cas above to make sure that entry index is set properly */
+}
+
+int gpr_stack_lockfree_pop(gpr_stack_lockfree *stack) {
+  lockfree_node head;
+  lockfree_node newhead;
+  do {
+    head.atm = gpr_atm_acq_load(&(stack->head.atm));
+    if (head.contents.index == INVALID_ENTRY_INDEX) {
+      return -1;
+    }
+    newhead.atm =
+        gpr_atm_no_barrier_load(&(stack->entries[head.contents.index].atm));
+
+  } while (!gpr_atm_no_barrier_cas(&(stack->head.atm), head.atm, newhead.atm));
+  return head.contents.index;
+}
diff --git a/src/core/support/stack_lockfree.h b/src/core/support/stack_lockfree.h
new file mode 100644
index 0000000000..0bcf73635d
--- /dev/null
+++ b/src/core/support/stack_lockfree.h
@@ -0,0 +1,50 @@
+/*
+ *
+ * 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_SUPPORT_STACK_LOCKFREE_H
+#define GRPC_INTERNAL_CORE_SUPPORT_STACK_LOCKFREE_H
+
+typedef struct gpr_stack_lockfree gpr_stack_lockfree;
+
+/* This stack must specify the maximum number of entries to track.
+   The current implementation only allows up to 65534 entries */
+gpr_stack_lockfree* gpr_stack_lockfree_create(int entries);
+void gpr_stack_lockfree_destroy(gpr_stack_lockfree* stack);
+
+/* Pass in a valid entry number for the next stack entry */
+void gpr_stack_lockfree_push(gpr_stack_lockfree* stack, int entry);
+
+/* Returns -1 on empty or the actual entry number */
+int gpr_stack_lockfree_pop(gpr_stack_lockfree* stack);
+
+#endif /* GRPC_INTERNAL_CORE_SUPPORT_STACK_LOCKFREE_H */
diff --git a/src/core/support/sync_win32.c b/src/core/support/sync_win32.c
index 72f39f8d46..29b77fc4c2 100644
--- a/src/core/support/sync_win32.c
+++ b/src/core/support/sync_win32.c
@@ -86,7 +86,7 @@ int gpr_cv_wait(gpr_cv *cv, gpr_mu *mu, gpr_timespec abs_deadline) {
   if (gpr_time_cmp(abs_deadline, gpr_inf_future) == 0) {
     SleepConditionVariableCS(cv, &mu->cs, INFINITE);
   } else {
-    gpr_timespec now = gpr_now();
+    gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
     gpr_int64 now_ms = now.tv_sec * 1000 + now.tv_nsec / 1000000;
     gpr_int64 deadline_ms =
         abs_deadline.tv_sec * 1000 + abs_deadline.tv_nsec / 1000000;
diff --git a/src/core/support/time_posix.c b/src/core/support/time_posix.c
index afb58ef231..f9b7958783 100644
--- a/src/core/support/time_posix.c
+++ b/src/core/support/time_posix.c
@@ -55,22 +55,52 @@ static gpr_timespec gpr_from_timespec(struct timespec ts) {
   return rv;
 }
 
-gpr_timespec gpr_now(void) {
+/** maps gpr_clock_type --> clockid_t for clock_gettime */
+static clockid_t clockid_for_gpr_clock[] = {CLOCK_MONOTONIC, CLOCK_REALTIME};
+
+void gpr_time_init(void) {}
+
+gpr_timespec gpr_now(gpr_clock_type clock) {
   struct timespec now;
-  clock_gettime(CLOCK_REALTIME, &now);
+  clock_gettime(clockid_for_gpr_clock[clock], &now);
   return gpr_from_timespec(now);
 }
 #else
 /* For some reason Apple's OSes haven't implemented clock_gettime. */
 
 #include <sys/time.h>
+#include <mach/mach.h>
+#include <mach/mach_time.h>
+
+static double g_time_scale;
+static uint64_t g_time_start;
+
+void gpr_time_init(void) {
+  mach_timebase_info_data_t tb = {0, 1};
+  mach_timebase_info(&tb);
+  g_time_scale = tb.numer;
+  g_time_scale /= tb.denom;
+  g_time_start = mach_absolute_time();
+}
 
-gpr_timespec gpr_now(void) {
+gpr_timespec gpr_now(gpr_clock_type clock) {
   gpr_timespec now;
   struct timeval now_tv;
-  gettimeofday(&now_tv, NULL);
-  now.tv_sec = now_tv.tv_sec;
-  now.tv_nsec = now_tv.tv_usec * 1000;
+  double now_dbl;
+
+  switch (clock) {
+    case GPR_CLOCK_REALTIME:
+      gettimeofday(&now_tv, NULL);
+      now.tv_sec = now_tv.tv_sec;
+      now.tv_nsec = now_tv.tv_usec * 1000;
+      break;
+    case GPR_CLOCK_MONOTONIC:
+      now_dbl = (mach_absolute_time() - g_time_start) * g_time_scale;
+      now.tv_sec = now_dbl * 1e-9;
+      now.tv_nsec = now_dbl - now.tv_sec * 1e9;
+      break;
+  }
+
   return now;
 }
 #endif
@@ -83,7 +113,7 @@ void gpr_sleep_until(gpr_timespec until) {
   for (;;) {
     /* We could simplify by using clock_nanosleep instead, but it might be
      * slightly less portable. */
-    now = gpr_now();
+    now = gpr_now(GPR_CLOCK_REALTIME);
     if (gpr_time_cmp(until, now) <= 0) {
       return;
     }
diff --git a/src/core/support/time_win32.c b/src/core/support/time_win32.c
index 9db267c01b..fa77c74eeb 100644
--- a/src/core/support/time_win32.c
+++ b/src/core/support/time_win32.c
@@ -40,12 +40,34 @@
 #include <grpc/support/time.h>
 #include <sys/timeb.h>
 
-gpr_timespec gpr_now(void) {
+static LARGE_INTEGER g_start_time;
+static double g_time_scale;
+
+void gpr_time_init(void) {
+  LARGE_INTEGER frequency;
+  QueryPerformanceFrequency(&frequency);
+  QueryPerformanceCounter(&g_start_time);
+  g_time_scale = 1.0 / frequency.QuadPart;
+}
+
+gpr_timespec gpr_now(gpr_clock_type clock) {
   gpr_timespec now_tv;
   struct _timeb now_tb;
-  _ftime_s(&now_tb);
-  now_tv.tv_sec = now_tb.time;
-  now_tv.tv_nsec = now_tb.millitm * 1000000;
+  LARGE_INTEGER timestamp;
+  double now_dbl;
+  switch (clock) {
+    case GPR_CLOCK_REALTIME:
+      _ftime_s(&now_tb);
+      now_tv.tv_sec = now_tb.time;
+      now_tv.tv_nsec = now_tb.millitm * 1000000;
+      break;
+    case GPR_CLOCK_MONOTONIC:
+      QueryPerformanceCounter(&timestamp);
+      now_dbl = (timestamp.QuadPart - g_start_time.QuadPart) * g_time_scale;
+      now_tv.tv_sec = (time_t)now_dbl;
+      now_tv.tv_nsec = (int)((now_dbl - (double)now_tv.tv_sec) * 1e9);
+      break;
+  }
   return now_tv;
 }
 
@@ -57,13 +79,14 @@ void gpr_sleep_until(gpr_timespec until) {
   for (;;) {
     /* We could simplify by using clock_nanosleep instead, but it might be
      * slightly less portable. */
-    now = gpr_now();
+    now = gpr_now(GPR_CLOCK_REALTIME);
     if (gpr_time_cmp(until, now) <= 0) {
       return;
     }
 
     delta = gpr_time_sub(until, now);
-    sleep_millis = (DWORD)delta.tv_sec * GPR_MS_PER_SEC + delta.tv_nsec / GPR_NS_PER_MS;
+    sleep_millis =
+        (DWORD)delta.tv_sec * GPR_MS_PER_SEC + delta.tv_nsec / GPR_NS_PER_MS;
     Sleep(sleep_millis);
   }
 }
diff --git a/src/core/surface/call.c b/src/core/surface/call.c
index ca4a4e0a55..a5d849a076 100644
--- a/src/core/surface/call.c
+++ b/src/core/surface/call.c
@@ -50,6 +50,17 @@
 #include "src/core/surface/channel.h"
 #include "src/core/surface/completion_queue.h"
 
+/** The maximum number of completions possible.
+    Based upon the maximum number of individually queueable ops in the batch
+   api:
+      - initial metadata send
+      - message send
+      - status/close send (depending on client/server)
+      - initial metadata recv
+      - message recv
+      - status/close recv (depending on client/server) */
+#define MAX_CONCURRENT_COMPLETIONS 6
+
 typedef enum { REQ_INITIAL = 0, REQ_READY, REQ_DONE } req_state;
 
 typedef enum {
@@ -136,6 +147,7 @@ struct grpc_call {
   grpc_mdctx *metadata_context;
   /* TODO(ctiller): share with cq if possible? */
   gpr_mu mu;
+  gpr_mu completion_mu;
 
   /* how far through the stream have we read? */
   read_state read_state;
@@ -163,6 +175,8 @@ struct grpc_call {
   gpr_uint8 error_status_set;
   /** should the alarm be cancelled */
   gpr_uint8 cancel_alarm;
+  /** bitmask of allocated completion events in completions */
+  gpr_uint8 allocated_completions;
 
   /* flags with bits corresponding to write states allowing us to determine
      what was sent */
@@ -251,6 +265,9 @@ struct grpc_call {
   grpc_iomgr_closure on_done_recv;
   grpc_iomgr_closure on_done_send;
   grpc_iomgr_closure on_done_bind;
+
+  /** completion events - for completion queue use */
+  grpc_cq_completion completions[MAX_CONCURRENT_COMPLETIONS];
 };
 
 #define CALL_STACK_FROM_CALL(call) ((grpc_call_stack *)((call) + 1))
@@ -287,6 +304,7 @@ grpc_call *grpc_call_create(grpc_channel *channel, grpc_completion_queue *cq,
       gpr_malloc(sizeof(grpc_call) + channel_stack->call_stack_size);
   memset(call, 0, sizeof(grpc_call));
   gpr_mu_init(&call->mu);
+  gpr_mu_init(&call->completion_mu);
   call->channel = channel;
   call->cq = cq;
   if (cq) {
@@ -350,6 +368,29 @@ grpc_completion_queue *grpc_call_get_completion_queue(grpc_call *call) {
   return call->cq;
 }
 
+static grpc_cq_completion *allocate_completion(grpc_call *call) {
+  gpr_uint8 i;
+  gpr_mu_lock(&call->completion_mu);
+  for (i = 0; i < GPR_ARRAY_SIZE(call->completions); i++) {
+    if (call->allocated_completions & (1u << i)) {
+      continue;
+    }
+    call->allocated_completions |= 1u << i;
+    gpr_mu_unlock(&call->completion_mu);
+    return &call->completions[i];
+  }
+  gpr_log(GPR_ERROR, "should never reach here");
+  abort();
+}
+
+static void done_completion(void *call, grpc_cq_completion *completion) {
+  grpc_call *c = call;
+  gpr_mu_lock(&c->completion_mu);
+  c->allocated_completions &= ~(1u << (completion - c->completions));
+  gpr_mu_unlock(&c->completion_mu);
+  GRPC_CALL_INTERNAL_UNREF(c, "completion", 1);
+}
+
 #ifdef GRPC_CALL_REF_COUNT_DEBUG
 void grpc_call_internal_ref(grpc_call *c, const char *reason) {
   gpr_log(GPR_DEBUG, "CALL:   ref %p %d -> %d [%s]", c,
@@ -366,6 +407,7 @@ static void destroy_call(void *call, int ignored_success) {
   grpc_call_stack_destroy(CALL_STACK_FROM_CALL(c));
   GRPC_CHANNEL_INTERNAL_UNREF(c->channel, "call");
   gpr_mu_destroy(&c->mu);
+  gpr_mu_destroy(&c->completion_mu);
   for (i = 0; i < STATUS_SOURCE_COUNT; i++) {
     if (c->status[i].details) {
       GRPC_MDSTR_UNREF(c->status[i].details);
@@ -1221,7 +1263,8 @@ 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, deadline, call_alarm, call, gpr_now());
+  grpc_alarm_init(&call->alarm, deadline, call_alarm, call,
+                  gpr_now(GPR_CLOCK_REALTIME));
 }
 
 /* we offset status by a small amount when storing it into transport metadata
@@ -1344,11 +1387,13 @@ static void set_cancelled_value(grpc_status_code status, void *dest) {
 }
 
 static void finish_batch(grpc_call *call, int success, void *tag) {
-  grpc_cq_end_op(call->cq, tag, call, success);
+  grpc_cq_end_op(call->cq, tag, success, done_completion, call,
+                 allocate_completion(call));
 }
 
 static void finish_batch_with_close(grpc_call *call, int success, void *tag) {
-  grpc_cq_end_op(call->cq, tag, call, 1);
+  grpc_cq_end_op(call->cq, tag, 1, done_completion, call,
+                 allocate_completion(call));
 }
 
 static int are_write_flags_valid(gpr_uint32 flags) {
@@ -1371,8 +1416,10 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
   GRPC_CALL_LOG_BATCH(GPR_INFO, call, ops, nops, tag);
 
   if (nops == 0) {
-    grpc_cq_begin_op(call->cq, call);
-    grpc_cq_end_op(call->cq, tag, call, 1);
+    grpc_cq_begin_op(call->cq);
+    GRPC_CALL_INTERNAL_REF(call, "completion");
+    grpc_cq_end_op(call->cq, tag, 1, done_completion, call,
+                   allocate_completion(call));
     return GRPC_CALL_OK;
   }
 
@@ -1494,7 +1541,8 @@ grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
     }
   }
 
-  grpc_cq_begin_op(call->cq, call);
+  GRPC_CALL_INTERNAL_REF(call, "completion");
+  grpc_cq_begin_op(call->cq);
 
   return grpc_call_start_ioreq_and_call_back(call, reqs, out, finish_func, tag);
 }
diff --git a/src/core/surface/channel.c b/src/core/surface/channel.c
index c6e2e5c675..a6438ff512 100644
--- a/src/core/surface/channel.c
+++ b/src/core/surface/channel.c
@@ -91,6 +91,7 @@ grpc_channel *grpc_channel_create_from_filters(
   size_t size =
       sizeof(grpc_channel) + grpc_channel_stack_size(filters, num_filters);
   grpc_channel *channel = gpr_malloc(size);
+  memset(channel, 0, sizeof(*channel));
   GPR_ASSERT(grpc_is_initialized() && "call grpc_init()");
   channel->is_client = is_client;
   /* decremented by grpc_channel_destroy */
diff --git a/src/core/surface/completion_queue.c b/src/core/surface/completion_queue.c
index 030a8b4e6f..c67f75fc5c 100644
--- a/src/core/surface/completion_queue.c
+++ b/src/core/surface/completion_queue.c
@@ -45,34 +45,20 @@
 #include <grpc/support/atm.h>
 #include <grpc/support/log.h>
 
-#define NUM_TAG_BUCKETS 31
-
-/* A single event: extends grpc_event to form a linked list with a destruction
-   function (on_finish) that is hidden from outside this module */
-typedef struct event {
-  grpc_event base;
-  struct event *queue_next;
-  struct event *queue_prev;
-  struct event *bucket_next;
-  struct event *bucket_prev;
-} event;
-
 /* Completion queue structure */
 struct grpc_completion_queue {
-  /* When refs drops to zero, we are in shutdown mode, and will be destroyable
-     once all queued events are drained */
-  gpr_refcount refs;
-  /* Once owning_refs drops to zero, we will destroy the cq */
+  /** completed events */
+  grpc_cq_completion completed_head;
+  grpc_cq_completion *completed_tail;
+  /** Number of pending events (+1 if we're not shutdown) */
+  gpr_refcount pending_events;
+  /** Once owning_refs drops to zero, we will destroy the cq */
   gpr_refcount owning_refs;
-  /* the set of low level i/o things that concern this cq */
+  /** the set of low level i/o things that concern this cq */
   grpc_pollset pollset;
-  /* 0 initially, 1 once we've begun shutting down */
+  /** 0 initially, 1 once we've begun shutting down */
   int shutdown;
   int shutdown_called;
-  /* Head of a linked list of queued events (prev points to the last element) */
-  event *queue;
-  /* Fixed size chained hash table of events for pluck() */
-  event *buckets[NUM_TAG_BUCKETS];
   int is_server_cq;
 };
 
@@ -80,19 +66,20 @@ grpc_completion_queue *grpc_completion_queue_create(void) {
   grpc_completion_queue *cc = gpr_malloc(sizeof(grpc_completion_queue));
   memset(cc, 0, sizeof(*cc));
   /* Initial ref is dropped by grpc_completion_queue_shutdown */
-  gpr_ref_init(&cc->refs, 1);
+  gpr_ref_init(&cc->pending_events, 1);
   /* One for destroy(), one for pollset_shutdown */
   gpr_ref_init(&cc->owning_refs, 2);
   grpc_pollset_init(&cc->pollset);
+  cc->completed_tail = &cc->completed_head;
+  cc->completed_head.next = (gpr_uintptr)cc->completed_tail;
   return cc;
 }
 
 #ifdef GRPC_CQ_REF_COUNT_DEBUG
 void grpc_cq_internal_ref(grpc_completion_queue *cc, const char *reason,
                           const char *file, int line) {
-  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "CQ:%p   ref %d -> %d %s",
-          cc, (int)cc->owning_refs.count, (int)cc->owning_refs.count + 1,
-          reason);
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "CQ:%p   ref %d -> %d %s", cc,
+          (int)cc->owning_refs.count, (int)cc->owning_refs.count + 1, reason);
 #else
 void grpc_cq_internal_ref(grpc_completion_queue *cc) {
 #endif
@@ -107,186 +94,135 @@ static void on_pollset_destroy_done(void *arg) {
 #ifdef GRPC_CQ_REF_COUNT_DEBUG
 void grpc_cq_internal_unref(grpc_completion_queue *cc, const char *reason,
                             const char *file, int line) {
-  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "CQ:%p unref %d -> %d %s",
-          cc, (int)cc->owning_refs.count, (int)cc->owning_refs.count - 1,
-          reason);
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "CQ:%p unref %d -> %d %s", cc,
+          (int)cc->owning_refs.count, (int)cc->owning_refs.count - 1, reason);
 #else
 void grpc_cq_internal_unref(grpc_completion_queue *cc) {
 #endif
   if (gpr_unref(&cc->owning_refs)) {
-    GPR_ASSERT(cc->queue == NULL);
+    GPR_ASSERT(cc->completed_head.next == (gpr_uintptr)&cc->completed_head);
     grpc_pollset_destroy(&cc->pollset);
     gpr_free(cc);
   }
 }
 
-/* Create and append an event to the queue. Returns the event so that its data
-   members can be filled in.
-   Requires GRPC_POLLSET_MU(&cc->pollset) locked. */
-static event *add_locked(grpc_completion_queue *cc, grpc_completion_type type,
-                         void *tag, grpc_call *call) {
-  event *ev = gpr_malloc(sizeof(event));
-  gpr_uintptr bucket = ((gpr_uintptr)tag) % NUM_TAG_BUCKETS;
-  ev->base.type = type;
-  ev->base.tag = tag;
-  if (cc->queue == NULL) {
-    cc->queue = ev->queue_next = ev->queue_prev = ev;
-  } else {
-    ev->queue_next = cc->queue;
-    ev->queue_prev = cc->queue->queue_prev;
-    ev->queue_next->queue_prev = ev->queue_prev->queue_next = ev;
-  }
-  if (cc->buckets[bucket] == NULL) {
-    cc->buckets[bucket] = ev->bucket_next = ev->bucket_prev = ev;
-  } else {
-    ev->bucket_next = cc->buckets[bucket];
-    ev->bucket_prev = cc->buckets[bucket]->bucket_prev;
-    ev->bucket_next->bucket_prev = ev->bucket_prev->bucket_next = ev;
-  }
-  grpc_pollset_kick(&cc->pollset);
-  return ev;
-}
-
-void grpc_cq_begin_op(grpc_completion_queue *cc, grpc_call *call) {
-  gpr_ref(&cc->refs);
-  if (call) GRPC_CALL_INTERNAL_REF(call, "cq");
+void grpc_cq_begin_op(grpc_completion_queue *cc) {
+  gpr_ref(&cc->pending_events);
 }
 
 /* Signal the end of an operation - if this is the last waiting-to-be-queued
    event, then enter shutdown mode */
-void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, grpc_call *call,
-                    int success) {
-  event *ev;
-  int shutdown = 0;
-  gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
-  ev = add_locked(cc, GRPC_OP_COMPLETE, tag, call);
-  ev->base.success = success;
-  if (gpr_unref(&cc->refs)) {
+/* Queue a GRPC_OP_COMPLETED operation */
+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 = gpr_unref(&cc->pending_events);
+
+  storage->tag = tag;
+  storage->done = done;
+  storage->done_arg = done_arg;
+  storage->next =
+      ((gpr_uintptr)&cc->completed_head) | ((gpr_uintptr)(success != 0));
+
+  if (!shutdown) {
+    gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
+    cc->completed_tail->next =
+        ((gpr_uintptr)storage) | (1u & (gpr_uintptr)cc->completed_tail->next);
+    cc->completed_tail = storage;
+    grpc_pollset_kick(&cc->pollset);
+    gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
+  } else {
+    gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
+    cc->completed_tail->next =
+        ((gpr_uintptr)storage) | (1u & (gpr_uintptr)cc->completed_tail->next);
+    cc->completed_tail = storage;
     GPR_ASSERT(!cc->shutdown);
     GPR_ASSERT(cc->shutdown_called);
     cc->shutdown = 1;
-    shutdown = 1;
-  }
-  gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
-  if (call) GRPC_CALL_INTERNAL_UNREF(call, "cq", 0);
-  if (shutdown) {
+    gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
     grpc_pollset_shutdown(&cc->pollset, on_pollset_destroy_done, cc);
   }
 }
 
-/* Create a GRPC_QUEUE_SHUTDOWN event without queuing it anywhere */
-static event *create_shutdown_event(void) {
-  event *ev = gpr_malloc(sizeof(event));
-  ev->base.type = GRPC_QUEUE_SHUTDOWN;
-  ev->base.tag = NULL;
-  return ev;
-}
-
 grpc_event grpc_completion_queue_next(grpc_completion_queue *cc,
                                       gpr_timespec deadline) {
-  event *ev = NULL;
   grpc_event ret;
 
   GRPC_CQ_INTERNAL_REF(cc, "next");
   gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
   for (;;) {
-    if (cc->queue != NULL) {
-      gpr_uintptr bucket;
-      ev = cc->queue;
-      bucket = ((gpr_uintptr)ev->base.tag) % NUM_TAG_BUCKETS;
-      cc->queue = ev->queue_next;
-      ev->queue_next->queue_prev = ev->queue_prev;
-      ev->queue_prev->queue_next = ev->queue_next;
-      ev->bucket_next->bucket_prev = ev->bucket_prev;
-      ev->bucket_prev->bucket_next = ev->bucket_next;
-      if (ev == cc->buckets[bucket]) {
-        cc->buckets[bucket] = ev->bucket_next;
-        if (ev == cc->buckets[bucket]) {
-          cc->buckets[bucket] = NULL;
-        }
-      }
-      if (cc->queue == ev) {
-        cc->queue = NULL;
+    if (cc->completed_tail != &cc->completed_head) {
+      grpc_cq_completion *c = (grpc_cq_completion *)cc->completed_head.next;
+      cc->completed_head.next = c->next & ~(gpr_uintptr)1;
+      if (c == cc->completed_tail) {
+        cc->completed_tail = &cc->completed_head;
       }
+      gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
+      ret.type = GRPC_OP_COMPLETE;
+      ret.success = c->next & 1u;
+      ret.tag = c->tag;
+      c->done(c->done_arg, c);
       break;
     }
     if (cc->shutdown) {
-      ev = create_shutdown_event();
+      gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
+      memset(&ret, 0, sizeof(ret));
+      ret.type = GRPC_QUEUE_SHUTDOWN;
       break;
     }
     if (!grpc_pollset_work(&cc->pollset, deadline)) {
       gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
       memset(&ret, 0, sizeof(ret));
       ret.type = GRPC_QUEUE_TIMEOUT;
-      GRPC_SURFACE_TRACE_RETURNED_EVENT(cc, &ret);
-      GRPC_CQ_INTERNAL_UNREF(cc, "next");
-      return ret;
+      break;
     }
   }
-  gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
-  ret = ev->base;
-  gpr_free(ev);
   GRPC_SURFACE_TRACE_RETURNED_EVENT(cc, &ret);
   GRPC_CQ_INTERNAL_UNREF(cc, "next");
   return ret;
 }
 
-static event *pluck_event(grpc_completion_queue *cc, void *tag) {
-  gpr_uintptr bucket = ((gpr_uintptr)tag) % NUM_TAG_BUCKETS;
-  event *ev = cc->buckets[bucket];
-  if (ev == NULL) return NULL;
-  do {
-    if (ev->base.tag == tag) {
-      ev->queue_next->queue_prev = ev->queue_prev;
-      ev->queue_prev->queue_next = ev->queue_next;
-      ev->bucket_next->bucket_prev = ev->bucket_prev;
-      ev->bucket_prev->bucket_next = ev->bucket_next;
-      if (ev == cc->buckets[bucket]) {
-        cc->buckets[bucket] = ev->bucket_next;
-        if (ev == cc->buckets[bucket]) {
-          cc->buckets[bucket] = NULL;
-        }
-      }
-      if (cc->queue == ev) {
-        cc->queue = ev->queue_next;
-        if (cc->queue == ev) {
-          cc->queue = NULL;
-        }
-      }
-      return ev;
-    }
-    ev = ev->bucket_next;
-  } while (ev != cc->buckets[bucket]);
-  return NULL;
-}
-
 grpc_event grpc_completion_queue_pluck(grpc_completion_queue *cc, void *tag,
                                        gpr_timespec deadline) {
-  event *ev = NULL;
   grpc_event ret;
+  grpc_cq_completion *c;
+  grpc_cq_completion *prev;
 
   GRPC_CQ_INTERNAL_REF(cc, "pluck");
   gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
   for (;;) {
-    if ((ev = pluck_event(cc, tag))) {
-      break;
+    prev = &cc->completed_head;
+    while ((c = (grpc_cq_completion *)(prev->next & ~(gpr_uintptr)1)) !=
+           &cc->completed_head) {
+      if (c->tag == tag) {
+        prev->next =
+            (prev->next & (gpr_uintptr)1) | (c->next & ~(gpr_uintptr)1);
+        if (c == cc->completed_tail) {
+          cc->completed_tail = prev;
+        }
+        gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
+        ret.type = GRPC_OP_COMPLETE;
+        ret.success = c->next & 1u;
+        ret.tag = c->tag;
+        c->done(c->done_arg, c);
+        goto done;
+      }
+      prev = c;
     }
     if (cc->shutdown) {
-      ev = create_shutdown_event();
+      gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
+      memset(&ret, 0, sizeof(ret));
+      ret.type = GRPC_QUEUE_SHUTDOWN;
       break;
     }
     if (!grpc_pollset_work(&cc->pollset, deadline)) {
       gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
       memset(&ret, 0, sizeof(ret));
       ret.type = GRPC_QUEUE_TIMEOUT;
-      GRPC_SURFACE_TRACE_RETURNED_EVENT(cc, &ret);
-      GRPC_CQ_INTERNAL_UNREF(cc, "pluck");
-      return ret;
+      break;
     }
   }
-  gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
-  ret = ev->base;
-  gpr_free(ev);
+done:
   GRPC_SURFACE_TRACE_RETURNED_EVENT(cc, &ret);
   GRPC_CQ_INTERNAL_UNREF(cc, "pluck");
   return ret;
@@ -303,7 +239,7 @@ void grpc_completion_queue_shutdown(grpc_completion_queue *cc) {
   cc->shutdown_called = 1;
   gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
 
-  if (gpr_unref(&cc->refs)) {
+  if (gpr_unref(&cc->pending_events)) {
     gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
     GPR_ASSERT(!cc->shutdown);
     cc->shutdown = 1;
@@ -324,8 +260,8 @@ grpc_pollset *grpc_cq_pollset(grpc_completion_queue *cc) {
 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_time_from_millis(100)));
+  grpc_pollset_work(&cc->pollset, gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
+                                               gpr_time_from_millis(100)));
   gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
 }
 
diff --git a/src/core/surface/completion_queue.h b/src/core/surface/completion_queue.h
index 1b9010f462..f944f48d8e 100644
--- a/src/core/surface/completion_queue.h
+++ b/src/core/surface/completion_queue.h
@@ -39,6 +39,17 @@
 #include "src/core/iomgr/pollset.h"
 #include <grpc/grpc.h>
 
+typedef struct grpc_cq_completion {
+  /** user supplied tag */
+  void *tag;
+  /** done callback - called when this queue element is no longer
+      needed by the completion queue */
+  void (*done)(void *done_arg, struct grpc_cq_completion *c);
+  void *done_arg;
+  /** next pointer; low bit is used to indicate success or not */
+  gpr_uintptr next;
+} grpc_cq_completion;
+
 #ifdef GRPC_CQ_REF_COUNT_DEBUG
 void grpc_cq_internal_ref(grpc_completion_queue *cc, const char *reason,
                           const char *file, int line);
@@ -57,11 +68,12 @@ void grpc_cq_internal_unref(grpc_completion_queue *cc);
 
 /* Flag that an operation is beginning: the completion channel will not finish
    shutdown until a corrensponding grpc_cq_end_* call is made */
-void grpc_cq_begin_op(grpc_completion_queue *cc, grpc_call *call);
+void grpc_cq_begin_op(grpc_completion_queue *cc);
 
 /* Queue a GRPC_OP_COMPLETED operation */
-void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, grpc_call *call,
-                    int success);
+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);
 
 grpc_pollset *grpc_cq_pollset(grpc_completion_queue *cc);
 
diff --git a/src/core/surface/init.c b/src/core/surface/init.c
index 3847ded28c..04e27d30ac 100644
--- a/src/core/surface/init.c
+++ b/src/core/surface/init.c
@@ -35,6 +35,7 @@
 
 #include <grpc/census.h>
 #include <grpc/grpc.h>
+#include <grpc/support/time.h>
 #include "src/core/channel/channel_stack.h"
 #include "src/core/client_config/resolver_registry.h"
 #include "src/core/client_config/resolvers/dns_resolver.h"
@@ -64,6 +65,7 @@ void grpc_init(void) {
 
   gpr_mu_lock(&g_init_mu);
   if (++g_initializations == 1) {
+    gpr_time_init();
     grpc_resolver_registry_init("dns:///");
     grpc_register_resolver_type("dns", grpc_dns_resolver_factory_create());
 #ifdef GPR_POSIX_SOCKET
diff --git a/src/core/surface/server.c b/src/core/surface/server.c
index 8f49f1c351..5bcba39753 100644
--- a/src/core/surface/server.c
+++ b/src/core/surface/server.c
@@ -72,12 +72,14 @@ typedef struct {
 
 typedef enum { BATCH_CALL, REGISTERED_CALL } requested_call_type;
 
-typedef struct {
+typedef struct requested_call {
   requested_call_type type;
+  struct requested_call *next;
   void *tag;
   grpc_completion_queue *cq_bound_to_call;
   grpc_completion_queue *cq_for_notification;
   grpc_call **call;
+  grpc_cq_completion completion;
   union {
     struct {
       grpc_call_details *details;
@@ -92,17 +94,11 @@ typedef struct {
   } data;
 } requested_call;
 
-typedef struct {
-  requested_call *calls;
-  size_t count;
-  size_t capacity;
-} requested_call_array;
-
 struct registered_method {
   char *method;
   char *host;
   call_data *pending;
-  requested_call_array requested;
+  requested_call *requests;
   registered_method *next;
 };
 
@@ -131,6 +127,7 @@ struct channel_data {
 typedef struct shutdown_tag {
   void *tag;
   grpc_completion_queue *cq;
+  grpc_cq_completion completion;
 } shutdown_tag;
 
 struct grpc_server {
@@ -153,7 +150,7 @@ struct grpc_server {
   gpr_mu mu_call;   /* mutex for call-specific state */
 
   registered_method *registered_methods;
-  requested_call_array requested_calls;
+  requested_call *requests;
 
   gpr_uint8 shutdown;
   gpr_uint8 shutdown_published;
@@ -166,6 +163,9 @@ struct grpc_server {
   listener *listeners;
   int listeners_destroyed;
   gpr_refcount internal_refcount;
+
+  /** when did we print the last shutdown progress message */
+  gpr_timespec last_shutdown_message_time;
 };
 
 typedef enum {
@@ -270,7 +270,8 @@ static void send_shutdown(grpc_channel *channel, int send_goaway,
 }
 
 static void channel_broadcaster_shutdown(channel_broadcaster *cb,
-                                         int send_goaway, int force_disconnect) {
+                                         int send_goaway,
+                                         int force_disconnect) {
   size_t i;
 
   for (i = 0; i < cb->num_channels; i++) {
@@ -329,22 +330,6 @@ static int call_list_remove(call_data *call, call_list list) {
   return 1;
 }
 
-static void requested_call_array_destroy(requested_call_array *array) {
-  gpr_free(array->calls);
-}
-
-static requested_call *requested_call_array_add(requested_call_array *array) {
-  requested_call *rc;
-  if (array->count == array->capacity) {
-    array->capacity = GPR_MAX(array->capacity + 8, array->capacity * 2);
-    array->calls =
-        gpr_realloc(array->calls, sizeof(requested_call) * array->capacity);
-  }
-  rc = &array->calls[array->count++];
-  memset(rc, 0, sizeof(*rc));
-  return rc;
-}
-
 static void server_ref(grpc_server *server) {
   gpr_ref(&server->internal_refcount);
 }
@@ -356,12 +341,10 @@ static void server_delete(grpc_server *server) {
   gpr_mu_destroy(&server->mu_global);
   gpr_mu_destroy(&server->mu_call);
   gpr_free(server->channel_filters);
-  requested_call_array_destroy(&server->requested_calls);
   while ((rm = server->registered_methods) != NULL) {
     server->registered_methods = rm->next;
     gpr_free(rm->method);
     gpr_free(rm->host);
-    requested_call_array_destroy(&rm->requested);
     gpr_free(rm);
   }
   for (i = 0; i < server->cq_count; i++) {
@@ -409,23 +392,24 @@ static void destroy_channel(channel_data *chand) {
 
 static void finish_start_new_rpc(grpc_server *server, grpc_call_element *elem,
                                  call_data **pending_root,
-                                 requested_call_array *array) {
-  requested_call rc;
+                                 requested_call **requests) {
+  requested_call *rc;
   call_data *calld = elem->call_data;
   gpr_mu_lock(&server->mu_call);
-  if (array->count == 0) {
+  rc = *requests;
+  if (rc == NULL) {
     gpr_mu_lock(&calld->mu_state);
     calld->state = PENDING;
     gpr_mu_unlock(&calld->mu_state);
     call_list_join(pending_root, calld, PENDING_START);
     gpr_mu_unlock(&server->mu_call);
   } else {
-    rc = array->calls[--array->count];
+    *requests = rc->next;
     gpr_mu_lock(&calld->mu_state);
     calld->state = ACTIVATED;
     gpr_mu_unlock(&calld->mu_state);
     gpr_mu_unlock(&server->mu_call);
-    begin_call(server, calld, &rc);
+    begin_call(server, calld, rc);
   }
 }
 
@@ -441,14 +425,14 @@ static void start_new_rpc(grpc_call_element *elem) {
     /* TODO(ctiller): unify these two searches */
     /* check for an exact match with host */
     hash = GRPC_MDSTR_KV_HASH(calld->host->hash, calld->path->hash);
-    for (i = 0; i < chand->registered_method_max_probes; i++) {
+    for (i = 0; i <= chand->registered_method_max_probes; i++) {
       rm = &chand->registered_methods[(hash + i) %
                                       chand->registered_method_slots];
       if (!rm) break;
       if (rm->host != calld->host) continue;
       if (rm->method != calld->path) continue;
       finish_start_new_rpc(server, elem, &rm->server_registered_method->pending,
-                           &rm->server_registered_method->requested);
+                           &rm->server_registered_method->requests);
       return;
     }
     /* check for a wildcard method definition (no host set) */
@@ -460,12 +444,12 @@ static void start_new_rpc(grpc_call_element *elem) {
       if (rm->host != NULL) continue;
       if (rm->method != calld->path) continue;
       finish_start_new_rpc(server, elem, &rm->server_registered_method->pending,
-                           &rm->server_registered_method->requested);
+                           &rm->server_registered_method->requests);
       return;
     }
   }
   finish_start_new_rpc(server, elem, &server->lists[PENDING_START],
-                       &server->requested_calls);
+                       &server->requests);
 }
 
 static void kill_zombie(void *elem, int success) {
@@ -481,26 +465,47 @@ static int num_listeners(grpc_server *server) {
   return n;
 }
 
+static void done_shutdown_event(void *server, grpc_cq_completion *completion) {
+  server_unref(server);
+}
+
+static int num_channels(grpc_server *server) {
+  channel_data *chand;
+  int n = 0;
+  for (chand = server->root_channel_data.next;
+       chand != &server->root_channel_data; chand = chand->next) {
+    n++;
+  }
+  return n;
+}
+
 static void maybe_finish_shutdown(grpc_server *server) {
   size_t i;
   if (!server->shutdown || server->shutdown_published) {
     return;
   }
 
-  if (server->root_channel_data.next != &server->root_channel_data) {
-    gpr_log(GPR_DEBUG,
-            "Waiting for all channels to close before destroying server");
-    return;
-  }
-  if (server->listeners_destroyed < num_listeners(server)) {
-    gpr_log(GPR_DEBUG, "Waiting for all listeners to be destroyed (@ %d/%d)",
-            server->listeners_destroyed, num_listeners(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), server->last_shutdown_message_time),
+            gpr_time_from_seconds(1)) >= 0) {
+      server->last_shutdown_message_time = gpr_now(GPR_CLOCK_REALTIME);
+      gpr_log(GPR_DEBUG,
+              "Waiting for %d channels and %d/%d listeners to be destroyed"
+              " before shutting down server",
+              num_channels(server),
+              num_listeners(server) - server->listeners_destroyed,
+              num_listeners(server));
+    }
     return;
   }
   server->shutdown_published = 1;
   for (i = 0; i < server->num_shutdown_tags; i++) {
-    grpc_cq_end_op(server->shutdown_tags[i].cq, server->shutdown_tags[i].tag,
-                   NULL, 1);
+    server_ref(server);
+    grpc_cq_end_op(server->shutdown_tags[i].cq, server->shutdown_tags[i].tag, 1,
+                   done_shutdown_event, server,
+                   &server->shutdown_tags[i].completion);
   }
 }
 
@@ -924,15 +929,14 @@ void grpc_server_setup_transport(grpc_server *s, grpc_transport *transport,
 void grpc_server_shutdown_and_notify(grpc_server *server,
                                      grpc_completion_queue *cq, void *tag) {
   listener *l;
-  requested_call_array requested_calls;
-  size_t i;
+  requested_call *requests = NULL;
   registered_method *rm;
   shutdown_tag *sdt;
   channel_broadcaster broadcaster;
 
   /* lock, and gather up some stuff to do */
   gpr_mu_lock(&server->mu_global);
-  grpc_cq_begin_op(cq, NULL);
+  grpc_cq_begin_op(cq);
   server->shutdown_tags =
       gpr_realloc(server->shutdown_tags,
                   sizeof(shutdown_tag) * (server->num_shutdown_tags + 1));
@@ -944,27 +948,21 @@ void grpc_server_shutdown_and_notify(grpc_server *server,
     return;
   }
 
+  server->last_shutdown_message_time = gpr_now(GPR_CLOCK_REALTIME);
+
   channel_broadcaster_init(server, &broadcaster);
 
   /* collect all unregistered then registered calls */
   gpr_mu_lock(&server->mu_call);
-  requested_calls = server->requested_calls;
-  memset(&server->requested_calls, 0, sizeof(server->requested_calls));
+  requests = server->requests;
+  server->requests = NULL;
   for (rm = server->registered_methods; rm; rm = rm->next) {
-    if (requested_calls.count + rm->requested.count >
-        requested_calls.capacity) {
-      requested_calls.capacity =
-          GPR_MAX(requested_calls.count + rm->requested.count,
-                  2 * requested_calls.capacity);
-      requested_calls.calls =
-          gpr_realloc(requested_calls.calls, sizeof(*requested_calls.calls) *
-                                                 requested_calls.capacity);
+    while (rm->requests != NULL) {
+      requested_call *c = rm->requests;
+      rm->requests = c->next;
+      c->next = requests;
+      requests = c;
     }
-    memcpy(requested_calls.calls + requested_calls.count, rm->requested.calls,
-           sizeof(*requested_calls.calls) * rm->requested.count);
-    requested_calls.count += rm->requested.count;
-    gpr_free(rm->requested.calls);
-    memset(&rm->requested, 0, sizeof(rm->requested));
   }
   gpr_mu_unlock(&server->mu_call);
 
@@ -973,10 +971,11 @@ void grpc_server_shutdown_and_notify(grpc_server *server,
   gpr_mu_unlock(&server->mu_global);
 
   /* terminate all the requested calls */
-  for (i = 0; i < requested_calls.count; i++) {
-    fail_call(server, &requested_calls.calls[i]);
+  while (requests != NULL) {
+    requested_call *next = requests->next;
+    fail_call(server, requests);
+    requests = next;
   }
-  gpr_free(requested_calls.calls);
 
   /* Shutdown listeners */
   for (l = server->listeners; l; l = l->next) {
@@ -1038,7 +1037,7 @@ void grpc_server_add_listener(grpc_server *server, void *arg,
 static grpc_call_error queue_call_request(grpc_server *server,
                                           requested_call *rc) {
   call_data *calld = NULL;
-  requested_call_array *requested_calls = NULL;
+  requested_call **requests = NULL;
   gpr_mu_lock(&server->mu_call);
   if (server->shutdown) {
     gpr_mu_unlock(&server->mu_call);
@@ -1049,12 +1048,12 @@ static grpc_call_error queue_call_request(grpc_server *server,
     case BATCH_CALL:
       calld =
           call_list_remove_head(&server->lists[PENDING_START], PENDING_START);
-      requested_calls = &server->requested_calls;
+      requests = &server->requests;
       break;
     case REGISTERED_CALL:
       calld = call_list_remove_head(
           &rc->data.registered.registered_method->pending, PENDING_START);
-      requested_calls = &rc->data.registered.registered_method->requested;
+      requests = &rc->data.registered.registered_method->requests;
       break;
   }
   if (calld != NULL) {
@@ -1066,7 +1065,8 @@ static grpc_call_error queue_call_request(grpc_server *server,
     begin_call(server, calld, rc);
     return GRPC_CALL_OK;
   } else {
-    *requested_call_array_add(requested_calls) = *rc;
+    rc->next = *requests;
+    *requests = rc;
     gpr_mu_unlock(&server->mu_call);
     return GRPC_CALL_OK;
   }
@@ -1077,22 +1077,23 @@ grpc_call_error grpc_server_request_call(
     grpc_metadata_array *initial_metadata,
     grpc_completion_queue *cq_bound_to_call,
     grpc_completion_queue *cq_for_notification, void *tag) {
-  requested_call rc;
+  requested_call *rc = gpr_malloc(sizeof(*rc));
   GRPC_SERVER_LOG_REQUEST_CALL(GPR_INFO, server, call, details,
                                initial_metadata, cq_bound_to_call,
                                cq_for_notification, tag);
   if (!grpc_cq_is_server_cq(cq_for_notification)) {
+    gpr_free(rc);
     return GRPC_CALL_ERROR_NOT_SERVER_COMPLETION_QUEUE;
   }
-  grpc_cq_begin_op(cq_for_notification, NULL);
-  rc.type = BATCH_CALL;
-  rc.tag = tag;
-  rc.cq_bound_to_call = cq_bound_to_call;
-  rc.cq_for_notification = cq_for_notification;
-  rc.call = call;
-  rc.data.batch.details = details;
-  rc.data.batch.initial_metadata = initial_metadata;
-  return queue_call_request(server, &rc);
+  grpc_cq_begin_op(cq_for_notification);
+  rc->type = BATCH_CALL;
+  rc->tag = tag;
+  rc->cq_bound_to_call = cq_bound_to_call;
+  rc->cq_for_notification = cq_for_notification;
+  rc->call = call;
+  rc->data.batch.details = details;
+  rc->data.batch.initial_metadata = initial_metadata;
+  return queue_call_request(server, rc);
 }
 
 grpc_call_error grpc_server_request_registered_call(
@@ -1100,22 +1101,23 @@ grpc_call_error grpc_server_request_registered_call(
     grpc_metadata_array *initial_metadata, grpc_byte_buffer **optional_payload,
     grpc_completion_queue *cq_bound_to_call,
     grpc_completion_queue *cq_for_notification, void *tag) {
-  requested_call rc;
+  requested_call *rc = gpr_malloc(sizeof(*rc));
   registered_method *registered_method = rm;
   if (!grpc_cq_is_server_cq(cq_for_notification)) {
+    gpr_free(rc);
     return GRPC_CALL_ERROR_NOT_SERVER_COMPLETION_QUEUE;
   }
-  grpc_cq_begin_op(cq_for_notification, NULL);
-  rc.type = REGISTERED_CALL;
-  rc.tag = tag;
-  rc.cq_bound_to_call = cq_bound_to_call;
-  rc.cq_for_notification = cq_for_notification;
-  rc.call = call;
-  rc.data.registered.registered_method = registered_method;
-  rc.data.registered.deadline = deadline;
-  rc.data.registered.initial_metadata = initial_metadata;
-  rc.data.registered.optional_payload = optional_payload;
-  return queue_call_request(server, &rc);
+  grpc_cq_begin_op(cq_for_notification);
+  rc->type = REGISTERED_CALL;
+  rc->tag = tag;
+  rc->cq_bound_to_call = cq_bound_to_call;
+  rc->cq_for_notification = cq_for_notification;
+  rc->call = call;
+  rc->data.registered.registered_method = registered_method;
+  rc->data.registered.deadline = deadline;
+  rc->data.registered.initial_metadata = initial_metadata;
+  rc->data.registered.optional_payload = optional_payload;
+  return queue_call_request(server, rc);
 }
 
 static void publish_registered_or_batch(grpc_call *call, int success,
@@ -1182,8 +1184,11 @@ static void begin_call(grpc_server *server, call_data *calld,
   }
 
   GRPC_CALL_INTERNAL_REF(calld->call, "server");
-  grpc_call_start_ioreq_and_call_back(calld->call, req, r - req, publish,
-                                      rc->tag);
+  grpc_call_start_ioreq_and_call_back(calld->call, req, r - req, publish, rc);
+}
+
+static void done_request_event(void *req, grpc_cq_completion *c) {
+  gpr_free(req);
 }
 
 static void fail_call(grpc_server *server, requested_call *rc) {
@@ -1196,15 +1201,19 @@ static void fail_call(grpc_server *server, requested_call *rc) {
       rc->data.registered.initial_metadata->count = 0;
       break;
   }
-  grpc_cq_end_op(rc->cq_for_notification, rc->tag, NULL, 0);
+  grpc_cq_end_op(rc->cq_for_notification, rc->tag, 0, done_request_event, rc,
+                 &rc->completion);
 }
 
 static void publish_registered_or_batch(grpc_call *call, int success,
-                                        void *tag) {
+                                        void *prc) {
   grpc_call_element *elem =
       grpc_call_stack_element(grpc_call_get_call_stack(call), 0);
+  requested_call *rc = prc;
   call_data *calld = elem->call_data;
-  grpc_cq_end_op(calld->cq_new, tag, call, success);
+  grpc_cq_end_op(calld->cq_new, rc->tag, success, done_request_event, rc,
+                 &rc->completion);
+  GRPC_CALL_INTERNAL_UNREF(call, "server", 0);
 }
 
 const grpc_channel_args *grpc_server_get_channel_args(grpc_server *server) {
diff --git a/src/core/surface/version.c b/src/core/surface/version.c
new file mode 100644
index 0000000000..4f5d648371
--- /dev/null
+++ b/src/core/surface/version.c
@@ -0,0 +1,41 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+/* This file is autogenerated from:
+   templates/src/core/surface/version.c.template */
+
+#include <grpc/grpc.h>
+
+const char *grpc_version_string(void) {
+	return "0.10.0.0";
+}
diff --git a/src/core/transport/chttp2/parsing.c b/src/core/transport/chttp2/parsing.c
index 130167f830..9597395aab 100644
--- a/src/core/transport/chttp2/parsing.c
+++ b/src/core/transport/chttp2/parsing.c
@@ -205,7 +205,8 @@ void grpc_chttp2_publish_reads(
     }
     if (stream_parsing->saw_rst_stream) {
       stream_global->cancelled = 1;
-      stream_global->cancelled_status = grpc_chttp2_http2_error_to_grpc_status(stream_parsing->rst_stream_reason);
+      stream_global->cancelled_status = grpc_chttp2_http2_error_to_grpc_status(
+          stream_parsing->rst_stream_reason);
       if (stream_parsing->rst_stream_reason == GRPC_CHTTP2_NO_ERROR) {
         stream_global->published_cancelled = 1;
       }
@@ -599,7 +600,7 @@ static void on_header(void *tp, grpc_mdelem *md) {
     }
     grpc_chttp2_incoming_metadata_buffer_set_deadline(
         &stream_parsing->incoming_metadata,
-        gpr_time_add(gpr_now(), *cached_timeout));
+        gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), *cached_timeout));
     GRPC_MDELEM_UNREF(md);
   } else {
     grpc_chttp2_incoming_metadata_buffer_add(&stream_parsing->incoming_metadata,
diff --git a/src/core/transport/chttp2/stream_encoder.c b/src/core/transport/chttp2/stream_encoder.c
index 49f6ec90c3..14eaccfc47 100644
--- a/src/core/transport/chttp2/stream_encoder.c
+++ b/src/core/transport/chttp2/stream_encoder.c
@@ -437,7 +437,8 @@ static void deadline_enc(grpc_chttp2_hpack_compressor *c, gpr_timespec deadline,
                          framer_state *st) {
   char timeout_str[GRPC_CHTTP2_TIMEOUT_ENCODE_MIN_BUFSIZE];
   grpc_mdelem *mdelem;
-  grpc_chttp2_encode_timeout(gpr_time_sub(deadline, gpr_now()), timeout_str);
+  grpc_chttp2_encode_timeout(
+      gpr_time_sub(deadline, gpr_now(GPR_CLOCK_REALTIME)), timeout_str);
   mdelem = grpc_mdelem_from_metadata_strings(
       c->mdctx, GRPC_MDSTR_REF(c->timeout_key_str),
       grpc_mdstr_from_string(c->mdctx, timeout_str));
diff --git a/src/core/transport/chttp2_transport.c b/src/core/transport/chttp2_transport.c
index 322ff39820..ac399e4a1d 100644
--- a/src/core/transport/chttp2_transport.c
+++ b/src/core/transport/chttp2_transport.c
@@ -876,11 +876,19 @@ static void update_global_window(void *args, gpr_uint32 id, void *stream) {
   grpc_chttp2_stream *s = stream;
   grpc_chttp2_transport_global *transport_global = &t->global;
   grpc_chttp2_stream_global *stream_global = &s->global;
+  int was_zero;
+  int is_zero;
 
   GRPC_CHTTP2_FLOWCTL_TRACE_STREAM("settings", transport_global, stream_global,
                                    outgoing_window,
                                    t->parsing.initial_window_update);
+  was_zero = stream_global->outgoing_window <= 0;
   stream_global->outgoing_window += t->parsing.initial_window_update;
+  is_zero = stream_global->outgoing_window <= 0;
+
+  if (was_zero && !is_zero) {
+    grpc_chttp2_list_add_writable_stream(transport_global, stream_global);
+  }
 }
 
 static void read_error_locked(grpc_chttp2_transport *t) {
diff --git a/src/core/transport/metadata.c b/src/core/transport/metadata.c
index 9cbb0952d0..e95b7a21f9 100644
--- a/src/core/transport/metadata.c
+++ b/src/core/transport/metadata.c
@@ -87,6 +87,7 @@ typedef struct internal_metadata {
   gpr_atm refcnt;
 
   /* private only data */
+  gpr_mu mu_user_data;
   void *user_data;
   void (*destroy_user_data)(void *user_data);
 
@@ -183,7 +184,7 @@ grpc_mdctx *grpc_mdctx_create(void) {
   /* This seed is used to prevent remote connections from controlling hash table
    * collisions. It needs to be somewhat unpredictable to a remote connection.
    */
-  return grpc_mdctx_create_with_seed(gpr_now().tv_nsec);
+  return grpc_mdctx_create_with_seed(gpr_now(GPR_CLOCK_REALTIME).tv_nsec);
 }
 
 static void discard_metadata(grpc_mdctx *ctx) {
@@ -200,6 +201,7 @@ static void discard_metadata(grpc_mdctx *ctx) {
       if (cur->user_data) {
         cur->destroy_user_data(cur->user_data);
       }
+      gpr_mu_destroy(&cur->mu_user_data);
       gpr_free(cur);
       cur = next;
       ctx->mdtab_free--;
@@ -467,6 +469,7 @@ grpc_mdelem *grpc_mdelem_from_metadata_strings(grpc_mdctx *ctx,
   md->user_data = NULL;
   md->destroy_user_data = NULL;
   md->bucket_next = ctx->mdtab[hash % ctx->mdtab_capacity];
+  gpr_mu_init(&md->mu_user_data);
 #ifdef GRPC_METADATA_REFCOUNT_DEBUG
   gpr_log(GPR_DEBUG, "ELM   NEW:%p:%d: '%s' = '%s'", md,
           gpr_atm_no_barrier_load(&md->refcnt),
@@ -581,18 +584,29 @@ size_t grpc_mdctx_get_mdtab_free_test_only(grpc_mdctx *ctx) {
 void *grpc_mdelem_get_user_data(grpc_mdelem *md,
                                 void (*if_destroy_func)(void *)) {
   internal_metadata *im = (internal_metadata *)md;
-  return im->destroy_user_data == if_destroy_func ? im->user_data : NULL;
+  void *result;
+  gpr_mu_lock(&im->mu_user_data);
+  result = im->destroy_user_data == if_destroy_func ? im->user_data : NULL;
+  gpr_mu_unlock(&im->mu_user_data);
+  return result;
 }
 
 void grpc_mdelem_set_user_data(grpc_mdelem *md, void (*destroy_func)(void *),
                                void *user_data) {
   internal_metadata *im = (internal_metadata *)md;
   GPR_ASSERT((user_data == NULL) == (destroy_func == NULL));
+  gpr_mu_lock(&im->mu_user_data);
   if (im->destroy_user_data) {
-    im->destroy_user_data(im->user_data);
+    /* user data can only be set once */
+    gpr_mu_unlock(&im->mu_user_data);
+    if (destroy_func != NULL) {
+      destroy_func(user_data);
+    }
+    return;
   }
   im->destroy_user_data = destroy_func;
   im->user_data = user_data;
+  gpr_mu_unlock(&im->mu_user_data);
 }
 
 gpr_slice grpc_mdstr_as_base64_encoded_and_huffman_compressed(grpc_mdstr *gs) {
diff --git a/src/cpp/client/client_context.cc b/src/cpp/client/client_context.cc
index 0eba554e33..cc5f51d618 100644
--- a/src/cpp/client/client_context.cc
+++ b/src/cpp/client/client_context.cc
@@ -39,6 +39,7 @@
 #include <grpc++/time.h>
 
 #include "src/core/channel/compress_filter.h"
+#include "src/cpp/common/create_auth_context.h"
 
 namespace grpc {
 
@@ -96,6 +97,13 @@ void ClientContext::set_compression_algorithm(
   AddMetadata(GRPC_COMPRESS_REQUEST_ALGORITHM_KEY, algorithm_name);
 }
 
+std::shared_ptr<const AuthContext> ClientContext::auth_context() const {
+  if (auth_context_.get() == nullptr) {
+    auth_context_ = CreateAuthContext(call_);
+  }
+  return auth_context_;
+}
+
 void ClientContext::TryCancel() {
   if (call_) {
     grpc_call_cancel(call_);
diff --git a/src/cpp/common/create_auth_context.h b/src/cpp/common/create_auth_context.h
new file mode 100644
index 0000000000..9082a90c6d
--- /dev/null
+++ b/src/cpp/common/create_auth_context.h
@@ -0,0 +1,42 @@
+/*
+ *
+ * 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 <memory>
+
+#include <grpc/grpc.h>
+#include <grpc++/auth_context.h>
+
+namespace grpc {
+
+std::shared_ptr<const AuthContext> CreateAuthContext(grpc_call* call);
+
+}  // namespace grpc
diff --git a/src/cpp/common/insecure_create_auth_context.cc b/src/cpp/common/insecure_create_auth_context.cc
new file mode 100644
index 0000000000..07fc0bd549
--- /dev/null
+++ b/src/cpp/common/insecure_create_auth_context.cc
@@ -0,0 +1,45 @@
+/*
+ *
+ * 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 <memory>
+
+#include <grpc/grpc.h>
+#include <grpc++/auth_context.h>
+
+namespace grpc {
+
+std::shared_ptr<const AuthContext> CreateAuthContext(grpc_call* call) {
+  (void)call;
+  return std::shared_ptr<const AuthContext>();
+}
+
+}  // namespace grpc
diff --git a/src/cpp/common/secure_auth_context.cc b/src/cpp/common/secure_auth_context.cc
new file mode 100644
index 0000000000..4513723653
--- /dev/null
+++ b/src/cpp/common/secure_auth_context.cc
@@ -0,0 +1,80 @@
+/*
+ *
+ * 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 "src/cpp/common/secure_auth_context.h"
+
+#include <grpc/grpc_security.h>
+
+namespace grpc {
+
+SecureAuthContext::SecureAuthContext(grpc_auth_context* ctx) : ctx_(ctx) {}
+
+SecureAuthContext::~SecureAuthContext() { grpc_auth_context_release(ctx_); }
+
+std::vector<grpc::string> SecureAuthContext::GetPeerIdentity() const {
+  if (!ctx_) {
+    return std::vector<grpc::string>();
+  }
+  grpc_auth_property_iterator iter = grpc_auth_context_peer_identity(ctx_);
+  std::vector<grpc::string> identity;
+  const grpc_auth_property* property = nullptr;
+  while ((property = grpc_auth_property_iterator_next(&iter))) {
+    identity.push_back(grpc::string(property->value, property->value_length));
+  }
+  return identity;
+}
+
+grpc::string SecureAuthContext::GetPeerIdentityPropertyName() const {
+  if (!ctx_) {
+    return "";
+  }
+  const char* name = grpc_auth_context_peer_identity_property_name(ctx_);
+  return name == nullptr ? "" : name;
+}
+
+std::vector<grpc::string> SecureAuthContext::FindPropertyValues(
+    const grpc::string& name) const {
+  if (!ctx_) {
+    return std::vector<grpc::string>();
+  }
+  grpc_auth_property_iterator iter =
+      grpc_auth_context_find_properties_by_name(ctx_, name.c_str());
+  const grpc_auth_property* property = nullptr;
+  std::vector<grpc::string> values;
+  while ((property = grpc_auth_property_iterator_next(&iter))) {
+    values.push_back(grpc::string(property->value, property->value_length));
+  }
+  return values;
+}
+
+}  // namespace grpc
diff --git a/src/cpp/common/secure_auth_context.h b/src/cpp/common/secure_auth_context.h
new file mode 100644
index 0000000000..bba46803cd
--- /dev/null
+++ b/src/cpp/common/secure_auth_context.h
@@ -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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CPP_COMMON_SECURE_AUTH_CONTEXT_H
+#define GRPC_INTERNAL_CPP_COMMON_SECURE_AUTH_CONTEXT_H
+
+#include <grpc++/auth_context.h>
+
+struct grpc_auth_context;
+
+namespace grpc {
+
+class SecureAuthContext GRPC_FINAL : public AuthContext {
+ public:
+  SecureAuthContext(grpc_auth_context* ctx);
+
+  ~SecureAuthContext() GRPC_OVERRIDE;
+
+  std::vector<grpc::string> GetPeerIdentity() const GRPC_OVERRIDE;
+
+  grpc::string GetPeerIdentityPropertyName() const GRPC_OVERRIDE;
+
+  std::vector<grpc::string> FindPropertyValues(const grpc::string& name) const
+      GRPC_OVERRIDE;
+
+ private:
+  grpc_auth_context* ctx_;
+};
+
+}  // namespace grpc
+
+#endif  // GRPC_INTERNAL_CPP_COMMON_SECURE_AUTH_CONTEXT_H
diff --git a/src/cpp/common/secure_create_auth_context.cc b/src/cpp/common/secure_create_auth_context.cc
new file mode 100644
index 0000000000..d81f4bbc4a
--- /dev/null
+++ b/src/cpp/common/secure_create_auth_context.cc
@@ -0,0 +1,50 @@
+/*
+ *
+ * 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 <memory>
+
+#include <grpc/grpc.h>
+#include <grpc/grpc_security.h>
+#include <grpc++/auth_context.h>
+#include "src/cpp/common/secure_auth_context.h"
+
+namespace grpc {
+
+std::shared_ptr<const AuthContext> CreateAuthContext(grpc_call* call) {
+  if (call == nullptr) {
+    return std::shared_ptr<const AuthContext>();
+  }
+  return std::shared_ptr<const AuthContext>(
+      new SecureAuthContext(grpc_call_auth_context(call)));
+}
+
+}  // namespace grpc
diff --git a/src/cpp/server/async_server_context.cc b/src/cpp/server/async_server_context.cc
deleted file mode 100644
index e1f29452a4..0000000000
--- a/src/cpp/server/async_server_context.cc
+++ /dev/null
@@ -1,99 +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++/async_server_context.h>
-
-#include <grpc/grpc.h>
-#include <grpc/support/log.h>
-#include "src/cpp/proto/proto_utils.h"
-#include <grpc++/config.h>
-#include <grpc++/status.h>
-
-namespace grpc {
-
-AsyncServerContext::AsyncServerContext(
-    grpc_call* call, const grpc::string& method, const grpc::string& host,
-    system_clock::time_point absolute_deadline)
-    : method_(method),
-      host_(host),
-      absolute_deadline_(absolute_deadline),
-      request_(nullptr),
-      call_(call) {}
-
-AsyncServerContext::~AsyncServerContext() { grpc_call_destroy(call_); }
-
-void AsyncServerContext::Accept(grpc_completion_queue* cq) {
-  GPR_ASSERT(grpc_call_server_accept_old(call_, cq, this) == GRPC_CALL_OK);
-  GPR_ASSERT(grpc_call_server_end_initial_metadata_old(
-                 call_, GRPC_WRITE_BUFFER_HINT) == GRPC_CALL_OK);
-}
-
-bool AsyncServerContext::StartRead(grpc::protobuf::Message* request) {
-  GPR_ASSERT(request);
-  request_ = request;
-  grpc_call_error err = grpc_call_start_read_old(call_, this);
-  return err == GRPC_CALL_OK;
-}
-
-bool AsyncServerContext::StartWrite(const grpc::protobuf::Message& response,
-                                    int flags) {
-  grpc_byte_buffer* buffer = nullptr;
-  GRPC_TIMER_MARK(SER_PROTO_BEGIN, call_->call());
-  if (!SerializeProto(response, &buffer)) {
-    return false;
-  }
-  GRPC_TIMER_MARK(SER_PROTO_END, call_->call());
-  grpc_call_error err = grpc_call_start_write_old(call_, buffer, this, flags);
-  grpc_byte_buffer_destroy(buffer);
-  return err == GRPC_CALL_OK;
-}
-
-bool AsyncServerContext::StartWriteStatus(const Status& status) {
-  grpc_call_error err = grpc_call_start_write_status_old(
-      call_, static_cast<grpc_status_code>(status.code()),
-      status.details().empty() ? nullptr
-                               : const_cast<char*>(status.details().c_str()),
-      this);
-  return err == GRPC_CALL_OK;
-}
-
-bool AsyncServerContext::ParseRead(grpc_byte_buffer* read_buffer) {
-  GPR_ASSERT(request_);
-  GRPC_TIMER_MARK(DESER_PROTO_BEGIN, call_->call());
-  bool success = DeserializeProto(read_buffer, request_);
-  GRPC_TIMER_MARK(DESER_PROTO_END, call_->call());
-  request_ = nullptr;
-  return success;
-}
-
-}  // namespace grpc
diff --git a/src/cpp/server/server.cc b/src/cpp/server/server.cc
index f9d20ff579..e6761d6244 100644
--- a/src/cpp/server/server.cc
+++ b/src/cpp/server/server.cc
@@ -118,7 +118,7 @@ class Server::SyncRequest GRPC_FINAL : public CompletionQueueTag {
           has_request_payload_(mrd->has_request_payload_),
           request_payload_(mrd->request_payload_),
           method_(mrd->method_) {
-      ctx_.call_ = mrd->call_;
+      ctx_.set_call(mrd->call_);
       ctx_.cq_ = &cq_;
       GPR_ASSERT(mrd->in_flight_);
       mrd->in_flight_ = false;
@@ -326,7 +326,7 @@ bool Server::BaseAsyncRequest::FinalizeResult(void** tag, bool* status) {
     }
   }
   grpc_metadata_array_destroy(&initial_metadata_array_);
-  context_->call_ = call_;
+  context_->set_call(call_);
   context_->cq_ = call_cq_;
   Call call(call_, server_, call_cq_, server_->max_message_size_);
   if (*status && call_) {
diff --git a/src/cpp/server/server_context.cc b/src/cpp/server/server_context.cc
index 087e28d33a..e028b9dc02 100644
--- a/src/cpp/server/server_context.cc
+++ b/src/cpp/server/server_context.cc
@@ -40,6 +40,7 @@
 #include <grpc++/time.h>
 
 #include "src/core/channel/compress_filter.h"
+#include "src/cpp/common/create_auth_context.h"
 
 namespace grpc {
 
@@ -166,4 +167,16 @@ void ServerContext::set_compression_algorithm(
   AddInitialMetadata(GRPC_COMPRESS_REQUEST_ALGORITHM_KEY, algorithm_name);
 }
 
+void ServerContext::set_call(grpc_call* call) {
+  call_ = call;
+  auth_context_ = CreateAuthContext(call);
+}
+
+std::shared_ptr<const AuthContext> ServerContext::auth_context() const {
+  if (auth_context_.get() == nullptr) {
+    auth_context_ = CreateAuthContext(call_);
+  }
+  return auth_context_;
+}
+
 }  // namespace grpc
diff --git a/src/csharp/Grpc.Auth/Grpc.Auth.csproj b/src/csharp/Grpc.Auth/Grpc.Auth.csproj
index e6abbbfdf0..fdec2e7bd7 100644
--- a/src/csharp/Grpc.Auth/Grpc.Auth.csproj
+++ b/src/csharp/Grpc.Auth/Grpc.Auth.csproj
@@ -68,6 +68,9 @@
     <Reference Include="System.Net.Http.WebRequest" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="..\Grpc.Core\Version.cs">
+      <Link>Version.cs</Link>
+    </Compile>
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="GoogleCredential.cs" />
     <Compile Include="OAuth2InterceptorFactory.cs" />
@@ -81,6 +84,7 @@
   </ItemGroup>
   <ItemGroup>
     <None Include="app.config" />
+    <None Include="Grpc.Auth.nuspec" />
     <None Include="packages.config" />
   </ItemGroup>
   <Import Project="..\packages\Microsoft.Bcl.Build.1.0.14\tools\Microsoft.Bcl.Build.targets" Condition="Exists('..\packages\Microsoft.Bcl.Build.1.0.14\tools\Microsoft.Bcl.Build.targets')" />
diff --git a/src/csharp/Grpc.Auth/Grpc.Auth.nuspec b/src/csharp/Grpc.Auth/Grpc.Auth.nuspec
index e7a538b21b..1262bdbdab 100644
--- a/src/csharp/Grpc.Auth/Grpc.Auth.nuspec
+++ b/src/csharp/Grpc.Auth/Grpc.Auth.nuspec
@@ -5,19 +5,19 @@
     <title>gRPC C# Auth</title>
     <summary>Auth library for C# implementation of gRPC - an RPC library and framework</summary>
     <description>Auth library for C# implementation of gRPC - an RPC library and framework. See project site for more info.</description>
-    <version>0.5.1</version>
+    <version>$version$</version>
     <authors>Google Inc.</authors>
     <owners>grpc-packages</owners>
     <licenseUrl>https://github.com/grpc/grpc/blob/master/LICENSE</licenseUrl>
     <projectUrl>https://github.com/grpc/grpc</projectUrl>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
-    <releaseNotes>Release 0.5.1 of gRPC C#</releaseNotes>
+    <releaseNotes>Release $version$ of gRPC C#</releaseNotes>
     <copyright>Copyright 2015, Google Inc.</copyright>
     <tags>gRPC RPC Protocol HTTP/2 Auth OAuth2</tags>
 	<dependencies>
 	  <dependency id="BouncyCastle" version="1.7.0" />
 	  <dependency id="Google.Apis.Auth" version="1.9.1" />
-	  <dependency id="Grpc.Core" version="0.5.1" />
+	  <dependency id="Grpc.Core" version="$version$" />
     </dependencies>
   </metadata>
   <files>
diff --git a/src/csharp/Grpc.Auth/Properties/AssemblyInfo.cs b/src/csharp/Grpc.Auth/Properties/AssemblyInfo.cs
index c442ccc977..70cb32d5b2 100644
--- a/src/csharp/Grpc.Auth/Properties/AssemblyInfo.cs
+++ b/src/csharp/Grpc.Auth/Properties/AssemblyInfo.cs
@@ -9,6 +9,5 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]
-[assembly: AssemblyVersion("0.5.*")]
 
 [assembly: InternalsVisibleTo("Grpc.Auth.Tests")]
diff --git a/src/csharp/Grpc.Core.Tests/ClientServerTest.cs b/src/csharp/Grpc.Core.Tests/ClientServerTest.cs
index 21f94d3cf5..e797dd82f2 100644
--- a/src/csharp/Grpc.Core.Tests/ClientServerTest.cs
+++ b/src/csharp/Grpc.Core.Tests/ClientServerTest.cs
@@ -73,12 +73,6 @@ namespace Grpc.Core.Tests
         Server server;
         Channel channel;
 
-        [TestFixtureSetUp]
-        public void InitClass()
-        {
-            GrpcEnvironment.Initialize();
-        }
-
         [SetUp]
         public void Init()
         {
diff --git a/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj b/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
index 92e28b7d74..927954c448 100644
--- a/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
+++ b/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
@@ -37,6 +37,9 @@
     </Reference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="..\Grpc.Core\Version.cs">
+      <Link>Version.cs</Link>
+    </Compile>
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="ClientServerTest.cs" />
     <Compile Include="ServerTest.cs" />
@@ -63,4 +66,4 @@
     <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
   </ItemGroup>
   <ItemGroup />
-</Project>
+</Project>
+\ No newline at end of file
diff --git a/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs b/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs
index 6a132a5b22..9ae12776f3 100644
--- a/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs
+++ b/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs
@@ -43,16 +43,17 @@ namespace Grpc.Core.Tests
         [Test]
         public void InitializeAndShutdownGrpcEnvironment()
         {
-            GrpcEnvironment.Initialize();
-            Assert.IsNotNull(GrpcEnvironment.ThreadPool.CompletionQueue);
+            var env = GrpcEnvironment.GetInstance();
+            Assert.IsNotNull(env.CompletionQueue);
             GrpcEnvironment.Shutdown();
         }
 
         [Test]
         public void SubsequentInvocations()
         {
-            GrpcEnvironment.Initialize();
-            GrpcEnvironment.Initialize();
+            var env1 = GrpcEnvironment.GetInstance();
+            var env2 = GrpcEnvironment.GetInstance();
+            Assert.IsTrue(object.ReferenceEquals(env1, env2));
             GrpcEnvironment.Shutdown();
             GrpcEnvironment.Shutdown();
         }
@@ -60,15 +61,13 @@ namespace Grpc.Core.Tests
         [Test]
         public void InitializeAfterShutdown()
         {
-            GrpcEnvironment.Initialize();
-            var tp1 = GrpcEnvironment.ThreadPool;
+            var env1 = GrpcEnvironment.GetInstance();
             GrpcEnvironment.Shutdown();
 
-            GrpcEnvironment.Initialize();
-            var tp2 = GrpcEnvironment.ThreadPool;
+            var env2 = GrpcEnvironment.GetInstance();
             GrpcEnvironment.Shutdown();
 
-            Assert.IsFalse(object.ReferenceEquals(tp1, tp2));
+            Assert.IsFalse(object.ReferenceEquals(env1, env2));
         }
     }
 }
diff --git a/src/csharp/Grpc.Core.Tests/PInvokeTest.cs b/src/csharp/Grpc.Core.Tests/PInvokeTest.cs
index 8b3c910251..714c2f7494 100644
--- a/src/csharp/Grpc.Core.Tests/PInvokeTest.cs
+++ b/src/csharp/Grpc.Core.Tests/PInvokeTest.cs
@@ -53,18 +53,6 @@ namespace Grpc.Core.Tests
         [DllImport("grpc_csharp_ext.dll")]
         static extern IntPtr grpcsharp_test_nop(IntPtr ptr);
 
-        [TestFixtureSetUp]
-        public void Init()
-        {
-            GrpcEnvironment.Initialize();
-        }
-
-        [TestFixtureTearDown]
-        public void Cleanup()
-        {
-            GrpcEnvironment.Shutdown();
-        }
-
         /// <summary>
         /// (~1.26us .NET Windows)
         /// </summary>
diff --git a/src/csharp/Grpc.Core.Tests/Properties/AssemblyInfo.cs b/src/csharp/Grpc.Core.Tests/Properties/AssemblyInfo.cs
index 7f6133a992..c2e5e81e91 100644
--- a/src/csharp/Grpc.Core.Tests/Properties/AssemblyInfo.cs
+++ b/src/csharp/Grpc.Core.Tests/Properties/AssemblyInfo.cs
@@ -9,4 +9,3 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]
-[assembly: AssemblyVersion("0.5.*")]
diff --git a/src/csharp/Grpc.Core.Tests/ServerTest.cs b/src/csharp/Grpc.Core.Tests/ServerTest.cs
index 02c773c9cc..1119aa370e 100644
--- a/src/csharp/Grpc.Core.Tests/ServerTest.cs
+++ b/src/csharp/Grpc.Core.Tests/ServerTest.cs
@@ -44,13 +44,10 @@ namespace Grpc.Core.Tests
         [Test]
         public void StartAndShutdownServer()
         {
-            GrpcEnvironment.Initialize();
-
             Server server = new Server();
             server.AddListeningPort("localhost", Server.PickUnusedPort);
             server.Start();
             server.ShutdownAsync().Wait();
-
             GrpcEnvironment.Shutdown();
         }
     }
diff --git a/src/csharp/Grpc.Core/Calls.cs b/src/csharp/Grpc.Core/Calls.cs
index 9f8baac684..750282258f 100644
--- a/src/csharp/Grpc.Core/Calls.cs
+++ b/src/csharp/Grpc.Core/Calls.cs
@@ -58,7 +58,7 @@ namespace Grpc.Core
             where TResponse : class
         {
             var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.Name);
+            asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name);
             var asyncResult = asyncCall.UnaryCallAsync(req, call.Headers);
             RegisterCancellationCallback(asyncCall, token);
             return await asyncResult;
@@ -69,7 +69,7 @@ namespace Grpc.Core
             where TResponse : class
         {
             var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.Name);
+            asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name);
             asyncCall.StartServerStreamingCall(req, call.Headers);
             RegisterCancellationCallback(asyncCall, token);
             var responseStream = new ClientResponseStream<TRequest, TResponse>(asyncCall);
@@ -81,7 +81,7 @@ namespace Grpc.Core
             where TResponse : class
         {
             var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.Name);
+            asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name);
             var resultTask = asyncCall.ClientStreamingCallAsync(call.Headers);
             RegisterCancellationCallback(asyncCall, token);
             var requestStream = new ClientRequestStream<TRequest, TResponse>(asyncCall);
@@ -93,7 +93,7 @@ namespace Grpc.Core
             where TResponse : class
         {
             var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.Name);
+            asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name);
             asyncCall.StartDuplexStreamingCall(call.Headers);
             RegisterCancellationCallback(asyncCall, token);
             var requestStream = new ClientRequestStream<TRequest, TResponse>(asyncCall);
@@ -108,13 +108,5 @@ namespace Grpc.Core
                 token.Register(() => asyncCall.Cancel());
             }
         }
-
-        /// <summary>
-        /// Gets shared completion queue used for async calls.
-        /// </summary>
-        private static CompletionQueueSafeHandle GetCompletionQueue()
-        {
-            return GrpcEnvironment.ThreadPool.CompletionQueue;
-        }
     }
 }
diff --git a/src/csharp/Grpc.Core/Channel.cs b/src/csharp/Grpc.Core/Channel.cs
index d6bfbb7bc4..5baf260003 100644
--- a/src/csharp/Grpc.Core/Channel.cs
+++ b/src/csharp/Grpc.Core/Channel.cs
@@ -42,8 +42,10 @@ namespace Grpc.Core
     /// </summary>
     public class Channel : IDisposable
     {
+        readonly GrpcEnvironment environment;
         readonly ChannelSafeHandle handle;
         readonly string target;
+        bool disposed;
 
         /// <summary>
         /// Creates a channel that connects to a specific host.
@@ -54,6 +56,7 @@ namespace Grpc.Core
         /// <param name="options">Channel options.</param>
         public Channel(string host, Credentials credentials = null, IEnumerable<ChannelOption> options = null)
         {
+            this.environment = GrpcEnvironment.GetInstance();
             using (ChannelArgsSafeHandle nativeChannelArgs = ChannelOptions.CreateChannelArgs(options))
             {
                 if (credentials != null)
@@ -105,10 +108,35 @@ namespace Grpc.Core
             }
         }
 
+        internal CompletionQueueSafeHandle CompletionQueue
+        {
+            get
+            {
+                return this.environment.CompletionQueue;
+            }
+        }
+
+        internal CompletionRegistry CompletionRegistry
+        {
+            get
+            {
+                return this.environment.CompletionRegistry;
+            }
+        }
+
+        internal GrpcEnvironment Environment
+        {
+            get
+            {
+                return this.environment;
+            }
+        }
+
         protected virtual void Dispose(bool disposing)
         {
-            if (handle != null && !handle.IsInvalid)
+            if (disposing && handle != null && !disposed)
             {
+                disposed = true;
                 handle.Dispose();
             }
         }
diff --git a/src/csharp/Grpc.Core/Grpc.Core.csproj b/src/csharp/Grpc.Core/Grpc.Core.csproj
index a36a6a5acc..cde42c3b7e 100644
--- a/src/csharp/Grpc.Core/Grpc.Core.csproj
+++ b/src/csharp/Grpc.Core/Grpc.Core.csproj
@@ -33,8 +33,9 @@
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
-    <Reference Include="System.Collections.Immutable">
-      <HintPath>..\packages\Microsoft.Bcl.Immutable.1.0.34\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+    <Reference Include="System.Collections.Immutable, Version=1.1.36.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath>..\packages\System.Collections.Immutable.1.1.36\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
     </Reference>
     <Reference Include="System.Interactive.Async">
       <HintPath>..\packages\Ix-Async.1.2.3\lib\net45\System.Interactive.Async.dll</HintPath>
@@ -48,6 +49,7 @@
     <Compile Include="IAsyncStreamWriter.cs" />
     <Compile Include="IAsyncStreamReader.cs" />
     <Compile Include="Internal\GrpcLog.cs" />
+    <Compile Include="Version.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="RpcException.cs" />
     <Compile Include="Calls.cs" />
@@ -103,6 +105,7 @@
     <Compile Include="ChannelOptions.cs" />
   </ItemGroup>
   <ItemGroup>
+    <None Include="Grpc.Core.nuspec" />
     <None Include="packages.config" />
   </ItemGroup>
   <Choose>
@@ -130,4 +133,4 @@
   </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')" />
-</Project>
+</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 629b978fdf..5ace6dcf89 100644
--- a/src/csharp/Grpc.Core/Grpc.Core.nuspec
+++ b/src/csharp/Grpc.Core/Grpc.Core.nuspec
@@ -5,19 +5,19 @@
     <title>gRPC C# Core</title>
     <summary>Core C# implementation of gRPC - an RPC library and framework</summary>
     <description>Core C# implementation of gRPC - an RPC library and framework. See project site for more info.</description>
-    <version>0.5.1</version>
+    <version>$version$</version>
     <authors>Google Inc.</authors>
     <owners>grpc-packages</owners>
     <licenseUrl>https://github.com/grpc/grpc/blob/master/LICENSE</licenseUrl>
     <projectUrl>https://github.com/grpc/grpc</projectUrl>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
-    <releaseNotes>Release 0.5.1 of gRPC C#</releaseNotes>
+    <releaseNotes>Release $version$ of gRPC C#</releaseNotes>
     <copyright>Copyright 2015, Google Inc.</copyright>
     <tags>gRPC RPC Protocol HTTP/2</tags>
 	<dependencies>
-	  <dependency id="Microsoft.Bcl.Immutable" version="1.0.34" />
+	  <dependency id="System.Collections.Immutable" version="1.1.36" />
 	  <dependency id="Ix-Async" version="1.2.3" />
-	  <dependency id="grpc.native.csharp_ext" version="0.9.1" />
+	  <dependency id="grpc.native.csharp_ext" version="$GrpcNativeCsharpExtVersion$" />
     </dependencies>
   </metadata>
   <files>
diff --git a/src/csharp/Grpc.Core/GrpcEnvironment.cs b/src/csharp/Grpc.Core/GrpcEnvironment.cs
index 30ff289714..47d1651aab 100644
--- a/src/csharp/Grpc.Core/GrpcEnvironment.cs
+++ b/src/csharp/Grpc.Core/GrpcEnvironment.cs
@@ -33,7 +33,9 @@
 
 using System;
 using System.Runtime.InteropServices;
+using System.Threading.Tasks;
 using Grpc.Core.Internal;
+using Grpc.Core.Utils;
 
 namespace Grpc.Core
 {
@@ -51,20 +53,18 @@ namespace Grpc.Core
         static extern void grpcsharp_shutdown();
 
         static object staticLock = new object();
-        static volatile GrpcEnvironment instance;
+        static GrpcEnvironment instance;
 
         readonly GrpcThreadPool threadPool;
         readonly CompletionRegistry completionRegistry;
+        readonly DebugStats debugStats = new DebugStats();
         bool isClosed;
 
         /// <summary>
-        /// Makes sure GRPC environment is initialized. Subsequent invocations don't have any
-        /// effect unless you call Shutdown first.
-        /// Although normal use cases assume you will call this just once in your application's
-        /// lifetime (and call Shutdown once you're done), for the sake of easier testing it's
-        /// allowed to initialize the environment again after it has been successfully shutdown.
+        /// Returns an instance of initialized gRPC environment.
+        /// Subsequent invocations return the same instance unless Shutdown has been called first.
         /// </summary>
-        public static void Initialize()
+        internal static GrpcEnvironment GetInstance()
         {
             lock (staticLock)
             {
@@ -72,12 +72,13 @@ namespace Grpc.Core
                 {
                     instance = new GrpcEnvironment();
                 }
+                return instance;
             }
         }
 
         /// <summary>
-        /// Shuts down the GRPC environment if it was initialized before.
-        /// Repeated invocations have no effect.
+        /// Shuts down the gRPC environment if it was initialized before.
+        /// Blocks until the environment has been fully shutdown.
         /// </summary>
         public static void Shutdown()
         {
@@ -87,50 +88,55 @@ namespace Grpc.Core
                 {
                     instance.Close();
                     instance = null;
-
-                    CheckDebugStats();
                 }
             }
         }
 
-        internal static GrpcThreadPool ThreadPool
+        /// <summary>
+        /// Creates gRPC environment.
+        /// </summary>
+        private GrpcEnvironment()
+        {
+            GrpcLog.RedirectNativeLogs(Console.Error);
+            grpcsharp_init();
+            completionRegistry = new CompletionRegistry(this);
+            threadPool = new GrpcThreadPool(this, THREAD_POOL_SIZE);
+            threadPool.Start();
+            // TODO: use proper logging here
+            Console.WriteLine("GRPC initialized.");
+        }
+
+        /// <summary>
+        /// Gets the completion registry used by this gRPC environment.
+        /// </summary>
+        internal CompletionRegistry CompletionRegistry
         {
             get
             {
-                var inst = instance;
-                if (inst == null)
-                {
-                    throw new InvalidOperationException("GRPC environment not initialized");
-                }
-                return inst.threadPool;
+                return this.completionRegistry;
             }
         }
 
-        internal static CompletionRegistry CompletionRegistry
+        /// <summary>
+        /// Gets the completion queue used by this gRPC environment.
+        /// </summary>
+        internal CompletionQueueSafeHandle CompletionQueue
         {
             get
             {
-                var inst = instance;
-                if (inst == null)
-                {
-                    throw new InvalidOperationException("GRPC environment not initialized");
-                }
-                return inst.completionRegistry;
+                return this.threadPool.CompletionQueue;
             }
         }
 
         /// <summary>
-        /// Creates gRPC environment.
+        /// Gets the completion queue used by this gRPC environment.
         /// </summary>
-        private GrpcEnvironment()
+        internal DebugStats DebugStats
         {
-            GrpcLog.RedirectNativeLogs(Console.Error);
-            grpcsharp_init();
-            completionRegistry = new CompletionRegistry();
-            threadPool = new GrpcThreadPool(THREAD_POOL_SIZE);
-            threadPool.Start();
-            // TODO: use proper logging here
-            Console.WriteLine("GRPC initialized.");
+            get
+            {
+                return this.debugStats;
+            }
         }
 
         /// <summary>
@@ -146,32 +152,28 @@ namespace Grpc.Core
             grpcsharp_shutdown();
             isClosed = true;
 
+            debugStats.CheckOK();
+
             // TODO: use proper logging here
             Console.WriteLine("GRPC shutdown.");
         }
 
-        private static void CheckDebugStats()
+        /// <summary>
+        /// Shuts down this environment asynchronously.
+        /// </summary>
+        private Task CloseAsync()
         {
-            var remainingClientCalls = DebugStats.ActiveClientCalls.Count;
-            if (remainingClientCalls != 0)
-            {                
-                DebugWarning(string.Format("Detected {0} client calls that weren't disposed properly.", remainingClientCalls));
-            }
-            var remainingServerCalls = DebugStats.ActiveServerCalls.Count;
-            if (remainingServerCalls != 0)
-            {
-                DebugWarning(string.Format("Detected {0} server calls that weren't disposed properly.", remainingServerCalls));
-            }
-            var pendingBatchCompletions = DebugStats.PendingBatchCompletions.Count;
-            if (pendingBatchCompletions != 0)
+            return Task.Run(() =>
             {
-                DebugWarning(string.Format("Detected {0} pending batch completions.", pendingBatchCompletions));
-            }
-        }
-
-        private static void DebugWarning(string message)
-        {
-            throw new Exception("Shutdown check: " + message);
+                try
+                {
+                    Close();
+                }
+                catch (Exception e)
+                {
+                    Console.WriteLine("Error occured while shutting down GrpcEnvironment: " + e);
+                }
+            });
         }
     }
 }
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCall.cs b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
index d350f45da6..24b75d1668 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCall.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
@@ -47,6 +47,8 @@ namespace Grpc.Core.Internal
     /// </summary>
     internal class AsyncCall<TRequest, TResponse> : AsyncCallBase<TRequest, TResponse>
     {
+        Channel channel;
+
         // Completion of a pending unary response if not null.
         TaskCompletionSource<TResponse> unaryResponseTcs;
 
@@ -61,8 +63,9 @@ namespace Grpc.Core.Internal
 
         public void Initialize(Channel channel, CompletionQueueSafeHandle cq, string methodName)
         {
-            var call = CallSafeHandle.Create(channel.Handle, cq, methodName, channel.Target, Timespec.InfFuture);
-            DebugStats.ActiveClientCalls.Increment();
+            this.channel = channel;
+            var call = CallSafeHandle.Create(channel.Handle, channel.CompletionRegistry, cq, methodName, channel.Target, Timespec.InfFuture);
+            channel.Environment.DebugStats.ActiveClientCalls.Increment();
             InitializeInternal(call);
         }
 
@@ -277,7 +280,7 @@ namespace Grpc.Core.Internal
 
         protected override void OnReleaseResources()
         {
-            DebugStats.ActiveClientCalls.Decrement();
+            channel.Environment.DebugStats.ActiveClientCalls.Decrement();
         }
 
         /// <summary>
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs b/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
index 4f510ba40a..309067ea9d 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
@@ -48,14 +48,17 @@ namespace Grpc.Core.Internal
     internal class AsyncCallServer<TRequest, TResponse> : AsyncCallBase<TResponse, TRequest>
     {
         readonly TaskCompletionSource<object> finishedServersideTcs = new TaskCompletionSource<object>();
+        readonly GrpcEnvironment environment;
 
-        public AsyncCallServer(Func<TResponse, byte[]> serializer, Func<byte[], TRequest> deserializer) : base(serializer, deserializer)
+        public AsyncCallServer(Func<TResponse, byte[]> serializer, Func<byte[], TRequest> deserializer, GrpcEnvironment environment) : base(serializer, deserializer)
         {
+            this.environment = Preconditions.CheckNotNull(environment);
         }
 
         public void Initialize(CallSafeHandle call)
         {
-            DebugStats.ActiveServerCalls.Increment();
+            call.SetCompletionRegistry(environment.CompletionRegistry);
+            environment.DebugStats.ActiveServerCalls.Increment();
             InitializeInternal(call);
         }
 
@@ -114,7 +117,7 @@ namespace Grpc.Core.Internal
 
         protected override void OnReleaseResources()
         {
-            DebugStats.ActiveServerCalls.Decrement();
+            environment.DebugStats.ActiveServerCalls.Decrement();
         }
 
         /// <summary>
diff --git a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
index ef92b44402..3b246ac01b 100644
--- a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
@@ -43,6 +43,7 @@ namespace Grpc.Core.Internal
     internal class CallSafeHandle : SafeHandleZeroIsInvalid
     {
         const uint GRPC_WRITE_BUFFER_HINT = 1;
+        CompletionRegistry completionRegistry;
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern CallSafeHandle grpcsharp_channel_create_call(ChannelSafeHandle channel, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline);
@@ -97,15 +98,22 @@ namespace Grpc.Core.Internal
         {
         }
 
-        public static CallSafeHandle Create(ChannelSafeHandle channel, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline)
+        public static CallSafeHandle Create(ChannelSafeHandle channel, CompletionRegistry registry, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline)
         {
-            return grpcsharp_channel_create_call(channel, cq, method, host, deadline);
+            var result = grpcsharp_channel_create_call(channel, cq, method, host, deadline);
+            result.SetCompletionRegistry(registry);
+            return result;
+        }
+
+        public void SetCompletionRegistry(CompletionRegistry completionRegistry)
+        {
+            this.completionRegistry = completionRegistry;
         }
 
         public void StartUnary(byte[] payload, BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_start_unary(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray)
                 .CheckOk();
         }
@@ -119,56 +127,56 @@ namespace Grpc.Core.Internal
         public void StartClientStreaming(BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_start_client_streaming(this, ctx, metadataArray).CheckOk();
         }
 
         public void StartServerStreaming(byte[] payload, BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_start_server_streaming(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray).CheckOk();
         }
 
         public void StartDuplexStreaming(BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_start_duplex_streaming(this, ctx, metadataArray).CheckOk();
         }
 
         public void StartSendMessage(byte[] payload, BatchCompletionDelegate callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_send_message(this, ctx, payload, new UIntPtr((ulong)payload.Length)).CheckOk();
         }
 
         public void StartSendCloseFromClient(BatchCompletionDelegate callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_send_close_from_client(this, ctx).CheckOk();
         }
 
         public void StartSendStatusFromServer(Status status, BatchCompletionDelegate callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_send_status_from_server(this, ctx, status.StatusCode, status.Detail).CheckOk();
         }
 
         public void StartReceiveMessage(BatchCompletionDelegate callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_recv_message(this, ctx).CheckOk();
         }
 
         public void StartServerSide(BatchCompletionDelegate callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_start_serverside(this, ctx).CheckOk();
         }
 
diff --git a/src/csharp/Grpc.Core/Internal/CompletionRegistry.cs b/src/csharp/Grpc.Core/Internal/CompletionRegistry.cs
index 80f006ae50..f6d8aa0600 100644
--- a/src/csharp/Grpc.Core/Internal/CompletionRegistry.cs
+++ b/src/csharp/Grpc.Core/Internal/CompletionRegistry.cs
@@ -45,11 +45,17 @@ namespace Grpc.Core.Internal
 
     internal class CompletionRegistry
     {
-        readonly ConcurrentDictionary<IntPtr, OpCompletionDelegate> dict = new ConcurrentDictionary<IntPtr, OpCompletionDelegate>();  
+        readonly GrpcEnvironment environment;
+        readonly ConcurrentDictionary<IntPtr, OpCompletionDelegate> dict = new ConcurrentDictionary<IntPtr, OpCompletionDelegate>();
+
+        public CompletionRegistry(GrpcEnvironment environment)
+        {
+            this.environment = environment;
+        }
 
         public void Register(IntPtr key, OpCompletionDelegate callback)
         {
-            DebugStats.PendingBatchCompletions.Increment();
+            environment.DebugStats.PendingBatchCompletions.Increment();
             Preconditions.CheckState(dict.TryAdd(key, callback));
         }
 
@@ -63,7 +69,7 @@ namespace Grpc.Core.Internal
         {
             OpCompletionDelegate value;
             Preconditions.CheckState(dict.TryRemove(key, out value));
-            DebugStats.PendingBatchCompletions.Decrement();
+            environment.DebugStats.PendingBatchCompletions.Decrement();
             return value;
         }
 
diff --git a/src/csharp/Grpc.Core/Internal/DebugStats.cs b/src/csharp/Grpc.Core/Internal/DebugStats.cs
index ef9d9afe11..8793450ff3 100644
--- a/src/csharp/Grpc.Core/Internal/DebugStats.cs
+++ b/src/csharp/Grpc.Core/Internal/DebugStats.cs
@@ -36,12 +36,39 @@ using System.Threading;
 
 namespace Grpc.Core.Internal
 {
-    internal static class DebugStats
+    internal class DebugStats
     {
-        public static readonly AtomicCounter ActiveClientCalls = new AtomicCounter();
+        public readonly AtomicCounter ActiveClientCalls = new AtomicCounter();
 
-        public static readonly AtomicCounter ActiveServerCalls = new AtomicCounter();
+        public readonly AtomicCounter ActiveServerCalls = new AtomicCounter();
 
-        public static readonly AtomicCounter PendingBatchCompletions = new AtomicCounter();
+        public readonly AtomicCounter PendingBatchCompletions = new AtomicCounter();
+
+        /// <summary>
+        /// Checks the debug stats and take action for any inconsistency found.
+        /// </summary>
+        public void CheckOK()
+        {
+            var remainingClientCalls = ActiveClientCalls.Count;
+            if (remainingClientCalls != 0)
+            {                
+                DebugWarning(string.Format("Detected {0} client calls that weren't disposed properly.", remainingClientCalls));
+            }
+            var remainingServerCalls = ActiveServerCalls.Count;
+            if (remainingServerCalls != 0)
+            {
+                DebugWarning(string.Format("Detected {0} server calls that weren't disposed properly.", remainingServerCalls));
+            }
+            var pendingBatchCompletions = PendingBatchCompletions.Count;
+            if (pendingBatchCompletions != 0)
+            {
+                DebugWarning(string.Format("Detected {0} pending batch completions.", pendingBatchCompletions));
+            }
+        }
+
+        private void DebugWarning(string message)
+        {
+            throw new Exception("Shutdown check: " + message);
+        }
     }
 }
diff --git a/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs b/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
index 89b44a4e2b..b77e893044 100644
--- a/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
+++ b/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
@@ -45,14 +45,16 @@ namespace Grpc.Core.Internal
     /// </summary>
     internal class GrpcThreadPool
     {
+        readonly GrpcEnvironment environment;
         readonly object myLock = new object();
         readonly List<Thread> threads = new List<Thread>();
         readonly int poolSize;
 
         CompletionQueueSafeHandle cq;
 
-        public GrpcThreadPool(int poolSize)
+        public GrpcThreadPool(GrpcEnvironment environment, int poolSize)
         {
+            this.environment = environment;
             this.poolSize = poolSize;
         }
 
@@ -80,7 +82,7 @@ namespace Grpc.Core.Internal
             {
                 cq.Shutdown();
 
-                Console.WriteLine("Waiting for GPRC threads to finish.");
+                Console.WriteLine("Waiting for GRPC threads to finish.");
                 foreach (var thread in threads)
                 {
                     thread.Join();
@@ -122,7 +124,7 @@ namespace Grpc.Core.Internal
                     IntPtr tag = ev.tag;
                     try
                     {
-                        var callback = GrpcEnvironment.CompletionRegistry.Extract(tag);
+                        var callback = environment.CompletionRegistry.Extract(tag);
                         callback(success);
                     }
                     catch (Exception e)
diff --git a/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs b/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
index c0e5bae13f..594e46b159 100644
--- a/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
@@ -42,7 +42,7 @@ namespace Grpc.Core.Internal
 {
     internal interface IServerCallHandler
     {
-        Task HandleCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq);
+        Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment);
     }
 
     internal class UnaryServerCallHandler<TRequest, TResponse> : IServerCallHandler
@@ -58,11 +58,12 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
-                method.RequestMarshaller.Deserializer);
+                method.RequestMarshaller.Deserializer,
+                environment);
 
             asyncCall.Initialize(call);
             var finishedTask = asyncCall.ServerSideCallAsync();
@@ -110,11 +111,12 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
-                method.RequestMarshaller.Deserializer);
+                method.RequestMarshaller.Deserializer,
+                environment);
 
             asyncCall.Initialize(call);
             var finishedTask = asyncCall.ServerSideCallAsync();
@@ -163,11 +165,12 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
-                method.RequestMarshaller.Deserializer);
+                method.RequestMarshaller.Deserializer,
+                environment);
 
             asyncCall.Initialize(call);
             var finishedTask = asyncCall.ServerSideCallAsync();
@@ -219,11 +222,12 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
-                method.RequestMarshaller.Deserializer);
+                method.RequestMarshaller.Deserializer,
+                environment);
 
             asyncCall.Initialize(call);
             var finishedTask = asyncCall.ServerSideCallAsync();
@@ -255,11 +259,11 @@ namespace Grpc.Core.Internal
 
     internal class NoSuchMethodCallHandler : IServerCallHandler
     {
-        public async Task HandleCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
         {
             // We don't care about the payload type here.
             var asyncCall = new AsyncCallServer<byte[], byte[]>(
-                (payload) => payload, (payload) => payload);
+                (payload) => payload, (payload) => payload, environment);
             
             asyncCall.Initialize(call);
             var finishedTask = asyncCall.ServerSideCallAsync();
diff --git a/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs b/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs
index 83dbb910aa..9e1170e6dd 100644
--- a/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs
@@ -91,19 +91,19 @@ namespace Grpc.Core.Internal
         {
             grpcsharp_server_start(this);
         }
-            
-        public void ShutdownAndNotify(CompletionQueueSafeHandle cq, BatchCompletionDelegate callback)
+    
+        public void ShutdownAndNotify(BatchCompletionDelegate callback, GrpcEnvironment environment)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
-            grpcsharp_server_shutdown_and_notify_callback(this, cq, ctx);
+            environment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            grpcsharp_server_shutdown_and_notify_callback(this, environment.CompletionQueue, ctx);
         }
 
-        public void RequestCall(CompletionQueueSafeHandle cq, BatchCompletionDelegate callback)
+        public void RequestCall(BatchCompletionDelegate callback, GrpcEnvironment environment)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
-            grpcsharp_server_request_call(this, cq, ctx).CheckOk();
+            environment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            grpcsharp_server_request_call(this, environment.CompletionQueue, ctx).CheckOk();
         }
 
         protected override bool ReleaseHandle()
diff --git a/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs b/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs
index 03b682181a..2b3d7530f2 100644
--- a/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs
+++ b/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs
@@ -9,6 +9,5 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]
-[assembly: AssemblyVersion("0.5.*")]
 
 [assembly: InternalsVisibleTo("Grpc.Core.Tests")]
diff --git a/src/csharp/Grpc.Core/Server.cs b/src/csharp/Grpc.Core/Server.cs
index 8e818885d1..cbf77196cf 100644
--- a/src/csharp/Grpc.Core/Server.cs
+++ b/src/csharp/Grpc.Core/Server.cs
@@ -52,6 +52,7 @@ namespace Grpc.Core
         /// </summary>
         public const int PickUnusedPort = 0;
 
+        readonly GrpcEnvironment environment;
         readonly ServerSafeHandle handle;
         readonly object myLock = new object();
 
@@ -67,9 +68,10 @@ namespace Grpc.Core
         /// <param name="options">Channel options.</param>
         public Server(IEnumerable<ChannelOption> options = null)
         {
+            this.environment = GrpcEnvironment.GetInstance();
             using (var channelArgs = ChannelOptions.CreateChannelArgs(options))
             {
-                this.handle = ServerSafeHandle.NewServer(GetCompletionQueue(), channelArgs);
+                this.handle = ServerSafeHandle.NewServer(environment.CompletionQueue, channelArgs);
             }
         }
 
@@ -144,7 +146,7 @@ namespace Grpc.Core
                 shutdownRequested = true;
             }
 
-            handle.ShutdownAndNotify(GetCompletionQueue(), HandleServerShutdown);
+            handle.ShutdownAndNotify(HandleServerShutdown, environment);
             await shutdownTcs.Task;
             handle.Dispose();
         }
@@ -173,7 +175,7 @@ namespace Grpc.Core
                 shutdownRequested = true;
             }
 
-            handle.ShutdownAndNotify(GetCompletionQueue(), HandleServerShutdown);
+            handle.ShutdownAndNotify(HandleServerShutdown, environment);
             handle.CancelAllCalls();
             await shutdownTcs.Task;
             handle.Dispose();
@@ -208,7 +210,7 @@ namespace Grpc.Core
             {
                 if (!shutdownRequested)
                 {
-                    handle.RequestCall(GetCompletionQueue(), HandleNewServerRpc);
+                    handle.RequestCall(HandleNewServerRpc, environment);
                 }
             }
         }
@@ -225,7 +227,7 @@ namespace Grpc.Core
                 {
                     callHandler = new NoSuchMethodCallHandler();
                 }
-                await callHandler.HandleCall(method, call, GetCompletionQueue());
+                await callHandler.HandleCall(method, call, environment);
             }
             catch (Exception e)
             {
@@ -259,10 +261,5 @@ namespace Grpc.Core
         {
             shutdownTcs.SetResult(null);
         }
-
-        private static CompletionQueueSafeHandle GetCompletionQueue()
-        {
-            return GrpcEnvironment.ThreadPool.CompletionQueue;
-        }
     }
 }
diff --git a/src/csharp/Grpc.Core/Version.cs b/src/csharp/Grpc.Core/Version.cs
new file mode 100644
index 0000000000..972f495bd7
--- /dev/null
+++ b/src/csharp/Grpc.Core/Version.cs
@@ -0,0 +1,6 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+
+// The current version of gRPC C#.
+[assembly: AssemblyVersion("0.6.0.*")]
+
diff --git a/src/csharp/Grpc.Core/packages.config b/src/csharp/Grpc.Core/packages.config
index fb7eaaeeda..6cdcdf2656 100644
--- a/src/csharp/Grpc.Core/packages.config
+++ b/src/csharp/Grpc.Core/packages.config
@@ -3,5 +3,5 @@
   <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="Microsoft.Bcl.Immutable" version="1.0.34" 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.MathClient/Grpc.Examples.MathClient.csproj b/src/csharp/Grpc.Examples.MathClient/Grpc.Examples.MathClient.csproj
index 19bb4347aa..5d5401593d 100644
--- a/src/csharp/Grpc.Examples.MathClient/Grpc.Examples.MathClient.csproj
+++ b/src/csharp/Grpc.Examples.MathClient/Grpc.Examples.MathClient.csproj
@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
@@ -35,6 +35,9 @@
     <Reference Include="System" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="..\Grpc.Core\Version.cs">
+      <Link>Version.cs</Link>
+    </Compile>
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="MathClient.cs" />
   </ItemGroup>
@@ -49,4 +52,4 @@
       <Name>Grpc.Examples</Name>
     </ProjectReference>
   </ItemGroup>
-</Project>
+</Project>
+\ No newline at end of file
diff --git a/src/csharp/Grpc.Examples.MathClient/MathClient.cs b/src/csharp/Grpc.Examples.MathClient/MathClient.cs
index 360fe928dd..b763721460 100644
--- a/src/csharp/Grpc.Examples.MathClient/MathClient.cs
+++ b/src/csharp/Grpc.Examples.MathClient/MathClient.cs
@@ -39,8 +39,6 @@ namespace math
     {
         public static void Main(string[] args)
         {
-            GrpcEnvironment.Initialize();
-
             using (Channel channel = new Channel("127.0.0.1", 23456))
             {
                 Math.IMathClient stub = new Math.MathClient(channel);
diff --git a/src/csharp/Grpc.Examples.MathClient/Properties/AssemblyInfo.cs b/src/csharp/Grpc.Examples.MathClient/Properties/AssemblyInfo.cs
index 4b77472fbd..0fb0dbd510 100644
--- a/src/csharp/Grpc.Examples.MathClient/Properties/AssemblyInfo.cs
+++ b/src/csharp/Grpc.Examples.MathClient/Properties/AssemblyInfo.cs
@@ -9,4 +9,3 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]
-[assembly: AssemblyVersion("0.5.*")]
diff --git a/src/csharp/Grpc.Examples.MathServer/Grpc.Examples.MathServer.csproj b/src/csharp/Grpc.Examples.MathServer/Grpc.Examples.MathServer.csproj
index ba6586ee5e..677d87da20 100644
--- a/src/csharp/Grpc.Examples.MathServer/Grpc.Examples.MathServer.csproj
+++ b/src/csharp/Grpc.Examples.MathServer/Grpc.Examples.MathServer.csproj
@@ -35,6 +35,9 @@
     <Reference Include="System" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="..\Grpc.Core\Version.cs">
+      <Link>Version.cs</Link>
+    </Compile>
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="MathServer.cs" />
   </ItemGroup>
diff --git a/src/csharp/Grpc.Examples.MathServer/MathServer.cs b/src/csharp/Grpc.Examples.MathServer/MathServer.cs
index d05e3f2808..f440985112 100644
--- a/src/csharp/Grpc.Examples.MathServer/MathServer.cs
+++ b/src/csharp/Grpc.Examples.MathServer/MathServer.cs
@@ -42,8 +42,6 @@ namespace math
         {
             string host = "0.0.0.0";
 
-            GrpcEnvironment.Initialize();
-
             Server server = new Server();
             server.AddServiceDefinition(Math.BindService(new MathServiceImpl()));
             int port = server.AddListeningPort(host, 23456);
diff --git a/src/csharp/Grpc.Examples.MathServer/Properties/AssemblyInfo.cs b/src/csharp/Grpc.Examples.MathServer/Properties/AssemblyInfo.cs
index c18fc251d4..63035b6c63 100644
--- a/src/csharp/Grpc.Examples.MathServer/Properties/AssemblyInfo.cs
+++ b/src/csharp/Grpc.Examples.MathServer/Properties/AssemblyInfo.cs
@@ -9,4 +9,3 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]
-[assembly: AssemblyVersion("0.5.*")]
diff --git a/src/csharp/Grpc.Examples.Tests/Grpc.Examples.Tests.csproj b/src/csharp/Grpc.Examples.Tests/Grpc.Examples.Tests.csproj
index 6e84add42b..d59d7515d1 100644
--- a/src/csharp/Grpc.Examples.Tests/Grpc.Examples.Tests.csproj
+++ b/src/csharp/Grpc.Examples.Tests/Grpc.Examples.Tests.csproj
@@ -43,6 +43,9 @@
     </Reference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="..\Grpc.Core\Version.cs">
+      <Link>Version.cs</Link>
+    </Compile>
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="MathClientServerTests.cs" />
   </ItemGroup>
diff --git a/src/csharp/Grpc.Examples.Tests/MathClientServerTests.cs b/src/csharp/Grpc.Examples.Tests/MathClientServerTests.cs
index aadd49f795..10dceb60aa 100644
--- a/src/csharp/Grpc.Examples.Tests/MathClientServerTests.cs
+++ b/src/csharp/Grpc.Examples.Tests/MathClientServerTests.cs
@@ -54,8 +54,6 @@ namespace math.Tests
         [TestFixtureSetUp]
         public void Init()
         {
-            GrpcEnvironment.Initialize();
-
             server = new Server();
             server.AddServiceDefinition(Math.BindService(new MathServiceImpl()));
             int port = server.AddListeningPort(host, Server.PickUnusedPort);
@@ -75,7 +73,6 @@ namespace math.Tests
         public void Cleanup()
         {
             channel.Dispose();
-
             server.ShutdownAsync().Wait();
             GrpcEnvironment.Shutdown();
         }
diff --git a/src/csharp/Grpc.Examples.Tests/Properties/AssemblyInfo.cs b/src/csharp/Grpc.Examples.Tests/Properties/AssemblyInfo.cs
index c1ba396a95..846afb4616 100644
--- a/src/csharp/Grpc.Examples.Tests/Properties/AssemblyInfo.cs
+++ b/src/csharp/Grpc.Examples.Tests/Properties/AssemblyInfo.cs
@@ -9,4 +9,3 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]
-[assembly: AssemblyVersion("0.5.*")]
diff --git a/src/csharp/Grpc.Examples/Grpc.Examples.csproj b/src/csharp/Grpc.Examples/Grpc.Examples.csproj
index 5ce490f403..eaf24a253c 100644
--- a/src/csharp/Grpc.Examples/Grpc.Examples.csproj
+++ b/src/csharp/Grpc.Examples/Grpc.Examples.csproj
@@ -40,6 +40,9 @@
     </Reference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="..\Grpc.Core\Version.cs">
+      <Link>Version.cs</Link>
+    </Compile>
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Math.cs" />
     <Compile Include="MathGrpc.cs" />
diff --git a/src/csharp/Grpc.Examples/Properties/AssemblyInfo.cs b/src/csharp/Grpc.Examples/Properties/AssemblyInfo.cs
index a63e05d7f6..92111389cb 100644
--- a/src/csharp/Grpc.Examples/Properties/AssemblyInfo.cs
+++ b/src/csharp/Grpc.Examples/Properties/AssemblyInfo.cs
@@ -9,4 +9,3 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]
-[assembly: AssemblyVersion("0.5.*")]
diff --git a/src/csharp/Grpc.HealthCheck.Tests/.gitignore b/src/csharp/Grpc.HealthCheck.Tests/.gitignore
new file mode 100644
index 0000000000..1746e3269e
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck.Tests/.gitignore
@@ -0,0 +1,2 @@
+bin
+obj
diff --git a/src/csharp/Grpc.HealthCheck.Tests/Grpc.HealthCheck.Tests.csproj b/src/csharp/Grpc.HealthCheck.Tests/Grpc.HealthCheck.Tests.csproj
new file mode 100644
index 0000000000..72e110302b
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck.Tests/Grpc.HealthCheck.Tests.csproj
@@ -0,0 +1,82 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{F8C6D937-C44B-4EE3-A431-B0FBAEACE47D}</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>Grpc.HealthCheck.Tests</RootNamespace>
+    <AssemblyName>Grpc.HealthCheck.Tests</AssemblyName>
+    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="Google.ProtocolBuffers">
+      <HintPath>..\packages\Google.ProtocolBuffers.2.4.1.555\lib\net40\Google.ProtocolBuffers.dll</HintPath>
+    </Reference>
+    <Reference Include="Google.ProtocolBuffers.Serialization">
+      <HintPath>..\packages\Google.ProtocolBuffers.2.4.1.555\lib\net40\Google.ProtocolBuffers.Serialization.dll</HintPath>
+    </Reference>
+    <Reference Include="nunit.framework">
+      <HintPath>..\packages\NUnit.2.6.4\lib\nunit.framework.dll</HintPath>
+    </Reference>
+    <Reference Include="System" />
+    <Reference Include="System.Core" />
+    <Reference Include="System.Xml.Linq" />
+    <Reference Include="System.Data.DataSetExtensions" />
+    <Reference Include="Microsoft.CSharp" />
+    <Reference Include="System.Data" />
+    <Reference Include="System.Xml" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="..\Grpc.Core\Version.cs">
+      <Link>Version.cs</Link>
+    </Compile>
+    <Compile Include="HealthServiceImplTest.cs" />
+    <Compile Include="HealthClientServerTest.cs" />
+    <Compile Include="Properties\AssemblyInfo.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\Grpc.Core\Grpc.Core.csproj">
+      <Project>{ccc4440e-49f7-4790-b0af-feabb0837ae7}</Project>
+      <Name>Grpc.Core</Name>
+    </ProjectReference>
+    <ProjectReference Include="..\Grpc.HealthCheck\Grpc.HealthCheck.csproj">
+      <Project>{aa5e328a-8835-49d7-98ed-c29f2b3049f0}</Project>
+      <Name>Grpc.HealthCheck</Name>
+    </ProjectReference>
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="packages.config" />
+  </ItemGroup>
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
+       Other similar extension points exist, see Microsoft.Common.targets.
+  <Target Name="BeforeBuild">
+  </Target>
+  <Target Name="AfterBuild">
+  </Target>
+  -->
+</Project>
+\ No newline at end of file
diff --git a/src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs b/src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs
new file mode 100644
index 0000000000..0ac1add8e4
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs
@@ -0,0 +1,97 @@
+#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.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+using Grpc.Core;
+using Grpc.Health.V1Alpha;
+using NUnit.Framework;
+
+namespace Grpc.HealthCheck.Tests
+{
+    /// <summary>
+    /// Health client talks to health server.
+    /// </summary>
+    public class HealthClientServerTest
+    {
+        const string Host = "localhost";
+        Server server;
+        Channel channel;
+        Grpc.Health.V1Alpha.Health.IHealthClient client;
+        Grpc.HealthCheck.HealthServiceImpl serviceImpl;
+
+        [TestFixtureSetUp]
+        public void Init()
+        {
+            serviceImpl = new HealthServiceImpl();
+
+            server = new Server();
+            server.AddServiceDefinition(Grpc.Health.V1Alpha.Health.BindService(serviceImpl));
+            int port = server.AddListeningPort(Host, Server.PickUnusedPort);
+            server.Start();
+            channel = new Channel(Host, port);
+
+            client = Grpc.Health.V1Alpha.Health.NewStub(channel);
+        }
+
+        [TestFixtureTearDown]
+        public void Cleanup()
+        {
+            channel.Dispose();
+
+            server.ShutdownAsync().Wait();
+            GrpcEnvironment.Shutdown();
+        }
+
+        [Test]
+        public void ServiceIsRunning()
+        {
+            serviceImpl.SetStatus("", "", HealthCheckResponse.Types.ServingStatus.SERVING);
+
+            var response = client.Check(HealthCheckRequest.CreateBuilder().SetHost("").SetService("").Build());
+            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.SERVING, response.Status);
+        }
+
+        [Test]
+        public void ServiceDoesntExist()
+        {
+            // TODO(jtattermusch): currently, this returns wrong status code, because we don't enable sending arbitrary status code from
+            // server handlers yet.
+            Assert.Throws(typeof(RpcException), () => client.Check(HealthCheckRequest.CreateBuilder().SetHost("").SetService("nonexistent.service").Build()));
+        }
+
+        // TODO(jtattermusch): add test with timeout once timeouts are supported
+    }
+}
+\ No newline at end of file
diff --git a/src/csharp/Grpc.HealthCheck.Tests/HealthServiceImplTest.cs b/src/csharp/Grpc.HealthCheck.Tests/HealthServiceImplTest.cs
new file mode 100644
index 0000000000..9b7c4f2140
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck.Tests/HealthServiceImplTest.cs
@@ -0,0 +1,107 @@
+#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.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+using Grpc.Core;
+using Grpc.Health.V1Alpha;
+using NUnit.Framework;
+
+namespace Grpc.HealthCheck.Tests
+{
+    /// <summary>
+    /// Tests for HealthCheckServiceImpl
+    /// </summary>
+    public class HealthServiceImplTest
+    {
+        [Test]
+        public void SetStatus()
+        {
+            var impl = new HealthServiceImpl();
+            impl.SetStatus("", "", HealthCheckResponse.Types.ServingStatus.SERVING);
+            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.SERVING, GetStatusHelper(impl, "", ""));
+
+            impl.SetStatus("", "", HealthCheckResponse.Types.ServingStatus.NOT_SERVING);
+            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.NOT_SERVING, GetStatusHelper(impl, "", ""));
+
+            impl.SetStatus("virtual-host", "", HealthCheckResponse.Types.ServingStatus.UNKNOWN);
+            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.UNKNOWN, GetStatusHelper(impl, "virtual-host", ""));
+
+            impl.SetStatus("virtual-host", "grpc.test.TestService", HealthCheckResponse.Types.ServingStatus.SERVING);
+            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.SERVING, GetStatusHelper(impl, "virtual-host", "grpc.test.TestService"));
+        }
+
+        [Test]
+        public void ClearStatus()
+        {
+            var impl = new HealthServiceImpl();
+            impl.SetStatus("", "", HealthCheckResponse.Types.ServingStatus.SERVING);
+            impl.SetStatus("virtual-host", "", HealthCheckResponse.Types.ServingStatus.UNKNOWN);
+
+            impl.ClearStatus("", "");
+
+            Assert.Throws(Is.TypeOf(typeof(RpcException)).And.Property("Status").Property("StatusCode").EqualTo(StatusCode.NotFound), () => GetStatusHelper(impl, "", ""));
+            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.UNKNOWN, GetStatusHelper(impl, "virtual-host", ""));
+        }
+
+        [Test]
+        public void ClearAll()
+        {
+            var impl = new HealthServiceImpl();
+            impl.SetStatus("", "", HealthCheckResponse.Types.ServingStatus.SERVING);
+            impl.SetStatus("virtual-host", "", HealthCheckResponse.Types.ServingStatus.UNKNOWN);
+
+            impl.ClearAll();
+            Assert.Throws(typeof(RpcException), () => GetStatusHelper(impl, "", ""));
+            Assert.Throws(typeof(RpcException), () => GetStatusHelper(impl, "virtual-host", ""));
+        }
+
+        [Test]
+        public void NullsRejected()
+        {
+            var impl = new HealthServiceImpl();
+            Assert.Throws(typeof(NullReferenceException), () => impl.SetStatus(null, "", HealthCheckResponse.Types.ServingStatus.SERVING));
+            Assert.Throws(typeof(NullReferenceException), () => impl.SetStatus("", null, HealthCheckResponse.Types.ServingStatus.SERVING));
+
+            Assert.Throws(typeof(NullReferenceException), () => impl.ClearStatus(null, ""));
+            Assert.Throws(typeof(NullReferenceException), () => impl.ClearStatus("", null));
+        }
+
+        private static HealthCheckResponse.Types.ServingStatus GetStatusHelper(HealthServiceImpl impl, string host, string service)
+        {
+            return impl.Check(null, HealthCheckRequest.CreateBuilder().SetHost(host).SetService(service).Build()).Result.Status;
+        }
+    }
+}
diff --git a/src/csharp/Grpc.HealthCheck.Tests/Properties/AssemblyInfo.cs b/src/csharp/Grpc.HealthCheck.Tests/Properties/AssemblyInfo.cs
new file mode 100644
index 0000000000..d5660305be
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck.Tests/Properties/AssemblyInfo.cs
@@ -0,0 +1,11 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+
+[assembly: AssemblyTitle("Grpc.HealthCheck.Tests")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("")]
+[assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
diff --git a/src/csharp/Grpc.HealthCheck.Tests/packages.config b/src/csharp/Grpc.HealthCheck.Tests/packages.config
new file mode 100644
index 0000000000..050c4eaed6
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck.Tests/packages.config
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="Google.ProtocolBuffers" version="2.4.1.555" targetFramework="net45" />
+  <package id="NUnit" version="2.6.4" targetFramework="net45" />
+</packages>
+\ No newline at end of file
diff --git a/src/csharp/Grpc.HealthCheck/.gitignore b/src/csharp/Grpc.HealthCheck/.gitignore
new file mode 100644
index 0000000000..1746e3269e
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck/.gitignore
@@ -0,0 +1,2 @@
+bin
+obj
diff --git a/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.csproj b/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.csproj
new file mode 100644
index 0000000000..4ebb6446dd
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.csproj
@@ -0,0 +1,79 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{AA5E328A-8835-49D7-98ED-C29F2B3049F0}</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>Grpc.HealthCheck</RootNamespace>
+    <AssemblyName>Grpc.HealthCheck</AssemblyName>
+    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+    <DocumentationFile>bin\$(Configuration)\Grpc.HealthCheck.Xml</DocumentationFile>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="Google.ProtocolBuffers">
+      <HintPath>..\packages\Google.ProtocolBuffers.2.4.1.555\lib\net40\Google.ProtocolBuffers.dll</HintPath>
+    </Reference>
+    <Reference Include="Google.ProtocolBuffers.Serialization">
+      <HintPath>..\packages\Google.ProtocolBuffers.2.4.1.555\lib\net40\Google.ProtocolBuffers.Serialization.dll</HintPath>
+    </Reference>
+    <Reference Include="System" />
+    <Reference Include="System.Core" />
+    <Reference Include="System.Interactive.Async">
+      <HintPath>..\packages\Ix-Async.1.2.3\lib\net45\System.Interactive.Async.dll</HintPath>
+    </Reference>
+    <Reference Include="System.Xml.Linq" />
+    <Reference Include="System.Data.DataSetExtensions" />
+    <Reference Include="Microsoft.CSharp" />
+    <Reference Include="System.Data" />
+    <Reference Include="System.Xml" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="..\Grpc.Core\Version.cs">
+      <Link>Version.cs</Link>
+    </Compile>
+    <Compile Include="HealthServiceImpl.cs" />
+    <Compile Include="Health.cs" />
+    <Compile Include="HealthGrpc.cs" />
+    <Compile Include="Properties\AssemblyInfo.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="Grpc.HealthCheck.nuspec" />
+    <None Include="packages.config" />
+    <None Include="proto\health.proto" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\Grpc.Core\Grpc.Core.csproj">
+      <Project>{ccc4440e-49f7-4790-b0af-feabb0837ae7}</Project>
+      <Name>Grpc.Core</Name>
+    </ProjectReference>
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
+       Other similar extension points exist, see Microsoft.Common.targets.
+  <Target Name="BeforeBuild">
+  </Target>
+  <Target Name="AfterBuild">
+  </Target>
+  -->
+</Project>
+\ No newline at end of file
diff --git a/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.nuspec b/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.nuspec
new file mode 100644
index 0000000000..ca35b36805
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.nuspec
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<package>
+  <metadata>
+    <id>Grpc.HealthCheck</id>
+    <title>gRPC C# Healthchecking</title>
+    <summary>Implementation of gRPC health service</summary>
+    <description>Example implementation of grpc.health.v1alpha service that can be used for health-checking.</description>
+    <version>$version$</version>
+    <authors>Google Inc.</authors>
+    <owners>grpc-packages</owners>
+    <licenseUrl>https://github.com/grpc/grpc/blob/master/LICENSE</licenseUrl>
+    <projectUrl>https://github.com/grpc/grpc</projectUrl>
+    <requireLicenseAcceptance>false</requireLicenseAcceptance>
+    <copyright>Copyright 2015, Google Inc.</copyright>
+    <tags>gRPC health check</tags>
+	<dependencies>
+	  <dependency id="Google.ProtocolBuffers" version="2.4.1.555" />
+	  <dependency id="Grpc.Core" version="$version$" />
+	  <dependency id="Ix-Async" version="1.2.3" />
+    </dependencies>
+  </metadata>
+  <files>
+    <file src="bin/Release/Grpc.HealthCheck.dll" target="lib/net45" />
+	<file src="bin/Release/Grpc.HealthCheck.pdb" target="lib/net45" />
+	<file src="bin/Release/Grpc.HealthCheck.xml" target="lib/net45" />
+	<file src="**\*.cs" target="src" />
+  </files>
+</package>
diff --git a/src/csharp/Grpc.HealthCheck/Health.cs b/src/csharp/Grpc.HealthCheck/Health.cs
new file mode 100644
index 0000000000..361382d4bd
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck/Health.cs
@@ -0,0 +1,687 @@
+// Generated by the protocol buffer compiler.  DO NOT EDIT!
+// source: health.proto
+#pragma warning disable 1591, 0612, 3021
+#region Designer generated code
+
+using pb = global::Google.ProtocolBuffers;
+using pbc = global::Google.ProtocolBuffers.Collections;
+using pbd = global::Google.ProtocolBuffers.Descriptors;
+using scg = global::System.Collections.Generic;
+namespace Grpc.Health.V1Alpha {
+
+  namespace Proto {
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    public static partial class Health {
+
+      #region Extension registration
+      public static void RegisterAllExtensions(pb::ExtensionRegistry registry) {
+      }
+      #endregion
+      #region Static variables
+      internal static pbd::MessageDescriptor internal__static_grpc_health_v1alpha_HealthCheckRequest__Descriptor;
+      internal static pb::FieldAccess.FieldAccessorTable<global::Grpc.Health.V1Alpha.HealthCheckRequest, global::Grpc.Health.V1Alpha.HealthCheckRequest.Builder> internal__static_grpc_health_v1alpha_HealthCheckRequest__FieldAccessorTable;
+      internal static pbd::MessageDescriptor internal__static_grpc_health_v1alpha_HealthCheckResponse__Descriptor;
+      internal static pb::FieldAccess.FieldAccessorTable<global::Grpc.Health.V1Alpha.HealthCheckResponse, global::Grpc.Health.V1Alpha.HealthCheckResponse.Builder> internal__static_grpc_health_v1alpha_HealthCheckResponse__FieldAccessorTable;
+      #endregion
+      #region Descriptor
+      public static pbd::FileDescriptor Descriptor {
+        get { return descriptor; }
+      }
+      private static pbd::FileDescriptor descriptor;
+
+      static Health() {
+        byte[] descriptorData = global::System.Convert.FromBase64String(
+            string.Concat(
+              "CgxoZWFsdGgucHJvdG8SE2dycGMuaGVhbHRoLnYxYWxwaGEiMwoSSGVhbHRo", 
+              "Q2hlY2tSZXF1ZXN0EgwKBGhvc3QYASABKAkSDwoHc2VydmljZRgCIAEoCSKZ", 
+              "AQoTSGVhbHRoQ2hlY2tSZXNwb25zZRJGCgZzdGF0dXMYASABKA4yNi5ncnBj", 
+              "LmhlYWx0aC52MWFscGhhLkhlYWx0aENoZWNrUmVzcG9uc2UuU2VydmluZ1N0", 
+              "YXR1cyI6Cg1TZXJ2aW5nU3RhdHVzEgsKB1VOS05PV04QABILCgdTRVJWSU5H", 
+              "EAESDwoLTk9UX1NFUlZJTkcQAjJkCgZIZWFsdGgSWgoFQ2hlY2sSJy5ncnBj", 
+              "LmhlYWx0aC52MWFscGhhLkhlYWx0aENoZWNrUmVxdWVzdBooLmdycGMuaGVh", 
+              "bHRoLnYxYWxwaGEuSGVhbHRoQ2hlY2tSZXNwb25zZUIWqgITR3JwYy5IZWFs", 
+            "dGguVjFBbHBoYQ=="));
+        pbd::FileDescriptor.InternalDescriptorAssigner assigner = delegate(pbd::FileDescriptor root) {
+          descriptor = root;
+          internal__static_grpc_health_v1alpha_HealthCheckRequest__Descriptor = Descriptor.MessageTypes[0];
+          internal__static_grpc_health_v1alpha_HealthCheckRequest__FieldAccessorTable = 
+              new pb::FieldAccess.FieldAccessorTable<global::Grpc.Health.V1Alpha.HealthCheckRequest, global::Grpc.Health.V1Alpha.HealthCheckRequest.Builder>(internal__static_grpc_health_v1alpha_HealthCheckRequest__Descriptor,
+                  new string[] { "Host", "Service", });
+          internal__static_grpc_health_v1alpha_HealthCheckResponse__Descriptor = Descriptor.MessageTypes[1];
+          internal__static_grpc_health_v1alpha_HealthCheckResponse__FieldAccessorTable = 
+              new pb::FieldAccess.FieldAccessorTable<global::Grpc.Health.V1Alpha.HealthCheckResponse, global::Grpc.Health.V1Alpha.HealthCheckResponse.Builder>(internal__static_grpc_health_v1alpha_HealthCheckResponse__Descriptor,
+                  new string[] { "Status", });
+          pb::ExtensionRegistry registry = pb::ExtensionRegistry.CreateInstance();
+          RegisterAllExtensions(registry);
+          return registry;
+        };
+        pbd::FileDescriptor.InternalBuildGeneratedFileFrom(descriptorData,
+            new pbd::FileDescriptor[] {
+            }, assigner);
+      }
+      #endregion
+
+    }
+  }
+  #region Messages
+  [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+  public sealed partial class HealthCheckRequest : pb::GeneratedMessage<HealthCheckRequest, HealthCheckRequest.Builder> {
+    private HealthCheckRequest() { }
+    private static readonly HealthCheckRequest defaultInstance = new HealthCheckRequest().MakeReadOnly();
+    private static readonly string[] _healthCheckRequestFieldNames = new string[] { "host", "service" };
+    private static readonly uint[] _healthCheckRequestFieldTags = new uint[] { 10, 18 };
+    public static HealthCheckRequest DefaultInstance {
+      get { return defaultInstance; }
+    }
+
+    public override HealthCheckRequest DefaultInstanceForType {
+      get { return DefaultInstance; }
+    }
+
+    protected override HealthCheckRequest ThisMessage {
+      get { return this; }
+    }
+
+    public static pbd::MessageDescriptor Descriptor {
+      get { return global::Grpc.Health.V1Alpha.Proto.Health.internal__static_grpc_health_v1alpha_HealthCheckRequest__Descriptor; }
+    }
+
+    protected override pb::FieldAccess.FieldAccessorTable<HealthCheckRequest, HealthCheckRequest.Builder> InternalFieldAccessors {
+      get { return global::Grpc.Health.V1Alpha.Proto.Health.internal__static_grpc_health_v1alpha_HealthCheckRequest__FieldAccessorTable; }
+    }
+
+    public const int HostFieldNumber = 1;
+    private bool hasHost;
+    private string host_ = "";
+    public bool HasHost {
+      get { return hasHost; }
+    }
+    public string Host {
+      get { return host_; }
+    }
+
+    public const int ServiceFieldNumber = 2;
+    private bool hasService;
+    private string service_ = "";
+    public bool HasService {
+      get { return hasService; }
+    }
+    public string Service {
+      get { return service_; }
+    }
+
+    public override bool IsInitialized {
+      get {
+        return true;
+      }
+    }
+
+    public override void WriteTo(pb::ICodedOutputStream output) {
+      CalcSerializedSize();
+      string[] field_names = _healthCheckRequestFieldNames;
+      if (hasHost) {
+        output.WriteString(1, field_names[0], Host);
+      }
+      if (hasService) {
+        output.WriteString(2, field_names[1], Service);
+      }
+      UnknownFields.WriteTo(output);
+    }
+
+    private int memoizedSerializedSize = -1;
+    public override int SerializedSize {
+      get {
+        int size = memoizedSerializedSize;
+        if (size != -1) return size;
+        return CalcSerializedSize();
+      }
+    }
+
+    private int CalcSerializedSize() {
+      int size = memoizedSerializedSize;
+      if (size != -1) return size;
+
+      size = 0;
+      if (hasHost) {
+        size += pb::CodedOutputStream.ComputeStringSize(1, Host);
+      }
+      if (hasService) {
+        size += pb::CodedOutputStream.ComputeStringSize(2, Service);
+      }
+      size += UnknownFields.SerializedSize;
+      memoizedSerializedSize = size;
+      return size;
+    }
+    public static HealthCheckRequest ParseFrom(pb::ByteString data) {
+      return ((Builder) CreateBuilder().MergeFrom(data)).BuildParsed();
+    }
+    public static HealthCheckRequest ParseFrom(pb::ByteString data, pb::ExtensionRegistry extensionRegistry) {
+      return ((Builder) CreateBuilder().MergeFrom(data, extensionRegistry)).BuildParsed();
+    }
+    public static HealthCheckRequest ParseFrom(byte[] data) {
+      return ((Builder) CreateBuilder().MergeFrom(data)).BuildParsed();
+    }
+    public static HealthCheckRequest ParseFrom(byte[] data, pb::ExtensionRegistry extensionRegistry) {
+      return ((Builder) CreateBuilder().MergeFrom(data, extensionRegistry)).BuildParsed();
+    }
+    public static HealthCheckRequest ParseFrom(global::System.IO.Stream input) {
+      return ((Builder) CreateBuilder().MergeFrom(input)).BuildParsed();
+    }
+    public static HealthCheckRequest ParseFrom(global::System.IO.Stream input, pb::ExtensionRegistry extensionRegistry) {
+      return ((Builder) CreateBuilder().MergeFrom(input, extensionRegistry)).BuildParsed();
+    }
+    public static HealthCheckRequest ParseDelimitedFrom(global::System.IO.Stream input) {
+      return CreateBuilder().MergeDelimitedFrom(input).BuildParsed();
+    }
+    public static HealthCheckRequest ParseDelimitedFrom(global::System.IO.Stream input, pb::ExtensionRegistry extensionRegistry) {
+      return CreateBuilder().MergeDelimitedFrom(input, extensionRegistry).BuildParsed();
+    }
+    public static HealthCheckRequest ParseFrom(pb::ICodedInputStream input) {
+      return ((Builder) CreateBuilder().MergeFrom(input)).BuildParsed();
+    }
+    public static HealthCheckRequest ParseFrom(pb::ICodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
+      return ((Builder) CreateBuilder().MergeFrom(input, extensionRegistry)).BuildParsed();
+    }
+    private HealthCheckRequest MakeReadOnly() {
+      return this;
+    }
+
+    public static Builder CreateBuilder() { return new Builder(); }
+    public override Builder ToBuilder() { return CreateBuilder(this); }
+    public override Builder CreateBuilderForType() { return new Builder(); }
+    public static Builder CreateBuilder(HealthCheckRequest prototype) {
+      return new Builder(prototype);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    public sealed partial class Builder : pb::GeneratedBuilder<HealthCheckRequest, Builder> {
+      protected override Builder ThisBuilder {
+        get { return this; }
+      }
+      public Builder() {
+        result = DefaultInstance;
+        resultIsReadOnly = true;
+      }
+      internal Builder(HealthCheckRequest cloneFrom) {
+        result = cloneFrom;
+        resultIsReadOnly = true;
+      }
+
+      private bool resultIsReadOnly;
+      private HealthCheckRequest result;
+
+      private HealthCheckRequest PrepareBuilder() {
+        if (resultIsReadOnly) {
+          HealthCheckRequest original = result;
+          result = new HealthCheckRequest();
+          resultIsReadOnly = false;
+          MergeFrom(original);
+        }
+        return result;
+      }
+
+      public override bool IsInitialized {
+        get { return result.IsInitialized; }
+      }
+
+      protected override HealthCheckRequest MessageBeingBuilt {
+        get { return PrepareBuilder(); }
+      }
+
+      public override Builder Clear() {
+        result = DefaultInstance;
+        resultIsReadOnly = true;
+        return this;
+      }
+
+      public override Builder Clone() {
+        if (resultIsReadOnly) {
+          return new Builder(result);
+        } else {
+          return new Builder().MergeFrom(result);
+        }
+      }
+
+      public override pbd::MessageDescriptor DescriptorForType {
+        get { return global::Grpc.Health.V1Alpha.HealthCheckRequest.Descriptor; }
+      }
+
+      public override HealthCheckRequest DefaultInstanceForType {
+        get { return global::Grpc.Health.V1Alpha.HealthCheckRequest.DefaultInstance; }
+      }
+
+      public override HealthCheckRequest BuildPartial() {
+        if (resultIsReadOnly) {
+          return result;
+        }
+        resultIsReadOnly = true;
+        return result.MakeReadOnly();
+      }
+
+      public override Builder MergeFrom(pb::IMessage other) {
+        if (other is HealthCheckRequest) {
+          return MergeFrom((HealthCheckRequest) other);
+        } else {
+          base.MergeFrom(other);
+          return this;
+        }
+      }
+
+      public override Builder MergeFrom(HealthCheckRequest other) {
+        if (other == global::Grpc.Health.V1Alpha.HealthCheckRequest.DefaultInstance) return this;
+        PrepareBuilder();
+        if (other.HasHost) {
+          Host = other.Host;
+        }
+        if (other.HasService) {
+          Service = other.Service;
+        }
+        this.MergeUnknownFields(other.UnknownFields);
+        return this;
+      }
+
+      public override Builder MergeFrom(pb::ICodedInputStream input) {
+        return MergeFrom(input, pb::ExtensionRegistry.Empty);
+      }
+
+      public override Builder MergeFrom(pb::ICodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
+        PrepareBuilder();
+        pb::UnknownFieldSet.Builder unknownFields = null;
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
+          if(tag == 0 && field_name != null) {
+            int field_ordinal = global::System.Array.BinarySearch(_healthCheckRequestFieldNames, field_name, global::System.StringComparer.Ordinal);
+            if(field_ordinal >= 0)
+              tag = _healthCheckRequestFieldTags[field_ordinal];
+            else {
+              if (unknownFields == null) {
+                unknownFields = pb::UnknownFieldSet.CreateBuilder(this.UnknownFields);
+              }
+              ParseUnknownField(input, unknownFields, extensionRegistry, tag, field_name);
+              continue;
+            }
+          }
+          switch (tag) {
+            case 0: {
+              throw pb::InvalidProtocolBufferException.InvalidTag();
+            }
+            default: {
+              if (pb::WireFormat.IsEndGroupTag(tag)) {
+                if (unknownFields != null) {
+                  this.UnknownFields = unknownFields.Build();
+                }
+                return this;
+              }
+              if (unknownFields == null) {
+                unknownFields = pb::UnknownFieldSet.CreateBuilder(this.UnknownFields);
+              }
+              ParseUnknownField(input, unknownFields, extensionRegistry, tag, field_name);
+              break;
+            }
+            case 10: {
+              result.hasHost = input.ReadString(ref result.host_);
+              break;
+            }
+            case 18: {
+              result.hasService = input.ReadString(ref result.service_);
+              break;
+            }
+          }
+        }
+
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
+      }
+
+
+      public bool HasHost {
+        get { return result.hasHost; }
+      }
+      public string Host {
+        get { return result.Host; }
+        set { SetHost(value); }
+      }
+      public Builder SetHost(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
+        PrepareBuilder();
+        result.hasHost = true;
+        result.host_ = value;
+        return this;
+      }
+      public Builder ClearHost() {
+        PrepareBuilder();
+        result.hasHost = false;
+        result.host_ = "";
+        return this;
+      }
+
+      public bool HasService {
+        get { return result.hasService; }
+      }
+      public string Service {
+        get { return result.Service; }
+        set { SetService(value); }
+      }
+      public Builder SetService(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
+        PrepareBuilder();
+        result.hasService = true;
+        result.service_ = value;
+        return this;
+      }
+      public Builder ClearService() {
+        PrepareBuilder();
+        result.hasService = false;
+        result.service_ = "";
+        return this;
+      }
+    }
+    static HealthCheckRequest() {
+      object.ReferenceEquals(global::Grpc.Health.V1Alpha.Proto.Health.Descriptor, null);
+    }
+  }
+
+  [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+  public sealed partial class HealthCheckResponse : pb::GeneratedMessage<HealthCheckResponse, HealthCheckResponse.Builder> {
+    private HealthCheckResponse() { }
+    private static readonly HealthCheckResponse defaultInstance = new HealthCheckResponse().MakeReadOnly();
+    private static readonly string[] _healthCheckResponseFieldNames = new string[] { "status" };
+    private static readonly uint[] _healthCheckResponseFieldTags = new uint[] { 8 };
+    public static HealthCheckResponse DefaultInstance {
+      get { return defaultInstance; }
+    }
+
+    public override HealthCheckResponse DefaultInstanceForType {
+      get { return DefaultInstance; }
+    }
+
+    protected override HealthCheckResponse ThisMessage {
+      get { return this; }
+    }
+
+    public static pbd::MessageDescriptor Descriptor {
+      get { return global::Grpc.Health.V1Alpha.Proto.Health.internal__static_grpc_health_v1alpha_HealthCheckResponse__Descriptor; }
+    }
+
+    protected override pb::FieldAccess.FieldAccessorTable<HealthCheckResponse, HealthCheckResponse.Builder> InternalFieldAccessors {
+      get { return global::Grpc.Health.V1Alpha.Proto.Health.internal__static_grpc_health_v1alpha_HealthCheckResponse__FieldAccessorTable; }
+    }
+
+    #region Nested types
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    public static partial class Types {
+      public enum ServingStatus {
+        UNKNOWN = 0,
+        SERVING = 1,
+        NOT_SERVING = 2,
+      }
+
+    }
+    #endregion
+
+    public const int StatusFieldNumber = 1;
+    private bool hasStatus;
+    private global::Grpc.Health.V1Alpha.HealthCheckResponse.Types.ServingStatus status_ = global::Grpc.Health.V1Alpha.HealthCheckResponse.Types.ServingStatus.UNKNOWN;
+    public bool HasStatus {
+      get { return hasStatus; }
+    }
+    public global::Grpc.Health.V1Alpha.HealthCheckResponse.Types.ServingStatus Status {
+      get { return status_; }
+    }
+
+    public override bool IsInitialized {
+      get {
+        return true;
+      }
+    }
+
+    public override void WriteTo(pb::ICodedOutputStream output) {
+      CalcSerializedSize();
+      string[] field_names = _healthCheckResponseFieldNames;
+      if (hasStatus) {
+        output.WriteEnum(1, field_names[0], (int) Status, Status);
+      }
+      UnknownFields.WriteTo(output);
+    }
+
+    private int memoizedSerializedSize = -1;
+    public override int SerializedSize {
+      get {
+        int size = memoizedSerializedSize;
+        if (size != -1) return size;
+        return CalcSerializedSize();
+      }
+    }
+
+    private int CalcSerializedSize() {
+      int size = memoizedSerializedSize;
+      if (size != -1) return size;
+
+      size = 0;
+      if (hasStatus) {
+        size += pb::CodedOutputStream.ComputeEnumSize(1, (int) Status);
+      }
+      size += UnknownFields.SerializedSize;
+      memoizedSerializedSize = size;
+      return size;
+    }
+    public static HealthCheckResponse ParseFrom(pb::ByteString data) {
+      return ((Builder) CreateBuilder().MergeFrom(data)).BuildParsed();
+    }
+    public static HealthCheckResponse ParseFrom(pb::ByteString data, pb::ExtensionRegistry extensionRegistry) {
+      return ((Builder) CreateBuilder().MergeFrom(data, extensionRegistry)).BuildParsed();
+    }
+    public static HealthCheckResponse ParseFrom(byte[] data) {
+      return ((Builder) CreateBuilder().MergeFrom(data)).BuildParsed();
+    }
+    public static HealthCheckResponse ParseFrom(byte[] data, pb::ExtensionRegistry extensionRegistry) {
+      return ((Builder) CreateBuilder().MergeFrom(data, extensionRegistry)).BuildParsed();
+    }
+    public static HealthCheckResponse ParseFrom(global::System.IO.Stream input) {
+      return ((Builder) CreateBuilder().MergeFrom(input)).BuildParsed();
+    }
+    public static HealthCheckResponse ParseFrom(global::System.IO.Stream input, pb::ExtensionRegistry extensionRegistry) {
+      return ((Builder) CreateBuilder().MergeFrom(input, extensionRegistry)).BuildParsed();
+    }
+    public static HealthCheckResponse ParseDelimitedFrom(global::System.IO.Stream input) {
+      return CreateBuilder().MergeDelimitedFrom(input).BuildParsed();
+    }
+    public static HealthCheckResponse ParseDelimitedFrom(global::System.IO.Stream input, pb::ExtensionRegistry extensionRegistry) {
+      return CreateBuilder().MergeDelimitedFrom(input, extensionRegistry).BuildParsed();
+    }
+    public static HealthCheckResponse ParseFrom(pb::ICodedInputStream input) {
+      return ((Builder) CreateBuilder().MergeFrom(input)).BuildParsed();
+    }
+    public static HealthCheckResponse ParseFrom(pb::ICodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
+      return ((Builder) CreateBuilder().MergeFrom(input, extensionRegistry)).BuildParsed();
+    }
+    private HealthCheckResponse MakeReadOnly() {
+      return this;
+    }
+
+    public static Builder CreateBuilder() { return new Builder(); }
+    public override Builder ToBuilder() { return CreateBuilder(this); }
+    public override Builder CreateBuilderForType() { return new Builder(); }
+    public static Builder CreateBuilder(HealthCheckResponse prototype) {
+      return new Builder(prototype);
+    }
+
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    public sealed partial class Builder : pb::GeneratedBuilder<HealthCheckResponse, Builder> {
+      protected override Builder ThisBuilder {
+        get { return this; }
+      }
+      public Builder() {
+        result = DefaultInstance;
+        resultIsReadOnly = true;
+      }
+      internal Builder(HealthCheckResponse cloneFrom) {
+        result = cloneFrom;
+        resultIsReadOnly = true;
+      }
+
+      private bool resultIsReadOnly;
+      private HealthCheckResponse result;
+
+      private HealthCheckResponse PrepareBuilder() {
+        if (resultIsReadOnly) {
+          HealthCheckResponse original = result;
+          result = new HealthCheckResponse();
+          resultIsReadOnly = false;
+          MergeFrom(original);
+        }
+        return result;
+      }
+
+      public override bool IsInitialized {
+        get { return result.IsInitialized; }
+      }
+
+      protected override HealthCheckResponse MessageBeingBuilt {
+        get { return PrepareBuilder(); }
+      }
+
+      public override Builder Clear() {
+        result = DefaultInstance;
+        resultIsReadOnly = true;
+        return this;
+      }
+
+      public override Builder Clone() {
+        if (resultIsReadOnly) {
+          return new Builder(result);
+        } else {
+          return new Builder().MergeFrom(result);
+        }
+      }
+
+      public override pbd::MessageDescriptor DescriptorForType {
+        get { return global::Grpc.Health.V1Alpha.HealthCheckResponse.Descriptor; }
+      }
+
+      public override HealthCheckResponse DefaultInstanceForType {
+        get { return global::Grpc.Health.V1Alpha.HealthCheckResponse.DefaultInstance; }
+      }
+
+      public override HealthCheckResponse BuildPartial() {
+        if (resultIsReadOnly) {
+          return result;
+        }
+        resultIsReadOnly = true;
+        return result.MakeReadOnly();
+      }
+
+      public override Builder MergeFrom(pb::IMessage other) {
+        if (other is HealthCheckResponse) {
+          return MergeFrom((HealthCheckResponse) other);
+        } else {
+          base.MergeFrom(other);
+          return this;
+        }
+      }
+
+      public override Builder MergeFrom(HealthCheckResponse other) {
+        if (other == global::Grpc.Health.V1Alpha.HealthCheckResponse.DefaultInstance) return this;
+        PrepareBuilder();
+        if (other.HasStatus) {
+          Status = other.Status;
+        }
+        this.MergeUnknownFields(other.UnknownFields);
+        return this;
+      }
+
+      public override Builder MergeFrom(pb::ICodedInputStream input) {
+        return MergeFrom(input, pb::ExtensionRegistry.Empty);
+      }
+
+      public override Builder MergeFrom(pb::ICodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
+        PrepareBuilder();
+        pb::UnknownFieldSet.Builder unknownFields = null;
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
+          if(tag == 0 && field_name != null) {
+            int field_ordinal = global::System.Array.BinarySearch(_healthCheckResponseFieldNames, field_name, global::System.StringComparer.Ordinal);
+            if(field_ordinal >= 0)
+              tag = _healthCheckResponseFieldTags[field_ordinal];
+            else {
+              if (unknownFields == null) {
+                unknownFields = pb::UnknownFieldSet.CreateBuilder(this.UnknownFields);
+              }
+              ParseUnknownField(input, unknownFields, extensionRegistry, tag, field_name);
+              continue;
+            }
+          }
+          switch (tag) {
+            case 0: {
+              throw pb::InvalidProtocolBufferException.InvalidTag();
+            }
+            default: {
+              if (pb::WireFormat.IsEndGroupTag(tag)) {
+                if (unknownFields != null) {
+                  this.UnknownFields = unknownFields.Build();
+                }
+                return this;
+              }
+              if (unknownFields == null) {
+                unknownFields = pb::UnknownFieldSet.CreateBuilder(this.UnknownFields);
+              }
+              ParseUnknownField(input, unknownFields, extensionRegistry, tag, field_name);
+              break;
+            }
+            case 8: {
+              object unknown;
+              if(input.ReadEnum(ref result.status_, out unknown)) {
+                result.hasStatus = true;
+              } else if(unknown is int) {
+                if (unknownFields == null) {
+                  unknownFields = pb::UnknownFieldSet.CreateBuilder(this.UnknownFields);
+                }
+                unknownFields.MergeVarintField(1, (ulong)(int)unknown);
+              }
+              break;
+            }
+          }
+        }
+
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
+      }
+
+
+      public bool HasStatus {
+       get { return result.hasStatus; }
+      }
+      public global::Grpc.Health.V1Alpha.HealthCheckResponse.Types.ServingStatus Status {
+        get { return result.Status; }
+        set { SetStatus(value); }
+      }
+      public Builder SetStatus(global::Grpc.Health.V1Alpha.HealthCheckResponse.Types.ServingStatus value) {
+        PrepareBuilder();
+        result.hasStatus = true;
+        result.status_ = value;
+        return this;
+      }
+      public Builder ClearStatus() {
+        PrepareBuilder();
+        result.hasStatus = false;
+        result.status_ = global::Grpc.Health.V1Alpha.HealthCheckResponse.Types.ServingStatus.UNKNOWN;
+        return this;
+      }
+    }
+    static HealthCheckResponse() {
+      object.ReferenceEquals(global::Grpc.Health.V1Alpha.Proto.Health.Descriptor, null);
+    }
+  }
+
+  #endregion
+
+}
+
+#endregion Designer generated code
diff --git a/src/csharp/Grpc.HealthCheck/HealthGrpc.cs b/src/csharp/Grpc.HealthCheck/HealthGrpc.cs
new file mode 100644
index 0000000000..ed9fc4ed77
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck/HealthGrpc.cs
@@ -0,0 +1,78 @@
+// Generated by the protocol buffer compiler.  DO NOT EDIT!
+// source: health.proto
+#region Designer generated code
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Grpc.Core;
+
+namespace Grpc.Health.V1Alpha {
+  public static class Health
+  {
+    static readonly string __ServiceName = "grpc.health.v1alpha.Health";
+
+    static readonly Marshaller<global::Grpc.Health.V1Alpha.HealthCheckRequest> __Marshaller_HealthCheckRequest = Marshallers.Create((arg) => arg.ToByteArray(), global::Grpc.Health.V1Alpha.HealthCheckRequest.ParseFrom);
+    static readonly Marshaller<global::Grpc.Health.V1Alpha.HealthCheckResponse> __Marshaller_HealthCheckResponse = Marshallers.Create((arg) => arg.ToByteArray(), global::Grpc.Health.V1Alpha.HealthCheckResponse.ParseFrom);
+
+    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,
+        "Check",
+        __Marshaller_HealthCheckRequest,
+        __Marshaller_HealthCheckResponse);
+
+    // client-side stub interface
+    public interface IHealthClient
+    {
+      global::Grpc.Health.V1Alpha.HealthCheckResponse Check(global::Grpc.Health.V1Alpha.HealthCheckRequest request, CancellationToken token = default(CancellationToken));
+      Task<global::Grpc.Health.V1Alpha.HealthCheckResponse> CheckAsync(global::Grpc.Health.V1Alpha.HealthCheckRequest request, CancellationToken token = default(CancellationToken));
+    }
+
+    // server-side interface
+    public interface IHealth
+    {
+      Task<global::Grpc.Health.V1Alpha.HealthCheckResponse> Check(ServerCallContext context, global::Grpc.Health.V1Alpha.HealthCheckRequest request);
+    }
+
+    // client stub
+    public class HealthClient : AbstractStub<HealthClient, StubConfiguration>, IHealthClient
+    {
+      public HealthClient(Channel channel) : this(channel, StubConfiguration.Default)
+      {
+      }
+      public HealthClient(Channel channel, StubConfiguration config) : base(channel, config)
+      {
+      }
+      public global::Grpc.Health.V1Alpha.HealthCheckResponse Check(global::Grpc.Health.V1Alpha.HealthCheckRequest request, CancellationToken token = default(CancellationToken))
+      {
+        var call = CreateCall(__ServiceName, __Method_Check);
+        return Calls.BlockingUnaryCall(call, request, token);
+      }
+      public Task<global::Grpc.Health.V1Alpha.HealthCheckResponse> CheckAsync(global::Grpc.Health.V1Alpha.HealthCheckRequest request, CancellationToken token = default(CancellationToken))
+      {
+        var call = CreateCall(__ServiceName, __Method_Check);
+        return Calls.AsyncUnaryCall(call, request, token);
+      }
+    }
+
+    // creates service definition that can be registered with a server
+    public static ServerServiceDefinition BindService(IHealth serviceImpl)
+    {
+      return ServerServiceDefinition.CreateBuilder(__ServiceName)
+          .AddMethod(__Method_Check, serviceImpl.Check).Build();
+    }
+
+    // creates a new client stub
+    public static IHealthClient NewStub(Channel channel)
+    {
+      return new HealthClient(channel);
+    }
+
+    // creates a new client stub
+    public static IHealthClient NewStub(Channel channel, StubConfiguration config)
+    {
+      return new HealthClient(channel, config);
+    }
+  }
+}
+#endregion
diff --git a/src/csharp/Grpc.HealthCheck/HealthServiceImpl.cs b/src/csharp/Grpc.HealthCheck/HealthServiceImpl.cs
new file mode 100644
index 0000000000..db3a2a0942
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck/HealthServiceImpl.cs
@@ -0,0 +1,132 @@
+#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.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+using Grpc.Core;
+using Grpc.Core.Utils;
+using Grpc.Health.V1Alpha;
+
+namespace Grpc.HealthCheck
+{
+    /// <summary>
+    /// Implementation of a simple Health service. Useful for health checking.
+    /// 
+    /// Registering service with a server:
+    /// <code>
+    /// var serviceImpl = new HealthServiceImpl();
+    /// server = new Server();
+    /// server.AddServiceDefinition(Grpc.Health.V1Alpha.Health.BindService(serviceImpl));
+    /// </code>
+    /// </summary>
+    public class HealthServiceImpl : Grpc.Health.V1Alpha.Health.IHealth
+    {
+        private readonly object myLock = new object();
+        private readonly Dictionary<Key, HealthCheckResponse.Types.ServingStatus> statusMap = 
+            new Dictionary<Key, HealthCheckResponse.Types.ServingStatus>();
+
+        /// <summary>
+        /// Sets the health status for given host and service.
+        /// </summary>
+        /// <param name="host">The host. Cannot be null.</param>
+        /// <param name="service">The service. Cannot be null.</param>
+        /// <param name="status">the health status</param>
+        public void SetStatus(string host, string service, HealthCheckResponse.Types.ServingStatus status)
+        {
+            lock (myLock)
+            {
+                statusMap[CreateKey(host, service)] = status;
+            }
+        }
+
+        /// <summary>
+        /// Clears health status for given host and service.
+        /// </summary>
+        /// <param name="host">The host. Cannot be null.</param>
+        /// <param name="service">The service. Cannot be null.</param>
+        public void ClearStatus(string host, string service)
+        {
+            lock (myLock)
+            {
+                statusMap.Remove(CreateKey(host, service));
+            }
+        }
+        
+        /// <summary>
+        /// Clears statuses for all hosts and services.
+        /// </summary>
+        public void ClearAll()
+        {
+            lock (myLock)
+            {
+                statusMap.Clear();
+            }
+        }
+
+        public Task<HealthCheckResponse> Check(ServerCallContext context, HealthCheckRequest request)
+        {
+            lock (myLock)
+            {
+                var host = request.HasHost ? request.Host : "";
+                var service = request.HasService ? request.Service : "";
+
+                HealthCheckResponse.Types.ServingStatus status;
+                if (!statusMap.TryGetValue(CreateKey(host, service), out status))
+                {
+                    // TODO(jtattermusch): returning specific status from server handler is not supported yet.
+                    throw new RpcException(new Status(StatusCode.NotFound, ""));
+                }
+                return Task.FromResult(HealthCheckResponse.CreateBuilder().SetStatus(status).Build());
+            }
+        }
+
+        private static Key CreateKey(string host, string service)
+        {
+            return new Key(host, service);
+        }
+
+        private struct Key
+        {
+            public Key(string host, string service)
+            {
+                this.Host = Preconditions.CheckNotNull(host);
+                this.Service = Preconditions.CheckNotNull(service);
+            }
+
+            readonly string Host;
+            readonly string Service;
+        }
+    }
+}
diff --git a/src/csharp/Grpc.HealthCheck/Properties/AssemblyInfo.cs b/src/csharp/Grpc.HealthCheck/Properties/AssemblyInfo.cs
new file mode 100644
index 0000000000..41a54a98bc
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck/Properties/AssemblyInfo.cs
@@ -0,0 +1,11 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+
+[assembly: AssemblyTitle("Grpc.HealthCheck")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("")]
+[assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
+\ No newline at end of file
diff --git a/src/csharp/Grpc.HealthCheck/packages.config b/src/csharp/Grpc.HealthCheck/packages.config
new file mode 100644
index 0000000000..094a30981e
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck/packages.config
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="Google.ProtocolBuffers" version="2.4.1.555" targetFramework="net45" />
+  <package id="Ix-Async" version="1.2.3" targetFramework="net45" />
+</packages>
+\ No newline at end of file
diff --git a/src/csharp/Grpc.HealthCheck/proto/health.proto b/src/csharp/Grpc.HealthCheck/proto/health.proto
new file mode 100644
index 0000000000..08df7e104e
--- /dev/null
+++ b/src/csharp/Grpc.HealthCheck/proto/health.proto
@@ -0,0 +1,52 @@
+// 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.
+
+// TODO(jtattermusch): switch to proto3 once C# supports that.
+syntax = "proto2";
+
+package grpc.health.v1alpha;
+option csharp_namespace = "Grpc.Health.V1Alpha";
+
+message HealthCheckRequest {
+  optional string host = 1;
+  optional string service = 2;
+}
+
+message HealthCheckResponse {
+  enum ServingStatus {
+    UNKNOWN = 0;
+    SERVING = 1;
+    NOT_SERVING = 2;
+  }
+  optional ServingStatus status = 1;
+}
+
+service Health {
+  rpc Check(HealthCheckRequest) returns (HealthCheckResponse);
+}
+\ No newline at end of file
diff --git a/src/csharp/Grpc.IntegrationTesting.Client/Grpc.IntegrationTesting.Client.csproj b/src/csharp/Grpc.IntegrationTesting.Client/Grpc.IntegrationTesting.Client.csproj
index df05c535e2..328acb5b47 100644
--- a/src/csharp/Grpc.IntegrationTesting.Client/Grpc.IntegrationTesting.Client.csproj
+++ b/src/csharp/Grpc.IntegrationTesting.Client/Grpc.IntegrationTesting.Client.csproj
@@ -36,6 +36,9 @@
     <Reference Include="System" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="..\Grpc.Core\Version.cs">
+      <Link>Version.cs</Link>
+    </Compile>
     <Compile Include="Program.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
diff --git a/src/csharp/Grpc.IntegrationTesting.Client/Properties/AssemblyInfo.cs b/src/csharp/Grpc.IntegrationTesting.Client/Properties/AssemblyInfo.cs
index 26c0dcc3b9..f51f2796c4 100644
--- a/src/csharp/Grpc.IntegrationTesting.Client/Properties/AssemblyInfo.cs
+++ b/src/csharp/Grpc.IntegrationTesting.Client/Properties/AssemblyInfo.cs
@@ -9,4 +9,3 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]
-[assembly: AssemblyVersion("0.5.*")]
diff --git a/src/csharp/Grpc.IntegrationTesting.Server/Grpc.IntegrationTesting.Server.csproj b/src/csharp/Grpc.IntegrationTesting.Server/Grpc.IntegrationTesting.Server.csproj
index 235897c888..ae184c1dc7 100644
--- a/src/csharp/Grpc.IntegrationTesting.Server/Grpc.IntegrationTesting.Server.csproj
+++ b/src/csharp/Grpc.IntegrationTesting.Server/Grpc.IntegrationTesting.Server.csproj
@@ -36,6 +36,9 @@
     <Reference Include="System" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="..\Grpc.Core\Version.cs">
+      <Link>Version.cs</Link>
+    </Compile>
     <Compile Include="Program.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
diff --git a/src/csharp/Grpc.IntegrationTesting.Server/Properties/AssemblyInfo.cs b/src/csharp/Grpc.IntegrationTesting.Server/Properties/AssemblyInfo.cs
index 2d518d7b72..f68d9a3ddc 100644
--- a/src/csharp/Grpc.IntegrationTesting.Server/Properties/AssemblyInfo.cs
+++ b/src/csharp/Grpc.IntegrationTesting.Server/Properties/AssemblyInfo.cs
@@ -9,4 +9,3 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]
-[assembly: AssemblyVersion("0.5.*")]
diff --git a/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj b/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
index b3a0a2917b..af4a75a034 100644
--- a/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
+++ b/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
@@ -54,6 +54,10 @@
     <Reference Include="Google.ProtocolBuffers">
       <HintPath>..\packages\Google.ProtocolBuffers.2.4.1.521\lib\net40\Google.ProtocolBuffers.dll</HintPath>
     </Reference>
+    <Reference Include="System.Collections.Immutable, Version=1.1.36.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath>..\packages\System.Collections.Immutable.1.1.36\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+    </Reference>
     <Reference Include="System.Interactive.Async">
       <HintPath>..\packages\Ix-Async.1.2.3\lib\net45\System.Interactive.Async.dll</HintPath>
     </Reference>
@@ -69,11 +73,11 @@
     <Reference Include="Newtonsoft.Json">
       <HintPath>..\packages\Newtonsoft.Json.6.0.6\lib\net45\Newtonsoft.Json.dll</HintPath>
     </Reference>
-    <Reference Include="System.Collections.Immutable">
-      <HintPath>..\packages\Microsoft.Bcl.Immutable.1.0.34\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
-    </Reference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="..\Grpc.Core\Version.cs">
+      <Link>Version.cs</Link>
+    </Compile>
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Empty.cs" />
     <Compile Include="Messages.cs" />
diff --git a/src/csharp/Grpc.IntegrationTesting/InteropClient.cs b/src/csharp/Grpc.IntegrationTesting/InteropClient.cs
index f0be522bc6..bdcb2c505c 100644
--- a/src/csharp/Grpc.IntegrationTesting/InteropClient.cs
+++ b/src/csharp/Grpc.IntegrationTesting/InteropClient.cs
@@ -102,8 +102,6 @@ namespace Grpc.IntegrationTesting
 
         private void Run()
         {
-            GrpcEnvironment.Initialize();
-
             Credentials credentials = null;
             if (options.useTls)
             {
@@ -135,7 +133,6 @@ namespace Grpc.IntegrationTesting
                 TestService.ITestServiceClient client = new TestService.TestServiceClient(channel, stubConfig);
                 RunTestCase(options.testCase, client);
             }
-
             GrpcEnvironment.Shutdown();
         }
 
diff --git a/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs b/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs
index 1a733450c1..6c2da9d2ee 100644
--- a/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs
+++ b/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs
@@ -55,8 +55,6 @@ namespace Grpc.IntegrationTesting
         [TestFixtureSetUp]
         public void Init()
         {
-            GrpcEnvironment.Initialize();
-
             server = new Server();
             server.AddServiceDefinition(TestService.BindService(new TestServiceImpl()));
             int port = server.AddListeningPort(host, Server.PickUnusedPort, TestCredentials.CreateTestServerCredentials());
@@ -74,7 +72,6 @@ namespace Grpc.IntegrationTesting
         public void Cleanup()
         {
             channel.Dispose();
-
             server.ShutdownAsync().Wait();
             GrpcEnvironment.Shutdown();
         }
diff --git a/src/csharp/Grpc.IntegrationTesting/InteropServer.cs b/src/csharp/Grpc.IntegrationTesting/InteropServer.cs
index 87c3cbe1d4..9475e66c40 100644
--- a/src/csharp/Grpc.IntegrationTesting/InteropServer.cs
+++ b/src/csharp/Grpc.IntegrationTesting/InteropServer.cs
@@ -88,8 +88,6 @@ namespace Grpc.IntegrationTesting
 
         private void Run()
         {
-            GrpcEnvironment.Initialize();
-
             var server = new Server();
             server.AddServiceDefinition(TestService.BindService(new TestServiceImpl()));
 
diff --git a/src/csharp/Grpc.IntegrationTesting/Properties/AssemblyInfo.cs b/src/csharp/Grpc.IntegrationTesting/Properties/AssemblyInfo.cs
index f73575e8bd..1beb0bbb41 100644
--- a/src/csharp/Grpc.IntegrationTesting/Properties/AssemblyInfo.cs
+++ b/src/csharp/Grpc.IntegrationTesting/Properties/AssemblyInfo.cs
@@ -9,4 +9,3 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]
-[assembly: AssemblyVersion("0.5.*")]
diff --git a/src/csharp/Grpc.IntegrationTesting/packages.config b/src/csharp/Grpc.IntegrationTesting/packages.config
index 291b7b8599..c74ac75d79 100644
--- a/src/csharp/Grpc.IntegrationTesting/packages.config
+++ b/src/csharp/Grpc.IntegrationTesting/packages.config
@@ -7,8 +7,8 @@
   <package id="Microsoft.Bcl" version="1.1.9" targetFramework="net45" />
   <package id="Microsoft.Bcl.Async" version="1.0.168" targetFramework="net45" />
   <package id="Microsoft.Bcl.Build" version="1.0.14" targetFramework="net45" />
-  <package id="Microsoft.Bcl.Immutable" version="1.0.34" targetFramework="net45" />
   <package id="Microsoft.Net.Http" version="2.2.28" targetFramework="net45" />
   <package id="Newtonsoft.Json" version="6.0.6" 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/Grpc.Tools.nuspec b/src/csharp/Grpc.Tools.nuspec
index 913d4c8f4b..eabf5dc7db 100644
--- a/src/csharp/Grpc.Tools.nuspec
+++ b/src/csharp/Grpc.Tools.nuspec
@@ -5,13 +5,13 @@
     <title>gRPC C# Tools</title>
     <summary>Tools for C# implementation of gRPC - an RPC library and framework</summary>
     <description>Precompiled Windows binaries for generating protocol buffer messages and gRPC client/server code</description>
-    <version>0.5.1</version>
+    <version>$version$</version>
     <authors>Google Inc.</authors>
     <owners>grpc-packages</owners>
     <licenseUrl>https://github.com/grpc/grpc/blob/master/LICENSE</licenseUrl>
     <projectUrl>https://github.com/grpc/grpc</projectUrl>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
-    <releaseNotes>protoc.exe - protocol buffer compiler v3.0.0-alpha-3; grpc_csharp_plugin.exe - gRPC C# protoc plugin version 0.5.1</releaseNotes>
+    <releaseNotes>protoc.exe - protocol buffer compiler v3.0.0-alpha-3; grpc_csharp_plugin.exe - gRPC C# protoc plugin version $version$</releaseNotes>
     <copyright>Copyright 2015, Google Inc.</copyright>
     <tags>gRPC RPC Protocol HTTP/2</tags>
   </metadata>
diff --git a/src/csharp/Grpc.nuspec b/src/csharp/Grpc.nuspec
index cf4c74fa2d..7fbd861923 100644
--- a/src/csharp/Grpc.nuspec
+++ b/src/csharp/Grpc.nuspec
@@ -5,17 +5,17 @@
     <title>gRPC C#</title>
     <summary>C# implementation of gRPC - an RPC library and framework</summary>
     <description>C# implementation of gRPC - an RPC library and framework. See project site for more info.</description>
-    <version>0.5.1</version>
+    <version>$version$</version>
     <authors>Google Inc.</authors>
     <owners>grpc-packages</owners>
     <licenseUrl>https://github.com/grpc/grpc/blob/master/LICENSE</licenseUrl>
     <projectUrl>https://github.com/grpc/grpc</projectUrl>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
-    <releaseNotes>Release 0.5.1 of gRPC C#</releaseNotes>
+    <releaseNotes>Release $version$ of gRPC C#</releaseNotes>
     <copyright>Copyright 2015, Google Inc.</copyright>
     <tags>gRPC RPC Protocol HTTP/2</tags>
     <dependencies>
-      <dependency id="Grpc.Core" version="0.5.1" />
+      <dependency id="Grpc.Core" version="$version$" />
     </dependencies>
   </metadata>
   <files/>
diff --git a/src/csharp/Grpc.sln b/src/csharp/Grpc.sln
index 978739f23a..705e4fb1c2 100644
--- a/src/csharp/Grpc.sln
+++ b/src/csharp/Grpc.sln
@@ -28,57 +28,68 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = ".nuget", ".nuget", "{B5B871
 		.nuget\packages.config = .nuget\packages.config
 	EndProjectSection
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Grpc.HealthCheck", "Grpc.HealthCheck\Grpc.HealthCheck.csproj", "{AA5E328A-8835-49D7-98ED-C29F2B3049F0}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Grpc.HealthCheck.Tests", "Grpc.HealthCheck.Tests\Grpc.HealthCheck.Tests.csproj", "{F8C6D937-C44B-4EE3-A431-B0FBAEACE47D}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|x86 = Debug|x86
 		Release|x86 = Release|x86
 	EndGlobalSection
 	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{7DC1433E-3225-42C7-B7EA-546D56E27A4B}.Debug|x86.ActiveCfg = Debug|Any CPU
-		{7DC1433E-3225-42C7-B7EA-546D56E27A4B}.Debug|x86.Build.0 = Debug|Any CPU
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-		{7DC1433E-3225-42C7-B7EA-546D56E27A4B}.Release|x86.Build.0 = Release|Any CPU
-		{CCC4440E-49F7-4790-B0AF-FEABB0837AE7}.Debug|x86.ActiveCfg = Debug|Any CPU
-		{CCC4440E-49F7-4790-B0AF-FEABB0837AE7}.Debug|x86.Build.0 = Debug|Any CPU
-		{CCC4440E-49F7-4790-B0AF-FEABB0837AE7}.Release|x86.ActiveCfg = Release|Any CPU
-		{CCC4440E-49F7-4790-B0AF-FEABB0837AE7}.Release|x86.Build.0 = Release|Any CPU
-		{86EC5CB4-4EA2-40A2-8057-86542A0353BB}.Debug|x86.ActiveCfg = Debug|Any CPU
-		{86EC5CB4-4EA2-40A2-8057-86542A0353BB}.Debug|x86.Build.0 = Debug|Any CPU
-		{86EC5CB4-4EA2-40A2-8057-86542A0353BB}.Release|x86.ActiveCfg = Release|Any CPU
-		{86EC5CB4-4EA2-40A2-8057-86542A0353BB}.Release|x86.Build.0 = Release|Any CPU
 		{143B1C29-C442-4BE0-BF3F-A8F92288AC9F}.Debug|x86.ActiveCfg = Debug|Any CPU
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 		{143B1C29-C442-4BE0-BF3F-A8F92288AC9F}.Release|x86.Build.0 = Release|Any CPU
-		{61ECB8EE-0C96-4F8E-B187-8E4D227417C0}.Debug|x86.ActiveCfg = Debug|x86
-		{61ECB8EE-0C96-4F8E-B187-8E4D227417C0}.Debug|x86.Build.0 = Debug|x86
-		{61ECB8EE-0C96-4F8E-B187-8E4D227417C0}.Release|x86.ActiveCfg = Release|x86
-		{61ECB8EE-0C96-4F8E-B187-8E4D227417C0}.Release|x86.Build.0 = Release|x86
-		{C61154BA-DD4A-4838-8420-0162A28925E0}.Debug|x86.ActiveCfg = Debug|x86
-		{C61154BA-DD4A-4838-8420-0162A28925E0}.Debug|x86.Build.0 = Debug|x86
-		{C61154BA-DD4A-4838-8420-0162A28925E0}.Release|x86.ActiveCfg = Release|x86
-		{C61154BA-DD4A-4838-8420-0162A28925E0}.Release|x86.Build.0 = Release|x86
 		{3D166931-BA2D-416E-95A3-D36E8F6E90B9}.Debug|x86.ActiveCfg = Debug|x86
 		{3D166931-BA2D-416E-95A3-D36E8F6E90B9}.Debug|x86.Build.0 = Debug|x86
 		{3D166931-BA2D-416E-95A3-D36E8F6E90B9}.Release|x86.ActiveCfg = Release|x86
 		{3D166931-BA2D-416E-95A3-D36E8F6E90B9}.Release|x86.Build.0 = Release|x86
+		{61ECB8EE-0C96-4F8E-B187-8E4D227417C0}.Debug|x86.ActiveCfg = Debug|x86
+		{61ECB8EE-0C96-4F8E-B187-8E4D227417C0}.Debug|x86.Build.0 = Debug|x86
+		{61ECB8EE-0C96-4F8E-B187-8E4D227417C0}.Release|x86.ActiveCfg = Release|x86
+		{61ECB8EE-0C96-4F8E-B187-8E4D227417C0}.Release|x86.Build.0 = Release|x86
+		{7DC1433E-3225-42C7-B7EA-546D56E27A4B}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{7DC1433E-3225-42C7-B7EA-546D56E27A4B}.Debug|x86.Build.0 = Debug|Any CPU
+		{7DC1433E-3225-42C7-B7EA-546D56E27A4B}.Release|x86.ActiveCfg = Release|Any CPU
+		{7DC1433E-3225-42C7-B7EA-546D56E27A4B}.Release|x86.Build.0 = Release|Any CPU
+		{86EC5CB4-4EA2-40A2-8057-86542A0353BB}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{86EC5CB4-4EA2-40A2-8057-86542A0353BB}.Debug|x86.Build.0 = Debug|Any CPU
+		{86EC5CB4-4EA2-40A2-8057-86542A0353BB}.Release|x86.ActiveCfg = Release|Any CPU
+		{86EC5CB4-4EA2-40A2-8057-86542A0353BB}.Release|x86.Build.0 = Release|Any CPU
 		{A654F3B8-E859-4E6A-B30D-227527DBEF0D}.Debug|x86.ActiveCfg = Debug|x86
 		{A654F3B8-E859-4E6A-B30D-227527DBEF0D}.Debug|x86.Build.0 = Debug|x86
 		{A654F3B8-E859-4E6A-B30D-227527DBEF0D}.Release|x86.ActiveCfg = Release|x86
 		{A654F3B8-E859-4E6A-B30D-227527DBEF0D}.Release|x86.Build.0 = Release|x86
-		{BF62FE08-373A-43D6-9D73-41CAA38B7011}.Debug|x86.ActiveCfg = Debug|x86
-		{BF62FE08-373A-43D6-9D73-41CAA38B7011}.Debug|x86.Build.0 = Debug|x86
-		{BF62FE08-373A-43D6-9D73-41CAA38B7011}.Release|x86.ActiveCfg = Release|x86
-		{BF62FE08-373A-43D6-9D73-41CAA38B7011}.Release|x86.Build.0 = Release|x86
+		{AA5E328A-8835-49D7-98ED-C29F2B3049F0}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{AA5E328A-8835-49D7-98ED-C29F2B3049F0}.Debug|x86.Build.0 = Debug|Any CPU
+		{AA5E328A-8835-49D7-98ED-C29F2B3049F0}.Release|x86.ActiveCfg = Release|Any CPU
+		{AA5E328A-8835-49D7-98ED-C29F2B3049F0}.Release|x86.Build.0 = Release|Any CPU
 		{AE21D0EE-9A2C-4C15-AB7F-5224EED5B0EA}.Debug|x86.ActiveCfg = Debug|Any CPU
 		{AE21D0EE-9A2C-4C15-AB7F-5224EED5B0EA}.Debug|x86.Build.0 = Debug|Any CPU
 		{AE21D0EE-9A2C-4C15-AB7F-5224EED5B0EA}.Release|x86.ActiveCfg = Release|Any CPU
 		{AE21D0EE-9A2C-4C15-AB7F-5224EED5B0EA}.Release|x86.Build.0 = Release|Any CPU
+		{BF62FE08-373A-43D6-9D73-41CAA38B7011}.Debug|x86.ActiveCfg = Debug|x86
+		{BF62FE08-373A-43D6-9D73-41CAA38B7011}.Debug|x86.Build.0 = Debug|x86
+		{BF62FE08-373A-43D6-9D73-41CAA38B7011}.Release|x86.ActiveCfg = Release|x86
+		{BF62FE08-373A-43D6-9D73-41CAA38B7011}.Release|x86.Build.0 = Release|x86
+		{C61154BA-DD4A-4838-8420-0162A28925E0}.Debug|x86.ActiveCfg = Debug|x86
+		{C61154BA-DD4A-4838-8420-0162A28925E0}.Debug|x86.Build.0 = Debug|x86
+		{C61154BA-DD4A-4838-8420-0162A28925E0}.Release|x86.ActiveCfg = Release|x86
+		{C61154BA-DD4A-4838-8420-0162A28925E0}.Release|x86.Build.0 = Release|x86
+		{CCC4440E-49F7-4790-B0AF-FEABB0837AE7}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{CCC4440E-49F7-4790-B0AF-FEABB0837AE7}.Debug|x86.Build.0 = Debug|Any CPU
+		{CCC4440E-49F7-4790-B0AF-FEABB0837AE7}.Release|x86.ActiveCfg = Release|Any CPU
+		{CCC4440E-49F7-4790-B0AF-FEABB0837AE7}.Release|x86.Build.0 = Release|Any CPU
+		{F8C6D937-C44B-4EE3-A431-B0FBAEACE47D}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{F8C6D937-C44B-4EE3-A431-B0FBAEACE47D}.Debug|x86.Build.0 = Debug|Any CPU
+		{F8C6D937-C44B-4EE3-A431-B0FBAEACE47D}.Release|x86.ActiveCfg = Release|Any CPU
+		{F8C6D937-C44B-4EE3-A431-B0FBAEACE47D}.Release|x86.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(NestedProjects) = preSolution
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection
-	GlobalSection(MonoDevelopProperties) = preSolution
-		StartupItem = Grpc.Examples\Grpc.Examples.csproj
-	EndGlobalSection
 EndGlobal
diff --git a/src/csharp/build_packages.bat b/src/csharp/build_packages.bat
index 3412129fb2..c3e5fe8817 100644
--- a/src/csharp/build_packages.bat
+++ b/src/csharp/build_packages.bat
@@ -1,5 +1,9 @@
 @rem Builds gRPC NuGet packages
 
+@rem Current package versions
+set VERSION=0.6.0
+set CORE_VERSION=0.10.0
+
 @rem Adjust the location of nuget.exe
 set NUGET=C:\nuget\nuget.exe
 
@@ -10,11 +14,12 @@ endlocal
 
 @call buildall.bat || goto :error
 
-%NUGET% pack ..\..\vsprojects\nuget_package\grpc.native.csharp_ext.nuspec || goto :error
-%NUGET% pack Grpc.Core\Grpc.Core.nuspec -Symbols || goto :error
-%NUGET% pack Grpc.Auth\Grpc.Auth.nuspec -Symbols || goto :error
-%NUGET% pack Grpc.Tools.nuspec || goto :error
-%NUGET% pack Grpc.nuspec || goto :error
+%NUGET% pack ..\..\vsprojects\nuget_package\grpc.native.csharp_ext.nuspec -Version %CORE_VERSION% || goto :error
+%NUGET% pack Grpc.Auth\Grpc.Auth.nuspec -Symbols -Version %VERSION% || goto :error
+%NUGET% pack Grpc.Core\Grpc.Core.nuspec -Symbols -Version %VERSION% -Properties GrpcNativeCsharpExtVersion=%CORE_VERSION% || goto :error
+%NUGET% pack Grpc.HealthCheck\Grpc.HealthCheck.nuspec -Symbols -Version %VERSION% || goto :error
+%NUGET% pack Grpc.Tools.nuspec -Version %VERSION% || goto :error
+%NUGET% pack Grpc.nuspec -Version %VERSION% || goto :error
 
 goto :EOF
 
diff --git a/src/csharp/ext/grpc_csharp_ext.c b/src/csharp/ext/grpc_csharp_ext.c
index ec125db78b..a55cc9e247 100644
--- a/src/csharp/ext/grpc_csharp_ext.c
+++ b/src/csharp/ext/grpc_csharp_ext.c
@@ -379,7 +379,7 @@ grpcsharp_channel_args_destroy(grpc_channel_args *args) {
 
 /* Timespec */
 
-GPR_EXPORT gpr_timespec GPR_CALLTYPE gprsharp_now(void) { return gpr_now(); }
+GPR_EXPORT gpr_timespec GPR_CALLTYPE gprsharp_now(void) { return gpr_now(GPR_CLOCK_REALTIME); }
 
 GPR_EXPORT gpr_timespec GPR_CALLTYPE gprsharp_inf_future(void) {
   return gpr_inf_future;
diff --git a/src/csharp/generate_proto_csharp.sh b/src/csharp/generate_proto_csharp.sh
index f980787bb7..6eb3887ea1 100755
--- a/src/csharp/generate_proto_csharp.sh
+++ b/src/csharp/generate_proto_csharp.sh
@@ -35,9 +35,13 @@ cd $(dirname $0)
 PLUGIN=protoc-gen-grpc=../../bins/opt/grpc_csharp_plugin
 EXAMPLES_DIR=Grpc.Examples
 INTEROP_DIR=Grpc.IntegrationTesting
+HEALTHCHECK_DIR=Grpc.HealthCheck
 
 protoc --plugin=$PLUGIN --grpc_out=$EXAMPLES_DIR \
     -I $EXAMPLES_DIR/proto $EXAMPLES_DIR/proto/math.proto
 
 protoc --plugin=$PLUGIN --grpc_out=$INTEROP_DIR \
     -I $INTEROP_DIR/proto $INTEROP_DIR/proto/test.proto
+	
+protoc --plugin=$PLUGIN --grpc_out=$HEALTHCHECK_DIR \
+    -I $HEALTHCHECK_DIR/proto $HEALTHCHECK_DIR/proto/health.proto
diff --git a/src/node/health_check/health.js b/src/node/health_check/health.js
new file mode 100644
index 0000000000..87e00197fe
--- /dev/null
+++ b/src/node/health_check/health.js
@@ -0,0 +1,70 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+'use strict';
+
+var grpc = require('../');
+
+var _ = require('lodash');
+
+var health_proto = grpc.load(__dirname + '/health.proto');
+
+var HealthClient = health_proto.grpc.health.v1alpha.Health;
+
+function HealthImplementation(statusMap) {
+  this.statusMap = _.clone(statusMap);
+}
+
+HealthImplementation.prototype.setStatus = function(host, service, status) {
+  if (!this.statusMap[host]) {
+    this.statusMap[host] = {};
+  }
+  this.statusMap[host][service] = status;
+};
+
+HealthImplementation.prototype.check = function(call, callback){
+  var host = call.request.host;
+  var service = call.request.service;
+  var status = _.get(this.statusMap, [host, service], null);
+  if (status === null) {
+    callback({code:grpc.status.NOT_FOUND});
+  } else {
+    callback(null, {status: status});
+  }
+};
+
+module.exports = {
+  Client: HealthClient,
+  service: HealthClient.service,
+  Implementation: HealthImplementation
+};
diff --git a/src/node/health_check/health.proto b/src/node/health_check/health.proto
new file mode 100644
index 0000000000..d31df1e0a7
--- /dev/null
+++ b/src/node/health_check/health.proto
@@ -0,0 +1,50 @@
+// 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.
+
+syntax = "proto3";
+
+package grpc.health.v1alpha;
+
+message HealthCheckRequest {
+  string host = 1;
+  string service = 2;
+}
+
+message HealthCheckResponse {
+  enum ServingStatus {
+    UNKNOWN = 0;
+    SERVING = 1;
+    NOT_SERVING = 2;
+  }
+  ServingStatus status = 1;
+}
+
+service Health {
+  rpc Check(HealthCheckRequest) returns (HealthCheckResponse);
+}
+\ No newline at end of file
diff --git a/src/node/package.json b/src/node/package.json
index 6b545705e1..1caf158792 100644
--- a/src/node/package.json
+++ b/src/node/package.json
@@ -1,6 +1,6 @@
 {
   "name": "grpc",
-  "version": "0.9.1",
+  "version": "0.10.0",
   "author": "Google Inc.",
   "description": "gRPC Library for Node",
   "homepage": "http://www.grpc.io/",
diff --git a/src/node/src/server.js b/src/node/src/server.js
index c6cf9e7eb8..00be400e61 100644
--- a/src/node/src/server.js
+++ b/src/node/src/server.js
@@ -55,7 +55,7 @@ var EventEmitter = require('events').EventEmitter;
  */
 function handleError(call, error) {
   var status = {
-    code: grpc.status.INTERNAL,
+    code: grpc.status.UNKNOWN,
     details: 'Unknown Error',
     metadata: {}
   };
@@ -142,12 +142,12 @@ function setUpWritable(stream, serialize) {
   stream.on('finish', sendStatus);
   /**
    * Set the pending status to a given error status. If the error does not have
-   * code or details properties, the code will be set to grpc.status.INTERNAL
+   * code or details properties, the code will be set to grpc.status.UNKNOWN
    * and the details will be set to 'Unknown Error'.
    * @param {Error} err The error object
    */
   function setStatus(err) {
-    var code = grpc.status.INTERNAL;
+    var code = grpc.status.UNKNOWN;
     var details = 'Unknown Error';
     var metadata = {};
     if (err.hasOwnProperty('message')) {
@@ -634,7 +634,8 @@ function makeServerConstructor(service_attr_map) {
         }
         var serialize = attrs.responseSerialize;
         var deserialize = attrs.requestDeserialize;
-        server.register(attrs.path, service_handlers[service_name][name],
+        server.register(attrs.path, _.bind(service_handlers[service_name][name],
+                                           service_handlers[service_name]),
                         serialize, deserialize, method_type);
       });
     }, this);
diff --git a/src/node/test/health_test.js b/src/node/test/health_test.js
new file mode 100644
index 0000000000..4d1a5082e0
--- /dev/null
+++ b/src/node/test/health_test.js
@@ -0,0 +1,103 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+'use strict';
+
+var assert = require('assert');
+
+var health = require('../health_check/health.js');
+
+var grpc = require('../');
+
+describe('Health Checking', function() {
+  var statusMap = {
+    '': {
+      '': 'SERVING',
+      'grpc.test.TestService': 'NOT_SERVING',
+    },
+    virtual_host: {
+      'grpc.test.TestService': 'SERVING'
+    }
+  };
+  var HealthServer = grpc.buildServer([health.service]);
+  var healthServer = new HealthServer({
+    'grpc.health.v1alpha.Health': new health.Implementation(statusMap)
+  });
+  var healthClient;
+  before(function() {
+    var port_num = healthServer.bind('0.0.0.0:0');
+    healthServer.listen();
+    healthClient = new health.Client('localhost:' + port_num);
+  });
+  after(function() {
+    healthServer.shutdown();
+  });
+  it('should say an enabled service is SERVING', function(done) {
+    healthClient.check({service: ''}, function(err, response) {
+      assert.ifError(err);
+      assert.strictEqual(response.status, 'SERVING');
+      done();
+    });
+  });
+  it('should say that a disabled service is NOT_SERVING', function(done) {
+    healthClient.check({service: 'grpc.test.TestService'},
+                       function(err, response) {
+                         assert.ifError(err);
+                         assert.strictEqual(response.status, 'NOT_SERVING');
+                         done();
+                       });
+  });
+  it('should say that a service on another host is SERVING', function(done) {
+    healthClient.check({host: 'virtual_host', service: 'grpc.test.TestService'},
+                       function(err, response) {
+                         assert.ifError(err);
+                         assert.strictEqual(response.status, 'SERVING');
+                         done();
+                       });
+  });
+  it('should get NOT_FOUND if the service is not registered', function(done) {
+    healthClient.check({service: 'not_registered'}, function(err, response) {
+      assert(err);
+      assert.strictEqual(err.code, grpc.status.NOT_FOUND);
+      done();
+    });
+  });
+  it('should get NOT_FOUND if the host is not registered', function(done) {
+    healthClient.check({host: 'wrong_host', service: 'grpc.test.TestService'},
+                       function(err, response) {
+                         assert(err);
+                         assert.strictEqual(err.code, grpc.status.NOT_FOUND);
+                         done();
+                       });
+  });
+});
diff --git a/src/php/bin/determine_extension_dir.sh b/src/php/bin/determine_extension_dir.sh
index 6bbd934bf1..3c1fc297fa 100755
--- a/src/php/bin/determine_extension_dir.sh
+++ b/src/php/bin/determine_extension_dir.sh
@@ -27,12 +27,12 @@
 # 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.
-
 set -e
 default_extension_dir=$(php-config --extension-dir)
-if command -v brew >/dev/null && [ -d $(brew --prefix)/opt/grpc-php ]; then
-  # homebrew and the grpc-php formula are installed
-  extension_dir="-d extension_dir="$(brew --prefix)/opt/grpc-php
+if command -v brew > /dev/null && \
+   brew ls --versions | grep php5[56]-grpc > /dev/null; then
+  # the grpc php extension was installed by homebrew
+  :
 elif [ ! -e $default_extension_dir/grpc.so ]; then
   # the grpc extension is not found in the default PHP extension dir
   # try the source modules directory
@@ -45,5 +45,5 @@ elif [ ! -e $default_extension_dir/grpc.so ]; then
   for f in $default_extension_dir/*.so; do
     ln -s $f $module_dir/$(basename $f) &> /dev/null || true
   done
-  extension_dir="-d extension_dir="$module_dir
+  extension_dir="-d extension_dir=${module_dir} -d extension=grpc.so"
 fi
diff --git a/src/php/bin/interop_client.sh b/src/php/bin/interop_client.sh
index 42e075cbe8..17b888dd4e 100755
--- a/src/php/bin/interop_client.sh
+++ b/src/php/bin/interop_client.sh
@@ -31,5 +31,5 @@
 set -e
 cd $(dirname $0)
 source ./determine_extension_dir.sh
-php $extension_dir -d extension=grpc.so \
+php $extension_dir \
   ../tests/interop/interop_client.php $@ 1>&2
diff --git a/src/php/bin/run_gen_code_test.sh b/src/php/bin/run_gen_code_test.sh
index 03a9101a45..6e56c7207c 100755
--- a/src/php/bin/run_gen_code_test.sh
+++ b/src/php/bin/run_gen_code_test.sh
@@ -31,8 +31,8 @@
 set -e
 cd $(dirname $0)
 source ./determine_extension_dir.sh
-export GRPC_TEST_HOST=localhost:7071
-php $extension_dir -d extension=grpc.so $(which phpunit) -v --debug --strict \
+export GRPC_TEST_HOST=localhost:50051
+php $extension_dir $(which phpunit) -v --debug --strict \
   ../tests/generated_code/GeneratedCodeTest.php
-php $extension_dir -d extension=grpc.so $(which phpunit) -v --debug --strict \
+php $extension_dir $(which phpunit) -v --debug --strict \
   ../tests/generated_code/GeneratedCodeWithCallbackTest.php
diff --git a/src/php/bin/run_tests.sh b/src/php/bin/run_tests.sh
index 4c37285455..953f408ea8 100755
--- a/src/php/bin/run_tests.sh
+++ b/src/php/bin/run_tests.sh
@@ -33,5 +33,5 @@
 set -e
 cd $(dirname $0)
 source ./determine_extension_dir.sh
-php $extension_dir -d extension=grpc.so $(which phpunit) -v --debug --strict \
+php $extension_dir $(which phpunit) -v --debug --strict \
   ../tests/unit_tests
diff --git a/src/php/ext/grpc/README.md b/src/php/ext/grpc/README.md
index 0ac09e1835..88d2c481ec 100644
--- a/src/php/ext/grpc/README.md
+++ b/src/php/ext/grpc/README.md
@@ -4,7 +4,7 @@ gRPC PHP Extension
 # Requirements
 
  * PHP 5.5+
- * [gRPC core library](https://github.com/grpc/grpc) 0.9.1
+ * [gRPC core library](https://github.com/grpc/grpc) 0.10.0
 
 # Installation
 
@@ -55,7 +55,7 @@ $ sudo pecl install grpc
 Note: before a stable release, you may need to do
 
 ```sh
-$ sudo pecl install grpc-0.5.0
+$ sudo pecl install grpc-0.5.1
 ```
 
 OR
diff --git a/src/php/ext/grpc/package.xml b/src/php/ext/grpc/package.xml
index 2c89829d51..bc2a05923b 100644
--- a/src/php/ext/grpc/package.xml
+++ b/src/php/ext/grpc/package.xml
@@ -10,11 +10,11 @@
   <email>grpc-packages@google.com</email>
   <active>yes</active>
  </lead>
- <date>2015-06-16</date>
- <time>20:12:55</time>
+ <date>2015-07-09</date>
+ <time>21:47:27</time>
  <version>
-  <release>0.5.0</release>
-  <api>0.5.0</api>
+  <release>0.5.1</release>
+  <api>0.5.1</api>
  </version>
  <stability>
   <release>alpha</release>
@@ -22,7 +22,7 @@
  </stability>
  <license>BSD</license>
  <notes>
-First alpha release
+Update to wrap gRPC C Core version 0.10.0
  </notes>
  <contents>
   <dir baseinstalldir="/" name="/">
@@ -34,15 +34,15 @@ First alpha release
    <file baseinstalldir="/" md5sum="f1b66029daeced20b47cf00cc6523fc8" name="channel.h" role="src" />
    <file baseinstalldir="/" md5sum="81a1193e93d8b6602add8ac360de565b" name="completion_queue.c" role="src" />
    <file baseinstalldir="/" md5sum="f10b5bb232d74a6878e829e2e76cdaa2" name="completion_queue.h" role="src" />
-   <file baseinstalldir="/" md5sum="a9181ed994a072ac5f41e7c9705c170f" name="config.m4" role="src" />
+   <file baseinstalldir="/" md5sum="a22f8eac0164761058cc4d9eb2ceb069" name="config.m4" role="src" />
    <file baseinstalldir="/" md5sum="8c3f1e11dac623001378bfd53b554f08" name="credentials.c" role="src" />
    <file baseinstalldir="/" md5sum="6988d6e97c19c8f8e3eb92371cf8246b" name="credentials.h" role="src" />
    <file baseinstalldir="/" md5sum="38a1bc979d810c36ebc2a52d4b7b5319" name="CREDITS" role="doc" />
    <file baseinstalldir="/" md5sum="3f35b472bbdef5a788cd90617d7d0847" name="LICENSE" role="doc" />
    <file baseinstalldir="/" md5sum="6aaa7a290122d230f2d8c4e4e05da4a9" name="php_grpc.c" role="src" />
    <file baseinstalldir="/" md5sum="673b07859d9f69232f8a754c56780686" name="php_grpc.h" role="src" />
-   <file baseinstalldir="/" md5sum="4d4d3382f8d10cae2e4378468e5516b9" name="README.md" role="doc" />
-   <file baseinstalldir="/" md5sum="53fda0ee6937f6ddc8e271886018d441" name="server.c" role="src" />
+   <file baseinstalldir="/" md5sum="c1d0b42fd77b7d6740bf7744bee90af5" name="README.md" role="doc" />
+   <file baseinstalldir="/" md5sum="30997dd423403e1f8ad09dcee598e5c4" name="server.c" role="src" />
    <file baseinstalldir="/" md5sum="4b730f06d14cbbb0642bdbd194749595" name="server.h" role="src" />
    <file baseinstalldir="/" md5sum="f6930beafb6c0e061899262f2f077e98" name="server_credentials.c" role="src" />
    <file baseinstalldir="/" md5sum="9c4b4cc06356a8a39a16a085a9b85996" name="server_credentials.h" role="src" />
@@ -78,5 +78,20 @@ First alpha release
 First alpha release
    </notes>
   </release>
+  <release>
+   <version>
+    <release>0.5.1</release>
+    <api>0.5.1</api>
+   </version>
+   <stability>
+    <release>alpha</release>
+    <api>alpha</api>
+   </stability>
+   <date>2015-07-09</date>
+   <license>BSD</license>
+   <notes>
+Update to wrap gRPC C Core version 0.10.0
+   </notes>
+  </release>
  </changelog>
 </package>
diff --git a/src/php/ext/grpc/timeval.c b/src/php/ext/grpc/timeval.c
index 8a278d6760..ccf7f0f81a 100644
--- a/src/php/ext/grpc/timeval.c
+++ b/src/php/ext/grpc/timeval.c
@@ -208,7 +208,7 @@ PHP_METHOD(Timeval, similar) {
  * @return Timeval The current time
  */
 PHP_METHOD(Timeval, now) {
-  zval *now = grpc_php_wrap_timeval(gpr_now());
+  zval *now = grpc_php_wrap_timeval(gpr_now(GPR_CLOCK_REALTIME));
   RETURN_DESTROY_ZVAL(now);
 }
 
diff --git a/src/python/interop/setup.py b/src/python/interop/setup.py
index 502fcbedd8..75012b0d8f 100644
--- a/src/python/interop/setup.py
+++ b/src/python/interop/setup.py
@@ -45,7 +45,7 @@ _PACKAGE_DATA = {
         'credentials/server1.pem',]
 }
 
-_INSTALL_REQUIRES = ['oauth2client>=1.4.7', 'grpcio>=0.4.0a4']
+_INSTALL_REQUIRES = ['oauth2client>=1.4.7', 'grpcio>=0.10.0a0']
 
 setuptools.setup(
     name='interop',
diff --git a/src/python/src/.gitignore b/src/python/src/.gitignore
index bc15a52cf1..144e501237 100644
--- a/src/python/src/.gitignore
+++ b/src/python/src/.gitignore
@@ -1,3 +1,4 @@
 MANIFEST
 grpcio.egg-info/
+build/
 dist/
diff --git a/src/python/src/grpc/_adapter/.gitignore b/src/python/src/grpc/_adapter/.gitignore
new file mode 100644
index 0000000000..a6f96cd6db
--- /dev/null
+++ b/src/python/src/grpc/_adapter/.gitignore
@@ -0,0 +1,5 @@
+*.a
+*.so
+*.dll
+*.pyc
+*.pyd
diff --git a/src/python/src/grpc/_cython/.gitignore b/src/python/src/grpc/_cython/.gitignore
new file mode 100644
index 0000000000..c315029288
--- /dev/null
+++ b/src/python/src/grpc/_cython/.gitignore
@@ -0,0 +1,7 @@
+*.h
+*.c
+*.a
+*.so
+*.dll
+*.pyc
+*.pyd
diff --git a/src/python/src/grpc/_cython/README.rst b/src/python/src/grpc/_cython/README.rst
new file mode 100644
index 0000000000..c0e66734e8
--- /dev/null
+++ b/src/python/src/grpc/_cython/README.rst
@@ -0,0 +1,52 @@
+GRPC Python Cython layer
+========================
+
+Package for the GRPC Python Cython layer.
+
+What is Cython?
+---------------
+
+Cython is both a superset of the Python language with extensions for dealing
+with C types and a tool that transpiles this superset into C code. It provides
+convenient means of statically typing expressions and of converting Python
+strings to pointers (among other niceties), thus dramatically smoothing the
+Python/C interop by allowing fluid use of APIs in both from the same source.
+See the wonderful `Cython website`_.
+
+Why Cython?
+-----------
+
+- **Python 2 and 3 support**
+  Cython generated C code has precompiler macros to target both Python 2 and
+  Python 3 C APIs, even while acting as a superset of just the Python 2
+  language (e.g. using ``basestring``).
+- **Significantly less semantic noise**
+  A lot of CPython code is just glue, especially human-error-prone
+  ``Py_INCREF``-ing and ``Py_DECREF``-ing around error handlers and such.
+  Cython takes care of that automagically.
+- **Possible PyPy support**
+  One of the major developments in Cython over the past few years was the
+  addition of support for PyPy. We might soon be able to provide such support
+  ourselves through our use of Cython.
+- **Less Python glue code**
+  There existed several adapter layers in and around the original CPython code
+  to smooth the surface exposed to Python due to how much trouble it was to
+  make such a smooth surface via the CPython API alone. Cython makes writing
+  such a surface incredibly easy, so these adapter layers may be removed.
+
+Implications for Users
+----------------------
+
+Nothing additional will be required for users. PyPI packages will contain
+Cython generated C code and thus not necessitate a Cython installation.
+
+Implications for GRPC Developers
+--------------------------------
+
+A typical edit-compile-debug cycle now requires Cython. We install Cython in
+the ``virtualenv`` generated for the Python tests in this repository, so
+initial test runs may take an extra 2+ minutes to complete.  Subsequent test
+runs won't reinstall ``Cython`` (unless required versions change and the
+``virtualenv`` doesn't have installed versions that satisfy the change).
+
+.. _`Cython website`: http://cython.org/
diff --git a/src/python/src/grpc/_cython/__init__.py b/src/python/src/grpc/_cython/__init__.py
new file mode 100644
index 0000000000..b89398809f
--- /dev/null
+++ b/src/python/src/grpc/_cython/__init__.py
@@ -0,0 +1,28 @@
+# 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/src/grpc/_cython/_cygrpc/__init__.py b/src/python/src/grpc/_cython/_cygrpc/__init__.py
new file mode 100644
index 0000000000..b89398809f
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/__init__.py
@@ -0,0 +1,28 @@
+# 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/src/grpc/_cython/_cygrpc/call.pxd b/src/python/src/grpc/_cython/_cygrpc/call.pxd
new file mode 100644
index 0000000000..fe9b81e3d3
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/call.pxd
@@ -0,0 +1,37 @@
+# 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.
+
+from grpc._cython._cygrpc cimport grpc
+
+
+cdef class Call:
+
+  cdef grpc.grpc_call *c_call
+  cdef list references
+
diff --git a/src/python/src/grpc/_cython/_cygrpc/call.pyx b/src/python/src/grpc/_cython/_cygrpc/call.pyx
new file mode 100644
index 0000000000..4349786b3a
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/call.pyx
@@ -0,0 +1,82 @@
+# 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.
+
+cimport cpython
+
+from grpc._cython._cygrpc cimport records
+
+
+cdef class Call:
+
+  def __cinit__(self):
+    # Create an *empty* call
+    self.c_call = NULL
+    self.references = []
+
+  def start_batch(self, operations, tag):
+    if not self.is_valid:
+      raise ValueError("invalid call object cannot be used from Python")
+    cdef records.Operations cy_operations = records.Operations(operations)
+    cdef records.OperationTag operation_tag = records.OperationTag(tag)
+    operation_tag.operation_call = self
+    operation_tag.batch_operations = cy_operations
+    cpython.Py_INCREF(operation_tag)
+    return grpc.grpc_call_start_batch(
+        self.c_call, cy_operations.c_ops, cy_operations.c_nops,
+        <cpython.PyObject *>operation_tag)
+
+  def cancel(self,
+             grpc.grpc_status_code error_code=grpc.GRPC_STATUS__DO_NOT_USE,
+             details=None):
+    if not self.is_valid:
+      raise ValueError("invalid call object cannot be used from Python")
+    if (details is None) != (error_code == grpc.GRPC_STATUS__DO_NOT_USE):
+      raise ValueError("if error_code is specified, so must details "
+                       "(and vice-versa)")
+    if isinstance(details, bytes):
+      pass
+    elif isinstance(details, basestring):
+      details = details.encode()
+    else:
+      raise TypeError("expected details to be str or bytes")
+    if error_code != grpc.GRPC_STATUS__DO_NOT_USE:
+      self.references.append(details)
+      return grpc.grpc_call_cancel_with_status(self.c_call, error_code, details)
+    else:
+      return grpc.grpc_call_cancel(self.c_call)
+
+  def __dealloc__(self):
+    if self.c_call != NULL:
+      grpc.grpc_call_destroy(self.c_call)
+
+  # The object *should* always be valid from Python. Used for debugging.
+  @property
+  def is_valid(self):
+    return self.c_call != NULL
+
diff --git a/src/python/src/grpc/_cython/_cygrpc/channel.pxd b/src/python/src/grpc/_cython/_cygrpc/channel.pxd
new file mode 100644
index 0000000000..3e341bf222
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/channel.pxd
@@ -0,0 +1,36 @@
+# 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.
+
+from grpc._cython._cygrpc cimport grpc
+
+
+cdef class Channel:
+
+  cdef grpc.grpc_channel *c_channel
+  cdef list references
diff --git a/src/python/src/grpc/_cython/_cygrpc/channel.pyx b/src/python/src/grpc/_cython/_cygrpc/channel.pyx
new file mode 100644
index 0000000000..b20313818d
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/channel.pyx
@@ -0,0 +1,84 @@
+# 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.
+
+from grpc._cython._cygrpc cimport call
+from grpc._cython._cygrpc cimport completion_queue
+from grpc._cython._cygrpc cimport credentials
+from grpc._cython._cygrpc cimport records
+
+
+cdef class Channel:
+
+  def __cinit__(self, target, records.ChannelArgs arguments=None,
+                credentials.ClientCredentials client_credentials=None):
+    cdef grpc.grpc_channel_args *c_arguments = NULL
+    self.c_channel = NULL
+    self.references = []
+    if arguments is not None:
+      c_arguments = &arguments.c_args
+    if isinstance(target, bytes):
+      pass
+    elif isinstance(target, basestring):
+      target = target.encode()
+    else:
+      raise TypeError("expected target to be str or bytes")
+    if client_credentials is None:
+      self.c_channel = grpc.grpc_channel_create(target, c_arguments)
+    else:
+      self.c_channel = grpc.grpc_secure_channel_create(
+          client_credentials.c_credentials, target, c_arguments)
+      self.references.append(client_credentials)
+    self.references.append(target)
+    self.references.append(arguments)
+
+  def create_call(self, completion_queue.CompletionQueue queue not None,
+                  method, host, records.Timespec deadline not None):
+    if queue.is_shutting_down:
+      raise ValueError("queue must not be shutting down or shutdown")
+    if isinstance(method, bytes):
+      pass
+    elif isinstance(method, basestring):
+      method = method.encode()
+    else:
+      raise TypeError("expected method to be str or bytes")
+    if isinstance(host, bytes):
+      pass
+    elif isinstance(host, basestring):
+      host = host.encode()
+    else:
+      raise TypeError("expected host to be str or bytes")
+    cdef call.Call operation_call = call.Call()
+    operation_call.references = [self, method, host, queue]
+    operation_call.c_call = grpc.grpc_channel_create_call(
+        self.c_channel, queue.c_completion_queue, method, host, deadline.c_time)
+    return operation_call
+
+  def __dealloc__(self):
+    if self.c_channel != NULL:
+      grpc.grpc_channel_destroy(self.c_channel)
diff --git a/src/python/src/grpc/_cython/_cygrpc/completion_queue.pxd b/src/python/src/grpc/_cython/_cygrpc/completion_queue.pxd
new file mode 100644
index 0000000000..fd562ad75b
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/completion_queue.pxd
@@ -0,0 +1,39 @@
+# 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.
+
+from grpc._cython._cygrpc cimport grpc
+
+
+cdef class CompletionQueue:
+
+  cdef grpc.grpc_completion_queue *c_completion_queue
+  cdef object poll_condition
+  cdef bint is_polling
+  cdef bint is_shutting_down
+  cdef bint is_shutdown
diff --git a/src/python/src/grpc/_cython/_cygrpc/completion_queue.pyx b/src/python/src/grpc/_cython/_cygrpc/completion_queue.pyx
new file mode 100644
index 0000000000..886d85360a
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/completion_queue.pyx
@@ -0,0 +1,117 @@
+# 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.
+
+cimport cpython
+
+from grpc._cython._cygrpc cimport call
+from grpc._cython._cygrpc cimport records
+
+import threading
+import time
+
+
+cdef class CompletionQueue:
+
+  def __cinit__(self):
+    self.c_completion_queue = grpc.grpc_completion_queue_create()
+    self.is_shutting_down = False
+    self.is_shutdown = False
+    self.poll_condition = threading.Condition()
+    self.is_polling = False
+
+  def poll(self, records.Timespec deadline=None):
+    # We name this 'poll' to avoid problems with CPython's expectations for
+    # 'special' methods (like next and __next__).
+    cdef grpc.gpr_timespec c_deadline = grpc.gpr_inf_future
+    cdef records.OperationTag tag = None
+    cdef object user_tag = None
+    cdef call.Call operation_call = None
+    cdef records.CallDetails request_call_details = None
+    cdef records.Metadata request_metadata = None
+    cdef records.Operations batch_operations = None
+    if deadline is not None:
+      c_deadline = deadline.c_time
+    cdef grpc.grpc_event event
+
+    # Poll within a critical section
+    with self.poll_condition:
+      while self.is_polling:
+        self.poll_condition.wait(float(deadline) - time.time())
+      self.is_polling = True
+    with nogil:
+      event = grpc.grpc_completion_queue_next(
+          self.c_completion_queue, c_deadline)
+    with self.poll_condition:
+      self.is_polling = False
+      self.poll_condition.notify()
+
+    if event.type == grpc.GRPC_QUEUE_TIMEOUT:
+      return records.Event(event.type, False, None, None, None, None, None)
+    elif event.type == grpc.GRPC_QUEUE_SHUTDOWN:
+      self.is_shutdown = True
+      return records.Event(event.type, True, None, None, None, None, None)
+    else:
+      if event.tag != NULL:
+        tag = <records.OperationTag>event.tag
+        # We receive event tags only after they've been inc-ref'd elsewhere in
+        # the code.
+        cpython.Py_DECREF(tag)
+        if tag.shutting_down_server is not None:
+          tag.shutting_down_server.notify_shutdown_complete()
+        user_tag = tag.user_tag
+        operation_call = tag.operation_call
+        request_call_details = tag.request_call_details
+        request_metadata = tag.request_metadata
+        batch_operations = tag.batch_operations
+        if tag.is_new_request:
+          # Stuff in the tag not explicitly handled by us needs to live through
+          # the life of the call
+          operation_call.references.extend(tag.references)
+      return records.Event(
+          event.type, event.success, user_tag, operation_call,
+          request_call_details, request_metadata, batch_operations)
+
+  def shutdown(self):
+    grpc.grpc_completion_queue_shutdown(self.c_completion_queue)
+    self.is_shutting_down = True
+
+  def clear(self):
+    if not self.is_shutting_down:
+      raise ValueError('queue must be shutting down to be cleared')
+    while self.poll().type != grpc.GRPC_QUEUE_SHUTDOWN:
+      pass
+
+  def __dealloc__(self):
+    if self.c_completion_queue != NULL:
+      # Ensure shutdown, pump the queue
+      if not self.is_shutting_down:
+        self.shutdown()
+      while not self.is_shutdown:
+        self.poll()
+      grpc.grpc_completion_queue_destroy(self.c_completion_queue)
diff --git a/src/python/src/grpc/_cython/_cygrpc/credentials.pxd b/src/python/src/grpc/_cython/_cygrpc/credentials.pxd
new file mode 100644
index 0000000000..6b74a267e0
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/credentials.pxd
@@ -0,0 +1,45 @@
+# 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.
+
+from grpc._cython._cygrpc cimport grpc
+
+
+cdef class ClientCredentials:
+
+  cdef grpc.grpc_credentials *c_credentials
+  cdef grpc.grpc_ssl_pem_key_cert_pair c_ssl_pem_key_cert_pair
+  cdef list references
+
+
+cdef class ServerCredentials:
+
+  cdef grpc.grpc_server_credentials *c_credentials
+  cdef grpc.grpc_ssl_pem_key_cert_pair *c_ssl_pem_key_cert_pairs
+  cdef size_t c_ssl_pem_key_cert_pairs_count
+  cdef list references
diff --git a/src/python/src/grpc/_cython/_cygrpc/credentials.pyx b/src/python/src/grpc/_cython/_cygrpc/credentials.pyx
new file mode 100644
index 0000000000..c14d8844dd
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/credentials.pyx
@@ -0,0 +1,217 @@
+# 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.
+
+from grpc._cython._cygrpc cimport records
+
+
+cdef class ClientCredentials:
+
+  def __cinit__(self):
+    self.c_credentials = NULL
+    self.c_ssl_pem_key_cert_pair.private_key = NULL
+    self.c_ssl_pem_key_cert_pair.certificate_chain = NULL
+    self.references = []
+
+  # The object *can* be invalid in Python if we fail to make the credentials
+  # (and the core thus returns NULL credentials). Used primarily for debugging.
+  @property
+  def is_valid(self):
+    return self.c_credentials != NULL
+
+  def __dealloc__(self):
+    if self.c_credentials != NULL:
+      grpc.grpc_credentials_release(self.c_credentials)
+
+
+cdef class ServerCredentials:
+
+  def __cinit__(self):
+    self.c_credentials = NULL
+
+  def __dealloc__(self):
+    if self.c_credentials != NULL:
+      grpc.grpc_server_credentials_release(self.c_credentials)
+
+
+def client_credentials_google_default():
+  cdef ClientCredentials credentials = ClientCredentials();
+  credentials.c_credentials = grpc.grpc_google_default_credentials_create()
+  return credentials
+
+def client_credentials_ssl(pem_root_certificates,
+                           records.SslPemKeyCertPair ssl_pem_key_cert_pair):
+  if pem_root_certificates is None:
+    pass
+  elif isinstance(pem_root_certificates, bytes):
+    pass
+  elif isinstance(pem_root_certificates, basestring):
+    pem_root_certificates = pem_root_certificates.encode()
+  else:
+    raise TypeError("expected str or bytes for pem_root_certificates")
+  cdef ClientCredentials credentials = ClientCredentials()
+  cdef const char *c_pem_root_certificates = NULL
+  if pem_root_certificates is not None:
+    c_pem_root_certificates = pem_root_certificates
+    credentials.references.append(pem_root_certificates)
+  if ssl_pem_key_cert_pair is not None:
+    credentials.c_credentials = grpc.grpc_ssl_credentials_create(
+        c_pem_root_certificates, &ssl_pem_key_cert_pair.c_pair
+    )
+    credentials.references.append(ssl_pem_key_cert_pair)
+  else:
+    credentials.c_credentials = grpc.grpc_ssl_credentials_create(
+      c_pem_root_certificates, NULL
+    )
+
+def client_credentials_composite_credentials(
+    ClientCredentials credentials_1 not None,
+    ClientCredentials credentials_2 not None):
+  if not credentials_1.is_valid or not credentials_2.is_valid:
+    raise ValueError("passed credentials must both be valid")
+  cdef ClientCredentials credentials = ClientCredentials()
+  credentials.c_credentials = grpc.grpc_composite_credentials_create(
+      credentials_1.c_credentials, credentials_2.c_credentials)
+  credentials.references.append(credentials_1)
+  credentials.references.append(credentials_2)
+  return credentials
+
+def client_credentials_compute_engine():
+  cdef ClientCredentials credentials = ClientCredentials()
+  credentials.c_credentials = grpc.grpc_compute_engine_credentials_create()
+  return credentials
+
+def client_credentials_service_account(
+    json_key, scope, records.Timespec token_lifetime not None):
+  if isinstance(json_key, bytes):
+    pass
+  elif isinstance(json_key, basestring):
+    json_key = json_key.encode()
+  else:
+    raise TypeError("expected json_key to be str or bytes")
+  if isinstance(scope, bytes):
+    pass
+  elif isinstance(scope, basestring):
+    scope = scope.encode()
+  else:
+    raise TypeError("expected scope to be str or bytes")
+  cdef ClientCredentials credentials = ClientCredentials()
+  credentials.c_credentials = grpc.grpc_service_account_credentials_create(
+      json_key, scope, token_lifetime.c_time)
+  credentials.references.extend([json_key, scope])
+  return credentials
+
+def client_credentials_jwt(json_key, records.Timespec token_lifetime not None):
+  if isinstance(json_key, bytes):
+    pass
+  elif isinstance(json_key, basestring):
+    json_key = json_key.encode()
+  else:
+    raise TypeError("expected json_key to be str or bytes")
+  cdef ClientCredentials credentials = ClientCredentials()
+  credentials.c_credentials = grpc.grpc_jwt_credentials_create(
+      json_key, token_lifetime.c_time)
+  credentials.references.append(json_key)
+  return credentials
+
+def client_credentials_refresh_token(json_refresh_token):
+  if isinstance(json_refresh_token, bytes):
+    pass
+  elif isinstance(json_refresh_token, basestring):
+    json_refresh_token = json_refresh_token.encode()
+  else:
+    raise TypeError("expected json_refresh_token to be str or bytes")
+  cdef ClientCredentials credentials = ClientCredentials()
+  credentials.c_credentials = grpc.grpc_refresh_token_credentials_create(
+      json_refresh_token)
+  credentials.references.append(json_refresh_token)
+  return credentials
+
+def client_credentials_fake_transport_security():
+  cdef ClientCredentials credentials = ClientCredentials()
+  credentials.c_credentials = (
+      grpc.grpc_fake_transport_security_credentials_create())
+  return credentials
+
+def client_credentials_iam(authorization_token, authority_selector):
+  if isinstance(authorization_token, bytes):
+    pass
+  elif isinstance(authorization_token, basestring):
+    authorization_token = authorization_token.encode()
+  else:
+    raise TypeError("expected authorization_token to be str or bytes")
+  if isinstance(authority_selector, bytes):
+    pass
+  elif isinstance(authority_selector, basestring):
+    authority_selector = authority_selector.encode()
+  else:
+    raise TypeError("expected authority_selector to be str or bytes")
+  cdef ClientCredentials credentials = ClientCredentials()
+  credentials.c_credentials = grpc.grpc_iam_credentials_create(
+      authorization_token, authority_selector)
+  credentials.references.append(authorization_token)
+  credentials.references.append(authority_selector)
+  return credentials
+
+def server_credentials_ssl(pem_root_certs, pem_key_cert_pairs):
+  if pem_root_certs is None:
+    pass
+  elif isinstance(pem_root_certs, bytes):
+    pass
+  elif isinstance(pem_root_certs, basestring):
+    pem_root_certs = pem_root_certs.encode()
+  else:
+    raise TypeError("expected pem_root_certs to be str or bytes")
+  pem_key_cert_pairs = list(pem_key_cert_pairs)
+  for pair in pem_key_cert_pairs:
+    if not isinstance(pair, records.SslPemKeyCertPair):
+      raise TypeError("expected pem_key_cert_pairs to be sequence of "
+                      "records.SslPemKeyCertPair")
+  cdef ServerCredentials credentials = ServerCredentials()
+  credentials.references.append(pem_key_cert_pairs)
+  credentials.references.append(pem_root_certs)
+  credentials.c_ssl_pem_key_cert_pairs_count = len(pem_key_cert_pairs)
+  credentials.c_ssl_pem_key_cert_pairs = (
+      <grpc.grpc_ssl_pem_key_cert_pair *>grpc.gpr_malloc(
+          sizeof(grpc.grpc_ssl_pem_key_cert_pair) *
+              credentials.c_ssl_pem_key_cert_pairs_count
+      ))
+  for i in range(credentials.c_ssl_pem_key_cert_pairs_count):
+    credentials.c_ssl_pem_key_cert_pairs[i] = (
+        (<records.SslPemKeyCertPair>pem_key_cert_pairs[i]).c_pair)
+  credentials.c_credentials = grpc.grpc_ssl_server_credentials_create(
+      pem_root_certs, credentials.c_ssl_pem_key_cert_pairs,
+      credentials.c_ssl_pem_key_cert_pairs_count
+  )
+  return credentials
+
+def server_credentials_fake_transport_security():
+  cdef ServerCredentials credentials = ServerCredentials()
+  credentials.c_credentials = (
+      grpc.grpc_fake_transport_security_server_credentials_create())
+  return credentials
diff --git a/src/python/src/grpc/_cython/_cygrpc/grpc.pxd b/src/python/src/grpc/_cython/_cygrpc/grpc.pxd
new file mode 100644
index 0000000000..7db8fbe31c
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/grpc.pxd
@@ -0,0 +1,344 @@
+# 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.
+
+cimport libc.time
+
+
+cdef extern from "grpc/support/alloc.h":
+  void *gpr_malloc(size_t size)
+  void gpr_free(void *ptr)
+  void *gpr_realloc(void *p, size_t size)
+
+cdef extern from "grpc/support/slice.h":
+  ctypedef struct gpr_slice:
+    # don't worry about writing out the members of gpr_slice; we never access
+    # them directly.
+    pass
+
+  gpr_slice gpr_slice_ref(gpr_slice s)
+  void gpr_slice_unref(gpr_slice s)
+  gpr_slice gpr_slice_new(void *p, size_t len, void (*destroy)(void *))
+  gpr_slice gpr_slice_new_with_len(
+      void *p, size_t len, void (*destroy)(void *, size_t))
+  gpr_slice gpr_slice_malloc(size_t length)
+  gpr_slice gpr_slice_from_copied_string(const char *source)
+  gpr_slice gpr_slice_from_copied_buffer(const char *source, size_t len)
+
+  # Declare functions for function-like macros (because Cython)...
+  void *gpr_slice_start_ptr "GPR_SLICE_START_PTR" (gpr_slice s)
+  size_t gpr_slice_length "GPR_SLICE_LENGTH" (gpr_slice s)
+
+
+cdef extern from "grpc/support/port_platform.h":
+  # As long as the header file gets this type right, we don't need to get this
+  # type exactly; just close enough that the operations will be supported in the
+  # underlying C layers.
+  ctypedef unsigned int gpr_uint32
+
+
+cdef extern from "grpc/support/time.h":
+
+  ctypedef struct gpr_timespec:
+    libc.time.time_t seconds "tv_sec"
+    int nanoseconds "tv_nsec"
+
+  cdef gpr_timespec gpr_time_0
+  cdef gpr_timespec gpr_inf_future
+  cdef gpr_timespec gpr_inf_past
+
+  gpr_timespec gpr_now()
+
+
+cdef extern from "grpc/status.h":
+  ctypedef enum grpc_status_code:
+    GRPC_STATUS_OK
+    GRPC_STATUS_CANCELLED
+    GRPC_STATUS_UNKNOWN
+    GRPC_STATUS_INVALID_ARGUMENT
+    GRPC_STATUS_DEADLINE_EXCEEDED
+    GRPC_STATUS_NOT_FOUND
+    GRPC_STATUS_ALREADY_EXISTS
+    GRPC_STATUS_PERMISSION_DENIED
+    GRPC_STATUS_UNAUTHENTICATED
+    GRPC_STATUS_RESOURCE_EXHAUSTED
+    GRPC_STATUS_FAILED_PRECONDITION
+    GRPC_STATUS_ABORTED
+    GRPC_STATUS_OUT_OF_RANGE
+    GRPC_STATUS_UNIMPLEMENTED
+    GRPC_STATUS_INTERNAL
+    GRPC_STATUS_UNAVAILABLE
+    GRPC_STATUS_DATA_LOSS
+    GRPC_STATUS__DO_NOT_USE
+
+
+cdef extern from "grpc/byte_buffer_reader.h":
+  struct grpc_byte_buffer_reader:
+    # We don't care about the internals
+    pass
+
+
+cdef extern from "grpc/byte_buffer.h":
+  ctypedef struct grpc_byte_buffer:
+    # We don't care about the internals.
+    pass
+
+  grpc_byte_buffer *grpc_raw_byte_buffer_create(gpr_slice *slices,
+                                                size_t nslices)
+  size_t grpc_byte_buffer_length(grpc_byte_buffer *bb)
+  void grpc_byte_buffer_destroy(grpc_byte_buffer *byte_buffer)
+
+  void grpc_byte_buffer_reader_init(grpc_byte_buffer_reader *reader,
+                                    grpc_byte_buffer *buffer)
+  int grpc_byte_buffer_reader_next(grpc_byte_buffer_reader *reader,
+                                   gpr_slice *slice)
+  void grpc_byte_buffer_reader_destroy(grpc_byte_buffer_reader *reader)
+
+
+cdef extern from "grpc/grpc.h":
+
+  ctypedef struct grpc_completion_queue:
+    # We don't care about the internals (and in fact don't know them)
+    pass
+
+  ctypedef struct grpc_channel:
+    # We don't care about the internals (and in fact don't know them)
+    pass
+
+  ctypedef struct grpc_server:
+    # We don't care about the internals (and in fact don't know them)
+    pass
+
+  ctypedef struct grpc_call:
+    # We don't care about the internals (and in fact don't know them)
+    pass
+
+  ctypedef enum grpc_arg_type:
+    grpc_arg_string "GRPC_ARG_STRING"
+    grpc_arg_integer "GRPC_ARG_INTEGER"
+    grpc_arg_pointer "GRPC_ARG_POINTER"
+
+  ctypedef struct grpc_arg_value_pointer:
+    void *address "p"
+    void *(*copy)(void *)
+    void (*destroy)(void *)
+
+  union grpc_arg_value:
+    char *string
+    int integer
+    grpc_arg_value_pointer pointer
+
+  ctypedef struct grpc_arg:
+    grpc_arg_type type
+    char *key
+    grpc_arg_value value
+
+  ctypedef struct grpc_channel_args:
+    size_t arguments_length "num_args"
+    grpc_arg *arguments "args"
+
+  ctypedef enum grpc_call_error:
+    GRPC_CALL_OK
+    GRPC_CALL_ERROR
+    GRPC_CALL_ERROR_NOT_ON_SERVER
+    GRPC_CALL_ERROR_NOT_ON_CLIENT
+    GRPC_CALL_ERROR_ALREADY_ACCEPTED
+    GRPC_CALL_ERROR_ALREADY_INVOKED
+    GRPC_CALL_ERROR_NOT_INVOKED
+    GRPC_CALL_ERROR_ALREADY_FINISHED
+    GRPC_CALL_ERROR_TOO_MANY_OPERATIONS
+    GRPC_CALL_ERROR_INVALID_FLAGS
+    GRPC_CALL_ERROR_INVALID_METADATA
+
+  ctypedef struct grpc_metadata:
+    const char *key
+    const char *value
+    size_t value_length
+    # ignore the 'internal_data.obfuscated' fields.
+
+  ctypedef enum grpc_completion_type:
+    GRPC_QUEUE_SHUTDOWN
+    GRPC_QUEUE_TIMEOUT
+    GRPC_OP_COMPLETE
+
+  ctypedef struct grpc_event:
+    grpc_completion_type type
+    int success
+    void *tag
+
+  ctypedef struct grpc_metadata_array:
+    size_t count
+    size_t capacity
+    grpc_metadata *metadata
+
+  void grpc_metadata_array_init(grpc_metadata_array *array)
+  void grpc_metadata_array_destroy(grpc_metadata_array *array)
+
+  ctypedef struct grpc_call_details:
+    char *method
+    size_t method_capacity
+    char *host
+    size_t host_capacity
+    gpr_timespec deadline
+
+  void grpc_call_details_init(grpc_call_details *details)
+  void grpc_call_details_destroy(grpc_call_details *details)
+
+  ctypedef enum grpc_op_type:
+    GRPC_OP_SEND_INITIAL_METADATA
+    GRPC_OP_SEND_MESSAGE
+    GRPC_OP_SEND_CLOSE_FROM_CLIENT
+    GRPC_OP_SEND_STATUS_FROM_SERVER
+    GRPC_OP_RECV_INITIAL_METADATA
+    GRPC_OP_RECV_MESSAGE
+    GRPC_OP_RECV_STATUS_ON_CLIENT
+    GRPC_OP_RECV_CLOSE_ON_SERVER
+
+  ctypedef struct grpc_op_data_send_initial_metadata:
+    size_t count
+    grpc_metadata *metadata
+
+  ctypedef struct grpc_op_data_send_status_from_server:
+    size_t trailing_metadata_count
+    grpc_metadata *trailing_metadata
+    grpc_status_code status
+    const char *status_details
+
+  ctypedef struct grpc_op_data_recv_status_on_client:
+    grpc_metadata_array *trailing_metadata
+    grpc_status_code *status
+    char **status_details
+    size_t *status_details_capacity
+
+  ctypedef struct grpc_op_data_recv_close_on_server:
+    int *cancelled
+
+  union grpc_op_data:
+    grpc_op_data_send_initial_metadata send_initial_metadata
+    grpc_byte_buffer *send_message
+    grpc_op_data_send_status_from_server send_status_from_server
+    grpc_metadata_array *receive_initial_metadata "recv_initial_metadata"
+    grpc_byte_buffer **receive_message "recv_message"
+    grpc_op_data_recv_status_on_client receive_status_on_client "recv_status_on_client"
+    grpc_op_data_recv_close_on_server receive_close_on_server "recv_close_on_server"
+
+  ctypedef struct grpc_op:
+    grpc_op_type type "op"
+    gpr_uint32 flags
+    grpc_op_data data
+
+  void grpc_init()
+  void grpc_shutdown()
+
+  grpc_completion_queue *grpc_completion_queue_create()
+  grpc_event grpc_completion_queue_next(grpc_completion_queue *cq,
+                                        gpr_timespec deadline) nogil
+  void grpc_completion_queue_shutdown(grpc_completion_queue *cq)
+  void grpc_completion_queue_destroy(grpc_completion_queue *cq)
+
+  grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
+                                        size_t nops, void *tag)
+  grpc_call_error grpc_call_cancel(grpc_call *call)
+  grpc_call_error grpc_call_cancel_with_status(grpc_call *call,
+                                               grpc_status_code status,
+                                               const char *description)
+  void grpc_call_destroy(grpc_call *call)
+
+
+  grpc_channel *grpc_channel_create(const char *target,
+                                    const grpc_channel_args *args)
+  grpc_call *grpc_channel_create_call(grpc_channel *channel,
+                                      grpc_completion_queue *completion_queue,
+                                      const char *method, const char *host,
+                                      gpr_timespec deadline)
+  void grpc_channel_destroy(grpc_channel *channel)
+
+  grpc_server *grpc_server_create(const grpc_channel_args *args)
+  grpc_call_error grpc_server_request_call(
+      grpc_server *server, grpc_call **call, grpc_call_details *details,
+      grpc_metadata_array *request_metadata, grpc_completion_queue
+      *cq_bound_to_call, grpc_completion_queue *cq_for_notification, void
+      *tag_new)
+  void grpc_server_register_completion_queue(grpc_server *server,
+                                             grpc_completion_queue *cq)
+  int grpc_server_add_http2_port(grpc_server *server, const char *addr)
+  void grpc_server_start(grpc_server *server)
+  void grpc_server_shutdown_and_notify(
+      grpc_server *server, grpc_completion_queue *cq, void *tag)
+  void grpc_server_cancel_all_calls(grpc_server *server)
+  void grpc_server_destroy(grpc_server *server)
+
+
+cdef extern from "grpc/grpc_security.h":
+
+  ctypedef struct grpc_ssl_pem_key_cert_pair:
+    const char *private_key
+    const char *certificate_chain "cert_chain"
+
+  ctypedef struct grpc_credentials:
+    # We don't care about the internals (and in fact don't know them)
+    pass
+
+  grpc_credentials *grpc_google_default_credentials_create()
+  grpc_credentials *grpc_ssl_credentials_create(
+      const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pair)
+
+  grpc_credentials *grpc_composite_credentials_create(grpc_credentials *creds1,
+                                                      grpc_credentials *creds2)
+  grpc_credentials *grpc_compute_engine_credentials_create()
+  grpc_credentials *grpc_service_account_credentials_create(
+      const char *json_key, const char *scope, gpr_timespec token_lifetime)
+  grpc_credentials *grpc_jwt_credentials_create(const char *json_key,
+                                                gpr_timespec token_lifetime)
+  grpc_credentials *grpc_refresh_token_credentials_create(
+      const char *json_refresh_token)
+  grpc_credentials *grpc_fake_transport_security_credentials_create()
+  grpc_credentials *grpc_iam_credentials_create(const char *authorization_token,
+                                                const char *authority_selector)
+  void grpc_credentials_release(grpc_credentials *creds)
+
+  grpc_channel *grpc_secure_channel_create(
+      grpc_credentials *creds, const char *target,
+      const grpc_channel_args *args)
+
+  ctypedef struct grpc_server_credentials:
+    # We don't care about the internals (and in fact don't know them)
+    pass
+
+  grpc_server_credentials *grpc_ssl_server_credentials_create(
+      const char *pem_root_certs,
+      grpc_ssl_pem_key_cert_pair *pem_key_cert_pairs,
+      size_t num_key_cert_pairs);
+  grpc_server_credentials *grpc_fake_transport_security_server_credentials_create()
+  void grpc_server_credentials_release(grpc_server_credentials *creds)
+
+  int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
+                                        grpc_server_credentials *creds)
+
+  grpc_call_error grpc_call_set_credentials(grpc_call *call,
+                                            grpc_credentials *creds)
diff --git a/src/python/src/grpc/_cython/_cygrpc/records.pxd b/src/python/src/grpc/_cython/_cygrpc/records.pxd
new file mode 100644
index 0000000000..9ee487882a
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/records.pxd
@@ -0,0 +1,129 @@
+# 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.
+
+from grpc._cython._cygrpc cimport grpc
+from grpc._cython._cygrpc cimport call
+from grpc._cython._cygrpc cimport server
+
+
+cdef class Timespec:
+
+  cdef grpc.gpr_timespec c_time
+
+
+cdef class CallDetails:
+
+  cdef grpc.grpc_call_details c_details
+
+
+cdef class OperationTag:
+
+  cdef object user_tag
+  cdef list references
+  # This allows CompletionQueue to notify the Python Server object that the
+  # underlying GRPC core server has shutdown
+  cdef server.Server shutting_down_server
+  cdef call.Call operation_call
+  cdef CallDetails request_call_details
+  cdef Metadata request_metadata
+  cdef Operations batch_operations
+  cdef bint is_new_request
+
+
+cdef class Event:
+
+  cdef readonly grpc.grpc_completion_type type
+  cdef readonly bint success
+  cdef readonly object tag
+
+  # For operations with calls
+  cdef readonly call.Call operation_call
+
+  # For Server.request_call
+  cdef readonly CallDetails request_call_details
+  cdef readonly Metadata request_metadata
+
+  # For Call.start_batch
+  cdef readonly Operations batch_operations
+
+
+cdef class ByteBuffer:
+
+  cdef grpc.grpc_byte_buffer *c_byte_buffer
+
+
+cdef class SslPemKeyCertPair:
+
+  cdef grpc.grpc_ssl_pem_key_cert_pair c_pair
+  cdef readonly object private_key, certificate_chain
+
+
+cdef class ChannelArg:
+
+  cdef grpc.grpc_arg c_arg
+  cdef readonly object key, value
+
+
+cdef class ChannelArgs:
+
+  cdef grpc.grpc_channel_args c_args
+  cdef list args
+
+
+cdef class Metadatum:
+
+  cdef grpc.grpc_metadata c_metadata
+  cdef object _key, _value
+
+
+cdef class Metadata:
+
+  cdef grpc.grpc_metadata_array c_metadata_array
+  cdef object metadata
+
+
+cdef class Operation:
+
+  cdef grpc.grpc_op c_op
+  cdef ByteBuffer _received_message
+  cdef Metadata _received_metadata
+  cdef grpc.grpc_status_code _received_status_code
+  cdef char *_received_status_details
+  cdef size_t _received_status_details_capacity
+  cdef int _received_cancelled
+  cdef readonly bint is_valid
+  cdef object references
+
+
+cdef class Operations:
+
+  cdef grpc.grpc_op *c_ops
+  cdef size_t c_nops
+  cdef list operations
+
diff --git a/src/python/src/grpc/_cython/_cygrpc/records.pyx b/src/python/src/grpc/_cython/_cygrpc/records.pyx
new file mode 100644
index 0000000000..4814769fd2
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/records.pyx
@@ -0,0 +1,575 @@
+# 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.
+
+from grpc._cython._cygrpc cimport grpc
+from grpc._cython._cygrpc cimport call
+from grpc._cython._cygrpc cimport server
+
+
+class StatusCode:
+  ok = grpc.GRPC_STATUS_OK
+  cancelled = grpc.GRPC_STATUS_CANCELLED
+  unknown = grpc.GRPC_STATUS_UNKNOWN
+  invalid_argument = grpc.GRPC_STATUS_INVALID_ARGUMENT
+  deadline_exceeded = grpc.GRPC_STATUS_DEADLINE_EXCEEDED
+  not_found = grpc.GRPC_STATUS_NOT_FOUND
+  already_exists = grpc.GRPC_STATUS_ALREADY_EXISTS
+  permission_denied = grpc.GRPC_STATUS_PERMISSION_DENIED
+  unauthenticated = grpc.GRPC_STATUS_UNAUTHENTICATED
+  resource_exhausted = grpc.GRPC_STATUS_RESOURCE_EXHAUSTED
+  failed_precondition = grpc.GRPC_STATUS_FAILED_PRECONDITION
+  aborted = grpc.GRPC_STATUS_ABORTED
+  out_of_range = grpc.GRPC_STATUS_OUT_OF_RANGE
+  unimplemented = grpc.GRPC_STATUS_UNIMPLEMENTED
+  internal = grpc.GRPC_STATUS_INTERNAL
+  unavailable = grpc.GRPC_STATUS_UNAVAILABLE
+  data_loss = grpc.GRPC_STATUS_DATA_LOSS
+
+
+class CallError:
+  ok = grpc.GRPC_CALL_OK
+  error = grpc.GRPC_CALL_ERROR
+  not_on_server = grpc.GRPC_CALL_ERROR_NOT_ON_SERVER
+  not_on_client = grpc.GRPC_CALL_ERROR_NOT_ON_CLIENT
+  already_accepted = grpc.GRPC_CALL_ERROR_ALREADY_ACCEPTED
+  already_invoked = grpc.GRPC_CALL_ERROR_ALREADY_INVOKED
+  not_invoked = grpc.GRPC_CALL_ERROR_NOT_INVOKED
+  already_finished = grpc.GRPC_CALL_ERROR_ALREADY_FINISHED
+  too_many_operations = grpc.GRPC_CALL_ERROR_TOO_MANY_OPERATIONS
+  invalid_flags = grpc.GRPC_CALL_ERROR_INVALID_FLAGS
+  invalid_metadata = grpc.GRPC_CALL_ERROR_INVALID_METADATA
+
+
+class CompletionType:
+  queue_shutdown = grpc.GRPC_QUEUE_SHUTDOWN
+  queue_timeout = grpc.GRPC_QUEUE_TIMEOUT
+  operation_complete = grpc.GRPC_OP_COMPLETE
+
+
+class OperationType:
+  send_initial_metadata = grpc.GRPC_OP_SEND_INITIAL_METADATA
+  send_message = grpc.GRPC_OP_SEND_MESSAGE
+  send_close_from_client = grpc.GRPC_OP_SEND_CLOSE_FROM_CLIENT
+  send_status_from_server = grpc.GRPC_OP_SEND_STATUS_FROM_SERVER
+  receive_initial_metadata = grpc.GRPC_OP_RECV_INITIAL_METADATA
+  receive_message = grpc.GRPC_OP_RECV_MESSAGE
+  receive_status_on_client = grpc.GRPC_OP_RECV_STATUS_ON_CLIENT
+  receive_close_on_server = grpc.GRPC_OP_RECV_CLOSE_ON_SERVER
+
+
+cdef class Timespec:
+
+  def __cinit__(self, time):
+    if time is None:
+      self.c_time = grpc.gpr_now()
+    elif isinstance(time, float):
+      if time == float("+inf"):
+        self.c_time = grpc.gpr_inf_future
+      elif time == float("-inf"):
+        self.c_time = grpc.gpr_inf_past
+      else:
+        self.c_time.seconds = time
+        self.c_time.nanoseconds = (time - float(self.c_time.seconds)) * 1e9
+    else:
+      raise TypeError("expected time to be float")
+
+  @property
+  def seconds(self):
+    return self.c_time.seconds
+
+  @property
+  def nanoseconds(self):
+    return self.c_time.nanoseconds
+
+  def __float__(self):
+    return <double>self.c_time.seconds + <double>self.c_time.nanoseconds / 1e9
+
+  infinite_future = Timespec(float("+inf"))
+  infinite_past = Timespec(float("-inf"))
+
+
+cdef class CallDetails:
+
+  def __cinit__(self):
+    grpc.grpc_call_details_init(&self.c_details)
+
+  def __dealloc__(self):
+    grpc.grpc_call_details_destroy(&self.c_details)
+
+  @property
+  def method(self):
+    if self.c_details.method != NULL:
+      return <bytes>self.c_details.method
+    else:
+      return None
+
+  @property
+  def host(self):
+    if self.c_details.host != NULL:
+      return <bytes>self.c_details.host
+    else:
+      return None
+
+  @property
+  def deadline(self):
+    timespec = Timespec(float("-inf"))
+    timespec.c_time = self.c_details.deadline
+    return timespec
+
+
+cdef class OperationTag:
+
+  def __cinit__(self, user_tag):
+    self.user_tag = user_tag
+    self.references = []
+
+
+cdef class Event:
+
+  def __cinit__(self, grpc.grpc_completion_type type, bint success,
+                object tag, call.Call operation_call,
+                CallDetails request_call_details,
+                Metadata request_metadata,
+                Operations batch_operations):
+    self.type = type
+    self.success = success
+    self.tag = tag
+    self.operation_call = operation_call
+    self.request_call_details = request_call_details
+    self.request_metadata = request_metadata
+    self.batch_operations = batch_operations
+
+
+cdef class ByteBuffer:
+
+  def __cinit__(self, data):
+    if data is None:
+      self.c_byte_buffer = NULL
+      return
+    if isinstance(data, bytes):
+      pass
+    elif isinstance(data, basestring):
+      data = data.encode()
+    else:
+      raise TypeError("expected value to be of type str or bytes")
+
+    cdef char *c_data = data
+    data_slice = grpc.gpr_slice_from_copied_buffer(c_data, len(data))
+    self.c_byte_buffer = grpc.grpc_raw_byte_buffer_create(
+        &data_slice, 1)
+    grpc.gpr_slice_unref(data_slice)
+
+  def bytes(self):
+    cdef grpc.grpc_byte_buffer_reader reader
+    cdef grpc.gpr_slice data_slice
+    cdef size_t data_slice_length
+    cdef void *data_slice_pointer
+    if self.c_byte_buffer != NULL:
+      grpc.grpc_byte_buffer_reader_init(&reader, self.c_byte_buffer)
+      result = b""
+      while grpc.grpc_byte_buffer_reader_next(&reader, &data_slice):
+        data_slice_pointer = grpc.gpr_slice_start_ptr(data_slice)
+        data_slice_length = grpc.gpr_slice_length(data_slice)
+        result += (<char *>data_slice_pointer)[:data_slice_length]
+      grpc.grpc_byte_buffer_reader_destroy(&reader)
+      return result
+    else:
+      return None
+
+  def __len__(self):
+    if self.c_byte_buffer != NULL:
+      return grpc.grpc_byte_buffer_length(self.c_byte_buffer)
+    else:
+      return 0
+
+  def __str__(self):
+    return self.bytes()
+
+  def __dealloc__(self):
+    if self.c_byte_buffer != NULL:
+      grpc.grpc_byte_buffer_destroy(self.c_byte_buffer)
+
+
+cdef class SslPemKeyCertPair:
+
+  def __cinit__(self, private_key, certificate_chain):
+    if isinstance(private_key, bytes):
+      self.private_key = private_key
+    elif isinstance(private_key, basestring):
+      self.private_key = private_key.encode()
+    else:
+      raise TypeError("expected private_key to be of type str or bytes")
+    if isinstance(certificate_chain, bytes):
+      self.certificate_chain = certificate_chain
+    elif isinstance(certificate_chain, basestring):
+      self.certificate_chain = certificate_chain.encode()
+    else:
+      raise TypeError("expected certificate_chain to be of type str or bytes "
+                      "or int")
+    self.c_pair.private_key = self.private_key
+    self.c_pair.certificate_chain = self.certificate_chain
+
+
+cdef class ChannelArg:
+
+  def __cinit__(self, key, value):
+    if isinstance(key, bytes):
+      self.key = key
+    elif isinstance(key, basestring):
+      self.key = key.encode()
+    else:
+      raise TypeError("expected key to be of type str or bytes")
+    if isinstance(value, bytes):
+      self.value = value
+      self.c_arg.type = grpc.GRPC_ARG_STRING
+      self.c_arg.value.string = self.value
+    elif isinstance(value, basestring):
+      self.value = value.encode()
+      self.c_arg.type = grpc.GRPC_ARG_STRING
+      self.c_arg.value.string = self.value
+    elif isinstance(value, int):
+      self.value = int(value)
+      self.c_arg.type = grpc.GRPC_ARG_INTEGER
+      self.c_arg.value.integer = self.value
+    else:
+      raise TypeError("expected value to be of type str or bytes or int")
+    self.c_arg.key = self.key
+
+
+cdef class ChannelArgs:
+
+  def __cinit__(self, args):
+    self.args = list(args)
+    for arg in self.args:
+      if not isinstance(arg, ChannelArg):
+        raise TypeError("expected list of ChannelArg")
+    self.c_args.arguments_length = len(self.args)
+    self.c_args.arguments = <grpc.grpc_arg *>grpc.gpr_malloc(
+        self.c_args.arguments_length*sizeof(grpc.grpc_arg)
+    )
+    for i in range(self.c_args.arguments_length):
+      self.c_args.arguments[i] = (<ChannelArg>self.args[i]).c_arg
+
+  def __dealloc__(self):
+    grpc.gpr_free(self.c_args.arguments)
+
+  def __len__(self):
+    # self.args is never stale; it's only updated from this file
+    return len(self.args)
+
+  def __getitem__(self, size_t i):
+    # self.args is never stale; it's only updated from this file
+    return self.args[i]
+
+
+cdef class Metadatum:
+
+  def __cinit__(self, key, value):
+    if isinstance(key, bytes):
+      self._key = key
+    elif isinstance(key, basestring):
+      self._key = key.encode()
+    else:
+      raise TypeError("expected key to be of type str or bytes")
+    if isinstance(value, bytes):
+      self._value = value
+    elif isinstance(value, basestring):
+      self._value = value.encode()
+    else:
+      raise TypeError("expected value to be of type str or bytes")
+    self.c_metadata.key = self._key
+    self.c_metadata.value = self._value
+    self.c_metadata.value_length = len(self._value)
+
+  @property
+  def key(self):
+    return <bytes>self.c_metadata.key
+
+  @property
+  def value(self):
+    return <bytes>self.c_metadata.value[:self.c_metadata.value_length]
+
+  def __len__(self):
+    return 2
+
+  def __getitem__(self, size_t i):
+    if i == 0:
+      return self.key
+    elif i == 1:
+      return self.value
+    else:
+      raise IndexError("index must be 0 (key) or 1 (value)")
+
+  def __iter__(self):
+    return iter((self.key, self.value))
+
+
+cdef class _MetadataIterator:
+
+  cdef size_t i
+  cdef Metadata metadata
+
+  def __cinit__(self, Metadata metadata not None):
+    self.i = 0
+    self.metadata = metadata
+
+  def __next__(self):
+    if self.i < len(self.metadata):
+      result = self.metadata[self.i]
+      self.i = self.i + 1
+      return result
+    else:
+      raise StopIteration()
+
+
+cdef class Metadata:
+
+  def __cinit__(self, metadata):
+    self.metadata = list(metadata)
+    for metadatum in metadata:
+      if not isinstance(metadatum, Metadatum):
+        raise TypeError("expected list of Metadatum")
+    grpc.grpc_metadata_array_init(&self.c_metadata_array)
+    self.c_metadata_array.count = len(self.metadata)
+    self.c_metadata_array.capacity = len(self.metadata)
+    self.c_metadata_array.metadata = <grpc.grpc_metadata *>grpc.gpr_malloc(
+        self.c_metadata_array.count*sizeof(grpc.grpc_metadata)
+    )
+    for i in range(self.c_metadata_array.count):
+      self.c_metadata_array.metadata[i] = (
+          (<Metadatum>self.metadata[i]).c_metadata)
+
+  def __dealloc__(self):
+    # this frees the allocated memory for the grpc_metadata_array (although
+    # it'd be nice if that were documented somewhere...) TODO(atash): document
+    # this in the C core
+    grpc.grpc_metadata_array_destroy(&self.c_metadata_array)
+
+  def __len__(self):
+    return self.c_metadata_array.count
+
+  def __getitem__(self, size_t i):
+    return Metadatum(
+        key=<bytes>self.c_metadata_array.metadata[i].key,
+        value=<bytes>self.c_metadata_array.metadata[i].value[
+            :self.c_metadata_array.metadata[i].value_length])
+
+  def __iter__(self):
+    return _MetadataIterator(self)
+
+
+cdef class Operation:
+
+  def __cinit__(self):
+    self.references = []
+    self._received_status_details = NULL
+    self._received_status_details_capacity = 0
+    self.is_valid = False
+
+  @property
+  def type(self):
+    return self.c_op.type
+
+  @property
+  def received_message(self):
+    if self.c_op.type != grpc.GRPC_OP_RECV_MESSAGE:
+      raise TypeError("self must be an operation receiving a message")
+    return self._received_message
+
+  @property
+  def received_metadata(self):
+    if (self.c_op.type != grpc.GRPC_OP_RECV_INITIAL_METADATA and
+        self.c_op.type != grpc.GRPC_OP_RECV_STATUS_ON_CLIENT):
+      raise TypeError("self must be an operation receiving metadata")
+    return self._received_metadata
+
+  @property
+  def received_status_code(self):
+    if self.c_op.type != grpc.GRPC_OP_RECV_STATUS_ON_CLIENT:
+      raise TypeError("self must be an operation receiving a status code")
+    return self._received_status_code
+
+  @property
+  def received_status_details(self):
+    if self.c_op.type != grpc.GRPC_OP_RECV_STATUS_ON_CLIENT:
+      raise TypeError("self must be an operation receiving status details")
+    if self._received_status_details:
+      return self._received_status_details
+    else:
+      return None
+
+  @property
+  def received_cancelled(self):
+    if self.c_op.type != grpc.GRPC_OP_RECV_CLOSE_ON_SERVER:
+      raise TypeError("self must be an operation receiving cancellation "
+                      "information")
+    return False if self._received_cancelled == 0 else True
+
+  def __dealloc__(self):
+    # We *almost* don't need to do anything; most of the objects are handled by
+    # Python. The remaining one(s) are primitive fields filled in by GRPC core.
+    # This means that we need to clean up after receive_status_on_client.
+    if self.c_op.type == grpc.GRPC_OP_RECV_STATUS_ON_CLIENT:
+      grpc.gpr_free(self._received_status_details)
+
+def operation_send_initial_metadata(Metadata metadata):
+  cdef Operation op = Operation()
+  op.c_op.type = grpc.GRPC_OP_SEND_INITIAL_METADATA
+  op.c_op.data.send_initial_metadata.count = metadata.c_metadata_array.count
+  op.c_op.data.send_initial_metadata.metadata = (
+      metadata.c_metadata_array.metadata)
+  op.references.append(metadata)
+  op.is_valid = True
+  return op
+
+def operation_send_message(data):
+  cdef Operation op = Operation()
+  op.c_op.type = grpc.GRPC_OP_SEND_MESSAGE
+  byte_buffer = ByteBuffer(data)
+  op.c_op.data.send_message = byte_buffer.c_byte_buffer
+  op.references.append(byte_buffer)
+  op.is_valid = True
+  return op
+
+def operation_send_close_from_client():
+  cdef Operation op = Operation()
+  op.c_op.type = grpc.GRPC_OP_SEND_CLOSE_FROM_CLIENT
+  op.is_valid = True
+  return op
+
+def operation_send_status_from_server(
+    Metadata metadata, grpc.grpc_status_code code, details):
+  if isinstance(details, bytes):
+    pass
+  elif isinstance(details, basestring):
+    details = details.encode()
+  else:
+    raise TypeError("expected a str or bytes object for details")
+  cdef Operation op = Operation()
+  op.c_op.type = grpc.GRPC_OP_SEND_STATUS_FROM_SERVER
+  op.c_op.data.send_status_from_server.trailing_metadata_count = (
+      metadata.c_metadata_array.count)
+  op.c_op.data.send_status_from_server.trailing_metadata = (
+      metadata.c_metadata_array.metadata)
+  op.c_op.data.send_status_from_server.status = code
+  op.c_op.data.send_status_from_server.status_details = details
+  op.references.append(metadata)
+  op.references.append(details)
+  op.is_valid = True
+  return op
+
+def operation_receive_initial_metadata():
+  cdef Operation op = Operation()
+  op.c_op.type = grpc.GRPC_OP_RECV_INITIAL_METADATA
+  op._received_metadata = Metadata([])
+  op.c_op.data.receive_initial_metadata = (
+      &op._received_metadata.c_metadata_array)
+  op.is_valid = True
+  return op
+
+def operation_receive_message():
+  cdef Operation op = Operation()
+  op.c_op.type = grpc.GRPC_OP_RECV_MESSAGE
+  op._received_message = ByteBuffer(None)
+  # n.b. the c_op.data.receive_message field needs to be deleted by us,
+  # anyway, so we just let that be handled by the ByteBuffer() we allocated
+  # the line before.
+  op.c_op.data.receive_message = &op._received_message.c_byte_buffer
+  op.is_valid = True
+  return op
+
+def operation_receive_status_on_client():
+  cdef Operation op = Operation()
+  op.c_op.type = grpc.GRPC_OP_RECV_STATUS_ON_CLIENT
+  op._received_metadata = Metadata([])
+  op.c_op.data.receive_status_on_client.trailing_metadata = (
+      &op._received_metadata.c_metadata_array)
+  op.c_op.data.receive_status_on_client.status = (
+      &op._received_status_code)
+  op.c_op.data.receive_status_on_client.status_details = (
+      &op._received_status_details)
+  op.c_op.data.receive_status_on_client.status_details_capacity = (
+      &op._received_status_details_capacity)
+  op.is_valid = True
+  return op
+
+def operation_receive_close_on_server():
+  cdef Operation op = Operation()
+  op.c_op.type = grpc.GRPC_OP_RECV_CLOSE_ON_SERVER
+  op.c_op.data.receive_close_on_server.cancelled = &op._received_cancelled
+  op.is_valid = True
+  return op
+
+
+cdef class _OperationsIterator:
+
+  cdef size_t i
+  cdef Operations operations
+
+  def __cinit__(self, Operations operations not None):
+    self.i = 0
+    self.operations = operations
+
+  def __next__(self):
+    if self.i < len(self.operations):
+      result = self.operations[self.i]
+      self.i = self.i + 1
+      return result
+    else:
+      raise StopIteration()
+
+
+cdef class Operations:
+
+  def __cinit__(self, operations):
+    self.operations = list(operations)  # normalize iterable
+    self.c_ops = NULL
+    self.c_nops = 0
+    for operation in self.operations:
+      if not isinstance(operation, Operation):
+        raise TypeError("expected operations to be iterable of Operation")
+    self.c_nops = len(self.operations)
+    self.c_ops = <grpc.grpc_op *>grpc.gpr_malloc(
+        sizeof(grpc.grpc_op)*self.c_nops)
+    for i in range(self.c_nops):
+      self.c_ops[i] = (<Operation>(self.operations[i])).c_op
+
+  def __len__(self):
+    return self.c_nops
+
+  def __getitem__(self, size_t i):
+    # self.operations is never stale; it's only updated from this file
+    return self.operations[i]
+
+  def __dealloc__(self):
+    grpc.gpr_free(self.c_ops)
+
+  def __iter__(self):
+    return _OperationsIterator(self)
+
diff --git a/src/python/src/grpc/_cython/_cygrpc/server.pxd b/src/python/src/grpc/_cython/_cygrpc/server.pxd
new file mode 100644
index 0000000000..0257542a03
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/server.pxd
@@ -0,0 +1,45 @@
+# 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.
+
+from grpc._cython._cygrpc cimport grpc
+from grpc._cython._cygrpc cimport completion_queue
+
+
+cdef class Server:
+
+  cdef grpc.grpc_server *c_server
+  cdef bint is_started  # start has been called
+  cdef bint is_shutting_down  # shutdown has been called
+  cdef bint is_shutdown  # notification of complete shutdown received
+  # used at dealloc when user forgets to shutdown
+  cdef completion_queue.CompletionQueue backup_shutdown_queue
+  cdef list references
+  cdef list registered_completion_queues
+
+  cdef notify_shutdown_complete(self)
diff --git a/src/python/src/grpc/_cython/_cygrpc/server.pyx b/src/python/src/grpc/_cython/_cygrpc/server.pyx
new file mode 100644
index 0000000000..dcf9d38337
--- /dev/null
+++ b/src/python/src/grpc/_cython/_cygrpc/server.pyx
@@ -0,0 +1,158 @@
+# 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.
+
+cimport cpython
+
+from grpc._cython._cygrpc cimport call
+from grpc._cython._cygrpc cimport completion_queue
+from grpc._cython._cygrpc cimport credentials
+from grpc._cython._cygrpc cimport records
+
+import time
+
+
+cdef class Server:
+
+  def __cinit__(self, records.ChannelArgs arguments=None):
+    cdef grpc.grpc_channel_args *c_arguments = NULL
+    self.references = []
+    self.registered_completion_queues = []
+    if arguments is not None:
+      c_arguments = &arguments.c_args
+      self.references.append(arguments)
+    self.c_server = grpc.grpc_server_create(c_arguments)
+    self.is_started = False
+    self.is_shutting_down = False
+    self.is_shutdown = False
+
+  def request_call(
+      self, completion_queue.CompletionQueue call_queue not None,
+      completion_queue.CompletionQueue server_queue not None, tag):
+    if not self.is_started or self.is_shutting_down:
+      raise ValueError("server must be started and not shutting down")
+    if server_queue not in self.registered_completion_queues:
+      raise ValueError("server_queue must be a registered completion queue")
+    cdef records.OperationTag operation_tag = records.OperationTag(tag)
+    operation_tag.operation_call = call.Call()
+    operation_tag.request_call_details = records.CallDetails()
+    operation_tag.request_metadata = records.Metadata([])
+    operation_tag.references.extend([self, call_queue, server_queue])
+    operation_tag.is_new_request = True
+    operation_tag.batch_operations = records.Operations([])
+    cpython.Py_INCREF(operation_tag)
+    return grpc.grpc_server_request_call(
+        self.c_server, &operation_tag.operation_call.c_call,
+        &operation_tag.request_call_details.c_details,
+        &operation_tag.request_metadata.c_metadata_array,
+        call_queue.c_completion_queue, server_queue.c_completion_queue,
+        <cpython.PyObject *>operation_tag)
+
+  def register_completion_queue(
+      self, completion_queue.CompletionQueue queue not None):
+    if self.is_started:
+      raise ValueError("cannot register completion queues after start")
+    grpc.grpc_server_register_completion_queue(
+        self.c_server, queue.c_completion_queue)
+    self.registered_completion_queues.append(queue)
+
+  def start(self):
+    if self.is_started:
+      raise ValueError("the server has already started")
+    self.backup_shutdown_queue = completion_queue.CompletionQueue()
+    self.register_completion_queue(self.backup_shutdown_queue)
+    self.is_started = True
+    grpc.grpc_server_start(self.c_server)
+
+  def add_http2_port(self, address,
+                     credentials.ServerCredentials server_credentials=None):
+    if isinstance(address, bytes):
+      pass
+    elif isinstance(address, basestring):
+      address = address.encode()
+    else:
+      raise TypeError("expected address to be a str or bytes")
+    self.references.append(address)
+    if server_credentials is not None:
+      self.references.append(server_credentials)
+      return grpc.grpc_server_add_secure_http2_port(
+          self.c_server, address, server_credentials.c_credentials)
+    else:
+      return grpc.grpc_server_add_http2_port(self.c_server, address)
+
+  def shutdown(self, completion_queue.CompletionQueue queue not None, tag):
+    cdef records.OperationTag operation_tag
+    if queue.is_shutting_down:
+      raise ValueError("queue must be live")
+    elif not self.is_started:
+      raise ValueError("the server hasn't started yet")
+    elif self.is_shutting_down:
+      return
+    elif queue not in self.registered_completion_queues:
+      raise ValueError("expected registered completion queue")
+    else:
+      self.is_shutting_down = True
+      operation_tag = records.OperationTag(tag)
+      operation_tag.shutting_down_server = self
+      operation_tag.references.extend([self, queue])
+      cpython.Py_INCREF(operation_tag)
+      grpc.grpc_server_shutdown_and_notify(
+          self.c_server, queue.c_completion_queue,
+          <cpython.PyObject *>operation_tag)
+
+  cdef notify_shutdown_complete(self):
+    # called only by a completion queue on receiving our shutdown operation tag
+    self.is_shutdown = True
+
+  def cancel_all_calls(self):
+    if not self.is_shutting_down:
+      raise ValueError("the server must be shutting down to cancel all calls")
+    elif self.is_shutdown:
+      return
+    else:
+      grpc.grpc_server_cancel_all_calls(self.c_server)
+
+  def __dealloc__(self):
+    if self.c_server != NULL:
+      if not self.is_started:
+        pass
+      elif self.is_shutdown:
+        pass
+      elif not self.is_shutting_down:
+        # the user didn't call shutdown - use our backup queue
+        self.shutdown(self.backup_shutdown_queue, None)
+        # and now we wait
+        while not self.is_shutdown:
+          self.backup_shutdown_queue.poll()
+      else:
+        # We're in the process of shutting down, but have not shutdown; can't do
+        # much but repeatedly release the GIL and wait
+        while not self.is_shutdown:
+          time.sleep(0)
+      grpc.grpc_server_destroy(self.c_server)
+
diff --git a/src/python/src/grpc/_cython/adapter_low.py b/src/python/src/grpc/_cython/adapter_low.py
new file mode 100644
index 0000000000..7546dd1599
--- /dev/null
+++ b/src/python/src/grpc/_cython/adapter_low.py
@@ -0,0 +1,114 @@
+# 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.
+
+
+# Adapter from grpc._cython.types to the surface expected by
+# grpc._adapter._intermediary_low.
+#
+# TODO(atash): Once this is plugged into grpc._adapter._intermediary_low, remove
+# both grpc._adapter._intermediary_low and this file. The fore and rear links in
+# grpc._adapter should be able to use grpc._cython.types directly.
+
+from grpc._adapter import _types as type_interfaces
+from grpc._cython import cygrpc
+
+
+class ClientCredentials(object):
+  def __init__(self):
+    raise NotImplementedError()
+
+  @staticmethod
+  def google_default():
+    raise NotImplementedError()
+
+  @staticmethod
+  def ssl():
+    raise NotImplementedError()
+
+  @staticmethod
+  def composite():
+    raise NotImplementedError()
+
+  @staticmethod
+  def compute_engine():
+    raise NotImplementedError()
+
+  @staticmethod
+  def service_account():
+    raise NotImplementedError()
+
+  @staticmethod
+  def jwt():
+    raise NotImplementedError()
+
+  @staticmethod
+  def refresh_token():
+    raise NotImplementedError()
+
+  @staticmethod
+  def fake_transport_security():
+    raise NotImplementedError()
+
+  @staticmethod
+  def iam():
+    raise NotImplementedError()
+
+
+class ServerCredentials(object):
+  def __init__(self):
+    raise NotImplementedError()
+
+  @staticmethod
+  def ssl():
+    raise NotImplementedError()
+
+  @staticmethod
+  def fake_transport_security():
+    raise NotImplementedError()
+
+
+class CompletionQueue(type_interfaces.CompletionQueue):
+  def __init__(self):
+    raise NotImplementedError()
+
+
+class Call(type_interfaces.Call):
+  def __init__(self):
+    raise NotImplementedError()
+
+
+class Channel(type_interfaces.Channel):
+  def __init__(self):
+    raise NotImplementedError()
+
+
+class Server(type_interfaces.Server):
+  def __init__(self):
+    raise NotImplementedError()
+
diff --git a/src/python/src/grpc/_cython/adapter_low_test.py b/src/python/src/grpc/_cython/adapter_low_test.py
new file mode 100644
index 0000000000..9bab930e56
--- /dev/null
+++ b/src/python/src/grpc/_cython/adapter_low_test.py
@@ -0,0 +1,187 @@
+# 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.
+
+# Fork of grpc._adapter._low_test; the grpc._cython.types adapter in
+# grpc._cython.low should transparently support the semantics expected of
+# grpc._adapter._low.
+
+import time
+import unittest
+
+from grpc._adapter import _types
+from grpc._cython import adapter_low as _low
+
+
+class InsecureServerInsecureClient(unittest.TestCase):
+
+  def setUp(self):
+    self.server_completion_queue = _low.CompletionQueue()
+    self.server = _low.Server(self.server_completion_queue, [])
+    self.port = self.server.add_http2_port('[::]:0')
+    self.client_completion_queue = _low.CompletionQueue()
+    self.client_channel = _low.Channel('localhost:%d'%self.port, [])
+
+    self.server.start()
+
+  def tearDown(self):
+    self.server.shutdown()
+    del self.client_channel
+
+    self.client_completion_queue.shutdown()
+    while (self.client_completion_queue.next().type !=
+               _types.EventType.QUEUE_SHUTDOWN):
+      pass
+    self.server_completion_queue.shutdown()
+    while (self.server_completion_queue.next().type !=
+               _types.EventType.QUEUE_SHUTDOWN):
+      pass
+
+    del self.client_completion_queue
+    del self.server_completion_queue
+    del self.server
+
+  @unittest.skip('TODO(atash): implement grpc._cython.adapter_low')
+  def testEcho(self):
+    DEADLINE = time.time()+5
+    DEADLINE_TOLERANCE = 0.25
+    CLIENT_METADATA_ASCII_KEY = 'key'
+    CLIENT_METADATA_ASCII_VALUE = 'val'
+    CLIENT_METADATA_BIN_KEY = 'key-bin'
+    CLIENT_METADATA_BIN_VALUE = b'\0'*1000
+    SERVER_INITIAL_METADATA_KEY = 'init_me_me_me'
+    SERVER_INITIAL_METADATA_VALUE = 'whodawha?'
+    SERVER_TRAILING_METADATA_KEY = 'California_is_in_a_drought'
+    SERVER_TRAILING_METADATA_VALUE = 'zomg it is'
+    SERVER_STATUS_CODE = _types.StatusCode.OK
+    SERVER_STATUS_DETAILS = 'our work is never over'
+    REQUEST = 'in death a member of project mayhem has a name'
+    RESPONSE = 'his name is robert paulson'
+    METHOD = 'twinkies'
+    HOST = 'hostess'
+    server_request_tag = object()
+    request_call_result = self.server.request_call(self.server_completion_queue,
+                                                   server_request_tag)
+
+    self.assertEqual(_types.CallError.OK, request_call_result)
+
+    client_call_tag = object()
+    client_call = self.client_channel.create_call(self.client_completion_queue,
+                                                  METHOD, HOST, DEADLINE)
+    client_initial_metadata = [
+        (CLIENT_METADATA_ASCII_KEY, CLIENT_METADATA_ASCII_VALUE),
+        (CLIENT_METADATA_BIN_KEY, CLIENT_METADATA_BIN_VALUE)]
+    client_start_batch_result = client_call.start_batch([
+        _types.OpArgs.send_initial_metadata(client_initial_metadata),
+        _types.OpArgs.send_message(REQUEST),
+        _types.OpArgs.send_close_from_client(),
+        _types.OpArgs.recv_initial_metadata(),
+        _types.OpArgs.recv_message(),
+        _types.OpArgs.recv_status_on_client()
+    ], client_call_tag)
+    self.assertEqual(_types.CallError.OK, client_start_batch_result)
+
+    request_event = self.server_completion_queue.next(DEADLINE)
+    self.assertEqual(_types.EventType.OP_COMPLETE, request_event.type)
+    self.assertIsInstance(request_event.call, _low.Call)
+    self.assertIs(server_request_tag, request_event.tag)
+    self.assertEqual(1, len(request_event.results))
+    self.assertEqual(dict(client_initial_metadata),
+                      dict(request_event.results[0].initial_metadata))
+    self.assertEqual(METHOD, request_event.call_details.method)
+    self.assertEqual(HOST, request_event.call_details.host)
+    self.assertLess(abs(DEADLINE - request_event.call_details.deadline),
+                    DEADLINE_TOLERANCE)
+
+    server_call_tag = object()
+    server_call = request_event.call
+    server_initial_metadata = [
+        (SERVER_INITIAL_METADATA_KEY, SERVER_INITIAL_METADATA_VALUE)]
+    server_trailing_metadata = [
+        (SERVER_TRAILING_METADATA_KEY, SERVER_TRAILING_METADATA_VALUE)]
+    server_start_batch_result = server_call.start_batch([
+        _types.OpArgs.send_initial_metadata(server_initial_metadata),
+        _types.OpArgs.recv_message(),
+        _types.OpArgs.send_message(RESPONSE),
+        _types.OpArgs.recv_close_on_server(),
+        _types.OpArgs.send_status_from_server(
+            server_trailing_metadata, SERVER_STATUS_CODE, SERVER_STATUS_DETAILS)
+    ], server_call_tag)
+    self.assertEqual(_types.CallError.OK, server_start_batch_result)
+
+    client_event = self.client_completion_queue.next(DEADLINE)
+    server_event = self.server_completion_queue.next(DEADLINE)
+
+    self.assertEqual(6, len(client_event.results))
+    found_client_op_types = set()
+    for client_result in client_event.results:
+      # we expect each op type to be unique
+      self.assertNotIn(client_result.type, found_client_op_types)
+      found_client_op_types.add(client_result.type)
+      if client_result.type == _types.OpType.RECV_INITIAL_METADATA:
+        self.assertEqual(dict(server_initial_metadata),
+                          dict(client_result.initial_metadata))
+      elif client_result.type == _types.OpType.RECV_MESSAGE:
+        self.assertEqual(RESPONSE, client_result.message)
+      elif client_result.type == _types.OpType.RECV_STATUS_ON_CLIENT:
+        self.assertEqual(dict(server_trailing_metadata),
+                          dict(client_result.trailing_metadata))
+        self.assertEqual(SERVER_STATUS_DETAILS, client_result.status.details)
+        self.assertEqual(SERVER_STATUS_CODE, client_result.status.code)
+    self.assertEqual(set([
+          _types.OpType.SEND_INITIAL_METADATA,
+          _types.OpType.SEND_MESSAGE,
+          _types.OpType.SEND_CLOSE_FROM_CLIENT,
+          _types.OpType.RECV_INITIAL_METADATA,
+          _types.OpType.RECV_MESSAGE,
+          _types.OpType.RECV_STATUS_ON_CLIENT
+      ]), found_client_op_types)
+
+    self.assertEqual(5, len(server_event.results))
+    found_server_op_types = set()
+    for server_result in server_event.results:
+      self.assertNotIn(client_result.type, found_server_op_types)
+      found_server_op_types.add(server_result.type)
+      if server_result.type == _types.OpType.RECV_MESSAGE:
+        self.assertEqual(REQUEST, server_result.message)
+      elif server_result.type == _types.OpType.RECV_CLOSE_ON_SERVER:
+        self.assertFalse(server_result.cancelled)
+    self.assertEqual(set([
+          _types.OpType.SEND_INITIAL_METADATA,
+          _types.OpType.RECV_MESSAGE,
+          _types.OpType.SEND_MESSAGE,
+          _types.OpType.RECV_CLOSE_ON_SERVER,
+          _types.OpType.SEND_STATUS_FROM_SERVER
+      ]), found_server_op_types)
+
+    del client_call
+    del server_call
+
+
+if __name__ == '__main__':
+  unittest.main(verbosity=2)
diff --git a/src/python/src/grpc/_cython/cygrpc.pyx b/src/python/src/grpc/_cython/cygrpc.pyx
new file mode 100644
index 0000000000..dcb06f345c
--- /dev/null
+++ b/src/python/src/grpc/_cython/cygrpc.pyx
@@ -0,0 +1,111 @@
+# 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.
+
+cimport cpython
+
+from grpc._cython._cygrpc cimport grpc
+from grpc._cython._cygrpc cimport call
+from grpc._cython._cygrpc cimport channel
+from grpc._cython._cygrpc cimport credentials
+from grpc._cython._cygrpc cimport completion_queue
+from grpc._cython._cygrpc cimport records
+from grpc._cython._cygrpc cimport server
+
+from grpc._cython._cygrpc import call
+from grpc._cython._cygrpc import channel
+from grpc._cython._cygrpc import credentials
+from grpc._cython._cygrpc import completion_queue
+from grpc._cython._cygrpc import records
+from grpc._cython._cygrpc import server
+
+StatusCode = records.StatusCode
+CallError = records.CallError
+CompletionType = records.CompletionType
+OperationType = records.OperationType
+Timespec = records.Timespec
+CallDetails = records.CallDetails
+Event = records.Event
+ByteBuffer = records.ByteBuffer
+SslPemKeyCertPair = records.SslPemKeyCertPair
+ChannelArg = records.ChannelArg
+ChannelArgs = records.ChannelArgs
+Metadatum = records.Metadatum
+Metadata = records.Metadata
+Operation = records.Operation
+
+operation_send_initial_metadata = records.operation_send_initial_metadata
+operation_send_message = records.operation_send_message
+operation_send_close_from_client = records.operation_send_close_from_client
+operation_send_status_from_server = records.operation_send_status_from_server
+operation_receive_initial_metadata = records.operation_receive_initial_metadata
+operation_receive_message = records.operation_receive_message
+operation_receive_status_on_client = records.operation_receive_status_on_client
+operation_receive_close_on_server = records.operation_receive_close_on_server
+
+Operations = records.Operations
+
+ClientCredentials = credentials.ClientCredentials
+ServerCredentials = credentials.ServerCredentials
+
+client_credentials_google_default = (
+    credentials.client_credentials_google_default)
+client_credentials_ssl = credentials.client_credentials_ssl
+client_credentials_composite_credentials = (
+    credentials.client_credentials_composite_credentials)
+client_credentials_compute_engine = (
+    credentials.client_credentials_compute_engine)
+client_credentials_jwt = credentials.client_credentials_jwt
+client_credentials_refresh_token = credentials.client_credentials_refresh_token
+client_credentials_fake_transport_security = (
+    credentials.client_credentials_fake_transport_security)
+client_credentials_iam = credentials.client_credentials_iam
+server_credentials_ssl = credentials.server_credentials_ssl
+server_credentials_fake_transport_security = (
+    credentials.server_credentials_fake_transport_security)
+
+CompletionQueue = completion_queue.CompletionQueue
+Channel = channel.Channel
+Server = server.Server
+Call = call.Call
+
+
+#
+# Global state
+#
+
+cdef class _ModuleState:
+
+  def __cinit__(self):
+    grpc.grpc_init()
+
+  def __dealloc__(self):
+    grpc.grpc_shutdown()
+
+_module_state = _ModuleState()
+
diff --git a/src/python/src/grpc/_cython/cygrpc_test.py b/src/python/src/grpc/_cython/cygrpc_test.py
new file mode 100644
index 0000000000..838e1e2254
--- /dev/null
+++ b/src/python/src/grpc/_cython/cygrpc_test.py
@@ -0,0 +1,276 @@
+# 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 time
+import unittest
+
+from grpc._cython import cygrpc
+from grpc._cython import test_utilities
+
+
+class TypeSmokeTest(unittest.TestCase):
+
+  def testStringsInUtilitiesUpDown(self):
+    self.assertEqual(0, cygrpc.StatusCode.ok)
+    metadatum = cygrpc.Metadatum('a', 'b')
+    self.assertEqual('a'.encode(), metadatum.key)
+    self.assertEqual('b'.encode(), metadatum.value)
+    metadata = cygrpc.Metadata([metadatum])
+    self.assertEqual(1, len(metadata))
+    self.assertEqual(metadatum.key, metadata[0].key)
+
+  def testMetadataIteration(self):
+    metadata = cygrpc.Metadata([
+        cygrpc.Metadatum('a', 'b'), cygrpc.Metadatum('c', 'd')])
+    iterator = iter(metadata)
+    metadatum = next(iterator)
+    self.assertIsInstance(metadatum, cygrpc.Metadatum)
+    self.assertEqual(metadatum.key, 'a'.encode())
+    self.assertEqual(metadatum.value, 'b'.encode())
+    metadatum = next(iterator)
+    self.assertIsInstance(metadatum, cygrpc.Metadatum)
+    self.assertEqual(metadatum.key, 'c'.encode())
+    self.assertEqual(metadatum.value, 'd'.encode())
+    with self.assertRaises(StopIteration):
+      next(iterator)
+
+  def testOperationsIteration(self):
+    operations = cygrpc.Operations([
+        cygrpc.operation_send_message('asdf')])
+    iterator = iter(operations)
+    operation = next(iterator)
+    self.assertIsInstance(operation, cygrpc.Operation)
+    # `Operation`s are write-only structures; can't directly debug anything out
+    # of them. Just check that we stop iterating.
+    with self.assertRaises(StopIteration):
+      next(iterator)
+
+  def testTimespec(self):
+    now = time.time()
+    timespec = cygrpc.Timespec(now)
+    self.assertAlmostEqual(now, float(timespec), places=8)
+
+  def testClientCredentialsUpDown(self):
+    credentials = cygrpc.client_credentials_fake_transport_security()
+    del credentials
+
+  def testServerCredentialsUpDown(self):
+    credentials = cygrpc.server_credentials_fake_transport_security()
+    del credentials
+
+  def testCompletionQueueUpDown(self):
+    completion_queue = cygrpc.CompletionQueue()
+    del completion_queue
+
+  def testServerUpDown(self):
+    server = cygrpc.Server(cygrpc.ChannelArgs([]))
+    del server
+
+  def testChannelUpDown(self):
+    channel = cygrpc.Channel('[::]:0', cygrpc.ChannelArgs([]))
+    del channel
+
+  def testSecureChannelUpDown(self):
+    channel = cygrpc.Channel(
+        '[::]:0', cygrpc.ChannelArgs([]),
+        cygrpc.client_credentials_fake_transport_security())
+    del channel
+
+  @unittest.skip('TODO(atash): undo skip after #2229 is merged')
+  def testServerStartNoExplicitShutdown(self):
+    server = cygrpc.Server()
+    completion_queue = cygrpc.CompletionQueue()
+    server.register_completion_queue(completion_queue)
+    port = server.add_http2_port('[::]:0')
+    self.assertIsInstance(port, int)
+    server.start()
+    del server
+
+  @unittest.skip('TODO(atash): undo skip after #2229 is merged')
+  def testServerStartShutdown(self):
+    completion_queue = cygrpc.CompletionQueue()
+    server = cygrpc.Server()
+    server.add_http2_port('[::]:0')
+    server.register_completion_queue(completion_queue)
+    server.start()
+    shutdown_tag = object()
+    server.shutdown(completion_queue, shutdown_tag)
+    event = completion_queue.poll()
+    self.assertEqual(cygrpc.CompletionType.operation_complete, event.type)
+    self.assertIs(shutdown_tag, event.tag)
+    del server
+    del completion_queue
+
+
+class InsecureServerInsecureClient(unittest.TestCase):
+
+  def setUp(self):
+    self.server_completion_queue = cygrpc.CompletionQueue()
+    self.server = cygrpc.Server()
+    self.server.register_completion_queue(self.server_completion_queue)
+    self.port = self.server.add_http2_port('[::]:0')
+    self.server.start()
+    self.client_completion_queue = cygrpc.CompletionQueue()
+    self.client_channel = cygrpc.Channel('localhost:{}'.format(self.port))
+
+  def tearDown(self):
+    del self.server
+    del self.client_completion_queue
+    del self.server_completion_queue
+
+  def testEcho(self):
+    DEADLINE = time.time()+5
+    DEADLINE_TOLERANCE = 0.25
+    CLIENT_METADATA_ASCII_KEY = b'key'
+    CLIENT_METADATA_ASCII_VALUE = b'val'
+    CLIENT_METADATA_BIN_KEY = b'key-bin'
+    CLIENT_METADATA_BIN_VALUE = b'\0'*1000
+    SERVER_INITIAL_METADATA_KEY = b'init_me_me_me'
+    SERVER_INITIAL_METADATA_VALUE = b'whodawha?'
+    SERVER_TRAILING_METADATA_KEY = b'California_is_in_a_drought'
+    SERVER_TRAILING_METADATA_VALUE = b'zomg it is'
+    SERVER_STATUS_CODE = cygrpc.StatusCode.ok
+    SERVER_STATUS_DETAILS = b'our work is never over'
+    REQUEST = b'in death a member of project mayhem has a name'
+    RESPONSE = b'his name is robert paulson'
+    METHOD = b'twinkies'
+    HOST = b'hostess'
+
+    cygrpc_deadline = cygrpc.Timespec(DEADLINE)
+
+    server_request_tag = object()
+    request_call_result = self.server.request_call(
+        self.server_completion_queue, self.server_completion_queue,
+        server_request_tag)
+
+    self.assertEqual(cygrpc.CallError.ok, request_call_result)
+
+    client_call_tag = object()
+    client_call = self.client_channel.create_call(self.client_completion_queue,
+                                                  METHOD, HOST, cygrpc_deadline)
+    client_initial_metadata = cygrpc.Metadata([
+        cygrpc.Metadatum(CLIENT_METADATA_ASCII_KEY,
+                         CLIENT_METADATA_ASCII_VALUE),
+        cygrpc.Metadatum(CLIENT_METADATA_BIN_KEY, CLIENT_METADATA_BIN_VALUE)])
+    client_start_batch_result = client_call.start_batch(cygrpc.Operations([
+        cygrpc.operation_send_initial_metadata(client_initial_metadata),
+        cygrpc.operation_send_message(REQUEST),
+        cygrpc.operation_send_close_from_client(),
+        cygrpc.operation_receive_initial_metadata(),
+        cygrpc.operation_receive_message(),
+        cygrpc.operation_receive_status_on_client()
+    ]), client_call_tag)
+    self.assertEqual(cygrpc.CallError.ok, client_start_batch_result)
+    client_event_future = test_utilities.CompletionQueuePollFuture(
+        self.client_completion_queue, cygrpc_deadline)
+
+    request_event = self.server_completion_queue.poll(cygrpc_deadline)
+    self.assertEqual(cygrpc.CompletionType.operation_complete,
+                      request_event.type)
+    self.assertIsInstance(request_event.operation_call, cygrpc.Call)
+    self.assertIs(server_request_tag, request_event.tag)
+    self.assertEqual(0, len(request_event.batch_operations))
+    self.assertEqual(dict(client_initial_metadata),
+                      dict(request_event.request_metadata))
+    self.assertEqual(METHOD, request_event.request_call_details.method)
+    self.assertEqual(HOST, request_event.request_call_details.host)
+    self.assertLess(
+        abs(DEADLINE - float(request_event.request_call_details.deadline)),
+        DEADLINE_TOLERANCE)
+
+    server_call_tag = object()
+    server_call = request_event.operation_call
+    server_initial_metadata = cygrpc.Metadata([
+        cygrpc.Metadatum(SERVER_INITIAL_METADATA_KEY,
+                         SERVER_INITIAL_METADATA_VALUE)])
+    server_trailing_metadata = cygrpc.Metadata([
+        cygrpc.Metadatum(SERVER_TRAILING_METADATA_KEY,
+                         SERVER_TRAILING_METADATA_VALUE)])
+    server_start_batch_result = server_call.start_batch([
+        cygrpc.operation_send_initial_metadata(server_initial_metadata),
+        cygrpc.operation_receive_message(),
+        cygrpc.operation_send_message(RESPONSE),
+        cygrpc.operation_receive_close_on_server(),
+        cygrpc.operation_send_status_from_server(
+            server_trailing_metadata, SERVER_STATUS_CODE, SERVER_STATUS_DETAILS)
+    ], server_call_tag)
+    self.assertEqual(cygrpc.CallError.ok, server_start_batch_result)
+
+    client_event = client_event_future.result()
+    server_event = self.server_completion_queue.poll(cygrpc_deadline)
+
+    self.assertEqual(6, len(client_event.batch_operations))
+    found_client_op_types = set()
+    for client_result in client_event.batch_operations:
+      # we expect each op type to be unique
+      self.assertNotIn(client_result.type, found_client_op_types)
+      found_client_op_types.add(client_result.type)
+      if client_result.type == cygrpc.OperationType.receive_initial_metadata:
+        self.assertEqual(dict(server_initial_metadata),
+                         dict(client_result.received_metadata))
+      elif client_result.type == cygrpc.OperationType.receive_message:
+        self.assertEqual(RESPONSE, client_result.received_message.bytes())
+      elif client_result.type == cygrpc.OperationType.receive_status_on_client:
+        self.assertEqual(dict(server_trailing_metadata),
+                         dict(client_result.received_metadata))
+        self.assertEqual(SERVER_STATUS_DETAILS,
+                         client_result.received_status_details)
+        self.assertEqual(SERVER_STATUS_CODE, client_result.received_status_code)
+    self.assertEqual(set([
+          cygrpc.OperationType.send_initial_metadata,
+          cygrpc.OperationType.send_message,
+          cygrpc.OperationType.send_close_from_client,
+          cygrpc.OperationType.receive_initial_metadata,
+          cygrpc.OperationType.receive_message,
+          cygrpc.OperationType.receive_status_on_client
+      ]), found_client_op_types)
+
+    self.assertEqual(5, len(server_event.batch_operations))
+    found_server_op_types = set()
+    for server_result in server_event.batch_operations:
+      self.assertNotIn(client_result.type, found_server_op_types)
+      found_server_op_types.add(server_result.type)
+      if server_result.type == cygrpc.OperationType.receive_message:
+        self.assertEqual(REQUEST, server_result.received_message.bytes())
+      elif server_result.type == cygrpc.OperationType.receive_close_on_server:
+        self.assertFalse(server_result.received_cancelled)
+    self.assertEqual(set([
+          cygrpc.OperationType.send_initial_metadata,
+          cygrpc.OperationType.receive_message,
+          cygrpc.OperationType.send_message,
+          cygrpc.OperationType.receive_close_on_server,
+          cygrpc.OperationType.send_status_from_server
+      ]), found_server_op_types)
+
+    del client_call
+    del server_call
+
+
+if __name__ == '__main__':
+  unittest.main(verbosity=2)
diff --git a/src/python/src/grpc/_cython/test_utilities.py b/src/python/src/grpc/_cython/test_utilities.py
new file mode 100644
index 0000000000..21ea3075b4
--- /dev/null
+++ b/src/python/src/grpc/_cython/test_utilities.py
@@ -0,0 +1,46 @@
+# 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 threading
+
+from grpc._cython._cygrpc import completion_queue
+
+
+class CompletionQueuePollFuture:
+
+  def __init__(self, completion_queue, deadline):
+    def poller_function():
+      self._event_result = completion_queue.poll(deadline)
+    self._event_result = None
+    self._thread = threading.Thread(target=poller_function)
+    self._thread.start()
+
+  def result(self):
+    self._thread.join()
+    return self._event_result
diff --git a/src/python/src/grpc/_links/__init__.py b/src/python/src/grpc/_links/__init__.py
new file mode 100644
index 0000000000..7086519106
--- /dev/null
+++ b/src/python/src/grpc/_links/__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/src/grpc/_links/_lonely_invocation_link_test.py b/src/python/src/grpc/_links/_lonely_invocation_link_test.py
new file mode 100644
index 0000000000..3d629f4387
--- /dev/null
+++ b/src/python/src/grpc/_links/_lonely_invocation_link_test.py
@@ -0,0 +1,88 @@
+# 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.
+
+"""A test of invocation-side code unconnected to an RPC server."""
+
+import unittest
+
+from grpc._adapter import _intermediary_low
+from grpc._links import invocation
+from grpc.framework.common import test_constants
+from grpc.framework.interfaces.links import links
+from grpc.framework.interfaces.links import test_cases
+from grpc.framework.interfaces.links import test_utilities
+
+_NULL_BEHAVIOR = lambda unused_argument: None
+
+
+class LonelyInvocationLinkTest(unittest.TestCase):
+
+  def testUpAndDown(self):
+    channel = _intermediary_low.Channel('nonexistent:54321', None)
+    invocation_link = invocation.invocation_link(channel, 'nonexistent', {}, {})
+
+    invocation_link.start()
+    invocation_link.stop()
+
+  def _test_lonely_invocation_with_termination(self, termination):
+    test_operation_id = object()
+    test_group = 'test package.Test Service'
+    test_method = 'test method'
+    invocation_link_mate = test_utilities.RecordingLink()
+
+    channel = _intermediary_low.Channel('nonexistent:54321', None)
+    invocation_link = invocation.invocation_link(
+        channel, 'nonexistent', {(test_group, test_method): _NULL_BEHAVIOR},
+        {(test_group, test_method): _NULL_BEHAVIOR})
+    invocation_link.join_link(invocation_link_mate)
+    invocation_link.start()
+
+    ticket = links.Ticket(
+        test_operation_id, 0, test_group, test_method,
+        links.Ticket.Subscription.FULL, test_constants.SHORT_TIMEOUT, 1, None,
+        None, None, None, None, termination)
+    invocation_link.accept_ticket(ticket)
+    invocation_link_mate.block_until_tickets_satisfy(test_cases.terminated)
+
+    invocation_link.stop()
+
+    self.assertIsNot(
+        invocation_link_mate.tickets()[-1].termination,
+        links.Ticket.Termination.COMPLETION)
+
+  def testLonelyInvocationLinkWithCommencementTicket(self):
+    self._test_lonely_invocation_with_termination(None)
+
+  def testLonelyInvocationLinkWithEntireTicket(self):
+    self._test_lonely_invocation_with_termination(
+        links.Ticket.Termination.COMPLETION)
+
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/src/python/src/grpc/_links/_proto_scenarios.py b/src/python/src/grpc/_links/_proto_scenarios.py
new file mode 100644
index 0000000000..ccf3c29782
--- /dev/null
+++ b/src/python/src/grpc/_links/_proto_scenarios.py
@@ -0,0 +1,261 @@
+# 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.
+
+"""Test scenarios using protocol buffers."""
+
+import abc
+import threading
+
+from grpc._junkdrawer import math_pb2
+
+
+class ProtoScenario(object):
+  """An RPC test scenario using protocol buffers."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def group_and_method(self):
+    """Access the test group and method.
+
+    Returns:
+      The test group and method as a pair.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def serialize_request(self, request):
+    """Serialize a request protocol buffer.
+
+    Args:
+      request: A request protocol buffer.
+
+    Returns:
+      The bytestring serialization of the given request protocol buffer.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def deserialize_request(self, request_bytestring):
+    """Deserialize a request protocol buffer.
+
+    Args:
+      request_bytestring: The bytestring serialization of a request protocol
+        buffer.
+
+    Returns:
+      The request protocol buffer deserialized from the given byte string.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def serialize_response(self, response):
+    """Serialize a response protocol buffer.
+
+    Args:
+      response: A response protocol buffer.
+
+    Returns:
+      The bytestring serialization of the given response protocol buffer.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def deserialize_response(self, response_bytestring):
+    """Deserialize a response protocol buffer.
+
+    Args:
+      response_bytestring: The bytestring serialization of a response protocol
+        buffer.
+
+    Returns:
+      The response protocol buffer deserialized from the given byte string.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def requests(self):
+    """Access the sequence of requests for this scenario.
+
+    Returns:
+      A sequence of request protocol buffers.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def response_for_request(self, request):
+    """Access the response for a particular request.
+
+    Args:
+      request: A request protocol buffer.
+
+    Returns:
+      The response protocol buffer appropriate for the given request.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def verify_requests(self, experimental_requests):
+    """Verify the requests transmitted through the system under test.
+
+    Args:
+      experimental_requests: The request protocol buffers transmitted through
+        the system under test.
+
+    Returns:
+      True if the requests satisfy this test scenario; False otherwise.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def verify_responses(self, experimental_responses):
+    """Verify the responses transmitted through the system under test.
+
+    Args:
+      experimental_responses: The response protocol buffers transmitted through
+        the system under test.
+
+    Returns:
+      True if the responses satisfy this test scenario; False otherwise.
+    """
+    raise NotImplementedError()
+
+
+class EmptyScenario(ProtoScenario):
+  """A scenario that transmits no protocol buffers in either direction."""
+
+  def group_and_method(self):
+    return 'math.Math', 'DivMany'
+
+  def serialize_request(self, request):
+    raise ValueError('This should not be necessary to call!')
+
+  def deserialize_request(self, request_bytestring):
+    raise ValueError('This should not be necessary to call!')
+
+  def serialize_response(self, response):
+    raise ValueError('This should not be necessary to call!')
+
+  def deserialize_response(self, response_bytestring):
+    raise ValueError('This should not be necessary to call!')
+
+  def requests(self):
+    return ()
+
+  def response_for_request(self, request):
+    raise ValueError('This should not be necessary to call!')
+
+  def verify_requests(self, experimental_requests):
+    return not experimental_requests
+
+  def verify_responses(self, experimental_responses):
+    return not experimental_responses
+
+
+class BidirectionallyUnaryScenario(ProtoScenario):
+  """A scenario that transmits no protocol buffers in either direction."""
+
+  _DIVIDEND = 59
+  _DIVISOR = 7
+  _QUOTIENT = 8
+  _REMAINDER = 3
+
+  _REQUEST = math_pb2.DivArgs(dividend=_DIVIDEND, divisor=_DIVISOR)
+  _RESPONSE = math_pb2.DivReply(quotient=_QUOTIENT, remainder=_REMAINDER)
+
+  def group_and_method(self):
+    return 'math.Math', 'Div'
+
+  def serialize_request(self, request):
+    return request.SerializeToString()
+
+  def deserialize_request(self, request_bytestring):
+    return math_pb2.DivArgs.FromString(request_bytestring)
+
+  def serialize_response(self, response):
+    return response.SerializeToString()
+
+  def deserialize_response(self, response_bytestring):
+    return math_pb2.DivReply.FromString(response_bytestring)
+
+  def requests(self):
+    return [self._REQUEST]
+
+  def response_for_request(self, request):
+    return self._RESPONSE
+
+  def verify_requests(self, experimental_requests):
+    return tuple(experimental_requests) == (self._REQUEST,)
+
+  def verify_responses(self, experimental_responses):
+    return tuple(experimental_responses) == (self._RESPONSE,)
+
+
+class BidirectionallyStreamingScenario(ProtoScenario):
+  """A scenario that transmits no protocol buffers in either direction."""
+
+  _STREAM_LENGTH = 200
+  _REQUESTS = tuple(
+      math_pb2.DivArgs(dividend=59 + index, divisor=7 + index)
+      for index in range(_STREAM_LENGTH))
+
+  def __init__(self):
+    self._lock = threading.Lock()
+    self._responses = []
+
+  def group_and_method(self):
+    return 'math.Math', 'DivMany'
+
+  def serialize_request(self, request):
+    return request.SerializeToString()
+
+  def deserialize_request(self, request_bytestring):
+    return math_pb2.DivArgs.FromString(request_bytestring)
+
+  def serialize_response(self, response):
+    return response.SerializeToString()
+
+  def deserialize_response(self, response_bytestring):
+    return math_pb2.DivReply.FromString(response_bytestring)
+
+  def requests(self):
+    return self._REQUESTS
+
+  def response_for_request(self, request):
+    quotient, remainder = divmod(request.dividend, request.divisor)
+    response = math_pb2.DivReply(quotient=quotient, remainder=remainder)
+    with self._lock:
+      self._responses.append(response)
+    return response
+
+  def verify_requests(self, experimental_requests):
+    return tuple(experimental_requests) == self._REQUESTS
+
+  def verify_responses(self, experimental_responses):
+    with self._lock:
+      return tuple(experimental_responses) == tuple(self._responses)
diff --git a/src/python/src/grpc/_links/_transmission_test.py b/src/python/src/grpc/_links/_transmission_test.py
new file mode 100644
index 0000000000..c5ef1edb25
--- /dev/null
+++ b/src/python/src/grpc/_links/_transmission_test.py
@@ -0,0 +1,226 @@
+# 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.
+
+"""Tests transmission of tickets across gRPC-on-the-wire."""
+
+import unittest
+
+from grpc._adapter import _intermediary_low
+from grpc._links import _proto_scenarios
+from grpc._links import invocation
+from grpc._links import service
+from grpc.framework.common import test_constants
+from grpc.framework.interfaces.links import links
+from grpc.framework.interfaces.links import test_cases
+from grpc.framework.interfaces.links import test_utilities
+
+_IDENTITY = lambda x: x
+
+
+class TransmissionTest(test_cases.TransmissionTest, unittest.TestCase):
+
+  def create_transmitting_links(self):
+    service_link = service.service_link(
+        {self.group_and_method(): self.deserialize_request},
+        {self.group_and_method(): self.serialize_response})
+    port = service_link.add_port(0, None)
+    service_link.start()
+    channel = _intermediary_low.Channel('localhost:%d' % port, None)
+    invocation_link = invocation.invocation_link(
+        channel, 'localhost',
+        {self.group_and_method(): self.serialize_request},
+        {self.group_and_method(): self.deserialize_response})
+    invocation_link.start()
+    return invocation_link, service_link
+
+  def destroy_transmitting_links(self, invocation_side_link, service_side_link):
+    invocation_side_link.stop()
+    service_side_link.stop_gracefully()
+
+  def create_invocation_initial_metadata(self):
+    return (
+        ('first invocation initial metadata key', 'just a string value'),
+        ('second invocation initial metadata key', '0123456789'),
+        ('third invocation initial metadata key-bin', '\x00\x57' * 100),
+    )
+
+  def create_invocation_terminal_metadata(self):
+    return None
+
+  def create_service_initial_metadata(self):
+    return (
+        ('first service initial metadata key', 'just another string value'),
+        ('second service initial metadata key', '9876543210'),
+        ('third service initial metadata key-bin', '\x00\x59\x02' * 100),
+    )
+
+  def create_service_terminal_metadata(self):
+    return (
+        ('first service terminal metadata key', 'yet another string value'),
+        ('second service terminal metadata key', 'abcdefghij'),
+        ('third service terminal metadata key-bin', '\x00\x37' * 100),
+    )
+
+  def create_invocation_completion(self):
+    return None, None
+
+  def create_service_completion(self):
+    return _intermediary_low.Code.OK, 'An exuberant test "details" message!'
+
+  def assertMetadataEqual(self, original_metadata, transmitted_metadata):
+    self.assertSequenceEqual(original_metadata, transmitted_metadata)
+
+
+class RoundTripTest(unittest.TestCase):
+
+  def testZeroMessageRoundTrip(self):
+    test_operation_id = object()
+    test_group = 'test package.Test Group'
+    test_method = 'test method'
+    identity_transformation = {(test_group, test_method): _IDENTITY}
+    test_code = _intermediary_low.Code.OK
+    test_message = 'a test message'
+
+    service_link = service.service_link(
+        identity_transformation, identity_transformation)
+    service_mate = test_utilities.RecordingLink()
+    service_link.join_link(service_mate)
+    port = service_link.add_port(0, None)
+    service_link.start()
+    channel = _intermediary_low.Channel('localhost:%d' % port, None)
+    invocation_link = invocation.invocation_link(
+        channel, 'localhost', identity_transformation, identity_transformation)
+    invocation_mate = test_utilities.RecordingLink()
+    invocation_link.join_link(invocation_mate)
+    invocation_link.start()
+
+    invocation_ticket = links.Ticket(
+        test_operation_id, 0, test_group, test_method,
+        links.Ticket.Subscription.FULL, test_constants.LONG_TIMEOUT, None, None,
+        None, None, None, None, links.Ticket.Termination.COMPLETION)
+    invocation_link.accept_ticket(invocation_ticket)
+    service_mate.block_until_tickets_satisfy(test_cases.terminated)
+
+    service_ticket = links.Ticket(
+        service_mate.tickets()[-1].operation_id, 0, None, None, None, None,
+        None, None, None, None, test_code, test_message,
+        links.Ticket.Termination.COMPLETION)
+    service_link.accept_ticket(service_ticket)
+    invocation_mate.block_until_tickets_satisfy(test_cases.terminated)
+
+    invocation_link.stop()
+    service_link.stop_gracefully()
+
+    self.assertIs(
+        service_mate.tickets()[-1].termination,
+        links.Ticket.Termination.COMPLETION)
+    self.assertIs(
+        invocation_mate.tickets()[-1].termination,
+        links.Ticket.Termination.COMPLETION)
+
+  def _perform_scenario_test(self, scenario):
+    test_operation_id = object()
+    test_group, test_method = scenario.group_and_method()
+    test_code = _intermediary_low.Code.OK
+    test_message = 'a scenario test message'
+
+    service_link = service.service_link(
+        {(test_group, test_method): scenario.deserialize_request},
+        {(test_group, test_method): scenario.serialize_response})
+    service_mate = test_utilities.RecordingLink()
+    service_link.join_link(service_mate)
+    port = service_link.add_port(0, None)
+    service_link.start()
+    channel = _intermediary_low.Channel('localhost:%d' % port, None)
+    invocation_link = invocation.invocation_link(
+        channel, 'localhost',
+        {(test_group, test_method): scenario.serialize_request},
+        {(test_group, test_method): scenario.deserialize_response})
+    invocation_mate = test_utilities.RecordingLink()
+    invocation_link.join_link(invocation_mate)
+    invocation_link.start()
+
+    invocation_ticket = links.Ticket(
+        test_operation_id, 0, test_group, test_method,
+        links.Ticket.Subscription.FULL, test_constants.LONG_TIMEOUT, None, None,
+        None, None, None, None, None)
+    invocation_link.accept_ticket(invocation_ticket)
+    requests = scenario.requests()
+    for request_index, request in enumerate(requests):
+      request_ticket = links.Ticket(
+          test_operation_id, 1 + request_index, None, None, None, None, 1, None,
+          request, None, None, None, None)
+      invocation_link.accept_ticket(request_ticket)
+      service_mate.block_until_tickets_satisfy(
+          test_cases.at_least_n_payloads_received_predicate(1 + request_index))
+      response_ticket = links.Ticket(
+          service_mate.tickets()[0].operation_id, request_index, None, None,
+          None, None, 1, None, scenario.response_for_request(request), None,
+          None, None, None)
+      service_link.accept_ticket(response_ticket)
+      invocation_mate.block_until_tickets_satisfy(
+          test_cases.at_least_n_payloads_received_predicate(1 + request_index))
+    request_count = len(requests)
+    invocation_completion_ticket = links.Ticket(
+        test_operation_id, request_count + 1, None, None, None, None, None,
+        None, None, None, None, None, links.Ticket.Termination.COMPLETION)
+    invocation_link.accept_ticket(invocation_completion_ticket)
+    service_mate.block_until_tickets_satisfy(test_cases.terminated)
+    service_completion_ticket = links.Ticket(
+        service_mate.tickets()[0].operation_id, request_count, None, None, None,
+        None, None, None, None, None, test_code, test_message,
+        links.Ticket.Termination.COMPLETION)
+    service_link.accept_ticket(service_completion_ticket)
+    invocation_mate.block_until_tickets_satisfy(test_cases.terminated)
+
+    invocation_link.stop()
+    service_link.stop_gracefully()
+
+    observed_requests = tuple(
+        ticket.payload for ticket in service_mate.tickets()
+        if ticket.payload is not None)
+    observed_responses = tuple(
+        ticket.payload for ticket in invocation_mate.tickets()
+        if ticket.payload is not None)
+    self.assertTrue(scenario.verify_requests(observed_requests))
+    self.assertTrue(scenario.verify_responses(observed_responses))
+
+  def testEmptyScenario(self):
+    self._perform_scenario_test(_proto_scenarios.EmptyScenario())
+
+  def testBidirectionallyUnaryScenario(self):
+    self._perform_scenario_test(_proto_scenarios.BidirectionallyUnaryScenario())
+
+  def testBidirectionallyStreamingScenario(self):
+    self._perform_scenario_test(
+        _proto_scenarios.BidirectionallyStreamingScenario())
+
+
+if __name__ == '__main__':
+  unittest.main(verbosity=2)
diff --git a/src/python/src/grpc/_links/invocation.py b/src/python/src/grpc/_links/invocation.py
new file mode 100644
index 0000000000..0058ae91f8
--- /dev/null
+++ b/src/python/src/grpc/_links/invocation.py
@@ -0,0 +1,363 @@
+# 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.
+
+"""The RPC-invocation-side bridge between RPC Framework and GRPC-on-the-wire."""
+
+import abc
+import enum
+import logging
+import threading
+import time
+
+from grpc._adapter import _intermediary_low
+from grpc.framework.foundation import activated
+from grpc.framework.foundation import logging_pool
+from grpc.framework.foundation import relay
+from grpc.framework.interfaces.links import links
+
+
+@enum.unique
+class _Read(enum.Enum):
+  AWAITING_METADATA = 'awaiting metadata'
+  READING = 'reading'
+  AWAITING_ALLOWANCE = 'awaiting allowance'
+  CLOSED = 'closed'
+
+
+@enum.unique
+class _HighWrite(enum.Enum):
+  OPEN = 'open'
+  CLOSED = 'closed'
+
+
+@enum.unique
+class _LowWrite(enum.Enum):
+  OPEN = 'OPEN'
+  ACTIVE = 'ACTIVE'
+  CLOSED = 'CLOSED'
+
+
+class _RPCState(object):
+
+  def __init__(
+      self, call, request_serializer, response_deserializer, sequence_number,
+      read, allowance, high_write, low_write):
+    self.call = call
+    self.request_serializer = request_serializer
+    self.response_deserializer = response_deserializer
+    self.sequence_number = sequence_number
+    self.read = read
+    self.allowance = allowance
+    self.high_write = high_write
+    self.low_write = low_write
+
+
+class _Kernel(object):
+
+  def __init__(
+      self, channel, host, request_serializers, response_deserializers,
+      ticket_relay):
+    self._lock = threading.Lock()
+    self._channel = channel
+    self._host = host
+    self._request_serializers = request_serializers
+    self._response_deserializers = response_deserializers
+    self._relay = ticket_relay
+
+    self._completion_queue = None
+    self._rpc_states = None
+    self._pool = None
+
+  def _on_write_event(self, operation_id, unused_event, rpc_state):
+    if rpc_state.high_write is _HighWrite.CLOSED:
+      rpc_state.call.complete(operation_id)
+      rpc_state.low_write = _LowWrite.CLOSED
+    else:
+      ticket = links.Ticket(
+          operation_id, rpc_state.sequence_number, None, None, None, None, 1,
+          None, None, None, None, None, None)
+      rpc_state.sequence_number += 1
+      self._relay.add_value(ticket)
+      rpc_state.low_write = _LowWrite.OPEN
+
+  def _on_read_event(self, operation_id, event, rpc_state):
+    if event.bytes is None:
+      rpc_state.read = _Read.CLOSED
+    else:
+      if 0 < rpc_state.allowance:
+        rpc_state.allowance -= 1
+        rpc_state.call.read(operation_id)
+      else:
+        rpc_state.read = _Read.AWAITING_ALLOWANCE
+      ticket = links.Ticket(
+          operation_id, rpc_state.sequence_number, None, None, None, None, None,
+          None, rpc_state.response_deserializer(event.bytes), None, None, None,
+          None)
+      rpc_state.sequence_number += 1
+      self._relay.add_value(ticket)
+
+  def _on_metadata_event(self, operation_id, event, rpc_state):
+    rpc_state.allowance -= 1
+    rpc_state.call.read(operation_id)
+    rpc_state.read = _Read.READING
+    ticket = links.Ticket(
+        operation_id, rpc_state.sequence_number, None, None,
+        links.Ticket.Subscription.FULL, None, None, event.metadata, None, None,
+        None, None, None)
+    rpc_state.sequence_number += 1
+    self._relay.add_value(ticket)
+
+  def _on_finish_event(self, operation_id, event, rpc_state):
+    self._rpc_states.pop(operation_id, None)
+    if event.status.code is _intermediary_low.Code.OK:
+      termination = links.Ticket.Termination.COMPLETION
+    elif event.status.code is _intermediary_low.Code.CANCELLED:
+      termination = links.Ticket.Termination.CANCELLATION
+    elif event.status.code is _intermediary_low.Code.DEADLINE_EXCEEDED:
+      termination = links.Ticket.Termination.EXPIRATION
+    else:
+      termination = links.Ticket.Termination.TRANSMISSION_FAILURE
+    ticket = links.Ticket(
+        operation_id, rpc_state.sequence_number, None, None, None, None, None,
+        None, None, event.metadata, event.status.code, event.status.details,
+        termination)
+    rpc_state.sequence_number += 1
+    self._relay.add_value(ticket)
+
+  def _spin(self, completion_queue):
+    while True:
+      event = completion_queue.get(None)
+      if event.kind is _intermediary_low.Event.Kind.STOP:
+        return
+      operation_id = event.tag
+      with self._lock:
+        if self._completion_queue is None:
+          continue
+        rpc_state = self._rpc_states.get(operation_id)
+        if rpc_state is not None:
+          if event.kind is _intermediary_low.Event.Kind.WRITE_ACCEPTED:
+            self._on_write_event(operation_id, event, rpc_state)
+          elif event.kind is _intermediary_low.Event.Kind.METADATA_ACCEPTED:
+            self._on_metadata_event(operation_id, event, rpc_state)
+          elif event.kind is _intermediary_low.Event.Kind.READ_ACCEPTED:
+            self._on_read_event(operation_id, event, rpc_state)
+          elif event.kind is _intermediary_low.Event.Kind.FINISH:
+            self._on_finish_event(operation_id, event, rpc_state)
+          elif event.kind is _intermediary_low.Event.Kind.COMPLETE_ACCEPTED:
+            pass
+          else:
+            logging.error('Illegal RPC event! %s', (event,))
+
+  def _invoke(
+      self, operation_id, group, method, initial_metadata, payload, termination,
+      timeout, allowance):
+    """Invoke an RPC.
+
+    Args:
+      operation_id: Any object to be used as an operation ID for the RPC.
+      group: The group to which the RPC method belongs.
+      method: The RPC method name.
+      initial_metadata: The initial metadata object for the RPC.
+      payload: A payload object for the RPC or None if no payload was given at
+        invocation-time.
+      termination: A links.Ticket.Termination value or None indicated whether or
+        not more writes will follow from this side of the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      allowance: The number of payloads (beyond the free first one) that the
+        local ticket exchange mate has granted permission to be read.
+    """
+    if termination is links.Ticket.Termination.COMPLETION:
+      high_write = _HighWrite.CLOSED
+    elif termination is None:
+      high_write = _HighWrite.OPEN
+    else:
+      return
+
+    request_serializer = self._request_serializers.get((group, method))
+    response_deserializer = self._response_deserializers.get((group, method))
+    if request_serializer is None or response_deserializer is None:
+      cancellation_ticket = links.Ticket(
+          operation_id, 0, None, None, None, None, None, None, None, None, None,
+          None, links.Ticket.Termination.CANCELLATION)
+      self._relay.add_value(cancellation_ticket)
+      return
+
+    call = _intermediary_low.Call(
+        self._channel, self._completion_queue, '/%s/%s' % (group, method),
+        self._host, time.time() + timeout)
+    if initial_metadata is not None:
+      for metadata_key, metadata_value in initial_metadata:
+        call.add_metadata(metadata_key, metadata_value)
+    call.invoke(self._completion_queue, operation_id, operation_id)
+    if payload is None:
+      if high_write is _HighWrite.CLOSED:
+        call.complete(operation_id)
+        low_write = _LowWrite.CLOSED
+      else:
+        low_write = _LowWrite.OPEN
+    else:
+      call.write(request_serializer(payload), operation_id)
+      low_write = _LowWrite.ACTIVE
+    self._rpc_states[operation_id] = _RPCState(
+        call, request_serializer, response_deserializer, 0,
+        _Read.AWAITING_METADATA, 1 if allowance is None else (1 + allowance),
+        high_write, low_write)
+
+  def _advance(self, operation_id, rpc_state, payload, termination, allowance):
+    if payload is not None:
+      rpc_state.call.write(rpc_state.request_serializer(payload), operation_id)
+      rpc_state.low_write = _LowWrite.ACTIVE
+
+    if allowance is not None:
+      if rpc_state.read is _Read.AWAITING_ALLOWANCE:
+        rpc_state.allowance += allowance - 1
+        rpc_state.call.read(operation_id)
+        rpc_state.read = _Read.READING
+      else:
+        rpc_state.allowance += allowance
+
+    if termination is links.Ticket.Termination.COMPLETION:
+      rpc_state.high_write = _HighWrite.CLOSED
+      if rpc_state.low_write is _LowWrite.OPEN:
+        rpc_state.call.complete(operation_id)
+        rpc_state.low_write = _LowWrite.CLOSED
+    elif termination is not None:
+      rpc_state.call.cancel()
+
+  def add_ticket(self, ticket):
+    with self._lock:
+      if self._completion_queue is None:
+        return
+      if ticket.sequence_number == 0:
+        self._invoke(
+            ticket.operation_id, ticket.group, ticket.method,
+            ticket.initial_metadata, ticket.payload, ticket.termination,
+            ticket.timeout, ticket.allowance)
+      else:
+        rpc_state = self._rpc_states.get(ticket.operation_id)
+        if rpc_state is not None:
+          self._advance(
+              ticket.operation_id, rpc_state, ticket.payload,
+              ticket.termination, ticket.allowance)
+
+  def start(self):
+    """Starts this object.
+
+    This method must be called before attempting to exchange tickets with this
+    object.
+    """
+    with self._lock:
+      self._completion_queue = _intermediary_low.CompletionQueue()
+      self._rpc_states = {}
+      self._pool = logging_pool.pool(1)
+      self._pool.submit(self._spin, self._completion_queue)
+
+  def stop(self):
+    """Stops this object.
+
+    This method must be called for proper termination of this object, and no
+    attempts to exchange tickets with this object may be made after this method
+    has been called.
+    """
+    with self._lock:
+      self._completion_queue.stop()
+      self._completion_queue = None
+      pool = self._pool
+      self._pool = None
+      self._rpc_states = None
+    pool.shutdown(wait=True)
+
+
+class InvocationLink(links.Link, activated.Activated):
+  """A links.Link for use on the invocation-side of a gRPC connection.
+
+  Implementations of this interface are only valid for use when activated.
+  """
+  __metaclass__ = abc.ABCMeta
+
+
+class _InvocationLink(InvocationLink):
+
+  def __init__(
+      self, channel, host, request_serializers, response_deserializers):
+    self._relay = relay.relay(None)
+    self._kernel = _Kernel(
+        channel, host, request_serializers, response_deserializers, self._relay)
+
+  def _start(self):
+    self._relay.start()
+    self._kernel.start()
+    return self
+
+  def _stop(self):
+    self._kernel.stop()
+    self._relay.stop()
+
+  def accept_ticket(self, ticket):
+    """See links.Link.accept_ticket for specification."""
+    self._kernel.add_ticket(ticket)
+
+  def join_link(self, link):
+    """See links.Link.join_link for specification."""
+    self._relay.set_behavior(link.accept_ticket)
+
+  def __enter__(self):
+    """See activated.Activated.__enter__ for specification."""
+    return self._start()
+
+  def __exit__(self, exc_type, exc_val, exc_tb):
+    """See activated.Activated.__exit__ for specification."""
+    self._stop()
+    return False
+
+  def start(self):
+    """See activated.Activated.start for specification."""
+    return self._start()
+
+  def stop(self):
+    """See activated.Activated.stop for specification."""
+    self._stop()
+
+
+def invocation_link(channel, host, request_serializers, response_deserializers):
+  """Creates an InvocationLink.
+
+  Args:
+    channel: A channel for use by the link.
+    host: The host to specify when invoking RPCs.
+    request_serializers: A dict from group-method pair to request object
+      serialization behavior.
+    response_deserializers: A dict from group-method pair to response object
+      deserialization behavior.
+
+  Returns:
+    An InvocationLink.
+  """
+  return _InvocationLink(
+      channel, host, request_serializers, response_deserializers)
diff --git a/src/python/src/grpc/_links/service.py b/src/python/src/grpc/_links/service.py
new file mode 100644
index 0000000000..7783e91824
--- /dev/null
+++ b/src/python/src/grpc/_links/service.py
@@ -0,0 +1,402 @@
+# 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.
+
+"""The RPC-service-side bridge between RPC Framework and GRPC-on-the-wire."""
+
+import abc
+import enum
+import logging
+import threading
+import time
+
+from grpc._adapter import _intermediary_low
+from grpc.framework.foundation import logging_pool
+from grpc.framework.foundation import relay
+from grpc.framework.interfaces.links import links
+
+
+@enum.unique
+class _Read(enum.Enum):
+  READING = 'reading'
+  AWAITING_ALLOWANCE = 'awaiting allowance'
+  CLOSED = 'closed'
+
+
+@enum.unique
+class _HighWrite(enum.Enum):
+  OPEN = 'open'
+  CLOSED = 'closed'
+
+
+@enum.unique
+class _LowWrite(enum.Enum):
+  """The possible categories of low-level write state."""
+
+  OPEN = 'OPEN'
+  ACTIVE = 'ACTIVE'
+  CLOSED = 'CLOSED'
+
+
+class _RPCState(object):
+
+  def __init__(
+      self, request_deserializer, response_serializer, sequence_number, read,
+      allowance, high_write, low_write, premetadataed, terminal_metadata, code,
+      message):
+    self.request_deserializer = request_deserializer
+    self.response_serializer = response_serializer
+    self.sequence_number = sequence_number
+    self.read = read
+    self.allowance = allowance
+    self.high_write = high_write
+    self.low_write = low_write
+    self.premetadataed = premetadataed
+    self.terminal_metadata = terminal_metadata
+    self.code = code
+    self.message = message
+
+
+def _metadatafy(call, metadata):
+  for metadata_key, metadata_value in metadata:
+    call.add_metadata(metadata_key, metadata_value)
+
+
+class _Kernel(object):
+
+  def __init__(self, request_deserializers, response_serializers, ticket_relay):
+    self._lock = threading.Lock()
+    self._request_deserializers = request_deserializers
+    self._response_serializers = response_serializers
+    self._relay = ticket_relay
+
+    self._completion_queue = None
+    self._server = None
+    self._rpc_states = {}
+    self._pool = None
+
+  def _on_service_acceptance_event(self, event, server):
+    server.service(None)
+
+    service_acceptance = event.service_acceptance
+    call = service_acceptance.call
+    call.accept(self._completion_queue, call)
+    try:
+      group, method = service_acceptance.method.split('/')[1:3]
+    except ValueError:
+      logging.info('Illegal path "%s"!', service_acceptance.method)
+      return
+    request_deserializer = self._request_deserializers.get((group, method))
+    response_serializer = self._response_serializers.get((group, method))
+    if request_deserializer is None or response_serializer is None:
+      # TODO(nathaniel): Terminate the RPC with code NOT_FOUND.
+      call.cancel()
+      return
+
+    call.read(call)
+    self._rpc_states[call] = _RPCState(
+        request_deserializer, response_serializer, 1, _Read.READING, 0,
+        _HighWrite.OPEN, _LowWrite.OPEN, False, None, None, None)
+    ticket = links.Ticket(
+        call, 0, group, method, links.Ticket.Subscription.FULL,
+        service_acceptance.deadline - time.time(), None, event.metadata, None,
+        None, None, None, None)
+    self._relay.add_value(ticket)
+
+  def _on_read_event(self, event):
+    call = event.tag
+    rpc_state = self._rpc_states.get(call, None)
+    if rpc_state is None:
+      return
+
+    if event.bytes is None:
+      rpc_state.read = _Read.CLOSED
+      payload = None
+      termination = links.Ticket.Termination.COMPLETION
+    else:
+      if 0 < rpc_state.allowance:
+        rpc_state.allowance -= 1
+        call.read(call)
+      else:
+        rpc_state.read = _Read.AWAITING_ALLOWANCE
+      payload = rpc_state.request_deserializer(event.bytes)
+      termination = None
+    ticket = links.Ticket(
+        call, rpc_state.sequence_number, None, None, None, None, None, None,
+        payload, None, None, None, termination)
+    rpc_state.sequence_number += 1
+    self._relay.add_value(ticket)
+
+  def _on_write_event(self, event):
+    call = event.tag
+    rpc_state = self._rpc_states.get(call, None)
+    if rpc_state is None:
+      return
+
+    if rpc_state.high_write is _HighWrite.CLOSED:
+      if rpc_state.terminal_metadata is not None:
+        _metadatafy(call, rpc_state.terminal_metadata)
+      call.status(
+          _intermediary_low.Status(rpc_state.code, rpc_state.message), call)
+      rpc_state.low_write = _LowWrite.CLOSED
+    else:
+      ticket = links.Ticket(
+          call, rpc_state.sequence_number, None, None, None, None, 1, None,
+          None, None, None, None, None)
+      rpc_state.sequence_number += 1
+      self._relay.add_value(ticket)
+      rpc_state.low_write = _LowWrite.OPEN
+
+  def _on_finish_event(self, event):
+    call = event.tag
+    rpc_state = self._rpc_states.pop(call, None)
+    if rpc_state is None:
+      return
+    code = event.status.code
+    if code is _intermediary_low.Code.OK:
+      return
+
+    if code is _intermediary_low.Code.CANCELLED:
+      termination = links.Ticket.Termination.CANCELLATION
+    elif code is _intermediary_low.Code.DEADLINE_EXCEEDED:
+      termination = links.Ticket.Termination.EXPIRATION
+    else:
+      termination = links.Ticket.Termination.TRANSMISSION_FAILURE
+    ticket = links.Ticket(
+        call, rpc_state.sequence_number, None, None, None, None, None, None,
+        None, None, None, None, termination)
+    rpc_state.sequence_number += 1
+    self._relay.add_value(ticket)
+
+  def _spin(self, completion_queue, server):
+    while True:
+      event = completion_queue.get(None)
+      if event.kind is _intermediary_low.Event.Kind.STOP:
+        return
+      with self._lock:
+        if self._server is None:
+          continue
+        elif event.kind is _intermediary_low.Event.Kind.SERVICE_ACCEPTED:
+          self._on_service_acceptance_event(event, server)
+        elif event.kind is _intermediary_low.Event.Kind.READ_ACCEPTED:
+          self._on_read_event(event)
+        elif event.kind is _intermediary_low.Event.Kind.WRITE_ACCEPTED:
+          self._on_write_event(event)
+        elif event.kind is _intermediary_low.Event.Kind.COMPLETE_ACCEPTED:
+          pass
+        elif event.kind is _intermediary_low.Event.Kind.FINISH:
+          self._on_finish_event(event)
+        else:
+          logging.error('Illegal event! %s', (event,))
+
+  def add_ticket(self, ticket):
+    with self._lock:
+      if self._server is None:
+        return
+      call = ticket.operation_id
+      rpc_state = self._rpc_states.get(call)
+      if rpc_state is None:
+        return
+
+      if ticket.initial_metadata is not None:
+        _metadatafy(call, ticket.initial_metadata)
+        call.premetadata()
+        rpc_state.premetadataed = True
+      elif not rpc_state.premetadataed:
+        if (ticket.terminal_metadata is not None or
+            ticket.payload is not None or
+            ticket.termination is links.Ticket.Termination.COMPLETION or
+            ticket.code is not None or
+            ticket.message is not None):
+          call.premetadata()
+          rpc_state.premetadataed = True
+
+      if ticket.allowance is not None:
+        if rpc_state.read is _Read.AWAITING_ALLOWANCE:
+          rpc_state.allowance += ticket.allowance - 1
+          call.read(call)
+          rpc_state.read = _Read.READING
+        else:
+          rpc_state.allowance += ticket.allowance
+
+      if ticket.payload is not None:
+        call.write(rpc_state.response_serializer(ticket.payload), call)
+        rpc_state.low_write = _LowWrite.ACTIVE
+
+      if ticket.terminal_metadata is not None:
+        rpc_state.terminal_metadata = ticket.terminal_metadata
+      if ticket.code is not None:
+        rpc_state.code = ticket.code
+      if ticket.message is not None:
+        rpc_state.message = ticket.message
+
+      if ticket.termination is links.Ticket.Termination.COMPLETION:
+        rpc_state.high_write = _HighWrite.CLOSED
+        if rpc_state.low_write is _LowWrite.OPEN:
+          if rpc_state.terminal_metadata is not None:
+            _metadatafy(call, rpc_state.terminal_metadata)
+          status = _intermediary_low.Status(
+              _intermediary_low.Code.OK
+              if rpc_state.code is None else rpc_state.code,
+              '' if rpc_state.message is None else rpc_state.message)
+          call.status(status, call)
+          rpc_state.low_write = _LowWrite.CLOSED
+      elif ticket.termination is not None:
+        call.cancel()
+        self._rpc_states.pop(call, None)
+
+  def add_port(self, port, server_credentials):
+    with self._lock:
+      address = '[::]:%d' % port
+      if self._server is None:
+        self._completion_queue = _intermediary_low.CompletionQueue()
+        self._server = _intermediary_low.Server(self._completion_queue)
+      if server_credentials is None:
+        return self._server.add_http2_addr(address)
+      else:
+        return self._server.add_secure_http2_addr(address, server_credentials)
+
+  def start(self):
+    with self._lock:
+      if self._server is None:
+        self._completion_queue = _intermediary_low.CompletionQueue()
+        self._server = _intermediary_low.Server(self._completion_queue)
+      self._pool = logging_pool.pool(1)
+      self._pool.submit(self._spin, self._completion_queue, self._server)
+      self._server.start()
+      self._server.service(None)
+
+  def graceful_stop(self):
+    with self._lock:
+      self._server.stop()
+      self._server = None
+      self._completion_queue.stop()
+      self._completion_queue = None
+      pool = self._pool
+      self._pool = None
+      self._rpc_states = None
+    pool.shutdown(wait=True)
+
+  def immediate_stop(self):
+    # TODO(nathaniel): Implementation.
+    raise NotImplementedError(
+        'TODO(nathaniel): after merge of rewritten lower layers')
+
+
+class ServiceLink(links.Link):
+  """A links.Link for use on the service-side of a gRPC connection.
+
+  Implementations of this interface are only valid for use between calls to
+  their start method and one of their stop methods.
+  """
+
+  @abc.abstractmethod
+  def add_port(self, port, server_credentials):
+    """Adds a port on which to service RPCs after this link has been started.
+
+    Args:
+      port: The port on which to service RPCs, or zero to request that a port be
+        automatically selected and used.
+      server_credentials: A ServerCredentials object, or None for insecure
+        service.
+
+    Returns:
+      A port on which RPCs will be serviced after this link has been started.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def start(self):
+    """Starts this object.
+
+    This method must be called before attempting to use this Link in ticket
+    exchange.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def stop_gracefully(self):
+    """Stops this link.
+
+    New RPCs will be rejected as soon as this method is called, but ongoing RPCs
+    will be allowed to continue until they terminate. This method blocks until
+    all RPCs have terminated.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def stop_immediately(self):
+    """Stops this link.
+
+    All in-progress RPCs will be terminated immediately.
+    """
+    raise NotImplementedError()
+
+
+class _ServiceLink(ServiceLink):
+
+  def __init__(self, request_deserializers, response_serializers):
+    self._relay = relay.relay(None)
+    self._kernel = _Kernel(
+        request_deserializers, response_serializers, self._relay)
+
+  def accept_ticket(self, ticket):
+    self._kernel.add_ticket(ticket)
+
+  def join_link(self, link):
+    self._relay.set_behavior(link.accept_ticket)
+
+  def add_port(self, port, server_credentials):
+    return self._kernel.add_port(port, server_credentials)
+
+  def start(self):
+    self._relay.start()
+    return self._kernel.start()
+
+  def stop_gracefully(self):
+    self._kernel.graceful_stop()
+    self._relay.stop()
+
+  def stop_immediately(self):
+    self._kernel.immediate_stop()
+    self._relay.stop()
+
+
+def service_link(request_deserializers, response_serializers):
+  """Creates a ServiceLink.
+
+  Args:
+    request_deserializers: A dict from group-method pair to request object
+      deserialization behavior.
+    response_serializers: A dict from group-method pair to response ojbect
+      serialization behavior.
+
+  Returns:
+    A ServiceLink.
+  """
+  return _ServiceLink(request_deserializers, response_serializers)
diff --git a/src/python/src/grpc/framework/common/test_constants.py b/src/python/src/grpc/framework/common/test_constants.py
new file mode 100644
index 0000000000..237b8754ed
--- /dev/null
+++ b/src/python/src/grpc/framework/common/test_constants.py
@@ -0,0 +1,37 @@
+# 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.
+
+"""Constants shared among tests throughout RPC Framework."""
+
+# Value for maximum duration in seconds of RPCs that may time out as part of a
+# test.
+SHORT_TIMEOUT = 4
+# Absurdly large value for maximum duration in seconds for should-not-time-out
+# RPCs made during tests.
+LONG_TIMEOUT = 3000
diff --git a/src/python/src/grpc/framework/common/test_control.py b/src/python/src/grpc/framework/common/test_control.py
new file mode 100644
index 0000000000..3960c4e649
--- /dev/null
+++ b/src/python/src/grpc/framework/common/test_control.py
@@ -0,0 +1,87 @@
+# 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.
+
+"""Code for instructing systems under test to block or fail."""
+
+import abc
+import contextlib
+import threading
+
+
+class Control(object):
+  """An object that accepts program control from a system under test.
+
+  Systems under test passed a Control should call its control() method
+  frequently during execution. The control() method may block, raise an
+  exception, or do nothing, all according to the enclosing test's desire for
+  the system under test to simulate hanging, failing, or functioning.
+  """
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def control(self):
+    """Potentially does anything."""
+    raise NotImplementedError()
+
+
+class PauseFailControl(Control):
+  """A Control that can be used to pause or fail code under control."""
+
+  def __init__(self):
+    self._condition = threading.Condition()
+    self._paused = False
+    self._fail = False
+
+  def control(self):
+    with self._condition:
+      if self._fail:
+        raise ValueError()
+
+      while self._paused:
+        self._condition.wait()
+
+  @contextlib.contextmanager
+  def pause(self):
+    """Pauses code under control while controlling code is in context."""
+    with self._condition:
+      self._paused = True
+    yield
+    with self._condition:
+      self._paused = False
+      self._condition.notify_all()
+
+  @contextlib.contextmanager
+  def fail(self):
+    """Fails code under control while controlling code is in context."""
+    with self._condition:
+      self._fail = True
+    yield
+    with self._condition:
+      self._fail = False
diff --git a/src/python/src/grpc/framework/common/test_coverage.py b/src/python/src/grpc/framework/common/test_coverage.py
new file mode 100644
index 0000000000..a7ed3582c4
--- /dev/null
+++ b/src/python/src/grpc/framework/common/test_coverage.py
@@ -0,0 +1,116 @@
+# 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.
+
+"""Governs coverage for tests of RPCs throughout RPC Framework."""
+
+import abc
+
+# This code is designed for use with the unittest module.
+# pylint: disable=invalid-name
+
+
+class Coverage(object):
+  """Specification of test coverage."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def testSuccessfulUnaryRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testSuccessfulUnaryRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testSuccessfulStreamRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testSuccessfulStreamRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testSequentialInvocations(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testParallelInvocations(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testWaitingForSomeButNotAllParallelInvocations(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testCancelledUnaryRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testCancelledUnaryRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testCancelledStreamRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testCancelledStreamRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testExpiredUnaryRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testExpiredUnaryRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testExpiredStreamRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testExpiredStreamRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testFailedUnaryRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testFailedUnaryRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testFailedStreamRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testFailedStreamRequestStreamResponse(self):
+    raise NotImplementedError()
diff --git a/src/python/src/grpc/framework/foundation/relay.py b/src/python/src/grpc/framework/foundation/relay.py
new file mode 100644
index 0000000000..9c23946552
--- /dev/null
+++ b/src/python/src/grpc/framework/foundation/relay.py
@@ -0,0 +1,175 @@
+# 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.
+
+"""Implementations of in-order work deference."""
+
+import abc
+import enum
+import threading
+
+from grpc.framework.foundation import activated
+from grpc.framework.foundation import logging_pool
+
+_NULL_BEHAVIOR = lambda unused_value: None
+
+
+class Relay(object):
+  """Performs work submitted to it in another thread.
+
+  Performs work in the order in which work was submitted to it; otherwise there
+  would be no reason to use an implementation of this interface instead of a
+  thread pool.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def add_value(self, value):
+    """Adds a value to be passed to the behavior registered with this Relay.
+
+    Args:
+      value: A value that will be passed to a call made in another thread to the
+        behavior registered with this Relay.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def set_behavior(self, behavior):
+    """Sets the behavior that this Relay should call when passed values.
+
+    Args:
+      behavior: The behavior that this Relay should call in another thread when
+        passed a value, or None to have passed values ignored.
+    """
+    raise NotImplementedError()
+
+
+class _PoolRelay(activated.Activated, Relay):
+
+  @enum.unique
+  class _State(enum.Enum):
+    INACTIVE = 'inactive'
+    IDLE = 'idle'
+    SPINNING = 'spinning'
+
+  def __init__(self, pool, behavior):
+    self._condition = threading.Condition()
+    self._pool = pool
+    self._own_pool = pool is None
+    self._state = _PoolRelay._State.INACTIVE
+    self._activated = False
+    self._spinning = False
+    self._values = []
+    self._behavior = _NULL_BEHAVIOR if behavior is None else behavior
+
+  def _spin(self, behavior, value):
+    while True:
+      behavior(value)
+      with self._condition:
+        if self._values:
+          value = self._values.pop(0)
+          behavior = self._behavior
+        else:
+          self._state = _PoolRelay._State.IDLE
+          self._condition.notify_all()
+          break
+
+  def add_value(self, value):
+    with self._condition:
+      if self._state is _PoolRelay._State.INACTIVE:
+        raise ValueError('add_value not valid on inactive Relay!')
+      elif self._state is _PoolRelay._State.IDLE:
+        self._pool.submit(self._spin, self._behavior, value)
+        self._state = _PoolRelay._State.SPINNING
+      else:
+        self._values.append(value)
+
+  def set_behavior(self, behavior):
+    with self._condition:
+      self._behavior = _NULL_BEHAVIOR if behavior is None else behavior
+
+  def _start(self):
+    with self._condition:
+      self._state = _PoolRelay._State.IDLE
+      if self._own_pool:
+        self._pool = logging_pool.pool(1)
+      return self
+
+  def _stop(self):
+    with self._condition:
+      while self._state is _PoolRelay._State.SPINNING:
+        self._condition.wait()
+      if self._own_pool:
+        self._pool.shutdown(wait=True)
+      self._state = _PoolRelay._State.INACTIVE
+
+  def __enter__(self):
+    return self._start()
+
+  def __exit__(self, exc_type, exc_val, exc_tb):
+    self._stop()
+    return False
+
+  def start(self):
+    return self._start()
+
+  def stop(self):
+    self._stop()
+
+
+def relay(behavior):
+  """Creates a Relay.
+
+  Args:
+    behavior: The behavior to be called by the created Relay, or None to have
+      passed values dropped until a different behavior is given to the returned
+      Relay later.
+
+  Returns:
+    An object that is both an activated.Activated and a Relay. The object is
+      only valid for use as a Relay when activated.
+  """
+  return _PoolRelay(None, behavior)
+
+
+def pool_relay(pool, behavior):
+  """Creates a Relay that uses a given thread pool.
+
+  This object will make use of at most one thread in the given pool.
+
+  Args:
+    pool: A futures.ThreadPoolExecutor for use by the created Relay.
+    behavior: The behavior to be called by the created Relay, or None to have
+      passed values dropped until a different behavior is given to the returned
+      Relay later.
+
+  Returns:
+    An object that is both an activated.Activated and a Relay. The object is
+      only valid for use as a Relay when activated.
+  """
+  return _PoolRelay(pool, behavior)
diff --git a/src/python/src/grpc/framework/interfaces/__init__.py b/src/python/src/grpc/framework/interfaces/__init__.py
new file mode 100644
index 0000000000..7086519106
--- /dev/null
+++ b/src/python/src/grpc/framework/interfaces/__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/src/grpc/framework/interfaces/links/__init__.py b/src/python/src/grpc/framework/interfaces/links/__init__.py
new file mode 100644
index 0000000000..7086519106
--- /dev/null
+++ b/src/python/src/grpc/framework/interfaces/links/__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/src/grpc/framework/interfaces/links/links.py b/src/python/src/grpc/framework/interfaces/links/links.py
new file mode 100644
index 0000000000..5ebbac8a6f
--- /dev/null
+++ b/src/python/src/grpc/framework/interfaces/links/links.py
@@ -0,0 +1,124 @@
+# 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.
+
+"""The low-level ticket-exchanging-links interface of RPC Framework."""
+
+import abc
+import collections
+import enum
+
+
+class Ticket(
+    collections.namedtuple(
+        'Ticket',
+        ['operation_id', 'sequence_number', 'group', 'method', 'subscription',
+         'timeout', 'allowance', 'initial_metadata', 'payload',
+         'terminal_metadata', 'code', 'message', 'termination'])):
+  """A sum type for all values sent from a front to a back.
+
+  Attributes:
+    operation_id: A unique-with-respect-to-equality hashable object identifying
+      a particular operation.
+    sequence_number: A zero-indexed integer sequence number identifying the
+      ticket's place in the stream of tickets sent in one direction for the
+      particular operation.
+    group: The group to which the method of the operation belongs. Must be
+      present in the first ticket from invocation side to service side. Ignored
+      for all other tickets exchanged during the operation.
+    method: The name of an operation. Must be present in the first ticket from
+      invocation side to service side. Ignored for all other tickets exchanged
+      during the operation.
+    subscription: A Subscription value describing the interest one side has in
+      receiving information from the other side. Must be present in the first
+      ticket from either side. Ignored for all other tickets exchanged during
+      the operation.
+    timeout: A nonzero length of time (measured from the beginning of the
+      operation) to allow for the entire operation. Must be present in the first
+      ticket from invocation side to service side. Optional for all other
+      tickets exchanged during the operation. Receipt of a value from the other
+      side of the operation indicates the value in use by that side. Setting a
+      value on a later ticket allows either side to request time extensions (or
+      even time reductions!) on in-progress operations.
+    allowance: A positive integer granting permission for a number of payloads
+      to be transmitted to the communicating side of the operation, or None if
+      no additional allowance is being granted with this ticket.
+    initial_metadata: An optional metadata value communicated from one side to
+      the other at the beginning of the operation. May be non-None in at most
+      one ticket from each side. Any non-None value must appear no later than
+      the first payload value.
+    payload: A customer payload object. May be None.
+    terminal_metadata: A metadata value comminicated from one side to the other
+      at the end of the operation. May be non-None in the same ticket as
+      the code and message, but must be None for all earlier tickets.
+    code: A value communicated at operation completion. May be None.
+    message: A value communicated at operation completion. May be None.
+    termination: A Termination value describing the end of the operation, or
+      None if the operation has not yet terminated. If set, no further tickets
+      may be sent in the same direction.
+  """
+
+  @enum.unique
+  class Subscription(enum.Enum):
+    """Identifies the level of subscription of a side of an operation."""
+
+    NONE = 'none'
+    TERMINATION = 'termination'
+    FULL = 'full'
+
+  @enum.unique
+  class Termination(enum.Enum):
+    """Identifies the termination of an operation."""
+
+    COMPLETION = 'completion'
+    CANCELLATION = 'cancellation'
+    EXPIRATION = 'expiration'
+    LOCAL_SHUTDOWN = 'local shutdown'
+    RECEPTION_FAILURE = 'reception failure'
+    TRANSMISSION_FAILURE = 'transmission failure'
+    LOCAL_FAILURE = 'local failure'
+    REMOTE_FAILURE = 'remote failure'
+
+
+class Link(object):
+  """Accepts and emits tickets."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def accept_ticket(self, ticket):
+    """Accept a Ticket.
+
+    Args:
+      ticket: Any Ticket.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def join_link(self, link):
+    """Mates this object with a peer with which it will exchange tickets."""
+    raise NotImplementedError()
diff --git a/src/python/src/grpc/framework/interfaces/links/test_cases.py b/src/python/src/grpc/framework/interfaces/links/test_cases.py
new file mode 100644
index 0000000000..3ac212ebdf
--- /dev/null
+++ b/src/python/src/grpc/framework/interfaces/links/test_cases.py
@@ -0,0 +1,332 @@
+# 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.
+
+"""Tests of the links interface of RPC Framework."""
+
+# unittest is referenced from specification in this module.
+import abc
+import unittest  # pylint: disable=unused-import
+
+from grpc.framework.common import test_constants
+from grpc.framework.interfaces.links import links
+from grpc.framework.interfaces.links import test_utilities
+
+
+def at_least_n_payloads_received_predicate(n):
+  def predicate(ticket_sequence):
+    payload_count = 0
+    for ticket in ticket_sequence:
+      if ticket.payload is not None:
+        payload_count += 1
+        if n <= payload_count:
+          return True
+    else:
+      return False
+  return predicate
+
+
+def terminated(ticket_sequence):
+  return ticket_sequence and ticket_sequence[-1].termination is not None
+
+_TRANSMISSION_GROUP = 'test.Group'
+_TRANSMISSION_METHOD = 'TestMethod'
+
+
+class TransmissionTest(object):
+  """Tests ticket transmission between two connected links.
+
+  This class must be mixed into a unittest.TestCase that implements the abstract
+  methods it provides.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  # This is a unittest.TestCase mix-in.
+  # pylint: disable=invalid-name
+
+  @abc.abstractmethod
+  def create_transmitting_links(self):
+    """Creates two connected links for use in this test.
+
+    Returns:
+      Two links.Links, the first of which will be used on the invocation side
+        of RPCs and the second of which will be used on the service side of
+        RPCs.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def destroy_transmitting_links(self, invocation_side_link, service_side_link):
+    """Destroys the two connected links created for this test.
+
+
+    Args:
+      invocation_side_link: The link used on the invocation side of RPCs in
+        this test.
+      service_side_link: The link used on the service side of RPCs in this
+        test.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def create_invocation_initial_metadata(self):
+    """Creates a value for use as invocation-side initial metadata.
+
+    Returns:
+      A metadata value appropriate for use as invocation-side initial metadata
+        or None if invocation-side initial metadata transmission is not
+        supported by the links under test.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def create_invocation_terminal_metadata(self):
+    """Creates a value for use as invocation-side terminal metadata.
+
+    Returns:
+      A metadata value appropriate for use as invocation-side terminal
+        metadata or None if invocation-side terminal metadata transmission is
+        not supported by the links under test.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def create_service_initial_metadata(self):
+    """Creates a value for use as service-side initial metadata.
+
+    Returns:
+      A metadata value appropriate for use as service-side initial metadata or
+        None if service-side initial metadata transmission is not supported by
+        the links under test.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def create_service_terminal_metadata(self):
+    """Creates a value for use as service-side terminal metadata.
+
+    Returns:
+      A metadata value appropriate for use as service-side terminal metadata or
+        None if service-side terminal metadata transmission is not supported by
+        the links under test.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def create_invocation_completion(self):
+    """Creates values for use as invocation-side code and message.
+
+    Returns:
+      An invocation-side code value and an invocation-side message value.
+        Either or both may be None if invocation-side code and/or
+        invocation-side message transmission is not supported by the links
+        under test.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def create_service_completion(self):
+    """Creates values for use as service-side code and message.
+
+    Returns:
+      A service-side code value and a service-side message value. Either or
+        both may be None if service-side code and/or service-side message
+        transmission is not supported by the links under test.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def assertMetadataEqual(self, original_metadata, transmitted_metadata):
+    """Asserts that two metadata objects are equal.
+
+    Args:
+      original_metadata: A metadata object used in this test.
+      transmitted_metadata: A metadata object obtained after transmission
+        through the system under test.
+
+    Raises:
+      AssertionError: if the two metadata objects are not equal.
+    """
+    raise NotImplementedError()
+
+  def group_and_method(self):
+    """Returns the group and method used in this test case.
+
+    Returns:
+      A pair of the group and method used in this test case.
+    """
+    return _TRANSMISSION_GROUP, _TRANSMISSION_METHOD
+
+  def serialize_request(self, request):
+    """Serializes a request value used in this test case.
+
+    Args:
+      request: A request value created by this test case.
+
+    Returns:
+      A bytestring that is the serialization of the given request.
+    """
+    return request
+
+  def deserialize_request(self, serialized_request):
+    """Deserializes a request value used in this test case.
+
+    Args:
+      serialized_request: A bytestring that is the serialization of some request
+        used in this test case.
+
+    Returns:
+      The request value encoded by the given bytestring.
+    """
+    return serialized_request
+
+  def serialize_response(self, response):
+    """Serializes a response value used in this test case.
+
+    Args:
+      response: A response value created by this test case.
+
+    Returns:
+      A bytestring that is the serialization of the given response.
+    """
+    return response
+
+  def deserialize_response(self, serialized_response):
+    """Deserializes a response value used in this test case.
+
+    Args:
+      serialized_response: A bytestring that is the serialization of some
+        response used in this test case.
+
+    Returns:
+      The response value encoded by the given bytestring.
+    """
+    return serialized_response
+
+  def _assert_is_valid_metadata_payload_sequence(
+      self, ticket_sequence, payloads, initial_metadata, terminal_metadata):
+    initial_metadata_seen = False
+    seen_payloads = []
+    terminal_metadata_seen = False
+
+    for ticket in ticket_sequence:
+      if ticket.initial_metadata is not None:
+        self.assertFalse(initial_metadata_seen)
+        self.assertFalse(seen_payloads)
+        self.assertFalse(terminal_metadata_seen)
+        self.assertMetadataEqual(initial_metadata, ticket.initial_metadata)
+        initial_metadata_seen = True
+
+      if ticket.payload is not None:
+        self.assertFalse(terminal_metadata_seen)
+        seen_payloads.append(ticket.payload)
+
+      if ticket.terminal_metadata is not None:
+        self.assertFalse(terminal_metadata_seen)
+        self.assertMetadataEqual(terminal_metadata, ticket.terminal_metadata)
+        terminal_metadata_seen = True
+    self.assertSequenceEqual(payloads, seen_payloads)
+
+  def _assert_is_valid_invocation_sequence(
+      self, ticket_sequence, group, method, payloads, initial_metadata,
+      terminal_metadata, termination):
+    self.assertLess(0, len(ticket_sequence))
+    self.assertEqual(group, ticket_sequence[0].group)
+    self.assertEqual(method, ticket_sequence[0].method)
+    self._assert_is_valid_metadata_payload_sequence(
+        ticket_sequence, payloads, initial_metadata, terminal_metadata)
+    self.assertIs(termination, ticket_sequence[-1].termination)
+
+  def _assert_is_valid_service_sequence(
+      self, ticket_sequence, payloads, initial_metadata, terminal_metadata,
+      code, message, termination):
+    self.assertLess(0, len(ticket_sequence))
+    self._assert_is_valid_metadata_payload_sequence(
+        ticket_sequence, payloads, initial_metadata, terminal_metadata)
+    self.assertEqual(code, ticket_sequence[-1].code)
+    self.assertEqual(message, ticket_sequence[-1].message)
+    self.assertIs(termination, ticket_sequence[-1].termination)
+
+  def setUp(self):
+    self._invocation_link, self._service_link = self.create_transmitting_links()
+    self._invocation_mate = test_utilities.RecordingLink()
+    self._service_mate = test_utilities.RecordingLink()
+    self._invocation_link.join_link(self._invocation_mate)
+    self._service_link.join_link(self._service_mate)
+
+  def tearDown(self):
+    self.destroy_transmitting_links(self._invocation_link, self._service_link)
+
+  def testSimplestRoundTrip(self):
+    """Tests transmission of one ticket in each direction."""
+    invocation_operation_id = object()
+    invocation_payload = b'\x07' * 1023
+    timeout = test_constants.LONG_TIMEOUT
+    invocation_initial_metadata = self.create_invocation_initial_metadata()
+    invocation_terminal_metadata = self.create_invocation_terminal_metadata()
+    invocation_code, invocation_message = self.create_invocation_completion()
+    service_payload = b'\x08' * 1025
+    service_initial_metadata = self.create_service_initial_metadata()
+    service_terminal_metadata = self.create_service_terminal_metadata()
+    service_code, service_message = self.create_service_completion()
+
+    original_invocation_ticket = links.Ticket(
+        invocation_operation_id, 0, _TRANSMISSION_GROUP, _TRANSMISSION_METHOD,
+        links.Ticket.Subscription.FULL, timeout, 0, invocation_initial_metadata,
+        invocation_payload, invocation_terminal_metadata, invocation_code,
+        invocation_message, links.Ticket.Termination.COMPLETION)
+    self._invocation_link.accept_ticket(original_invocation_ticket)
+
+    # TODO(nathaniel): This shouldn't be necessary. Detecting the end of the
+    # invocation-side ticket sequence shouldn't require granting allowance for
+    # another payload.
+    self._service_mate.block_until_tickets_satisfy(
+        at_least_n_payloads_received_predicate(1))
+    service_operation_id = self._service_mate.tickets()[0].operation_id
+    self._service_link.accept_ticket(
+        links.Ticket(
+            service_operation_id, 0, None, None, links.Ticket.Subscription.FULL,
+            None, 1, None, None, None, None, None, None))
+
+    self._service_mate.block_until_tickets_satisfy(terminated)
+    self._assert_is_valid_invocation_sequence(
+        self._service_mate.tickets(), _TRANSMISSION_GROUP, _TRANSMISSION_METHOD,
+        (invocation_payload,), invocation_initial_metadata,
+        invocation_terminal_metadata, links.Ticket.Termination.COMPLETION)
+
+    original_service_ticket = links.Ticket(
+        service_operation_id, 1, None, None, links.Ticket.Subscription.FULL,
+        timeout, 0, service_initial_metadata, service_payload,
+        service_terminal_metadata, service_code, service_message,
+        links.Ticket.Termination.COMPLETION)
+    self._service_link.accept_ticket(original_service_ticket)
+    self._invocation_mate.block_until_tickets_satisfy(terminated)
+    self._assert_is_valid_service_sequence(
+        self._invocation_mate.tickets(), (service_payload,),
+        service_initial_metadata, service_terminal_metadata, service_code,
+        service_message, links.Ticket.Termination.COMPLETION)
diff --git a/src/python/src/grpc/framework/interfaces/links/test_utilities.py b/src/python/src/grpc/framework/interfaces/links/test_utilities.py
new file mode 100644
index 0000000000..6c2e3346aa
--- /dev/null
+++ b/src/python/src/grpc/framework/interfaces/links/test_utilities.py
@@ -0,0 +1,66 @@
+# 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.
+
+"""State and behavior appropriate for use in tests."""
+
+import threading
+
+from grpc.framework.interfaces.links import links
+
+
+class RecordingLink(links.Link):
+  """A Link that records every ticket passed to it."""
+
+  def __init__(self):
+    self._condition = threading.Condition()
+    self._tickets = []
+
+  def accept_ticket(self, ticket):
+    with self._condition:
+      self._tickets.append(ticket)
+      self._condition.notify_all()
+
+  def join_link(self, link):
+    pass
+
+  def block_until_tickets_satisfy(self, predicate):
+    """Blocks until the received tickets satisfy the given predicate.
+
+    Args:
+      predicate: A callable that takes a sequence of tickets and returns a
+        boolean value.
+    """
+    with self._condition:
+      while not predicate(self._tickets):
+        self._condition.wait()
+
+  def tickets(self):
+    """Returns a copy of the list of all tickets received by this Link."""
+    with self._condition:
+      return tuple(self._tickets)
diff --git a/src/python/src/grpc/framework/interfaces/links/utilities.py b/src/python/src/grpc/framework/interfaces/links/utilities.py
new file mode 100644
index 0000000000..6e4fd76d93
--- /dev/null
+++ b/src/python/src/grpc/framework/interfaces/links/utilities.py
@@ -0,0 +1,44 @@
+# 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.
+
+"""Utilities provided as part of the links interface."""
+
+from grpc.framework.interfaces.links import links
+
+
+class _NullLink(links.Link):
+  """A do-nothing links.Link."""
+
+  def accept_ticket(self, ticket):
+    pass
+
+  def join_link(self, link):
+    pass
+
+NULL_LINK = _NullLink()
diff --git a/src/python/src/setup.py b/src/python/src/setup.py
index 5398b09936..a857ae98cc 100644
--- a/src/python/src/setup.py
+++ b/src/python/src/setup.py
@@ -29,11 +29,19 @@
 
 """A setup module for the GRPC Python package."""
 
+import os
+import sys
+
 from distutils import core as _core
 import setuptools
-import sys
 
-_EXTENSION_SOURCES = (
+
+# Use environment variables to determine whether or not the Cython extension
+# should *use* Cython or use the generated C files. Note that this requires the
+# C files to have been generated by building first *with* Cython support.
+_BUILD_WITH_CYTHON = os.environ.get('GRPC_PYTHON_BUILD_WITH_CYTHON', False)
+
+_C_EXTENSION_SOURCES = (
     'grpc/_adapter/_c/module.c',
     'grpc/_adapter/_c/types.c',
     'grpc/_adapter/_c/utility.c',
@@ -56,16 +64,19 @@ _EXTENSION_LIBRARIES = (
 if not "darwin" in sys.platform:
     _EXTENSION_LIBRARIES += ('rt',)
 
-_EXTENSION_MODULE = _core.Extension(
-    'grpc._adapter._c', sources=list(_EXTENSION_SOURCES),
+
+_C_EXTENSION_MODULE = _core.Extension(
+    'grpc._adapter._c', sources=list(_C_EXTENSION_SOURCES),
     include_dirs=list(_EXTENSION_INCLUDE_DIRECTORIES),
     libraries=list(_EXTENSION_LIBRARIES),
-    )
+)
+_EXTENSION_MODULES = [_C_EXTENSION_MODULE]
 
 _PACKAGES = (
     'grpc',
     'grpc._adapter',
     'grpc._junkdrawer',
+    'grpc._links',
     'grpc.early_adopter',
     'grpc.framework',
     'grpc.framework.alpha',
@@ -74,20 +85,23 @@ _PACKAGES = (
     'grpc.framework.face',
     'grpc.framework.face.testing',
     'grpc.framework.foundation',
+    'grpc.framework.interfaces',
+    'grpc.framework.interfaces.links',
 )
 
 _PACKAGE_DIRECTORIES = {
     'grpc': 'grpc',
     'grpc._adapter': 'grpc/_adapter',
     'grpc._junkdrawer': 'grpc/_junkdrawer',
+    'grpc._links': 'grpc/_links',
     'grpc.early_adopter': 'grpc/early_adopter',
     'grpc.framework': 'grpc/framework',
 }
 
 setuptools.setup(
     name='grpcio',
-    version='0.9.0a1',
-    ext_modules=[_EXTENSION_MODULE],
+    version='0.10.0a0',
+    ext_modules=_EXTENSION_MODULES,
     packages=list(_PACKAGES),
     package_dir=_PACKAGE_DIRECTORIES,
     install_requires=[
diff --git a/src/ruby/ext/grpc/rb_completion_queue.c b/src/ruby/ext/grpc/rb_completion_queue.c
index 8fb3949b3d..2d52d96dc8 100644
--- a/src/ruby/ext/grpc/rb_completion_queue.c
+++ b/src/ruby/ext/grpc/rb_completion_queue.c
@@ -91,7 +91,7 @@ static void grpc_rb_completion_queue_shutdown_drain(grpc_completion_queue *cq) {
    * - investigate further, this is probably another example of C-level cleanup
    * not working consistently in all cases.
    */
-  next_call.timeout = gpr_time_add(gpr_now(), gpr_time_from_micros(5e3));
+  next_call.timeout = gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_micros(5e3));
   do {
     rb_thread_call_without_gvl(grpc_rb_completion_queue_next_no_gil,
                                (void *)&next_call, NULL, NULL);
diff --git a/src/ruby/grpc.gemspec b/src/ruby/grpc.gemspec
index 319da9470a..dd4e27df51 100755
--- a/src/ruby/grpc.gemspec
+++ b/src/ruby/grpc.gemspec
@@ -14,7 +14,7 @@ Gem::Specification.new do |s|
   s.license       = 'BSD-3-Clause'
 
   s.required_ruby_version = '>= 2.0.0'
-  s.requirements << 'libgrpc ~> 0.9.1 needs to be installed'
+  s.requirements << 'libgrpc ~> 0.10.0 needs to be installed'
 
   s.files         = `git ls-files`.split("\n")
   s.test_files    = `git ls-files -- spec/*`.split("\n")
diff --git a/src/ruby/lib/grpc/generic/rpc_server.rb b/src/ruby/lib/grpc/generic/rpc_server.rb
index a7e20d6b82..67bf35ce02 100644
--- a/src/ruby/lib/grpc/generic/rpc_server.rb
+++ b/src/ruby/lib/grpc/generic/rpc_server.rb
@@ -398,14 +398,14 @@ module GRPC
       nil
     end
 
-    # Sends NOT_FOUND if the method can't be found
-    def found?(an_rpc)
+    # Sends UNIMPLEMENTED if the method is not implemented by this server
+    def implemented?(an_rpc)
       mth = an_rpc.method.to_sym
       return an_rpc if rpc_descs.key?(mth)
-      GRPC.logger.warn("NOT_FOUND: #{an_rpc}")
+      GRPC.logger.warn("UNIMPLEMENTED: #{an_rpc}")
       noop = proc { |x| x }
       c = ActiveCall.new(an_rpc.call, @cq, noop, noop, an_rpc.deadline)
-      c.send_status(StatusCodes::NOT_FOUND, '')
+      c.send_status(StatusCodes::UNIMPLEMENTED, '')
       nil
     end
 
@@ -446,7 +446,7 @@ module GRPC
       an_rpc.call.run_batch(@cq, handle_call_tag, INFINITE_FUTURE,
                             SEND_INITIAL_METADATA => connect_md)
       return nil unless available?(an_rpc)
-      return nil unless found?(an_rpc)
+      return nil unless implemented?(an_rpc)
 
       # Create the ActiveCall
       GRPC.logger.info("deadline is #{an_rpc.deadline}; (now=#{Time.now})")
diff --git a/src/ruby/lib/grpc/version.rb b/src/ruby/lib/grpc/version.rb
index 028fea5a4c..431e8774b5 100644
--- a/src/ruby/lib/grpc/version.rb
+++ b/src/ruby/lib/grpc/version.rb
@@ -29,5 +29,5 @@
 
 # GRPC contains the General RPC module.
 module GRPC
-  VERSION = '0.9.4'
+  VERSION = '0.10.0'
 end
author	David Garcia Quintas <dgq@google.com>	2015-07-15 14:07:18 -0700
committer	David Garcia Quintas <dgq@google.com>	2015-07-15 14:07:18 -0700
commit	e0d581b6ad1023635598d9de95bd951cd04b0354 (patch)
tree	a0601b1315a1dc7b499998a95adba61322825f3c /src
parent	658b6087cc07f8706d270ee0e31f28bbf732ec3d (diff)
parent	3e5d61670e23b040ed47b2df1e4c87ee2cfec4aa (diff)