Merge remote-tracking branch 'upstream/master' into timespec

158 files changed, 8707 insertions, 622 deletions

diff --git a/src/compiler/config.h b/src/compiler/config.h
index cd52aca57d..fea976c318 100644
--- a/src/compiler/config.h
+++ b/src/compiler/config.h
@@ -34,8 +34,8 @@
 #ifndef SRC_COMPILER_CONFIG_H
 #define SRC_COMPILER_CONFIG_H
 
-#include <grpc++/config.h>
-#include <grpc++/config_protobuf.h>
+#include <grpc++/support/config.h>
+#include <grpc++/support/config_protobuf.h>
 
 #ifndef GRPC_CUSTOM_DESCRIPTOR
 #include <google/protobuf/descriptor.h>
diff --git a/src/compiler/cpp_generator.cc b/src/compiler/cpp_generator.cc
index ea487bcd89..1bf2b16ed6 100644
--- a/src/compiler/cpp_generator.cc
+++ b/src/compiler/cpp_generator.cc
@@ -112,18 +112,18 @@ grpc::string GetHeaderPrologue(const grpc::protobuf::FileDescriptor *file,
 grpc::string GetHeaderIncludes(const grpc::protobuf::FileDescriptor *file,
                                const Parameters &params) {
   grpc::string temp =
-      "#include <grpc++/impl/internal_stub.h>\n"
+      "#include <grpc++/support/async_stream.h>\n"
       "#include <grpc++/impl/rpc_method.h>\n"
       "#include <grpc++/impl/proto_utils.h>\n"
       "#include <grpc++/impl/service_type.h>\n"
-      "#include <grpc++/async_unary_call.h>\n"
-      "#include <grpc++/status.h>\n"
-      "#include <grpc++/stream.h>\n"
-      "#include <grpc++/stub_options.h>\n"
+      "#include <grpc++/support/async_unary_call.h>\n"
+      "#include <grpc++/support/status.h>\n"
+      "#include <grpc++/support/stub_options.h>\n"
+      "#include <grpc++/support/sync_stream.h>\n"
       "\n"
       "namespace grpc {\n"
       "class CompletionQueue;\n"
-      "class ChannelInterface;\n"
+      "class Channel;\n"
       "class RpcService;\n"
       "class ServerCompletionQueue;\n"
       "class ServerContext;\n"
@@ -554,17 +554,17 @@ void PrintHeaderService(grpc::protobuf::io::Printer *printer,
   printer->Outdent();
   printer->Print("};\n");
   printer->Print(
-      "class Stub GRPC_FINAL : public StubInterface,"
-      " public ::grpc::InternalStub {\n public:\n");
+      "class Stub GRPC_FINAL : public StubInterface"
+      " {\n public:\n");
   printer->Indent();
-  printer->Print(
-      "Stub(const std::shared_ptr< ::grpc::ChannelInterface>& channel);\n");
+  printer->Print("Stub(const std::shared_ptr< ::grpc::Channel>& channel);\n");
   for (int i = 0; i < service->method_count(); ++i) {
     PrintHeaderClientMethod(printer, service->method(i), vars, true);
   }
   printer->Outdent();
   printer->Print("\n private:\n");
   printer->Indent();
+  printer->Print("std::shared_ptr< ::grpc::Channel> channel_;\n");
   for (int i = 0; i < service->method_count(); ++i) {
     PrintHeaderClientMethod(printer, service->method(i), vars, false);
   }
@@ -575,7 +575,7 @@ void PrintHeaderService(grpc::protobuf::io::Printer *printer,
   printer->Print("};\n");
   printer->Print(
       "static std::unique_ptr<Stub> NewStub(const std::shared_ptr< "
-      "::grpc::ChannelInterface>& channel, "
+      "::grpc::Channel>& channel, "
       "const ::grpc::StubOptions& options = ::grpc::StubOptions());\n");
 
   printer->Print("\n");
@@ -702,12 +702,13 @@ grpc::string GetSourceIncludes(const grpc::protobuf::FileDescriptor *file,
     grpc::protobuf::io::Printer printer(&output_stream, '$');
     std::map<grpc::string, grpc::string> vars;
 
-    printer.Print(vars, "#include <grpc++/async_unary_call.h>\n");
-    printer.Print(vars, "#include <grpc++/channel_interface.h>\n");
+    printer.Print(vars, "#include <grpc++/channel.h>\n");
     printer.Print(vars, "#include <grpc++/impl/client_unary_call.h>\n");
     printer.Print(vars, "#include <grpc++/impl/rpc_service_method.h>\n");
     printer.Print(vars, "#include <grpc++/impl/service_type.h>\n");
-    printer.Print(vars, "#include <grpc++/stream.h>\n");
+    printer.Print(vars, "#include <grpc++/support/async_unary_call.h>\n");
+    printer.Print(vars, "#include <grpc++/support/async_stream.h>\n");
+    printer.Print(vars, "#include <grpc++/support/sync_stream.h>\n");
 
     if (!file->package().empty()) {
       std::vector<grpc::string> parts =
@@ -738,7 +739,7 @@ void PrintSourceClientMethod(grpc::protobuf::io::Printer *printer,
                    "::grpc::ClientContext* context, "
                    "const $Request$& request, $Response$* response) {\n");
     printer->Print(*vars,
-                   "  return ::grpc::BlockingUnaryCall(channel(), "
+                   "  return ::grpc::BlockingUnaryCall(channel_.get(), "
                    "rpcmethod_$Method$_, "
                    "context, request, response);\n"
                    "}\n\n");
@@ -751,7 +752,7 @@ void PrintSourceClientMethod(grpc::protobuf::io::Printer *printer,
     printer->Print(*vars,
                    "  return new "
                    "::grpc::ClientAsyncResponseReader< $Response$>("
-                   "channel(), cq, "
+                   "channel_.get(), cq, "
                    "rpcmethod_$Method$_, "
                    "context, request);\n"
                    "}\n\n");
@@ -762,7 +763,7 @@ void PrintSourceClientMethod(grpc::protobuf::io::Printer *printer,
                    "::grpc::ClientContext* context, $Response$* response) {\n");
     printer->Print(*vars,
                    "  return new ::grpc::ClientWriter< $Request$>("
-                   "channel(), "
+                   "channel_.get(), "
                    "rpcmethod_$Method$_, "
                    "context, response);\n"
                    "}\n\n");
@@ -773,7 +774,7 @@ void PrintSourceClientMethod(grpc::protobuf::io::Printer *printer,
                    "::grpc::CompletionQueue* cq, void* tag) {\n");
     printer->Print(*vars,
                    "  return new ::grpc::ClientAsyncWriter< $Request$>("
-                   "channel(), cq, "
+                   "channel_.get(), cq, "
                    "rpcmethod_$Method$_, "
                    "context, response, tag);\n"
                    "}\n\n");
@@ -785,7 +786,7 @@ void PrintSourceClientMethod(grpc::protobuf::io::Printer *printer,
         "::grpc::ClientContext* context, const $Request$& request) {\n");
     printer->Print(*vars,
                    "  return new ::grpc::ClientReader< $Response$>("
-                   "channel(), "
+                   "channel_.get(), "
                    "rpcmethod_$Method$_, "
                    "context, request);\n"
                    "}\n\n");
@@ -796,7 +797,7 @@ void PrintSourceClientMethod(grpc::protobuf::io::Printer *printer,
                    "::grpc::CompletionQueue* cq, void* tag) {\n");
     printer->Print(*vars,
                    "  return new ::grpc::ClientAsyncReader< $Response$>("
-                   "channel(), cq, "
+                   "channel_.get(), cq, "
                    "rpcmethod_$Method$_, "
                    "context, request, tag);\n"
                    "}\n\n");
@@ -808,7 +809,7 @@ void PrintSourceClientMethod(grpc::protobuf::io::Printer *printer,
     printer->Print(*vars,
                    "  return new ::grpc::ClientReaderWriter< "
                    "$Request$, $Response$>("
-                   "channel(), "
+                   "channel_.get(), "
                    "rpcmethod_$Method$_, "
                    "context);\n"
                    "}\n\n");
@@ -820,7 +821,7 @@ void PrintSourceClientMethod(grpc::protobuf::io::Printer *printer,
     printer->Print(*vars,
                    "  return new "
                    "::grpc::ClientAsyncReaderWriter< $Request$, $Response$>("
-                   "channel(), cq, "
+                   "channel_.get(), cq, "
                    "rpcmethod_$Method$_, "
                    "context, tag);\n"
                    "}\n\n");
@@ -964,20 +965,19 @@ void PrintSourceService(grpc::protobuf::io::Printer *printer,
   }
   printer->Print(*vars, "};\n\n");
 
-  printer->Print(
-      *vars,
-      "std::unique_ptr< $ns$$Service$::Stub> $ns$$Service$::NewStub("
-      "const std::shared_ptr< ::grpc::ChannelInterface>& channel, "
-      "const ::grpc::StubOptions& options) {\n"
-      "  std::unique_ptr< $ns$$Service$::Stub> stub(new "
-      "$ns$$Service$::Stub(channel));\n"
-      "  return stub;\n"
-      "}\n\n");
+  printer->Print(*vars,
+                 "std::unique_ptr< $ns$$Service$::Stub> $ns$$Service$::NewStub("
+                 "const std::shared_ptr< ::grpc::Channel>& channel, "
+                 "const ::grpc::StubOptions& options) {\n"
+                 "  std::unique_ptr< $ns$$Service$::Stub> stub(new "
+                 "$ns$$Service$::Stub(channel));\n"
+                 "  return stub;\n"
+                 "}\n\n");
   printer->Print(*vars,
                  "$ns$$Service$::Stub::Stub(const std::shared_ptr< "
-                 "::grpc::ChannelInterface>& channel)\n");
+                 "::grpc::Channel>& channel)\n");
   printer->Indent();
-  printer->Print(": ::grpc::InternalStub(channel)");
+  printer->Print(": channel_(channel)");
   for (int i = 0; i < service->method_count(); ++i) {
     const grpc::protobuf::MethodDescriptor *method = service->method(i);
     (*vars)["Method"] = method->name();
@@ -991,13 +991,12 @@ void PrintSourceService(grpc::protobuf::io::Printer *printer,
     } else {
       (*vars)["StreamingType"] = "BIDI_STREAMING";
     }
-    printer->Print(
-        *vars,
-        ", rpcmethod_$Method$_("
-        "$prefix$$Service$_method_names[$Idx$], "
-        "::grpc::RpcMethod::$StreamingType$, "
-        "channel->RegisterMethod($prefix$$Service$_method_names[$Idx$])"
-        ")\n");
+    printer->Print(*vars,
+                   ", rpcmethod_$Method$_("
+                   "$prefix$$Service$_method_names[$Idx$], "
+                   "::grpc::RpcMethod::$StreamingType$, "
+                   "channel"
+                   ")\n");
   }
   printer->Print("{}\n\n");
   printer->Outdent();
diff --git a/src/compiler/python_generator.cc b/src/compiler/python_generator.cc
index 2982a89fad..72c457ac6b 100644
--- a/src/compiler/python_generator.cc
+++ b/src/compiler/python_generator.cc
@@ -42,7 +42,7 @@
 #include <tuple>
 #include <vector>
 
-#include <grpc++/config.h>
+#include <grpc++/support/config.h>
 #include "src/compiler/config.h"
 #include "src/compiler/generator_helpers.h"
 #include "src/compiler/python_generator.h"
diff --git a/src/core/channel/census_filter.c b/src/core/census/grpc_filter.c
index d996c3475e..fbedb35661 100644
--- a/src/core/channel/census_filter.c
+++ b/src/core/census/grpc_filter.c
@@ -31,11 +31,13 @@
  *
  */
 
-#include "src/core/channel/census_filter.h"
+#include "src/core/census/grpc_filter.h"
 
 #include <stdio.h>
 #include <string.h>
 
+#include "include/grpc/census.h"
+#include "src/core/census/rpc_stat_id.h"
 #include "src/core/channel/channel_stack.h"
 #include "src/core/channel/noop_filter.h"
 #include "src/core/statistics/census_interface.h"
@@ -47,24 +49,19 @@
 
 typedef struct call_data {
   census_op_id op_id;
-  census_rpc_stats stats;
+  census_context* ctxt;
   gpr_timespec start_ts;
+  int error;
 
   /* recv callback */
   grpc_stream_op_buffer* recv_ops;
-  void (*on_done_recv)(void* user_data, int success);
-  void* recv_user_data;
+  grpc_iomgr_closure* on_done_recv;
 } call_data;
 
 typedef struct channel_data {
   grpc_mdstr* path_str; /* pointer to meta data str with key == ":path" */
 } channel_data;
 
-static void init_rpc_stats(census_rpc_stats* stats) {
-  memset(stats, 0, sizeof(census_rpc_stats));
-  stats->cnt = 1;
-}
-
 static void extract_and_annotate_method_tag(grpc_stream_op_buffer* sopb,
                                             call_data* calld,
                                             channel_data* chand) {
@@ -77,8 +74,7 @@ static void extract_and_annotate_method_tag(grpc_stream_op_buffer* sopb,
       if (m->md->key == chand->path_str) {
         gpr_log(GPR_DEBUG, "%s",
                 (const char*)GPR_SLICE_START_PTR(m->md->value->slice));
-        census_add_method_tag(calld->op_id, (const char*)GPR_SLICE_START_PTR(
-                                                m->md->value->slice));
+        /* Add method tag here */
       }
     }
   }
@@ -95,8 +91,6 @@ static void client_mutate_op(grpc_call_element* elem,
 
 static void client_start_transport_op(grpc_call_element* elem,
                                       grpc_transport_stream_op* op) {
-  call_data* calld = elem->call_data;
-  GPR_ASSERT((calld->op_id.upper != 0) || (calld->op_id.lower != 0));
   client_mutate_op(elem, op);
   grpc_call_next_op(elem, op);
 }
@@ -108,7 +102,7 @@ static void server_on_done_recv(void* ptr, int success) {
   if (success) {
     extract_and_annotate_method_tag(calld->recv_ops, calld, chand);
   }
-  calld->on_done_recv(calld->recv_user_data, success);
+  calld->on_done_recv->cb(calld->on_done_recv->cb_arg, success);
 }
 
 static void server_mutate_op(grpc_call_element* elem,
@@ -118,9 +112,7 @@ static void server_mutate_op(grpc_call_element* elem,
     /* substitute our callback for the op callback */
     calld->recv_ops = op->recv_ops;
     calld->on_done_recv = op->on_done_recv;
-    calld->recv_user_data = op->recv_user_data;
-    op->on_done_recv = server_on_done_recv;
-    op->recv_user_data = elem;
+    op->on_done_recv = calld->on_done_recv;
   }
 }
 
@@ -132,35 +124,19 @@ static void server_start_transport_op(grpc_call_element* elem,
   grpc_call_next_op(elem, op);
 }
 
-static void channel_op(grpc_channel_element* elem,
-                       grpc_channel_element* from_elem, grpc_channel_op* op) {
-  switch (op->type) {
-    case GRPC_TRANSPORT_CLOSED:
-      /* TODO(hongyu): Annotate trace information for all calls of the channel
-       */
-      break;
-    default:
-      break;
-  }
-  grpc_channel_next_op(elem, op);
-}
-
 static void client_init_call_elem(grpc_call_element* elem,
                                   const void* server_transport_data,
                                   grpc_transport_stream_op* initial_op) {
   call_data* d = elem->call_data;
   GPR_ASSERT(d != NULL);
-  init_rpc_stats(&d->stats);
   d->start_ts = gpr_now(GPR_CLOCK_REALTIME);
-  d->op_id = census_tracing_start_op();
   if (initial_op) client_mutate_op(elem, initial_op);
 }
 
 static void client_destroy_call_elem(grpc_call_element* elem) {
   call_data* d = elem->call_data;
   GPR_ASSERT(d != NULL);
-  census_record_rpc_client_stats(d->op_id, &d->stats);
-  census_tracing_end_op(d->op_id);
+  /* TODO(hongyu): record rpc client stats and census_rpc_end_op here */
 }
 
 static void server_init_call_elem(grpc_call_element* elem,
@@ -168,29 +144,24 @@ static void server_init_call_elem(grpc_call_element* elem,
                                   grpc_transport_stream_op* initial_op) {
   call_data* d = elem->call_data;
   GPR_ASSERT(d != NULL);
-  init_rpc_stats(&d->stats);
   d->start_ts = gpr_now(GPR_CLOCK_REALTIME);
-  d->op_id = census_tracing_start_op();
+  /* TODO(hongyu): call census_tracing_start_op here. */
+  grpc_iomgr_closure_init(d->on_done_recv, server_on_done_recv, elem);
   if (initial_op) server_mutate_op(elem, initial_op);
 }
 
 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(GPR_CLOCK_REALTIME), d->start_ts));
-  census_record_rpc_server_stats(d->op_id, &d->stats);
-  census_tracing_end_op(d->op_id);
+  /* TODO(hongyu): record rpc server stats and census_tracing_end_op here */
 }
 
-static void init_channel_elem(grpc_channel_element* elem,
+static void init_channel_elem(grpc_channel_element* elem, grpc_channel* master,
                               const grpc_channel_args* args, grpc_mdctx* mdctx,
                               int is_first, int is_last) {
   channel_data* chand = elem->channel_data;
   GPR_ASSERT(chand != NULL);
-  GPR_ASSERT(!is_first);
-  GPR_ASSERT(!is_last);
-  chand->path_str = grpc_mdstr_from_string(mdctx, ":path");
+  chand->path_str = grpc_mdstr_from_string(mdctx, ":path", 0);
 }
 
 static void destroy_channel_elem(grpc_channel_element* elem) {
@@ -203,22 +174,24 @@ static void destroy_channel_elem(grpc_channel_element* elem) {
 
 const grpc_channel_filter grpc_client_census_filter = {
     client_start_transport_op,
-    channel_op,
+    grpc_channel_next_op,
     sizeof(call_data),
     client_init_call_elem,
     client_destroy_call_elem,
     sizeof(channel_data),
     init_channel_elem,
     destroy_channel_elem,
+    grpc_call_next_get_peer,
     "census-client"};
 
 const grpc_channel_filter grpc_server_census_filter = {
     server_start_transport_op,
-    channel_op,
+    grpc_channel_next_op,
     sizeof(call_data),
     server_init_call_elem,
     server_destroy_call_elem,
     sizeof(channel_data),
     init_channel_elem,
     destroy_channel_elem,
+    grpc_call_next_get_peer,
     "census-server"};
diff --git a/src/core/channel/census_filter.h b/src/core/census/grpc_filter.h
index 1453c05d28..1453c05d28 100644
--- a/src/core/channel/census_filter.h
+++ b/src/core/census/grpc_filter.h
diff --git a/src/core/channel/channel_args.c b/src/core/channel/channel_args.c
index c430b56fa2..54ee75af28 100644
--- a/src/core/channel/channel_args.c
+++ b/src/core/channel/channel_args.c
@@ -37,6 +37,7 @@
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/string_util.h>
+#include <grpc/support/useful.h>
 
 #include <string.h>
 
@@ -146,3 +147,65 @@ grpc_channel_args *grpc_channel_args_set_compression_algorithm(
   tmp.value.integer = algorithm;
   return grpc_channel_args_copy_and_add(a, &tmp, 1);
 }
+
+/** Returns 1 if the argument for compression algorithm's enabled states bitset
+ * was found in \a a, returning the arg's value in \a states. Otherwise, returns
+ * 0. */
+static int find_compression_algorithm_states_bitset(
+    const grpc_channel_args *a, int **states_arg) {
+  if (a != NULL) {
+    size_t i;
+    for (i = 0; i < a->num_args; ++i) {
+      if (a->args[i].type == GRPC_ARG_INTEGER &&
+          !strcmp(GRPC_COMPRESSION_ALGORITHM_STATE_ARG, a->args[i].key)) {
+        *states_arg = &a->args[i].value.integer;
+        return 1; /* GPR_TRUE */
+      }
+    }
+  }
+  return 0; /* GPR_FALSE */
+}
+
+grpc_channel_args *grpc_channel_args_compression_algorithm_set_state(
+    grpc_channel_args **a,
+    grpc_compression_algorithm algorithm,
+    int state) {
+  int *states_arg;
+  grpc_channel_args *result = *a;
+  const int states_arg_found =
+      find_compression_algorithm_states_bitset(*a, &states_arg);
+
+  if (states_arg_found) {
+    if (state != 0) {
+      GPR_BITSET(states_arg, algorithm);
+    } else {
+      GPR_BITCLEAR(states_arg, algorithm);
+    }
+  } else {
+    /* create a new arg */
+    grpc_arg tmp;
+    tmp.type = GRPC_ARG_INTEGER;
+    tmp.key = GRPC_COMPRESSION_ALGORITHM_STATE_ARG;
+    /* all enabled by default */
+    tmp.value.integer = (1u << GRPC_COMPRESS_ALGORITHMS_COUNT) - 1;
+    if (state != 0) {
+      GPR_BITSET(&tmp.value.integer, algorithm);
+    } else {
+      GPR_BITCLEAR(&tmp.value.integer, algorithm);
+    }
+    result = grpc_channel_args_copy_and_add(*a, &tmp, 1);
+    grpc_channel_args_destroy(*a);
+    *a = result;
+  }
+  return result;
+}
+
+int grpc_channel_args_compression_algorithm_get_states(
+    const grpc_channel_args *a) {
+  int *states_arg;
+  if (find_compression_algorithm_states_bitset(a, &states_arg)) {
+    return *states_arg;
+  } else {
+    return (1u << GRPC_COMPRESS_ALGORITHMS_COUNT) - 1; /* All algs. enabled */
+  }
+}
diff --git a/src/core/channel/channel_args.h b/src/core/channel/channel_args.h
index 7e6ddd3997..06a6012dee 100644
--- a/src/core/channel/channel_args.h
+++ b/src/core/channel/channel_args.h
@@ -67,4 +67,24 @@ grpc_compression_algorithm grpc_channel_args_get_compression_algorithm(
 grpc_channel_args *grpc_channel_args_set_compression_algorithm(
     grpc_channel_args *a, grpc_compression_algorithm algorithm);
 
+/** Sets the support for the given compression algorithm. By default, all
+ * compression algorithms are enabled. It's an error to disable an algorithm set
+ * by grpc_channel_args_set_compression_algorithm.
+ *
+ * Returns an instance will the updated algorithm states. The \a a pointer is
+ * modified to point to the returned instance (which may be different from the
+ * input value of \a a). */
+grpc_channel_args *grpc_channel_args_compression_algorithm_set_state(
+    grpc_channel_args **a,
+    grpc_compression_algorithm algorithm,
+    int enabled);
+
+/** Returns the bitset representing the support state (true for enabled, false
+ * for disabled) for compression algorithms.
+ *
+ * The i-th bit of the returned bitset corresponds to the i-th entry in the
+ * grpc_compression_algorithm enum. */
+int grpc_channel_args_compression_algorithm_get_states(
+    const grpc_channel_args *a);
+
 #endif /* GRPC_INTERNAL_CORE_CHANNEL_CHANNEL_ARGS_H */
diff --git a/src/core/client_config/resolvers/sockaddr_resolver.c b/src/core/client_config/resolvers/sockaddr_resolver.c
index 74584e7e2c..8419873908 100644
--- a/src/core/client_config/resolvers/sockaddr_resolver.c
+++ b/src/core/client_config/resolvers/sockaddr_resolver.c
@@ -60,9 +60,12 @@ typedef struct {
   grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
                                        size_t num_subchannels);
 
-  /** the address that we've 'resolved' */
-  struct sockaddr_storage addr;
-  int addr_len;
+  /** the addresses that we've 'resolved' */
+  struct sockaddr_storage *addrs;
+  /** the corresponding length of the addresses */
+  int *addrs_len;
+  /** how many elements in \a addrs */
+  size_t num_addrs;
 
   /** mutex guarding the rest of the state */
   gpr_mu mu;
@@ -119,17 +122,22 @@ static void sockaddr_next(grpc_resolver *resolver,
 static void sockaddr_maybe_finish_next_locked(sockaddr_resolver *r) {
   grpc_client_config *cfg;
   grpc_lb_policy *lb_policy;
-  grpc_subchannel *subchannel;
+  grpc_subchannel **subchannels;
   grpc_subchannel_args args;
 
   if (r->next_completion != NULL && !r->published) {
+    size_t i;
     cfg = grpc_client_config_create();
-    memset(&args, 0, sizeof(args));
-    args.addr = (struct sockaddr *)&r->addr;
-    args.addr_len = r->addr_len;
-    subchannel =
-        grpc_subchannel_factory_create_subchannel(r->subchannel_factory, &args);
-    lb_policy = r->lb_policy_factory(&subchannel, 1);
+    subchannels = gpr_malloc(sizeof(grpc_subchannel *) * r->num_addrs);
+    for (i = 0; i < r->num_addrs; i++) {
+      memset(&args, 0, sizeof(args));
+      args.addr = (struct sockaddr *)&r->addrs[i];
+      args.addr_len = r->addrs_len[i];
+      subchannels[i] = grpc_subchannel_factory_create_subchannel(
+          r->subchannel_factory, &args);
+    }
+    lb_policy = r->lb_policy_factory(subchannels, r->num_addrs);
+    gpr_free(subchannels);
     grpc_client_config_set_lb_policy(cfg, lb_policy);
     GRPC_LB_POLICY_UNREF(lb_policy, "unix");
     r->published = 1;
@@ -143,6 +151,8 @@ static void sockaddr_destroy(grpc_resolver *gr) {
   sockaddr_resolver *r = (sockaddr_resolver *)gr;
   gpr_mu_destroy(&r->mu);
   grpc_subchannel_factory_unref(r->subchannel_factory);
+  gpr_free(r->addrs);
+  gpr_free(r->addrs_len);
   gpr_free(r);
 }
 
@@ -238,13 +248,18 @@ done:
   return result;
 }
 
+static void do_nothing(void *ignored) {}
 static grpc_resolver *sockaddr_create(
     grpc_uri *uri,
     grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
                                          size_t num_subchannels),
     grpc_subchannel_factory *subchannel_factory,
     int parse(grpc_uri *uri, struct sockaddr_storage *dst, int *len)) {
+  size_t i;
+  int errors_found = 0; /* GPR_FALSE */
   sockaddr_resolver *r;
+  gpr_slice path_slice;
+  gpr_slice_buffer path_parts;
 
   if (0 != strcmp(uri->authority, "")) {
     gpr_log(GPR_ERROR, "authority based uri's not supported");
@@ -253,7 +268,29 @@ static grpc_resolver *sockaddr_create(
 
   r = gpr_malloc(sizeof(sockaddr_resolver));
   memset(r, 0, sizeof(*r));
-  if (!parse(uri, &r->addr, &r->addr_len)) {
+
+  path_slice = gpr_slice_new(uri->path, strlen(uri->path), do_nothing);
+  gpr_slice_buffer_init(&path_parts);
+
+  gpr_slice_split(path_slice, ",", &path_parts);
+  r->num_addrs = path_parts.count;
+  r->addrs = gpr_malloc(sizeof(struct sockaddr_storage) * r->num_addrs);
+  r->addrs_len = gpr_malloc(sizeof(int) * r->num_addrs);
+
+  for(i = 0; i < r->num_addrs; i++) {
+    grpc_uri ith_uri = *uri;
+    char* part_str = gpr_dump_slice(path_parts.slices[i], GPR_DUMP_ASCII);
+    ith_uri.path = part_str;
+    if (!parse(&ith_uri, &r->addrs[i], &r->addrs_len[i])) {
+      errors_found = 1; /* GPR_TRUE */
+    }
+    gpr_free(part_str);
+    if (errors_found) break;
+  }
+
+  gpr_slice_buffer_destroy(&path_parts);
+  gpr_slice_unref(path_slice);
+  if (errors_found) {
     gpr_free(r);
     return NULL;
   }
diff --git a/src/core/iomgr/pollset.h b/src/core/iomgr/pollset.h
index c474e4dbf1..337596cb74 100644
--- a/src/core/iomgr/pollset.h
+++ b/src/core/iomgr/pollset.h
@@ -74,10 +74,9 @@ void grpc_pollset_destroy(grpc_pollset *pollset);
    grpc_pollset_work, and it is guaranteed that GRPC_POLLSET_MU(pollset) will
    not be released by grpc_pollset_work AFTER worker has been destroyed.
 
-   Returns true if some work has been done, and false if the deadline
-   expired. */
-int grpc_pollset_work(grpc_pollset *pollset, grpc_pollset_worker *worker,
-                      gpr_timespec deadline);
+   Tries not to block past deadline. */
+void grpc_pollset_work(grpc_pollset *pollset, grpc_pollset_worker *worker,
+                       gpr_timespec now, gpr_timespec deadline);
 
 /* Break one polling thread out of polling work for this pollset.
    If specific_worker is GRPC_POLLSET_KICK_BROADCAST, kick ALL the workers.
diff --git a/src/core/iomgr/pollset_multipoller_with_epoll.c b/src/core/iomgr/pollset_multipoller_with_epoll.c
index 5ea9dd2101..fe66ebed77 100644
--- a/src/core/iomgr/pollset_multipoller_with_epoll.c
+++ b/src/core/iomgr/pollset_multipoller_with_epoll.c
@@ -181,7 +181,7 @@ static void multipoll_with_epoll_pollset_maybe_work(
   pfds[1].events = POLLIN;
   pfds[1].revents = 0;
 
-  poll_rv = poll(pfds, 2, timeout_ms);
+  poll_rv = grpc_poll_function(pfds, 2, timeout_ms);
 
   if (poll_rv < 0) {
     if (errno != EINTR) {
diff --git a/src/core/iomgr/pollset_multipoller_with_poll_posix.c b/src/core/iomgr/pollset_multipoller_with_poll_posix.c
index 001fcecf76..30ee6e24db 100644
--- a/src/core/iomgr/pollset_multipoller_with_poll_posix.c
+++ b/src/core/iomgr/pollset_multipoller_with_poll_posix.c
@@ -144,7 +144,7 @@ static void multipoll_with_poll_pollset_maybe_work(
                                         POLLOUT, &watchers[i]);
   }
 
-  r = poll(pfds, pfd_count, timeout);
+  r = grpc_poll_function(pfds, pfd_count, timeout);
 
   for (i = 1; i < pfd_count; i++) {
     grpc_fd_end_poll(&watchers[i], pfds[i].revents & POLLIN,
diff --git a/src/core/iomgr/pollset_posix.c b/src/core/iomgr/pollset_posix.c
index a01f9ff727..6bd1b61f24 100644
--- a/src/core/iomgr/pollset_posix.c
+++ b/src/core/iomgr/pollset_posix.c
@@ -38,7 +38,6 @@
 #include "src/core/iomgr/pollset_posix.h"
 
 #include <errno.h>
-#include <poll.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
@@ -57,6 +56,8 @@
 GPR_TLS_DECL(g_current_thread_poller);
 GPR_TLS_DECL(g_current_thread_worker);
 
+grpc_poll_function_type grpc_poll_function = poll;
+
 static void remove_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
   worker->prev->next = worker->next;
   worker->next->prev = worker->prev;
@@ -89,6 +90,7 @@ static void push_front_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
 }
 
 void grpc_pollset_kick(grpc_pollset *p, grpc_pollset_worker *specific_worker) {
+  /* pollset->mu already held */
   if (specific_worker != NULL) {
     if (specific_worker == GRPC_POLLSET_KICK_BROADCAST) {
       for (specific_worker = p->root_worker.next;
@@ -168,14 +170,10 @@ static void finish_shutdown(grpc_pollset *pollset) {
   pollset->shutdown_done_cb(pollset->shutdown_done_arg);
 }
 
-int grpc_pollset_work(grpc_pollset *pollset, grpc_pollset_worker *worker,
-                      gpr_timespec deadline) {
+void grpc_pollset_work(grpc_pollset *pollset, grpc_pollset_worker *worker,
+                       gpr_timespec now, gpr_timespec deadline) {
   /* pollset->mu already held */
-  gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
   int added_worker = 0;
-  if (gpr_time_cmp(now, deadline) > 0) {
-    return 0;
-  }
   /* this must happen before we (potentially) drop pollset->mu */
   worker->next = worker->prev = NULL;
   /* TODO(ctiller): pool these */
@@ -217,7 +215,6 @@ done:
       gpr_mu_lock(&pollset->mu);
     }
   }
-  return 1;
 }
 
 void grpc_pollset_shutdown(grpc_pollset *pollset,
@@ -456,7 +453,7 @@ static void basic_pollset_maybe_work(grpc_pollset *pollset,
 
   /* poll fd count (argument 2) is shortened by one if we have no events
      to poll on - such that it only includes the kicker */
-  r = poll(pfd, nfds, timeout);
+  r = grpc_poll_function(pfd, nfds, timeout);
   GRPC_TIMER_MARK(GRPC_PTAG_POLL_FINISHED, r);
 
   if (fd) {
diff --git a/src/core/iomgr/pollset_posix.h b/src/core/iomgr/pollset_posix.h
index a3ea353de6..69bd9cca8c 100644
--- a/src/core/iomgr/pollset_posix.h
+++ b/src/core/iomgr/pollset_posix.h
@@ -34,6 +34,8 @@
 #ifndef GRPC_INTERNAL_CORE_IOMGR_POLLSET_POSIX_H
 #define GRPC_INTERNAL_CORE_IOMGR_POLLSET_POSIX_H
 
+#include <poll.h>
+
 #include <grpc/support/sync.h>
 #include "src/core/iomgr/wakeup_fd_posix.h"
 
@@ -118,4 +120,8 @@ void grpc_poll_become_multipoller(grpc_pollset *pollset, struct grpc_fd **fds,
  * be locked) */
 int grpc_pollset_has_workers(grpc_pollset *pollset);
 
+/* override to allow tests to hook poll() usage */
+typedef int (*grpc_poll_function_type)(struct pollfd *, nfds_t, int);
+extern grpc_poll_function_type grpc_poll_function;
+
 #endif /* GRPC_INTERNAL_CORE_IOMGR_POLLSET_POSIX_H */
diff --git a/src/core/iomgr/pollset_windows.c b/src/core/iomgr/pollset_windows.c
index 8710395ab3..07522c8a0c 100644
--- a/src/core/iomgr/pollset_windows.c
+++ b/src/core/iomgr/pollset_windows.c
@@ -99,14 +99,9 @@ void grpc_pollset_destroy(grpc_pollset *pollset) {
   gpr_mu_destroy(&pollset->mu);
 }
 
-int grpc_pollset_work(grpc_pollset *pollset, grpc_pollset_worker *worker,
-                      gpr_timespec deadline) {
-  gpr_timespec now;
+void grpc_pollset_work(grpc_pollset *pollset, grpc_pollset_worker *worker, 
+                       gpr_timespec now, gpr_timespec deadline) {
   int added_worker = 0;
-  now = gpr_now(GPR_CLOCK_MONOTONIC);
-  if (gpr_time_cmp(now, deadline) > 0) {
-    return 0 /* GPR_FALSE */;
-  }
   worker->next = worker->prev = NULL;
   gpr_cv_init(&worker->cv);
   if (grpc_maybe_call_delayed_callbacks(&pollset->mu, 1 /* GPR_TRUE */)) {
@@ -127,7 +122,6 @@ done:
   if (added_worker) {
     remove_worker(pollset, worker);
   }
-  return 1 /* GPR_TRUE */;
 }
 
 void grpc_pollset_kick(grpc_pollset *p, grpc_pollset_worker *specific_worker) {
diff --git a/src/core/iomgr/tcp_windows.c b/src/core/iomgr/tcp_windows.c
index 123f46d71d..901793ec43 100644
--- a/src/core/iomgr/tcp_windows.c
+++ b/src/core/iomgr/tcp_windows.c
@@ -152,6 +152,7 @@ static void on_read(void *tcpp, int from_iocp) {
       gpr_log(GPR_ERROR, "ReadFile overlapped error: %s", utf8_message);
       gpr_free(utf8_message);
     }
+    gpr_slice_unref(tcp->read_slice);
     status = GRPC_ENDPOINT_CB_ERROR;
   } else {
     if (info->bytes_transfered != 0) {
diff --git a/src/core/iomgr/udp_server.c b/src/core/iomgr/udp_server.c
index 16482c08f7..6429c38b28 100644
--- a/src/core/iomgr/udp_server.c
+++ b/src/core/iomgr/udp_server.c
@@ -235,8 +235,10 @@ static int prepare_socket(int fd, const struct sockaddr *addr, int addr_len) {
   rc = setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &get_local_ip,
                   sizeof(get_local_ip));
   if (rc == 0 && addr->sa_family == AF_INET6) {
+#if !TARGET_OS_IPHONE
     rc = setsockopt(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &get_local_ip,
                     sizeof(get_local_ip));
+#endif
   }
 
   if (bind(fd, addr, addr_len) < 0) {
diff --git a/src/core/security/google_default_credentials.c b/src/core/security/google_default_credentials.c
index d6092ece32..3631de867a 100644
--- a/src/core/security/google_default_credentials.c
+++ b/src/core/security/google_default_credentials.c
@@ -115,7 +115,7 @@ static int is_stack_running_on_compute_engine(void) {
   gpr_mu_lock(GRPC_POLLSET_MU(&detector.pollset));
   while (!detector.is_done) {
     grpc_pollset_worker worker;
-    grpc_pollset_work(&detector.pollset, &worker,
+    grpc_pollset_work(&detector.pollset, &worker, gpr_now(GPR_CLOCK_MONOTONIC),
                       gpr_inf_future(GPR_CLOCK_MONOTONIC));
   }
   gpr_mu_unlock(GRPC_POLLSET_MU(&detector.pollset));
diff --git a/src/core/security/security_connector.c b/src/core/security/security_connector.c
index a354536dcd..ba9ac68c5f 100644
--- a/src/core/security/security_connector.c
+++ b/src/core/security/security_connector.c
@@ -575,6 +575,16 @@ grpc_security_status grpc_ssl_channel_security_connector_create(
   if (!check_request_metadata_creds(request_metadata_creds)) {
     goto error;
   }
+  if (config->pem_root_certs == NULL) {
+    pem_root_certs_size = grpc_get_default_ssl_roots(&pem_root_certs);
+    if (pem_root_certs == NULL || pem_root_certs_size == 0) {
+      gpr_log(GPR_ERROR, "Could not get default pem root certs.");
+      goto error;
+    }
+  } else {
+    pem_root_certs = config->pem_root_certs;
+    pem_root_certs_size = config->pem_root_certs_size;
+  }
 
   c = gpr_malloc(sizeof(grpc_ssl_channel_security_connector));
   memset(c, 0, sizeof(grpc_ssl_channel_security_connector));
@@ -590,16 +600,6 @@ grpc_security_status grpc_ssl_channel_security_connector_create(
   if (overridden_target_name != NULL) {
     c->overridden_target_name = gpr_strdup(overridden_target_name);
   }
-  if (config->pem_root_certs == NULL) {
-    pem_root_certs_size = grpc_get_default_ssl_roots(&pem_root_certs);
-    if (pem_root_certs == NULL || pem_root_certs_size == 0) {
-      gpr_log(GPR_ERROR, "Could not get default pem root certs.");
-      goto error;
-    }
-  } else {
-    pem_root_certs = config->pem_root_certs;
-    pem_root_certs_size = config->pem_root_certs_size;
-  }
   result = tsi_create_ssl_client_handshaker_factory(
       config->pem_private_key, config->pem_private_key_size,
       config->pem_cert_chain, config->pem_cert_chain_size, pem_root_certs,
diff --git a/src/core/security/server_auth_filter.c b/src/core/security/server_auth_filter.c
index 2f42f01f53..6e831431fa 100644
--- a/src/core/security/server_auth_filter.c
+++ b/src/core/security/server_auth_filter.c
@@ -104,24 +104,34 @@ static grpc_mdelem *remove_consumed_md(void *user_data, grpc_mdelem *md) {
   return md;
 }
 
-static void on_md_processing_done(void *user_data,
-                                  const grpc_metadata *consumed_md,
-                                  size_t num_consumed_md, int success) {
+static void on_md_processing_done(
+    void *user_data, const grpc_metadata *consumed_md, size_t num_consumed_md,
+    const grpc_metadata *response_md, size_t num_response_md,
+    grpc_status_code status, const char *error_details) {
   grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
 
-  if (success) {
+  /* TODO(jboeuf): Implement support for response_md. */
+  if (response_md != NULL && num_response_md > 0) {
+    gpr_log(GPR_INFO,
+            "response_md in auth metadata processing not supported for now. "
+            "Ignoring...");
+  }
+
+  if (status == GRPC_STATUS_OK) {
     calld->consumed_md = consumed_md;
     calld->num_consumed_md = num_consumed_md;
     grpc_metadata_batch_filter(&calld->md_op->data.metadata, remove_consumed_md,
                                elem);
-    calld->on_done_recv->cb(calld->on_done_recv->cb_arg, success);
+    calld->on_done_recv->cb(calld->on_done_recv->cb_arg, 1);
   } else {
-    gpr_slice message = gpr_slice_from_copied_string(
-        "Authentication metadata processing failed.");
+    gpr_slice message;
+    error_details = error_details != NULL
+                    ? error_details
+                    : "Authentication metadata processing failed.";
+    message = gpr_slice_from_copied_string(error_details);
     grpc_sopb_reset(calld->recv_ops);
-    grpc_transport_stream_op_add_close(&calld->transport_op,
-                                       GRPC_STATUS_UNAUTHENTICATED, &message);
+    grpc_transport_stream_op_add_close(&calld->transport_op, status, &message);
     grpc_call_next_op(elem, &calld->transport_op);
   }
 }
diff --git a/src/core/support/time_precise.h b/src/core/support/time_precise.h
index d40ad12d0c..574ebb8448 100644
--- a/src/core/support/time_precise.h
+++ b/src/core/support/time_precise.h
@@ -63,7 +63,6 @@ static void gpr_precise_clock_init() {
   gpr_precise_clock end_cycle;
   while (time(NULL) == start)
     ;
-  gpr_precise_clock_now();
   gpr_get_cycle_counter(&start_cycle);
   while (time(NULL) == start + 1)
     ;
diff --git a/src/core/surface/channel_create.c b/src/core/surface/channel_create.c
index 82ddfac757..707251da89 100644
--- a/src/core/surface/channel_create.c
+++ b/src/core/surface/channel_create.c
@@ -38,6 +38,7 @@
 
 #include <grpc/support/alloc.h>
 
+#include "src/core/census/grpc_filter.h"
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/client_channel.h"
 #include "src/core/channel/compress_filter.h"
@@ -165,10 +166,9 @@ grpc_channel *grpc_insecure_channel_create(const char *target,
   grpc_mdctx *mdctx = grpc_mdctx_create();
   int n = 0;
   GPR_ASSERT(!reserved);
-  /* TODO(census)
   if (grpc_channel_args_is_census_enabled(args)) {
     filters[n++] = &grpc_client_census_filter;
-    } */
+  }
   filters[n++] = &grpc_compress_filter;
   filters[n++] = &grpc_client_channel_filter;
   GPR_ASSERT(n <= MAX_FILTERS);
diff --git a/src/core/surface/completion_queue.c b/src/core/surface/completion_queue.c
index 77443a7ae8..b58115a93f 100644
--- a/src/core/surface/completion_queue.c
+++ b/src/core/surface/completion_queue.c
@@ -170,6 +170,9 @@ grpc_event grpc_completion_queue_next(grpc_completion_queue *cc,
                                       gpr_timespec deadline, void *reserved) {
   grpc_event ret;
   grpc_pollset_worker worker;
+  int first_loop = 1;
+  gpr_timespec now;
+
   GPR_ASSERT(!reserved);
 
   deadline = gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC);
@@ -196,12 +199,15 @@ grpc_event grpc_completion_queue_next(grpc_completion_queue *cc,
       ret.type = GRPC_QUEUE_SHUTDOWN;
       break;
     }
-    if (!grpc_pollset_work(&cc->pollset, &worker, deadline)) {
+    now = gpr_now(GPR_CLOCK_MONOTONIC);
+    if (!first_loop && gpr_time_cmp(now, deadline) >= 0) {
       gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
       memset(&ret, 0, sizeof(ret));
       ret.type = GRPC_QUEUE_TIMEOUT;
       break;
     }
+    first_loop = 0;
+    grpc_pollset_work(&cc->pollset, &worker, now, deadline);
   }
   GRPC_SURFACE_TRACE_RETURNED_EVENT(cc, &ret);
   GRPC_CQ_INTERNAL_UNREF(cc, "next");
@@ -239,6 +245,9 @@ grpc_event grpc_completion_queue_pluck(grpc_completion_queue *cc, void *tag,
   grpc_cq_completion *c;
   grpc_cq_completion *prev;
   grpc_pollset_worker worker;
+  gpr_timespec now;
+  int first_loop = 1;
+
   GPR_ASSERT(!reserved);
 
   deadline = gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC);
@@ -281,13 +290,16 @@ grpc_event grpc_completion_queue_pluck(grpc_completion_queue *cc, void *tag,
       ret.type = GRPC_QUEUE_TIMEOUT;
       break;
     }
-    if (!grpc_pollset_work(&cc->pollset, &worker, deadline)) {
+    now = gpr_now(GPR_CLOCK_MONOTONIC);
+    if (!first_loop && gpr_time_cmp(now, deadline) >= 0) {
       del_plucker(cc, tag, &worker);
       gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
       memset(&ret, 0, sizeof(ret));
       ret.type = GRPC_QUEUE_TIMEOUT;
       break;
     }
+    first_loop = 0;
+    grpc_pollset_work(&cc->pollset, &worker, now, deadline);
     del_plucker(cc, tag, &worker);
   }
 done:
diff --git a/src/core/surface/secure_channel_create.c b/src/core/surface/secure_channel_create.c
index 5b03ba95a7..eccee24698 100644
--- a/src/core/surface/secure_channel_create.c
+++ b/src/core/surface/secure_channel_create.c
@@ -38,6 +38,7 @@
 
 #include <grpc/support/alloc.h>
 
+#include "src/core/census/grpc_filter.h"
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/client_channel.h"
 #include "src/core/channel/compress_filter.h"
@@ -217,10 +218,9 @@ grpc_channel *grpc_secure_channel_create(grpc_credentials *creds,
   args_copy = grpc_channel_args_copy_and_add(
       new_args_from_connector != NULL ? new_args_from_connector : args,
       &connector_arg, 1);
-  /* TODO(census)
   if (grpc_channel_args_is_census_enabled(args)) {
     filters[n++] = &grpc_client_census_filter;
-    } */
+  }
   filters[n++] = &grpc_compress_filter;
   filters[n++] = &grpc_client_channel_filter;
   GPR_ASSERT(n <= MAX_FILTERS);
diff --git a/src/core/surface/server.c b/src/core/surface/server.c
index 1c402418e8..292bf6fab8 100644
--- a/src/core/surface/server.c
+++ b/src/core/surface/server.c
@@ -41,7 +41,7 @@
 #include <grpc/support/string_util.h>
 #include <grpc/support/useful.h>
 
-#include "src/core/channel/census_filter.h"
+#include "src/core/census/grpc_filter.h"
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/connected_channel.h"
 #include "src/core/iomgr/iomgr.h"
@@ -821,10 +821,9 @@ grpc_server *grpc_server_create_from_filters(
   server->channel_filters =
       gpr_malloc(server->channel_filter_count * sizeof(grpc_channel_filter *));
   server->channel_filters[0] = &server_surface_filter;
-  /* TODO(census): restore this once we rework census filter
   if (census_enabled) {
     server->channel_filters[1] = &grpc_server_census_filter;
-    } */
+  }
   for (i = 0; i < filter_count; i++) {
     server->channel_filters[i + 1 + census_enabled] = filters[i];
   }
diff --git a/src/core/transport/chttp2/stream_encoder.c b/src/core/transport/chttp2/stream_encoder.c
index 0f04169741..1ea697f71e 100644
--- a/src/core/transport/chttp2/stream_encoder.c
+++ b/src/core/transport/chttp2/stream_encoder.c
@@ -66,6 +66,8 @@ typedef struct {
   size_t header_idx;
   /* was the last frame emitted a header? (if yes, we'll need a CONTINUATION */
   gpr_uint8 last_was_header;
+  /* have we seen a regular (non-colon-prefixed) header yet? */
+  gpr_uint8 seen_regular_header;
   /* output stream id */
   gpr_uint32 stream_id;
   gpr_slice_buffer *output;
@@ -361,6 +363,15 @@ static grpc_mdelem *hpack_enc(grpc_chttp2_hpack_compressor *c,
   gpr_uint32 indices_key;
   int should_add_elem;
 
+  GPR_ASSERT (GPR_SLICE_LENGTH(elem->key->slice) > 0);
+  if (GPR_SLICE_START_PTR(elem->key->slice)[0] != ':') { /* regular header */
+    st->seen_regular_header = 1;
+  } else if (st->seen_regular_header != 0) { /* reserved header */
+    gpr_log(GPR_ERROR,
+            "Reserved header (colon-prefixed) happening after regular ones.");
+    abort();
+  }
+
   inc_filter(HASH_FRAGMENT_1(elem_hash), &c->filter_elems_sum, c->filter_elems);
 
   /* is this elem currently in the decoders table? */
@@ -566,6 +577,7 @@ void grpc_chttp2_encode(grpc_stream_op *ops, size_t ops_count, int eof,
 
   st.cur_frame_type = NONE;
   st.last_was_header = 0;
+  st.seen_regular_header = 0;
   st.stream_id = stream_id;
   st.output = output;
 
diff --git a/src/cpp/client/channel.cc b/src/cpp/client/channel.cc
index 17f31c22cb..8bf2e4687e 100644
--- a/src/cpp/client/channel.cc
+++ b/src/cpp/client/channel.cc
@@ -31,29 +31,26 @@
  *
  */
 
-#include "src/cpp/client/channel.h"
+#include <grpc++/channel.h>
 
 #include <memory>
 
 #include <grpc/grpc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/slice.h>
-
-#include "src/core/profiling/timers.h"
-#include <grpc++/channel_arguments.h>
 #include <grpc++/client_context.h>
 #include <grpc++/completion_queue.h>
-#include <grpc++/config.h>
 #include <grpc++/credentials.h>
 #include <grpc++/impl/call.h>
 #include <grpc++/impl/rpc_method.h>
-#include <grpc++/status.h>
-#include <grpc++/time.h>
+#include <grpc++/support/channel_arguments.h>
+#include <grpc++/support/config.h>
+#include <grpc++/support/status.h>
+#include <grpc++/support/time.h>
+#include "src/core/profiling/timers.h"
 
 namespace grpc {
 
-Channel::Channel(grpc_channel* channel) : c_channel_(channel) {}
-
 Channel::Channel(const grpc::string& host, grpc_channel* channel)
     : host_(host), c_channel_(channel) {}
 
diff --git a/src/cpp/client/channel_arguments.cc b/src/cpp/client/channel_arguments.cc
index da6602e7af..50422d06c9 100644
--- a/src/cpp/client/channel_arguments.cc
+++ b/src/cpp/client/channel_arguments.cc
@@ -31,10 +31,9 @@
  *
  */
 
-#include <grpc++/channel_arguments.h>
+#include <grpc++/support/channel_arguments.h>
 
 #include <grpc/support/log.h>
-
 #include "src/core/channel/channel_args.h"
 
 namespace grpc {
diff --git a/src/cpp/client/client_context.cc b/src/cpp/client/client_context.cc
index b8caa1eae4..c4d7cf2e51 100644
--- a/src/cpp/client/client_context.cc
+++ b/src/cpp/client/client_context.cc
@@ -38,7 +38,7 @@
 #include <grpc/support/string_util.h>
 #include <grpc++/credentials.h>
 #include <grpc++/server_context.h>
-#include <grpc++/time.h>
+#include <grpc++/support/time.h>
 
 #include "src/core/channel/compress_filter.h"
 #include "src/cpp/common/create_auth_context.h"
@@ -71,7 +71,7 @@ void ClientContext::AddMetadata(const grpc::string& meta_key,
 }
 
 void ClientContext::set_call(grpc_call* call,
-                             const std::shared_ptr<ChannelInterface>& channel) {
+                             const std::shared_ptr<Channel>& channel) {
   GPR_ASSERT(call_ == nullptr);
   call_ = call;
   channel_ = channel;
diff --git a/src/cpp/client/create_channel.cc b/src/cpp/client/create_channel.cc
index 5ae772f096..8c571cbbaa 100644
--- a/src/cpp/client/create_channel.cc
+++ b/src/cpp/client/create_channel.cc
@@ -34,15 +34,16 @@
 #include <memory>
 #include <sstream>
 
-#include "src/cpp/client/channel.h"
-#include <grpc++/channel_interface.h>
-#include <grpc++/channel_arguments.h>
+#include <grpc++/channel.h>
 #include <grpc++/create_channel.h>
+#include <grpc++/support/channel_arguments.h>
+
+#include "src/cpp/client/create_channel_internal.h"
 
 namespace grpc {
 class ChannelArguments;
 
-std::shared_ptr<ChannelInterface> CreateChannel(
+std::shared_ptr<Channel> CreateChannel(
     const grpc::string& target, const std::shared_ptr<Credentials>& creds,
     const ChannelArguments& args) {
   ChannelArguments cp_args = args;
@@ -50,10 +51,10 @@ std::shared_ptr<ChannelInterface> CreateChannel(
   user_agent_prefix << "grpc-c++/" << grpc_version_string();
   cp_args.SetString(GRPC_ARG_PRIMARY_USER_AGENT_STRING,
                     user_agent_prefix.str());
-  return creds ? creds->CreateChannel(target, cp_args)
-               : std::shared_ptr<ChannelInterface>(
-                     new Channel(grpc_lame_client_channel_create(
-                         NULL, GRPC_STATUS_INVALID_ARGUMENT,
-                         "Invalid credentials.")));
+  return creds
+             ? creds->CreateChannel(target, cp_args)
+             : CreateChannelInternal("", grpc_lame_client_channel_create(
+                                             NULL, GRPC_STATUS_INVALID_ARGUMENT,
+                                             "Invalid credentials."));
 }
 }  // namespace grpc
diff --git a/src/cpp/client/internal_stub.cc b/src/cpp/client/create_channel_internal.cc
index 91724a4837..9c5ab038cf 100644
--- a/src/cpp/client/internal_stub.cc
+++ b/src/cpp/client/create_channel_internal.cc
@@ -31,6 +31,16 @@
  *
  */
 
-#include <grpc++/impl/internal_stub.h>
+#include <memory>
 
-namespace grpc {}  // namespace grpc
+#include <grpc++/channel.h>
+
+struct grpc_channel;
+
+namespace grpc {
+
+std::shared_ptr<Channel> CreateChannelInternal(const grpc::string& host,
+                                               grpc_channel* c_channel) {
+  return std::shared_ptr<Channel>(new Channel(host, c_channel));
+}
+}  // namespace grpc
diff --git a/src/cpp/client/create_channel_internal.h b/src/cpp/client/create_channel_internal.h
new file mode 100644
index 0000000000..4385ec701e
--- /dev/null
+++ b/src/cpp/client/create_channel_internal.h
@@ -0,0 +1,51 @@
+/*
+ *
+ * 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_CLIENT_CREATE_CHANNEL_INTERNAL_H
+#define GRPC_INTERNAL_CPP_CLIENT_CREATE_CHANNEL_INTERNAL_H
+
+#include <memory>
+
+#include <grpc++/support/config.h>
+
+struct grpc_channel;
+
+namespace grpc {
+class Channel;
+
+std::shared_ptr<Channel> CreateChannelInternal(const grpc::string& host,
+                                               grpc_channel* c_channel);
+
+}  // namespace grpc
+
+#endif  // GRPC_INTERNAL_CPP_CLIENT_CREATE_CHANNEL_INTERNAL_H
diff --git a/src/cpp/client/generic_stub.cc b/src/cpp/client/generic_stub.cc
index 0c90578ae5..7a2fdf941c 100644
--- a/src/cpp/client/generic_stub.cc
+++ b/src/cpp/client/generic_stub.cc
@@ -31,7 +31,7 @@
  *
  */
 
-#include <grpc++/generic_stub.h>
+#include <grpc++/generic/generic_stub.h>
 
 #include <grpc++/impl/rpc_method.h>
 
@@ -44,8 +44,7 @@ std::unique_ptr<GenericClientAsyncReaderWriter> GenericStub::Call(
   return std::unique_ptr<GenericClientAsyncReaderWriter>(
       new GenericClientAsyncReaderWriter(
           channel_.get(), cq,
-          RpcMethod(method.c_str(), RpcMethod::BIDI_STREAMING, nullptr),
-          context, tag));
+          RpcMethod(method.c_str(), RpcMethod::BIDI_STREAMING), context, tag));
 }
 
 }  // namespace grpc
diff --git a/src/cpp/client/insecure_credentials.cc b/src/cpp/client/insecure_credentials.cc
index 2f9357b568..4a4d2cb97d 100644
--- a/src/cpp/client/insecure_credentials.cc
+++ b/src/cpp/client/insecure_credentials.cc
@@ -31,25 +31,27 @@
  *
  */
 
+#include <grpc++/credentials.h>
+
 #include <grpc/grpc.h>
 #include <grpc/support/log.h>
-
-#include <grpc++/channel_arguments.h>
-#include <grpc++/config.h>
-#include <grpc++/credentials.h>
-#include "src/cpp/client/channel.h"
+#include <grpc++/channel.h>
+#include <grpc++/support/channel_arguments.h>
+#include <grpc++/support/config.h>
+#include "src/cpp/client/create_channel_internal.h"
 
 namespace grpc {
 
 namespace {
 class InsecureCredentialsImpl GRPC_FINAL : public Credentials {
  public:
-  std::shared_ptr<grpc::ChannelInterface> CreateChannel(
+  std::shared_ptr<grpc::Channel> CreateChannel(
       const string& target, const grpc::ChannelArguments& args) GRPC_OVERRIDE {
     grpc_channel_args channel_args;
     args.SetChannelArgs(&channel_args);
-    return std::shared_ptr<ChannelInterface>(new Channel(
-        grpc_insecure_channel_create(target.c_str(), &channel_args, nullptr)));
+    return CreateChannelInternal(
+        "",
+        grpc_insecure_channel_create(target.c_str(), &channel_args, nullptr));
   }
 
   // InsecureCredentials should not be applied to a call.
diff --git a/src/cpp/client/secure_channel_arguments.cc b/src/cpp/client/secure_channel_arguments.cc
index d89df999ad..e17d3b58b0 100644
--- a/src/cpp/client/secure_channel_arguments.cc
+++ b/src/cpp/client/secure_channel_arguments.cc
@@ -31,9 +31,9 @@
  *
  */
 
-#include <grpc++/channel_arguments.h>
-#include <grpc/grpc_security.h>
+#include <grpc++/support/channel_arguments.h>
 
+#include <grpc/grpc_security.h>
 #include "src/core/channel/channel_args.h"
 
 namespace grpc {
diff --git a/src/cpp/client/secure_credentials.cc b/src/cpp/client/secure_credentials.cc
index 6cd6b77fcf..f368f2590a 100644
--- a/src/cpp/client/secure_credentials.cc
+++ b/src/cpp/client/secure_credentials.cc
@@ -32,21 +32,21 @@
  */
 
 #include <grpc/support/log.h>
-
-#include <grpc++/channel_arguments.h>
+#include <grpc++/channel.h>
 #include <grpc++/impl/grpc_library.h>
-#include "src/cpp/client/channel.h"
+#include <grpc++/support/channel_arguments.h>
+#include "src/cpp/client/create_channel_internal.h"
 #include "src/cpp/client/secure_credentials.h"
 
 namespace grpc {
 
-std::shared_ptr<grpc::ChannelInterface> SecureCredentials::CreateChannel(
+std::shared_ptr<grpc::Channel> SecureCredentials::CreateChannel(
     const string& target, const grpc::ChannelArguments& args) {
   grpc_channel_args channel_args;
   args.SetChannelArgs(&channel_args);
-  return std::shared_ptr<ChannelInterface>(new Channel(
+  return CreateChannelInternal(
       args.GetSslTargetNameOverride(),
-      grpc_secure_channel_create(c_creds_, target.c_str(), &channel_args)));
+      grpc_secure_channel_create(c_creds_, target.c_str(), &channel_args));
 }
 
 bool SecureCredentials::ApplyToCall(grpc_call* call) {
diff --git a/src/cpp/client/secure_credentials.h b/src/cpp/client/secure_credentials.h
index c2b8d43a15..62d3185477 100644
--- a/src/cpp/client/secure_credentials.h
+++ b/src/cpp/client/secure_credentials.h
@@ -36,7 +36,7 @@
 
 #include <grpc/grpc_security.h>
 
-#include <grpc++/config.h>
+#include <grpc++/support/config.h>
 #include <grpc++/credentials.h>
 
 namespace grpc {
@@ -48,7 +48,7 @@ class SecureCredentials GRPC_FINAL : public Credentials {
   grpc_credentials* GetRawCreds() { return c_creds_; }
   bool ApplyToCall(grpc_call* call) GRPC_OVERRIDE;
 
-  std::shared_ptr<grpc::ChannelInterface> CreateChannel(
+  std::shared_ptr<grpc::Channel> CreateChannel(
       const string& target, const grpc::ChannelArguments& args) GRPC_OVERRIDE;
   SecureCredentials* AsSecureCredentials() GRPC_OVERRIDE { return this; }
 
diff --git a/src/cpp/common/auth_property_iterator.cc b/src/cpp/common/auth_property_iterator.cc
index d3bfd5cb6b..5ccf8cf72c 100644
--- a/src/cpp/common/auth_property_iterator.cc
+++ b/src/cpp/common/auth_property_iterator.cc
@@ -31,7 +31,7 @@
  *
  */
 
-#include <grpc++/auth_context.h>
+#include <grpc++/support/auth_context.h>
 
 #include <grpc/grpc_security.h>
 
diff --git a/src/cpp/common/call.cc b/src/cpp/common/call.cc
index 0a5c976e01..16aa2c9fb9 100644
--- a/src/cpp/common/call.cc
+++ b/src/cpp/common/call.cc
@@ -34,10 +34,9 @@
 #include <grpc++/impl/call.h>
 
 #include <grpc/support/alloc.h>
-#include <grpc++/byte_buffer.h>
+#include <grpc++/channel.h>
 #include <grpc++/client_context.h>
-#include <grpc++/channel_interface.h>
-
+#include <grpc++/support/byte_buffer.h>
 #include "src/core/profiling/timers.h"
 
 namespace grpc {
diff --git a/src/cpp/common/completion_queue.cc b/src/cpp/common/completion_queue.cc
index fca33f8f54..a175beb452 100644
--- a/src/cpp/common/completion_queue.cc
+++ b/src/cpp/common/completion_queue.cc
@@ -36,7 +36,7 @@
 
 #include <grpc/grpc.h>
 #include <grpc/support/log.h>
-#include <grpc++/time.h>
+#include <grpc++/support/time.h>
 
 namespace grpc {
 
diff --git a/src/cpp/common/create_auth_context.h b/src/cpp/common/create_auth_context.h
index 9082a90c6d..b4962bae4e 100644
--- a/src/cpp/common/create_auth_context.h
+++ b/src/cpp/common/create_auth_context.h
@@ -33,7 +33,7 @@
 #include <memory>
 
 #include <grpc/grpc.h>
-#include <grpc++/auth_context.h>
+#include <grpc++/support/auth_context.h>
 
 namespace grpc {
 
diff --git a/src/cpp/common/insecure_create_auth_context.cc b/src/cpp/common/insecure_create_auth_context.cc
index 07fc0bd549..fe80c1a80c 100644
--- a/src/cpp/common/insecure_create_auth_context.cc
+++ b/src/cpp/common/insecure_create_auth_context.cc
@@ -33,7 +33,7 @@
 #include <memory>
 
 #include <grpc/grpc.h>
-#include <grpc++/auth_context.h>
+#include <grpc++/support/auth_context.h>
 
 namespace grpc {
 
diff --git a/src/cpp/common/secure_auth_context.h b/src/cpp/common/secure_auth_context.h
index 264ed620a3..01b7126189 100644
--- a/src/cpp/common/secure_auth_context.h
+++ b/src/cpp/common/secure_auth_context.h
@@ -34,7 +34,7 @@
 #ifndef GRPC_INTERNAL_CPP_COMMON_SECURE_AUTH_CONTEXT_H
 #define GRPC_INTERNAL_CPP_COMMON_SECURE_AUTH_CONTEXT_H
 
-#include <grpc++/auth_context.h>
+#include <grpc++/support/auth_context.h>
 
 struct grpc_auth_context;
 
diff --git a/src/cpp/common/secure_create_auth_context.cc b/src/cpp/common/secure_create_auth_context.cc
index d81f4bbc4a..f13d25a1dd 100644
--- a/src/cpp/common/secure_create_auth_context.cc
+++ b/src/cpp/common/secure_create_auth_context.cc
@@ -34,7 +34,7 @@
 
 #include <grpc/grpc.h>
 #include <grpc/grpc_security.h>
-#include <grpc++/auth_context.h>
+#include <grpc++/support/auth_context.h>
 #include "src/cpp/common/secure_auth_context.h"
 
 namespace grpc {
diff --git a/src/cpp/proto/proto_utils.cc b/src/cpp/proto/proto_utils.cc
index 05470ec627..be84c222a0 100644
--- a/src/cpp/proto/proto_utils.cc
+++ b/src/cpp/proto/proto_utils.cc
@@ -32,7 +32,6 @@
  */
 
 #include <grpc++/impl/proto_utils.h>
-#include <grpc++/config.h>
 
 #include <grpc/grpc.h>
 #include <grpc/byte_buffer.h>
@@ -40,6 +39,7 @@
 #include <grpc/support/slice.h>
 #include <grpc/support/slice_buffer.h>
 #include <grpc/support/port_platform.h>
+#include <grpc++/support/config.h>
 
 const int kMaxBufferLength = 8192;
 
diff --git a/src/cpp/server/async_generic_service.cc b/src/cpp/server/async_generic_service.cc
index 2e99afcb5f..6b9ea532b6 100644
--- a/src/cpp/server/async_generic_service.cc
+++ b/src/cpp/server/async_generic_service.cc
@@ -31,7 +31,7 @@
  *
  */
 
-#include <grpc++/async_generic_service.h>
+#include <grpc++/generic/async_generic_service.h>
 
 #include <grpc++/server.h>
 
diff --git a/src/cpp/server/create_default_thread_pool.cc b/src/cpp/server/create_default_thread_pool.cc
index 9f59d254f1..f3b07ec8ce 100644
--- a/src/cpp/server/create_default_thread_pool.cc
+++ b/src/cpp/server/create_default_thread_pool.cc
@@ -32,7 +32,8 @@
  */
 
 #include <grpc/support/cpu.h>
-#include <grpc++/dynamic_thread_pool.h>
+
+#include "src/cpp/server/dynamic_thread_pool.h"
 
 #ifndef GRPC_CUSTOM_DEFAULT_THREAD_POOL
 
diff --git a/src/cpp/server/dynamic_thread_pool.cc b/src/cpp/server/dynamic_thread_pool.cc
index b475f43b1d..4b226c2992 100644
--- a/src/cpp/server/dynamic_thread_pool.cc
+++ b/src/cpp/server/dynamic_thread_pool.cc
@@ -33,7 +33,8 @@
 
 #include <grpc++/impl/sync.h>
 #include <grpc++/impl/thd.h>
-#include <grpc++/dynamic_thread_pool.h>
+
+#include "src/cpp/server/dynamic_thread_pool.h"
 
 namespace grpc {
 DynamicThreadPool::DynamicThread::DynamicThread(DynamicThreadPool* pool)
diff --git a/src/cpp/client/channel.h b/src/cpp/server/dynamic_thread_pool.h
index 7e406ad788..5ba7533c05 100644
--- a/src/cpp/client/channel.h
+++ b/src/cpp/server/dynamic_thread_pool.h
@@ -31,50 +31,53 @@
  *
  */
 
-#ifndef GRPC_INTERNAL_CPP_CLIENT_CHANNEL_H
-#define GRPC_INTERNAL_CPP_CLIENT_CHANNEL_H
+#ifndef GRPC_INTERNAL_CPP_DYNAMIC_THREAD_POOL_H
+#define GRPC_INTERNAL_CPP_DYNAMIC_THREAD_POOL_H
 
+#include <list>
 #include <memory>
+#include <queue>
 
-#include <grpc++/channel_interface.h>
-#include <grpc++/config.h>
-#include <grpc++/impl/grpc_library.h>
+#include <grpc++/impl/sync.h>
+#include <grpc++/impl/thd.h>
+#include <grpc++/support/config.h>
 
-struct grpc_channel;
+#include "src/cpp/server/thread_pool_interface.h"
 
 namespace grpc {
-class Call;
-class CallOpSetInterface;
-class ChannelArguments;
-class CompletionQueue;
-class Credentials;
-class StreamContextInterface;
 
-class Channel GRPC_FINAL : public GrpcLibrary, public ChannelInterface {
+class DynamicThreadPool GRPC_FINAL : public ThreadPoolInterface {
  public:
-  explicit Channel(grpc_channel* c_channel);
-  Channel(const grpc::string& host, grpc_channel* c_channel);
-  ~Channel() GRPC_OVERRIDE;
+  explicit DynamicThreadPool(int reserve_threads);
+  ~DynamicThreadPool();
 
-  void* RegisterMethod(const char* method) GRPC_OVERRIDE;
-  Call CreateCall(const RpcMethod& method, ClientContext* context,
-                  CompletionQueue* cq) GRPC_OVERRIDE;
-  void PerformOpsOnCall(CallOpSetInterface* ops, Call* call) GRPC_OVERRIDE;
-
-  grpc_connectivity_state GetState(bool try_to_connect) GRPC_OVERRIDE;
+  void Add(const std::function<void()>& callback) GRPC_OVERRIDE;
 
  private:
-  void NotifyOnStateChangeImpl(grpc_connectivity_state last_observed,
-                               gpr_timespec deadline, CompletionQueue* cq,
-                               void* tag) GRPC_OVERRIDE;
+  class DynamicThread {
+   public:
+    DynamicThread(DynamicThreadPool* pool);
+    ~DynamicThread();
 
-  bool WaitForStateChangeImpl(grpc_connectivity_state last_observed,
-                              gpr_timespec deadline) GRPC_OVERRIDE;
+   private:
+    DynamicThreadPool* pool_;
+    std::unique_ptr<grpc::thread> thd_;
+    void ThreadFunc();
+  };
+  grpc::mutex mu_;
+  grpc::condition_variable cv_;
+  grpc::condition_variable shutdown_cv_;
+  bool shutdown_;
+  std::queue<std::function<void()>> callbacks_;
+  int reserve_threads_;
+  int nthreads_;
+  int threads_waiting_;
+  std::list<DynamicThread*> dead_threads_;
 
-  const grpc::string host_;
-  grpc_channel* const c_channel_;  // owned
+  void ThreadFunc();
+  static void ReapThreads(std::list<DynamicThread*>* tlist);
 };
 
 }  // namespace grpc
 
-#endif  // GRPC_INTERNAL_CPP_CLIENT_CHANNEL_H
+#endif  // GRPC_INTERNAL_CPP_DYNAMIC_THREAD_POOL_H
diff --git a/src/cpp/server/fixed_size_thread_pool.cc b/src/cpp/server/fixed_size_thread_pool.cc
index bafbc5802a..2bdc44be2e 100644
--- a/src/cpp/server/fixed_size_thread_pool.cc
+++ b/src/cpp/server/fixed_size_thread_pool.cc
@@ -33,7 +33,7 @@
 
 #include <grpc++/impl/sync.h>
 #include <grpc++/impl/thd.h>
-#include <grpc++/fixed_size_thread_pool.h>
+#include "src/cpp/server/fixed_size_thread_pool.h"
 
 namespace grpc {
 
diff --git a/src/cpp/server/fixed_size_thread_pool.h b/src/cpp/server/fixed_size_thread_pool.h
new file mode 100644
index 0000000000..394ae5821e
--- /dev/null
+++ b/src/cpp/server/fixed_size_thread_pool.h
@@ -0,0 +1,67 @@
+/*
+ *
+ * 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_FIXED_SIZE_THREAD_POOL_H
+#define GRPC_INTERNAL_CPP_FIXED_SIZE_THREAD_POOL_H
+
+#include <queue>
+#include <vector>
+
+#include <grpc++/impl/sync.h>
+#include <grpc++/impl/thd.h>
+#include <grpc++/support/config.h>
+
+#include "src/cpp/server/thread_pool_interface.h"
+
+namespace grpc {
+
+class FixedSizeThreadPool GRPC_FINAL : public ThreadPoolInterface {
+ public:
+  explicit FixedSizeThreadPool(int num_threads);
+  ~FixedSizeThreadPool();
+
+  void Add(const std::function<void()>& callback) GRPC_OVERRIDE;
+
+ private:
+  grpc::mutex mu_;
+  grpc::condition_variable cv_;
+  bool shutdown_;
+  std::queue<std::function<void()>> callbacks_;
+  std::vector<grpc::thread*> threads_;
+
+  void ThreadFunc();
+};
+
+}  // namespace grpc
+
+#endif  // GRPC_INTERNAL_CPP_FIXED_SIZE_THREAD_POOL_H
diff --git a/src/cpp/server/secure_server_credentials.h b/src/cpp/server/secure_server_credentials.h
index b9803f107e..d3d37b188d 100644
--- a/src/cpp/server/secure_server_credentials.h
+++ b/src/cpp/server/secure_server_credentials.h
@@ -34,10 +34,10 @@
 #ifndef GRPC_INTERNAL_CPP_SERVER_SECURE_SERVER_CREDENTIALS_H
 #define GRPC_INTERNAL_CPP_SERVER_SECURE_SERVER_CREDENTIALS_H
 
-#include <grpc/grpc_security.h>
-
 #include <grpc++/server_credentials.h>
 
+#include <grpc/grpc_security.h>
+
 namespace grpc {
 
 class SecureServerCredentials GRPC_FINAL : public ServerCredentials {
diff --git a/src/cpp/server/server.cc b/src/cpp/server/server.cc
index e039c07374..66cd27cc33 100644
--- a/src/cpp/server/server.cc
+++ b/src/cpp/server/server.cc
@@ -32,24 +32,71 @@
  */
 
 #include <grpc++/server.h>
+
 #include <utility>
 
 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc++/completion_queue.h>
-#include <grpc++/async_generic_service.h>
+#include <grpc++/generic/async_generic_service.h>
 #include <grpc++/impl/rpc_service_method.h>
 #include <grpc++/impl/service_type.h>
 #include <grpc++/server_context.h>
 #include <grpc++/server_credentials.h>
-#include <grpc++/thread_pool_interface.h>
-#include <grpc++/time.h>
+#include <grpc++/support/time.h>
 
 #include "src/core/profiling/timers.h"
+#include "src/cpp/server/thread_pool_interface.h"
 
 namespace grpc {
 
+class Server::UnimplementedAsyncRequestContext {
+ protected:
+  UnimplementedAsyncRequestContext() : generic_stream_(&server_context_) {}
+
+  GenericServerContext server_context_;
+  GenericServerAsyncReaderWriter generic_stream_;
+};
+
+class Server::UnimplementedAsyncRequest GRPC_FINAL
+    : public UnimplementedAsyncRequestContext,
+      public GenericAsyncRequest {
+ public:
+  UnimplementedAsyncRequest(Server* server, ServerCompletionQueue* cq)
+      : GenericAsyncRequest(server, &server_context_, &generic_stream_, cq, cq,
+                            NULL, false),
+        server_(server),
+        cq_(cq) {}
+
+  bool FinalizeResult(void** tag, bool* status) GRPC_OVERRIDE;
+
+  ServerContext* context() { return &server_context_; }
+  GenericServerAsyncReaderWriter* stream() { return &generic_stream_; }
+
+ private:
+  Server* const server_;
+  ServerCompletionQueue* const cq_;
+};
+
+typedef SneakyCallOpSet<CallOpSendInitialMetadata, CallOpServerSendStatus>
+    UnimplementedAsyncResponseOp;
+class Server::UnimplementedAsyncResponse GRPC_FINAL
+    : public UnimplementedAsyncResponseOp {
+ public:
+  UnimplementedAsyncResponse(UnimplementedAsyncRequest* request);
+  ~UnimplementedAsyncResponse() { delete request_; }
+
+  bool FinalizeResult(void** tag, bool* status) GRPC_OVERRIDE {
+    bool r = UnimplementedAsyncResponseOp::FinalizeResult(tag, status);
+    delete this;
+    return r;
+  }
+
+ private:
+  UnimplementedAsyncRequest* const request_;
+};
+
 class Server::ShutdownRequest GRPC_FINAL : public CompletionQueueTag {
  public:
   bool FinalizeResult(void** tag, bool* status) {
@@ -297,18 +344,23 @@ int Server::AddListeningPort(const grpc::string& addr,
   return creds->AddPortToServer(addr, server_);
 }
 
-bool Server::Start() {
+bool Server::Start(ServerCompletionQueue** cqs, size_t num_cqs) {
   GPR_ASSERT(!started_);
   started_ = true;
   grpc_server_start(server_);
 
   if (!has_generic_service_) {
-    unknown_method_.reset(new RpcServiceMethod(
-        "unknown", RpcMethod::BIDI_STREAMING, new UnknownMethodHandler));
-    // Use of emplace_back with just constructor arguments is not accepted here
-    // by gcc-4.4 because it can't match the anonymous nullptr with a proper
-    // constructor implicitly. Construct the object and use push_back.
-    sync_methods_->push_back(SyncRequest(unknown_method_.get(), nullptr));
+    if (!sync_methods_->empty()) {
+      unknown_method_.reset(new RpcServiceMethod(
+          "unknown", RpcMethod::BIDI_STREAMING, new UnknownMethodHandler));
+      // Use of emplace_back with just constructor arguments is not accepted
+      // here by gcc-4.4 because it can't match the anonymous nullptr with a 
+      // proper constructor implicitly. Construct the object and use push_back.
+      sync_methods_->push_back(SyncRequest(unknown_method_.get(), nullptr));
+    }
+    for (size_t i = 0; i < num_cqs; i++) {
+      new UnimplementedAsyncRequest(this, cqs[i]);
+    }
   }
   // Start processing rpcs.
   if (!sync_methods_->empty()) {
@@ -370,12 +422,14 @@ void Server::PerformOpsOnCall(CallOpSetInterface* ops, Call* call) {
 
 Server::BaseAsyncRequest::BaseAsyncRequest(
     Server* server, ServerContext* context,
-    ServerAsyncStreamingInterface* stream, CompletionQueue* call_cq, void* tag)
+    ServerAsyncStreamingInterface* stream, CompletionQueue* call_cq, void* tag,
+    bool delete_on_finalize)
     : server_(server),
       context_(context),
       stream_(stream),
       call_cq_(call_cq),
       tag_(tag),
+      delete_on_finalize_(delete_on_finalize),
       call_(nullptr) {
   memset(&initial_metadata_array_, 0, sizeof(initial_metadata_array_));
 }
@@ -402,14 +456,16 @@ bool Server::BaseAsyncRequest::FinalizeResult(void** tag, bool* status) {
   // just the pointers inside call are copied here
   stream_->BindCall(&call);
   *tag = tag_;
-  delete this;
+  if (delete_on_finalize_) {
+    delete this;
+  }
   return true;
 }
 
 Server::RegisteredAsyncRequest::RegisteredAsyncRequest(
     Server* server, ServerContext* context,
     ServerAsyncStreamingInterface* stream, CompletionQueue* call_cq, void* tag)
-    : BaseAsyncRequest(server, context, stream, call_cq, tag) {}
+    : BaseAsyncRequest(server, context, stream, call_cq, tag, true) {}
 
 void Server::RegisteredAsyncRequest::IssueRequest(
     void* registered_method, grpc_byte_buffer** payload,
@@ -423,8 +479,9 @@ void Server::RegisteredAsyncRequest::IssueRequest(
 Server::GenericAsyncRequest::GenericAsyncRequest(
     Server* server, GenericServerContext* context,
     ServerAsyncStreamingInterface* stream, CompletionQueue* call_cq,
-    ServerCompletionQueue* notification_cq, void* tag)
-    : BaseAsyncRequest(server, context, stream, call_cq, tag) {
+    ServerCompletionQueue* notification_cq, void* tag, bool delete_on_finalize)
+    : BaseAsyncRequest(server, context, stream, call_cq, tag,
+                       delete_on_finalize) {
   grpc_call_details_init(&call_details_);
   GPR_ASSERT(notification_cq);
   GPR_ASSERT(call_cq);
@@ -445,6 +502,25 @@ bool Server::GenericAsyncRequest::FinalizeResult(void** tag, bool* status) {
   return BaseAsyncRequest::FinalizeResult(tag, status);
 }
 
+bool Server::UnimplementedAsyncRequest::FinalizeResult(void** tag,
+                                                       bool* status) {
+  if (GenericAsyncRequest::FinalizeResult(tag, status) && *status) {
+    new UnimplementedAsyncRequest(server_, cq_);
+    new UnimplementedAsyncResponse(this);
+  } else {
+    delete this;
+  }
+  return false;
+}
+
+Server::UnimplementedAsyncResponse::UnimplementedAsyncResponse(
+    UnimplementedAsyncRequest* request)
+    : request_(request) {
+  Status status(StatusCode::UNIMPLEMENTED, "");
+  UnknownMethodHandler::FillOps(request_->context(), this);
+  request_->stream()->call_.PerformOps(this);
+}
+
 void Server::ScheduleCallback() {
   {
     grpc::unique_lock<grpc::mutex> lock(mu_);
diff --git a/src/cpp/server/server_builder.cc b/src/cpp/server/server_builder.cc
index 0b11d86173..b739cbfe62 100644
--- a/src/cpp/server/server_builder.cc
+++ b/src/cpp/server/server_builder.cc
@@ -37,8 +37,8 @@
 #include <grpc/support/log.h>
 #include <grpc++/impl/service_type.h>
 #include <grpc++/server.h>
-#include <grpc++/thread_pool_interface.h>
-#include <grpc++/fixed_size_thread_pool.h>
+#include "src/cpp/server/thread_pool_interface.h"
+#include "src/cpp/server/fixed_size_thread_pool.h"
 
 namespace grpc {
 
@@ -89,10 +89,6 @@ void ServerBuilder::AddListeningPort(const grpc::string& addr,
   ports_.push_back(port);
 }
 
-void ServerBuilder::SetThreadPool(ThreadPoolInterface* thread_pool) {
-  thread_pool_ = thread_pool;
-}
-
 std::unique_ptr<Server> ServerBuilder::BuildAndStart() {
   bool thread_pool_owned = false;
   if (!async_services_.empty() && !services_.empty()) {
@@ -103,12 +99,6 @@ std::unique_ptr<Server> ServerBuilder::BuildAndStart() {
     thread_pool_ = CreateDefaultThreadPool();
     thread_pool_owned = true;
   }
-  // Async services only, create a thread pool to handle requests to unknown
-  // services.
-  if (!thread_pool_ && !generic_service_ && !async_services_.empty()) {
-    thread_pool_ = new FixedSizeThreadPool(1);
-    thread_pool_owned = true;
-  }
   std::unique_ptr<Server> server(
       new Server(thread_pool_, thread_pool_owned, max_message_size_));
   for (auto cq = cqs_.begin(); cq != cqs_.end(); ++cq) {
@@ -138,7 +128,7 @@ std::unique_ptr<Server> ServerBuilder::BuildAndStart() {
       *port->selected_port = r;
     }
   }
-  if (!server->Start()) {
+  if (!server->Start(&cqs_[0], cqs_.size())) {
     return nullptr;
   }
   return server;
diff --git a/src/cpp/server/server_context.cc b/src/cpp/server/server_context.cc
index 03461ddda5..acc163d6b5 100644
--- a/src/cpp/server/server_context.cc
+++ b/src/cpp/server/server_context.cc
@@ -38,7 +38,7 @@
 #include <grpc/support/log.h>
 #include <grpc++/impl/call.h>
 #include <grpc++/impl/sync.h>
-#include <grpc++/time.h>
+#include <grpc++/support/time.h>
 
 #include "src/core/channel/compress_filter.h"
 #include "src/cpp/common/create_auth_context.h"
diff --git a/src/cpp/server/thread_pool_interface.h b/src/cpp/server/thread_pool_interface.h
new file mode 100644
index 0000000000..1ebe30fe2a
--- /dev/null
+++ b/src/cpp/server/thread_pool_interface.h
@@ -0,0 +1,54 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CPP_THREAD_POOL_INTERFACE_H
+#define GRPC_INTERNAL_CPP_THREAD_POOL_INTERFACE_H
+
+#include <functional>
+
+namespace grpc {
+
+// A thread pool interface for running callbacks.
+class ThreadPoolInterface {
+ public:
+  virtual ~ThreadPoolInterface() {}
+
+  // Schedule the given callback for execution.
+  virtual void Add(const std::function<void()>& callback) = 0;
+};
+
+ThreadPoolInterface* CreateDefaultThreadPool();
+
+}  // namespace grpc
+
+#endif  // GRPC_INTERNAL_CPP_THREAD_POOL_INTERFACE_H
diff --git a/src/cpp/util/byte_buffer.cc b/src/cpp/util/byte_buffer.cc
index a66c92c3e1..e46e656beb 100644
--- a/src/cpp/util/byte_buffer.cc
+++ b/src/cpp/util/byte_buffer.cc
@@ -32,7 +32,7 @@
  */
 
 #include <grpc/byte_buffer_reader.h>
-#include <grpc++/byte_buffer.h>
+#include <grpc++/support/byte_buffer.h>
 
 namespace grpc {
 
diff --git a/src/cpp/util/slice.cc b/src/cpp/util/slice.cc
index 57370dabc6..7e88423b6c 100644
--- a/src/cpp/util/slice.cc
+++ b/src/cpp/util/slice.cc
@@ -31,7 +31,7 @@
  *
  */
 
-#include <grpc++/slice.h>
+#include <grpc++/support/slice.h>
 
 namespace grpc {
 
diff --git a/src/cpp/util/status.cc b/src/cpp/util/status.cc
index 5bb9eda3d9..ad9850cf07 100644
--- a/src/cpp/util/status.cc
+++ b/src/cpp/util/status.cc
@@ -31,7 +31,7 @@
  *
  */
 
-#include <grpc++/status.h>
+#include <grpc++/support/status.h>
 
 namespace grpc {
 
diff --git a/src/cpp/util/string_ref.cc b/src/cpp/util/string_ref.cc
new file mode 100644
index 0000000000..8483e8c2ee
--- /dev/null
+++ b/src/cpp/util/string_ref.cc
@@ -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.
+ *
+ */
+
+#include <grpc++/support/string_ref.h>
+
+#include <string.h>
+
+#include <algorithm>
+
+namespace grpc {
+
+constexpr size_t string_ref::npos;
+
+string_ref& string_ref::operator=(const string_ref& rhs) {
+  data_ = rhs.data_;
+  length_ = rhs.length_;
+  return *this;
+}
+
+string_ref::string_ref(const char* s) : data_(s), length_(strlen(s)) {}
+
+string_ref string_ref::substr(size_t pos, size_t n) const {
+  if (pos > length_) pos = length_;
+  if (n > (length_ - pos)) n = length_ - pos;
+  return string_ref(data_ + pos, n);
+}
+
+int string_ref::compare(string_ref x) const {
+  size_t min_size = length_ < x.length_ ? length_ : x.length_;
+  int r = memcmp(data_, x.data_, min_size);
+  if (r < 0) return -1;
+  if (r > 0) return 1;
+  if (length_ < x.length_) return -1;
+  if (length_ > x.length_) return 1;
+  return 0;
+}
+
+bool string_ref::starts_with(string_ref x) const {
+  return length_ >= x.length_ && (memcmp(data_, x.data_, x.length_) == 0);
+}
+
+bool string_ref::ends_with(string_ref x) const {
+  return length_ >= x.length_ &&
+         (memcmp(data_ + (length_ - x.length_), x.data_, x.length_) == 0);
+}
+
+size_t string_ref::find(string_ref s) const {
+  auto it = std::search(cbegin(), cend(), s.cbegin(), s.cend());
+  return it == cend() ? npos : std::distance(cbegin(), it);
+}
+
+size_t string_ref::find(char c) const {
+  auto it = std::find_if(cbegin(), cend(), [c](char cc) { return cc == c; });
+  return it == cend() ? npos : std::distance(cbegin(), it);
+}
+
+bool operator==(string_ref x, string_ref y) {
+  return x.compare(y) == 0;
+}
+
+bool operator!=(string_ref x, string_ref y) {
+  return x.compare(y) != 0;
+}
+
+bool operator<(string_ref x, string_ref y) {
+  return x.compare(y) < 0;
+}
+
+bool operator<=(string_ref x, string_ref y) {
+  return x.compare(y) <= 0;
+}
+
+bool operator>(string_ref x, string_ref y) {
+  return x.compare(y) > 0;
+}
+
+bool operator>=(string_ref x, string_ref y) {
+  return x.compare(y) >= 0;
+}
+
+}  // namespace grpc
diff --git a/src/cpp/util/time.cc b/src/cpp/util/time.cc
index 799c597e0b..b3401eb26b 100644
--- a/src/cpp/util/time.cc
+++ b/src/cpp/util/time.cc
@@ -31,12 +31,12 @@
  *
  */
 
-#include <grpc++/config.h>
+#include <grpc++/support/config.h>
 
 #ifndef GRPC_CXX0X_NO_CHRONO
 
 #include <grpc/support/time.h>
-#include <grpc++/time.h>
+#include <grpc++/support/time.h>
 
 using std::chrono::duration_cast;
 using std::chrono::nanoseconds;
diff --git a/src/csharp/.gitignore b/src/csharp/.gitignore
index ae48956567..48365e32a5 100644
--- a/src/csharp/.gitignore
+++ b/src/csharp/.gitignore
@@ -5,4 +5,5 @@ test-results
 packages
 Grpc.v12.suo
 TestResult.xml
+/TestResults
 *.nupkg
diff --git a/src/csharp/Grpc.Auth/AuthInterceptors.cs b/src/csharp/Grpc.Auth/AuthInterceptors.cs
index 61338f7f0e..c8ab4d9af6 100644
--- a/src/csharp/Grpc.Auth/AuthInterceptors.cs
+++ b/src/csharp/Grpc.Auth/AuthInterceptors.cs
@@ -41,7 +41,8 @@ using Grpc.Core.Utils;
 namespace Grpc.Auth
 {
     /// <summary>
-    /// Factory methods to create authorization interceptors.
+    /// Factory methods to create authorization interceptors. Interceptors created can be registered with gRPC client classes (autogenerated client stubs that
+    /// inherit from <see cref="Grpc.Core.ClientBase"/>).
     /// </summary>
     public static class AuthInterceptors
     {
@@ -52,6 +53,8 @@ namespace Grpc.Auth
         /// Creates interceptor that will obtain access token from any credential type that implements
         /// <c>ITokenAccess</c>. (e.g. <c>GoogleCredential</c>).
         /// </summary>
+        /// <param name="credential">The credential to use to obtain access tokens.</param>
+        /// <returns>The header interceptor.</returns>
         public static HeaderInterceptor FromCredential(ITokenAccess credential)
         {
             return new HeaderInterceptor((method, authUri, metadata) =>
@@ -67,6 +70,7 @@ namespace Grpc.Auth
         /// Creates OAuth2 interceptor that will use given access token as authorization.
         /// </summary>
         /// <param name="accessToken">OAuth2 access token.</param>
+        /// <returns>The header interceptor.</returns>
         public static HeaderInterceptor FromAccessToken(string accessToken)
         {
             Preconditions.CheckNotNull(accessToken);
diff --git a/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj b/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
index ad4e94a695..b571fe9025 100644
--- a/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
+++ b/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
@@ -65,6 +65,7 @@
     </Compile>
     <Compile Include="ClientBaseTest.cs" />
     <Compile Include="ShutdownTest.cs" />
+    <Compile Include="Internal\AsyncCallTest.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="ClientServerTest.cs" />
     <Compile Include="ServerTest.cs" />
diff --git a/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs b/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs
index 4fdfab5a99..78295cf6d4 100644
--- a/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs
+++ b/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs
@@ -53,7 +53,7 @@ namespace Grpc.Core.Tests
         {
             var env1 = GrpcEnvironment.AddRef();
             var env2 = GrpcEnvironment.AddRef();
-            Assert.IsTrue(object.ReferenceEquals(env1, env2));
+            Assert.AreSame(env1, env2);
             GrpcEnvironment.Release();
             GrpcEnvironment.Release();
         }
@@ -61,18 +61,21 @@ namespace Grpc.Core.Tests
         [Test]
         public void InitializeAfterShutdown()
         {
+            Assert.AreEqual(0, GrpcEnvironment.GetRefCount());
+
             var env1 = GrpcEnvironment.AddRef();
             GrpcEnvironment.Release();
 
             var env2 = GrpcEnvironment.AddRef();
             GrpcEnvironment.Release();
 
-            Assert.IsFalse(object.ReferenceEquals(env1, env2));
+            Assert.AreNotSame(env1, env2);
         }
 
         [Test]
         public void ReleaseWithoutAddRef()
         {
+            Assert.AreEqual(0, GrpcEnvironment.GetRefCount());
             Assert.Throws(typeof(InvalidOperationException), () => GrpcEnvironment.Release());
         }
 
diff --git a/src/csharp/Grpc.Core.Tests/Internal/AsyncCallTest.cs b/src/csharp/Grpc.Core.Tests/Internal/AsyncCallTest.cs
new file mode 100644
index 0000000000..685c5f7d6c
--- /dev/null
+++ b/src/csharp/Grpc.Core.Tests/Internal/AsyncCallTest.cs
@@ -0,0 +1,222 @@
+#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.Runtime.InteropServices;
+using System.Threading.Tasks;
+
+using Grpc.Core.Internal;
+using NUnit.Framework;
+
+namespace Grpc.Core.Internal.Tests
+{
+    public class AsyncCallTest
+    {
+        Channel channel;
+        FakeNativeCall fakeCall;
+        AsyncCall<string, string> asyncCall;
+
+        [SetUp]
+        public void Init()
+        {
+            channel = new Channel("localhost", Credentials.Insecure);
+
+            fakeCall = new FakeNativeCall();
+
+            var callDetails = new CallInvocationDetails<string, string>(channel, "someMethod", null, Marshallers.StringMarshaller, Marshallers.StringMarshaller, new CallOptions());
+            asyncCall = new AsyncCall<string, string>(callDetails, fakeCall);
+        }
+
+        [TearDown]
+        public void Cleanup()
+        {
+            channel.ShutdownAsync().Wait();
+        }
+
+        [Test]
+        public void AsyncUnary_CompletionSuccess()
+        {
+            var resultTask = asyncCall.UnaryCallAsync("abc");
+            fakeCall.UnaryResponseClientHandler(true, new ClientSideStatus(Status.DefaultSuccess, new Metadata()), new byte[] { 1, 2, 3 }, new Metadata());
+            Assert.IsTrue(resultTask.IsCompleted);
+            Assert.IsTrue(fakeCall.IsDisposed);
+            Assert.AreEqual(Status.DefaultSuccess, asyncCall.GetStatus());
+        }
+
+        [Test]
+        public void AsyncUnary_CompletionFailure()
+        {
+            var resultTask = asyncCall.UnaryCallAsync("abc");
+            fakeCall.UnaryResponseClientHandler(false, new ClientSideStatus(new Status(StatusCode.Internal, ""), null), new byte[] { 1, 2, 3 }, new Metadata());
+
+            Assert.IsTrue(resultTask.IsCompleted);
+            Assert.IsTrue(fakeCall.IsDisposed);
+
+            Assert.AreEqual(StatusCode.Internal, asyncCall.GetStatus().StatusCode);
+            Assert.IsNull(asyncCall.GetTrailers());
+            var ex = Assert.Throws<RpcException>(() => resultTask.GetAwaiter().GetResult());
+            Assert.AreEqual(StatusCode.Internal, ex.Status.StatusCode);
+        }
+
+        internal class FakeNativeCall : INativeCall
+        {
+            public UnaryResponseClientHandler UnaryResponseClientHandler
+            {
+                get;
+                set;
+            }
+
+            public ReceivedStatusOnClientHandler ReceivedStatusOnClientHandler
+            {
+                get;
+                set;
+            }
+
+            public ReceivedMessageHandler ReceivedMessageHandler
+            {
+                get;
+                set;
+            }
+
+            public ReceivedResponseHeadersHandler ReceivedResponseHeadersHandler
+            {
+                get;
+                set;
+            }
+
+            public SendCompletionHandler SendCompletionHandler
+            {
+                get;
+                set;
+            }
+
+            public ReceivedCloseOnServerHandler ReceivedCloseOnServerHandler
+            {
+                get;
+                set;
+            }
+
+            public bool IsCancelled
+            {
+                get;
+                set;
+            }
+
+            public bool IsDisposed
+            {
+                get;
+                set;
+            }
+
+            public void Cancel()
+            {
+                IsCancelled = true;
+            }
+
+            public void CancelWithStatus(Status status)
+            {
+                IsCancelled = true;
+            }
+
+            public string GetPeer()
+            {
+                return "PEER";
+            }
+
+            public void StartUnary(UnaryResponseClientHandler callback, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
+            {
+                UnaryResponseClientHandler = callback;
+            }
+
+            public void StartUnary(BatchContextSafeHandle ctx, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
+            {
+                throw new NotImplementedException();
+            }
+
+            public void StartClientStreaming(UnaryResponseClientHandler callback, MetadataArraySafeHandle metadataArray)
+            {
+                UnaryResponseClientHandler = callback;
+            }
+
+            public void StartServerStreaming(ReceivedStatusOnClientHandler callback, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
+            {
+                ReceivedStatusOnClientHandler = callback;
+            }
+
+            public void StartDuplexStreaming(ReceivedStatusOnClientHandler callback, MetadataArraySafeHandle metadataArray)
+            {
+                ReceivedStatusOnClientHandler = callback;
+            }
+
+            public void StartReceiveMessage(ReceivedMessageHandler callback)
+            {
+                ReceivedMessageHandler = callback;
+            }
+
+            public void StartReceiveInitialMetadata(ReceivedResponseHeadersHandler callback)
+            {
+                ReceivedResponseHeadersHandler = callback;
+            }
+
+            public void StartSendInitialMetadata(SendCompletionHandler callback, MetadataArraySafeHandle metadataArray)
+            {
+                SendCompletionHandler = callback;
+            }
+
+            public void StartSendMessage(SendCompletionHandler callback, byte[] payload, WriteFlags writeFlags, bool sendEmptyInitialMetadata)
+            {
+                SendCompletionHandler = callback;
+            }
+
+            public void StartSendCloseFromClient(SendCompletionHandler callback)
+            {
+                SendCompletionHandler = callback;
+            }
+
+            public void StartSendStatusFromServer(SendCompletionHandler callback, Status status, MetadataArraySafeHandle metadataArray, bool sendEmptyInitialMetadata)
+            {
+                SendCompletionHandler = callback;
+            }
+
+            public void StartServerSide(ReceivedCloseOnServerHandler callback)
+            {
+                ReceivedCloseOnServerHandler = callback;
+            }
+
+            public void Dispose()
+            {
+                IsDisposed = true;
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/csharp/Grpc.Core.Tests/ResponseHeadersTest.cs b/src/csharp/Grpc.Core.Tests/ResponseHeadersTest.cs
index 706006702e..a1648f3671 100644
--- a/src/csharp/Grpc.Core.Tests/ResponseHeadersTest.cs
+++ b/src/csharp/Grpc.Core.Tests/ResponseHeadersTest.cs
@@ -32,13 +32,16 @@
 #endregion
 
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+
 using Grpc.Core;
 using Grpc.Core.Internal;
 using Grpc.Core.Utils;
+
 using NUnit.Framework;
 
 namespace Grpc.Core.Tests
@@ -74,6 +77,80 @@ namespace Grpc.Core.Tests
         }
 
         [Test]
+        public async Task ResponseHeadersAsync_UnaryCall()
+        {
+            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
+            {
+                await context.WriteResponseHeadersAsync(headers);
+                return "PASS";
+            });
+
+            var call = Calls.AsyncUnaryCall(helper.CreateUnaryCall(), "");
+            var responseHeaders = await call.ResponseHeadersAsync;
+
+            Assert.AreEqual(headers.Count, responseHeaders.Count);
+            Assert.AreEqual("ascii-header", responseHeaders[0].Key);
+            Assert.AreEqual("abcdefg", responseHeaders[0].Value);
+
+            Assert.AreEqual("PASS", await call.ResponseAsync);
+        }
+
+        [Test]
+        public async Task ResponseHeadersAsync_ClientStreamingCall()
+        {
+            helper.ClientStreamingHandler = new ClientStreamingServerMethod<string, string>(async (requestStream, context) =>
+            {
+                await context.WriteResponseHeadersAsync(headers);
+                return "PASS";
+            });
+
+            var call = Calls.AsyncClientStreamingCall(helper.CreateClientStreamingCall());
+            await call.RequestStream.CompleteAsync();
+            var responseHeaders = await call.ResponseHeadersAsync;
+
+            Assert.AreEqual("ascii-header", responseHeaders[0].Key);
+            Assert.AreEqual("PASS", await call.ResponseAsync);
+        }
+
+        [Test]
+        public async Task ResponseHeadersAsync_ServerStreamingCall()
+        {
+            helper.ServerStreamingHandler = new ServerStreamingServerMethod<string, string>(async (request, responseStream, context) =>
+            {
+                await context.WriteResponseHeadersAsync(headers);
+                await responseStream.WriteAsync("PASS");
+            });
+
+            var call = Calls.AsyncServerStreamingCall(helper.CreateServerStreamingCall(), "");
+            var responseHeaders = await call.ResponseHeadersAsync;
+
+            Assert.AreEqual("ascii-header", responseHeaders[0].Key);
+            CollectionAssert.AreEqual(new[] { "PASS" }, await call.ResponseStream.ToListAsync());
+        }
+
+        [Test]
+        public async Task ResponseHeadersAsync_DuplexStreamingCall()
+        {
+            helper.DuplexStreamingHandler = new DuplexStreamingServerMethod<string, string>(async (requestStream, responseStream, context) =>
+            {
+                await context.WriteResponseHeadersAsync(headers);
+                while (await requestStream.MoveNext())
+                {
+                    await responseStream.WriteAsync(requestStream.Current);
+                }
+            });
+
+            var call = Calls.AsyncDuplexStreamingCall(helper.CreateDuplexStreamingCall());
+            var responseHeaders = await call.ResponseHeadersAsync;
+
+            var messages = new[] { "PASS" };
+            await call.RequestStream.WriteAllAsync(messages);
+
+            Assert.AreEqual("ascii-header", responseHeaders[0].Key);
+            CollectionAssert.AreEqual(messages, await call.ResponseStream.ToListAsync());
+        }
+
+        [Test]
         public void WriteResponseHeaders_NullNotAllowed()
         {
             helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
diff --git a/src/csharp/Grpc.Core/AsyncClientStreamingCall.cs b/src/csharp/Grpc.Core/AsyncClientStreamingCall.cs
index fb9b562c77..5646fed3d9 100644
--- a/src/csharp/Grpc.Core/AsyncClientStreamingCall.cs
+++ b/src/csharp/Grpc.Core/AsyncClientStreamingCall.cs
@@ -40,18 +40,22 @@ namespace Grpc.Core
     /// <summary>
     /// Return type for client streaming calls.
     /// </summary>
+    /// <typeparam name="TRequest">Request message type for this call.</typeparam>
+    /// <typeparam name="TResponse">Response message type for this call.</typeparam>
     public sealed class AsyncClientStreamingCall<TRequest, TResponse> : IDisposable
     {
         readonly IClientStreamWriter<TRequest> requestStream;
         readonly Task<TResponse> responseAsync;
+        readonly Task<Metadata> responseHeadersAsync;
         readonly Func<Status> getStatusFunc;
         readonly Func<Metadata> getTrailersFunc;
         readonly Action disposeAction;
 
-        public AsyncClientStreamingCall(IClientStreamWriter<TRequest> requestStream, Task<TResponse> responseAsync, Func<Status> getStatusFunc, Func<Metadata> getTrailersFunc, Action disposeAction)
+        internal AsyncClientStreamingCall(IClientStreamWriter<TRequest> requestStream, Task<TResponse> responseAsync, Task<Metadata> responseHeadersAsync, Func<Status> getStatusFunc, Func<Metadata> getTrailersFunc, Action disposeAction)
         {
             this.requestStream = requestStream;
             this.responseAsync = responseAsync;
+            this.responseHeadersAsync = responseHeadersAsync;
             this.getStatusFunc = getStatusFunc;
             this.getTrailersFunc = getTrailersFunc;
             this.disposeAction = disposeAction;
@@ -69,6 +73,17 @@ namespace Grpc.Core
         }
 
         /// <summary>
+        /// Asynchronous access to response headers.
+        /// </summary>
+        public Task<Metadata> ResponseHeadersAsync
+        {
+            get
+            {
+                return this.responseHeadersAsync;
+            }
+        }
+
+        /// <summary>
         /// Async stream to send streaming requests.
         /// </summary>
         public IClientStreamWriter<TRequest> RequestStream
diff --git a/src/csharp/Grpc.Core/AsyncDuplexStreamingCall.cs b/src/csharp/Grpc.Core/AsyncDuplexStreamingCall.cs
index 183c84216a..e75108c7e5 100644
--- a/src/csharp/Grpc.Core/AsyncDuplexStreamingCall.cs
+++ b/src/csharp/Grpc.Core/AsyncDuplexStreamingCall.cs
@@ -32,24 +32,29 @@
 #endregion
 
 using System;
+using System.Threading.Tasks;
 
 namespace Grpc.Core
 {
     /// <summary>
     /// Return type for bidirectional streaming calls.
     /// </summary>
+    /// <typeparam name="TRequest">Request message type for this call.</typeparam>
+    /// <typeparam name="TResponse">Response message type for this call.</typeparam>
     public sealed class AsyncDuplexStreamingCall<TRequest, TResponse> : IDisposable
     {
         readonly IClientStreamWriter<TRequest> requestStream;
         readonly IAsyncStreamReader<TResponse> responseStream;
+        readonly Task<Metadata> responseHeadersAsync;
         readonly Func<Status> getStatusFunc;
         readonly Func<Metadata> getTrailersFunc;
         readonly Action disposeAction;
 
-        public AsyncDuplexStreamingCall(IClientStreamWriter<TRequest> requestStream, IAsyncStreamReader<TResponse> responseStream, Func<Status> getStatusFunc, Func<Metadata> getTrailersFunc, Action disposeAction)
+        internal AsyncDuplexStreamingCall(IClientStreamWriter<TRequest> requestStream, IAsyncStreamReader<TResponse> responseStream, Task<Metadata> responseHeadersAsync, Func<Status> getStatusFunc, Func<Metadata> getTrailersFunc, Action disposeAction)
         {
             this.requestStream = requestStream;
             this.responseStream = responseStream;
+            this.responseHeadersAsync = responseHeadersAsync;
             this.getStatusFunc = getStatusFunc;
             this.getTrailersFunc = getTrailersFunc;
             this.disposeAction = disposeAction;
@@ -78,6 +83,17 @@ namespace Grpc.Core
         }
 
         /// <summary>
+        /// Asynchronous access to response headers.
+        /// </summary>
+        public Task<Metadata> ResponseHeadersAsync
+        {
+            get
+            {
+                return this.responseHeadersAsync;
+            }
+        }
+
+        /// <summary>
         /// Gets the call status if the call has already finished.
         /// Throws InvalidOperationException otherwise.
         /// </summary>
diff --git a/src/csharp/Grpc.Core/AsyncServerStreamingCall.cs b/src/csharp/Grpc.Core/AsyncServerStreamingCall.cs
index ab2049f269..f953091984 100644
--- a/src/csharp/Grpc.Core/AsyncServerStreamingCall.cs
+++ b/src/csharp/Grpc.Core/AsyncServerStreamingCall.cs
@@ -32,22 +32,26 @@
 #endregion
 
 using System;
+using System.Threading.Tasks;
 
 namespace Grpc.Core
 {
     /// <summary>
     /// Return type for server streaming calls.
     /// </summary>
+    /// <typeparam name="TResponse">Response message type for this call.</typeparam>
     public sealed class AsyncServerStreamingCall<TResponse> : IDisposable
     {
         readonly IAsyncStreamReader<TResponse> responseStream;
+        readonly Task<Metadata> responseHeadersAsync;
         readonly Func<Status> getStatusFunc;
         readonly Func<Metadata> getTrailersFunc;
         readonly Action disposeAction;
 
-        public AsyncServerStreamingCall(IAsyncStreamReader<TResponse> responseStream, Func<Status> getStatusFunc, Func<Metadata> getTrailersFunc, Action disposeAction)
+        internal AsyncServerStreamingCall(IAsyncStreamReader<TResponse> responseStream, Task<Metadata> responseHeadersAsync, Func<Status> getStatusFunc, Func<Metadata> getTrailersFunc, Action disposeAction)
         {
             this.responseStream = responseStream;
+            this.responseHeadersAsync = responseHeadersAsync;
             this.getStatusFunc = getStatusFunc;
             this.getTrailersFunc = getTrailersFunc;
             this.disposeAction = disposeAction;
@@ -65,6 +69,17 @@ namespace Grpc.Core
         }
 
         /// <summary>
+        /// Asynchronous access to response headers.
+        /// </summary>
+        public Task<Metadata> ResponseHeadersAsync
+        {
+            get
+            {
+                return this.responseHeadersAsync;
+            }
+        }
+
+        /// <summary>
         /// Gets the call status if the call has already finished.
         /// Throws InvalidOperationException otherwise.
         /// </summary>
diff --git a/src/csharp/Grpc.Core/AsyncUnaryCall.cs b/src/csharp/Grpc.Core/AsyncUnaryCall.cs
index 224e343916..97df8f5e91 100644
--- a/src/csharp/Grpc.Core/AsyncUnaryCall.cs
+++ b/src/csharp/Grpc.Core/AsyncUnaryCall.cs
@@ -40,16 +40,19 @@ namespace Grpc.Core
     /// <summary>
     /// Return type for single request - single response call.
     /// </summary>
+    /// <typeparam name="TResponse">Response message type for this call.</typeparam>
     public sealed class AsyncUnaryCall<TResponse> : IDisposable
     {
         readonly Task<TResponse> responseAsync;
+        readonly Task<Metadata> responseHeadersAsync;
         readonly Func<Status> getStatusFunc;
         readonly Func<Metadata> getTrailersFunc;
         readonly Action disposeAction;
 
-        public AsyncUnaryCall(Task<TResponse> responseAsync, Func<Status> getStatusFunc, Func<Metadata> getTrailersFunc, Action disposeAction)
+        internal AsyncUnaryCall(Task<TResponse> responseAsync, Task<Metadata> responseHeadersAsync, Func<Status> getStatusFunc, Func<Metadata> getTrailersFunc, Action disposeAction)
         {
             this.responseAsync = responseAsync;
+            this.responseHeadersAsync = responseHeadersAsync;
             this.getStatusFunc = getStatusFunc;
             this.getTrailersFunc = getTrailersFunc;
             this.disposeAction = disposeAction;
@@ -67,6 +70,17 @@ namespace Grpc.Core
         }
 
         /// <summary>
+        /// Asynchronous access to response headers.
+        /// </summary>
+        public Task<Metadata> ResponseHeadersAsync
+        {
+            get
+            {
+                return this.responseHeadersAsync;
+            }
+        }
+
+        /// <summary>
         /// Allows awaiting this object directly.
         /// </summary>
         public TaskAwaiter<TResponse> GetAwaiter()
diff --git a/src/csharp/Grpc.Core/CallInvocationDetails.cs b/src/csharp/Grpc.Core/CallInvocationDetails.cs
index 6565073fc5..8228b8f317 100644
--- a/src/csharp/Grpc.Core/CallInvocationDetails.cs
+++ b/src/csharp/Grpc.Core/CallInvocationDetails.cs
@@ -40,6 +40,8 @@ namespace Grpc.Core
     /// <summary>
     /// Details about a client-side call to be invoked.
     /// </summary>
+    /// <typeparam name="TRequest">Request message type for the call.</typeparam>
+    /// <typeparam name="TResponse">Response message type for the call.</typeparam>
     public struct CallInvocationDetails<TRequest, TResponse>
     {
         readonly Channel channel;
@@ -50,7 +52,7 @@ namespace Grpc.Core
         CallOptions options;
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="Grpc.Core.CallInvocationDetails`2"/> struct.
+        /// Initializes a new instance of the <see cref="Grpc.Core.CallInvocationDetails{TRequest,TResponse}"/> struct.
         /// </summary>
         /// <param name="channel">Channel to use for this call.</param>
         /// <param name="method">Method to call.</param>
@@ -61,7 +63,7 @@ namespace Grpc.Core
         }
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="Grpc.Core.CallInvocationDetails`2"/> struct.
+        /// Initializes a new instance of the <see cref="Grpc.Core.CallInvocationDetails{TRequest,TResponse}"/> struct.
         /// </summary>
         /// <param name="channel">Channel to use for this call.</param>
         /// <param name="method">Method to call.</param>
@@ -73,7 +75,7 @@ namespace Grpc.Core
         }
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="Grpc.Core.CallInvocationDetails`2"/> struct.
+        /// Initializes a new instance of the <see cref="Grpc.Core.CallInvocationDetails{TRequest,TResponse}"/> struct.
         /// </summary>
         /// <param name="channel">Channel to use for this call.</param>
         /// <param name="method">Qualified method name.</param>
@@ -158,7 +160,7 @@ namespace Grpc.Core
         }
 
         /// <summary>
-        /// Returns new instance of <see cref="CallInvocationDetails"/> with
+        /// Returns new instance of <see cref="CallInvocationDetails{TRequest, TResponse}"/> with
         /// <c>Options</c> set to the value provided. Values of all other fields are preserved.
         /// </summary>
         public CallInvocationDetails<TRequest, TResponse> WithOptions(CallOptions options)
diff --git a/src/csharp/Grpc.Core/CallOptions.cs b/src/csharp/Grpc.Core/CallOptions.cs
index 3dfe80b48c..c3bc9c3156 100644
--- a/src/csharp/Grpc.Core/CallOptions.cs
+++ b/src/csharp/Grpc.Core/CallOptions.cs
@@ -118,6 +118,7 @@ namespace Grpc.Core
         /// Returns new instance of <see cref="CallOptions"/> with
         /// <c>Headers</c> set to the value provided. Values of all other fields are preserved.
         /// </summary>
+        /// <param name="headers">The headers.</param>
         public CallOptions WithHeaders(Metadata headers)
         {
             var newOptions = this;
@@ -129,6 +130,7 @@ namespace Grpc.Core
         /// Returns new instance of <see cref="CallOptions"/> with
         /// <c>Deadline</c> set to the value provided. Values of all other fields are preserved.
         /// </summary>
+        /// <param name="deadline">The deadline.</param>
         public CallOptions WithDeadline(DateTime deadline)
         {
             var newOptions = this;
@@ -140,6 +142,7 @@ namespace Grpc.Core
         /// Returns new instance of <see cref="CallOptions"/> with
         /// <c>CancellationToken</c> set to the value provided. Values of all other fields are preserved.
         /// </summary>
+        /// <param name="cancellationToken">The cancellation token.</param>
         public CallOptions WithCancellationToken(CancellationToken cancellationToken)
         {
             var newOptions = this;
diff --git a/src/csharp/Grpc.Core/Calls.cs b/src/csharp/Grpc.Core/Calls.cs
index 7067456638..94b3c2fe65 100644
--- a/src/csharp/Grpc.Core/Calls.cs
+++ b/src/csharp/Grpc.Core/Calls.cs
@@ -74,7 +74,7 @@ namespace Grpc.Core
         {
             var asyncCall = new AsyncCall<TRequest, TResponse>(call);
             var asyncResult = asyncCall.UnaryCallAsync(req);
-            return new AsyncUnaryCall<TResponse>(asyncResult, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
+            return new AsyncUnaryCall<TResponse>(asyncResult, asyncCall.ResponseHeadersAsync, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
         }
 
         /// <summary>
@@ -93,13 +93,14 @@ namespace Grpc.Core
             var asyncCall = new AsyncCall<TRequest, TResponse>(call);
             asyncCall.StartServerStreamingCall(req);
             var responseStream = new ClientResponseStream<TRequest, TResponse>(asyncCall);
-            return new AsyncServerStreamingCall<TResponse>(responseStream, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
+            return new AsyncServerStreamingCall<TResponse>(responseStream, asyncCall.ResponseHeadersAsync, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
         }
 
         /// <summary>
         /// Invokes a client streaming call asynchronously.
         /// In client streaming scenario, client sends a stream of requests and server responds with a single response.
         /// </summary>
+        /// <param name="call">The call defintion.</param>
         /// <returns>An awaitable call object providing access to the response.</returns>
         /// <typeparam name="TRequest">Type of request messages.</typeparam>
         /// <typeparam name="TResponse">The of response message.</typeparam>
@@ -110,7 +111,7 @@ namespace Grpc.Core
             var asyncCall = new AsyncCall<TRequest, TResponse>(call);
             var resultTask = asyncCall.ClientStreamingCallAsync();
             var requestStream = new ClientRequestStream<TRequest, TResponse>(asyncCall);
-            return new AsyncClientStreamingCall<TRequest, TResponse>(requestStream, resultTask, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
+            return new AsyncClientStreamingCall<TRequest, TResponse>(requestStream, resultTask, asyncCall.ResponseHeadersAsync, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
         }
 
         /// <summary>
@@ -130,7 +131,7 @@ namespace Grpc.Core
             asyncCall.StartDuplexStreamingCall();
             var requestStream = new ClientRequestStream<TRequest, TResponse>(asyncCall);
             var responseStream = new ClientResponseStream<TRequest, TResponse>(asyncCall);
-            return new AsyncDuplexStreamingCall<TRequest, TResponse>(requestStream, responseStream, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
+            return new AsyncDuplexStreamingCall<TRequest, TResponse>(requestStream, responseStream, asyncCall.ResponseHeadersAsync, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
         }
     }
 }
diff --git a/src/csharp/Grpc.Core/Channel.cs b/src/csharp/Grpc.Core/Channel.cs
index 2f8519dfa3..f1942727cd 100644
--- a/src/csharp/Grpc.Core/Channel.cs
+++ b/src/csharp/Grpc.Core/Channel.cs
@@ -43,7 +43,9 @@ using Grpc.Core.Utils;
 namespace Grpc.Core
 {
     /// <summary>
-    /// gRPC Channel
+    /// Represents a gRPC channel. Channels are an abstraction of long-lived connections to remote servers.
+    /// More client objects can reuse the same channel. Creating a channel is an expensive operation compared to invoking
+    /// a remote call so in general you should reuse a single channel for as many calls as possible.
     /// </summary>
     public class Channel
     {
@@ -58,7 +60,6 @@ namespace Grpc.Core
         readonly List<ChannelOption> options;
 
         bool shutdownRequested;
-        bool disposed;
 
         /// <summary>
         /// Creates a channel that connects to a specific host.
@@ -162,6 +163,7 @@ namespace Grpc.Core
         /// There is no need to call this explicitly unless your use case requires that.
         /// Starting an RPC on a new channel will request connection implicitly.
         /// </summary>
+        /// <param name="deadline">The deadline. <c>null</c> indicates no deadline.</param>
         public async Task ConnectAsync(DateTime? deadline = null)
         {
             var currentState = handle.CheckConnectivityState(true);
diff --git a/src/csharp/Grpc.Core/ChannelOptions.cs b/src/csharp/Grpc.Core/ChannelOptions.cs
index ad54b46ad5..f5ef63af54 100644
--- a/src/csharp/Grpc.Core/ChannelOptions.cs
+++ b/src/csharp/Grpc.Core/ChannelOptions.cs
@@ -44,9 +44,19 @@ namespace Grpc.Core
     /// </summary>
     public sealed class ChannelOption
     {
+        /// <summary>
+        /// Type of <c>ChannelOption</c>.
+        /// </summary>
         public enum OptionType
         {
+            /// <summary>
+            /// Channel option with integer value.
+            /// </summary>
             Integer,
+            
+            /// <summary>
+            /// Channel option with string value.
+            /// </summary>
             String
         }
 
@@ -79,6 +89,9 @@ namespace Grpc.Core
             this.intValue = intValue;
         }
 
+        /// <summary>
+        /// Gets the type of the <c>ChannelOption</c>.
+        /// </summary>
         public OptionType Type
         {
             get
@@ -87,6 +100,9 @@ namespace Grpc.Core
             }
         }
 
+        /// <summary>
+        /// Gets the name of the <c>ChannelOption</c>.
+        /// </summary>
         public string Name
         {
             get
@@ -95,6 +111,9 @@ namespace Grpc.Core
             }    
         }
 
+        /// <summary>
+        /// Gets the integer value the <c>ChannelOption</c>.
+        /// </summary>
         public int IntValue
         {
             get
@@ -104,6 +123,9 @@ namespace Grpc.Core
             }
         }
 
+        /// <summary>
+        /// Gets the string value the <c>ChannelOption</c>.
+        /// </summary>
         public string StringValue
         {
             get
@@ -140,7 +162,7 @@ namespace Grpc.Core
         /// <summary>Primary user agent: goes at the start of the user-agent metadata</summary>
         public const string PrimaryUserAgentString = "grpc.primary_user_agent";
 
-        /// <summary> Secondary user agent: goes at the end of the user-agent metadata</summary>
+        /// <summary>Secondary user agent: goes at the end of the user-agent metadata</summary>
         public const string SecondaryUserAgentString = "grpc.secondary_user_agent";
 
         /// <summary>
diff --git a/src/csharp/Grpc.Core/ClientBase.cs b/src/csharp/Grpc.Core/ClientBase.cs
index 903449439b..f4533e735c 100644
--- a/src/csharp/Grpc.Core/ClientBase.cs
+++ b/src/csharp/Grpc.Core/ClientBase.cs
@@ -53,6 +53,10 @@ namespace Grpc.Core
         readonly Channel channel;
         readonly string authUriBase;
 
+        /// <summary>
+        /// Initializes a new instance of <c>ClientBase</c> class.
+        /// </summary>
+        /// <param name="channel">The channel to use for remote call invocation.</param>
         public ClientBase(Channel channel)
         {
             this.channel = channel;
@@ -95,6 +99,11 @@ namespace Grpc.Core
         /// <summary>
         /// Creates a new call to given method.
         /// </summary>
+        /// <param name="method">The method to invoke.</param>
+        /// <param name="options">The call options.</param>
+        /// <typeparam name="TRequest">Request message type.</typeparam>
+        /// <typeparam name="TResponse">Response message type.</typeparam>
+        /// <returns>The call invocation details.</returns>
         protected CallInvocationDetails<TRequest, TResponse> CreateCall<TRequest, TResponse>(Method<TRequest, TResponse> method, CallOptions options)
             where TRequest : class
             where TResponse : class
diff --git a/src/csharp/Grpc.Core/ContextPropagationToken.cs b/src/csharp/Grpc.Core/ContextPropagationToken.cs
index a5bf1b5a70..1d899b97fd 100644
--- a/src/csharp/Grpc.Core/ContextPropagationToken.cs
+++ b/src/csharp/Grpc.Core/ContextPropagationToken.cs
@@ -44,8 +44,8 @@ namespace Grpc.Core
     /// In situations when a backend is making calls to another backend,
     /// it makes sense to propagate properties like deadline and cancellation 
     /// token of the server call to the child call.
-    /// C core provides some other contexts (like tracing context) that
-    /// are not accessible to C# layer, but this token still allows propagating them.
+    /// The gRPC native layer provides some other contexts (like tracing context) that
+    /// are not accessible to explicitly C# layer, but this token still allows propagating them.
     /// </summary>
     public class ContextPropagationToken
     {
@@ -143,13 +143,13 @@ namespace Grpc.Core
             this.propagateCancellation = propagateCancellation;
         }
             
-        /// <value><c>true</c> if parent call's deadline should be propagated to the child call.</value>
+        /// <summary><c>true</c> if parent call's deadline should be propagated to the child call.</summary>
         public bool IsPropagateDeadline
         {
             get { return this.propagateDeadline; }
         }
 
-        /// <value><c>true</c> if parent call's cancellation token should be propagated to the child call.</value>
+        /// <summary><c>true</c> if parent call's cancellation token should be propagated to the child call.</summary>
         public bool IsPropagateCancellation
         {
             get { return this.propagateCancellation; }
diff --git a/src/csharp/Grpc.Core/Grpc.Core.csproj b/src/csharp/Grpc.Core/Grpc.Core.csproj
index 055aff1444..ad2af17bc7 100644
--- a/src/csharp/Grpc.Core/Grpc.Core.csproj
+++ b/src/csharp/Grpc.Core/Grpc.Core.csproj
@@ -49,6 +49,7 @@
     <Compile Include="AsyncDuplexStreamingCall.cs" />
     <Compile Include="AsyncServerStreamingCall.cs" />
     <Compile Include="IClientStreamWriter.cs" />
+    <Compile Include="Internal\INativeCall.cs" />
     <Compile Include="IServerStreamWriter.cs" />
     <Compile Include="IAsyncStreamWriter.cs" />
     <Compile Include="IAsyncStreamReader.cs" />
diff --git a/src/csharp/Grpc.Core/GrpcEnvironment.cs b/src/csharp/Grpc.Core/GrpcEnvironment.cs
index 0a44eead74..e7c04185c2 100644
--- a/src/csharp/Grpc.Core/GrpcEnvironment.cs
+++ b/src/csharp/Grpc.Core/GrpcEnvironment.cs
@@ -102,6 +102,14 @@ namespace Grpc.Core
             }
         }
 
+        internal static int GetRefCount()
+        {
+            lock (staticLock)
+            {
+                return refCount;
+            }
+        }
+
         /// <summary>
         /// Gets application-wide logger used by gRPC.
         /// </summary>
@@ -177,7 +185,6 @@ namespace Grpc.Core
             return Marshal.PtrToStringAnsi(ptr);
         }
 
-
         internal static void GrpcNativeInit()
         {
             grpcsharp_init();
diff --git a/src/csharp/Grpc.Core/IAsyncStreamReader.cs b/src/csharp/Grpc.Core/IAsyncStreamReader.cs
index c0a0674e50..49e1ea7832 100644
--- a/src/csharp/Grpc.Core/IAsyncStreamReader.cs
+++ b/src/csharp/Grpc.Core/IAsyncStreamReader.cs
@@ -42,7 +42,7 @@ namespace Grpc.Core
     /// <summary>
     /// A stream of messages to be read.
     /// </summary>
-    /// <typeparam name="T"></typeparam>
+    /// <typeparam name="T">The message type.</typeparam>
     public interface IAsyncStreamReader<T> : IAsyncEnumerator<T>
     {
         // TODO(jtattermusch): consider just using IAsyncEnumerator instead of this interface.
diff --git a/src/csharp/Grpc.Core/IAsyncStreamWriter.cs b/src/csharp/Grpc.Core/IAsyncStreamWriter.cs
index 4e2acb9c71..9c0d2d312e 100644
--- a/src/csharp/Grpc.Core/IAsyncStreamWriter.cs
+++ b/src/csharp/Grpc.Core/IAsyncStreamWriter.cs
@@ -42,7 +42,7 @@ namespace Grpc.Core
     /// <summary>
     /// A writable stream of messages.
     /// </summary>
-    /// <typeparam name="T"></typeparam>
+    /// <typeparam name="T">The message type.</typeparam>
     public interface IAsyncStreamWriter<T>
     {
         /// <summary>
@@ -56,7 +56,7 @@ namespace Grpc.Core
         /// If null, default options will be used.
         /// Once set, this property maintains its value across subsequent
         /// writes.
-        /// <value>The write options.</value>
+        /// </summary>
         WriteOptions WriteOptions { get; set; }
     }
 }
diff --git a/src/csharp/Grpc.Core/IClientStreamWriter.cs b/src/csharp/Grpc.Core/IClientStreamWriter.cs
index a3028bc374..3fd0774db5 100644
--- a/src/csharp/Grpc.Core/IClientStreamWriter.cs
+++ b/src/csharp/Grpc.Core/IClientStreamWriter.cs
@@ -42,7 +42,7 @@ namespace Grpc.Core
     /// <summary>
     /// Client-side writable stream of messages with Close capability.
     /// </summary>
-    /// <typeparam name="T"></typeparam>
+    /// <typeparam name="T">The message type.</typeparam>
     public interface IClientStreamWriter<T> : IAsyncStreamWriter<T>
     {
         /// <summary>
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCall.cs b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
index bb9ba5b8dd..be5d611a53 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCall.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
@@ -51,22 +51,35 @@ namespace Grpc.Core.Internal
         static readonly ILogger Logger = GrpcEnvironment.Logger.ForType<AsyncCall<TRequest, TResponse>>();
 
         readonly CallInvocationDetails<TRequest, TResponse> details;
+        readonly INativeCall injectedNativeCall;  // for testing
 
         // Completion of a pending unary response if not null.
         TaskCompletionSource<TResponse> unaryResponseTcs;
 
+        // Indicates that steaming call has finished.
+        TaskCompletionSource<object> streamingCallFinishedTcs = new TaskCompletionSource<object>();
+
+        // Response headers set here once received.
+        TaskCompletionSource<Metadata> responseHeadersTcs = new TaskCompletionSource<Metadata>();
+
         // Set after status is received. Used for both unary and streaming response calls.
         ClientSideStatus? finishedStatus;
 
-        bool readObserverCompleted;  // True if readObserver has already been completed.
-
         public AsyncCall(CallInvocationDetails<TRequest, TResponse> callDetails)
-            : base(callDetails.RequestMarshaller.Serializer, callDetails.ResponseMarshaller.Deserializer)
+            : base(callDetails.RequestMarshaller.Serializer, callDetails.ResponseMarshaller.Deserializer, callDetails.Channel.Environment)
         {
             this.details = callDetails.WithOptions(callDetails.Options.Normalize());
             this.initialMetadataSent = true;  // we always send metadata at the very beginning of the call.
         }
 
+        /// <summary>
+        /// This constructor should only be used for testing.
+        /// </summary>
+        public AsyncCall(CallInvocationDetails<TRequest, TResponse> callDetails, INativeCall injectedNativeCall) : this(callDetails)
+        {
+            this.injectedNativeCall = injectedNativeCall;
+        }
+
         // TODO: this method is not Async, so it shouldn't be in AsyncCall class, but 
         // it is reusing fair amount of code in this class, so we are leaving it here.
         /// <summary>
@@ -100,7 +113,7 @@ namespace Grpc.Core.Internal
                         bool success = (ev.success != 0);
                         try
                         {
-                            HandleUnaryResponse(success, ctx);
+                            HandleUnaryResponse(success, ctx.GetReceivedStatusOnClient(), ctx.GetReceivedMessage(), ctx.GetReceivedInitialMetadata());
                         }
                         catch (Exception e)
                         {
@@ -125,7 +138,7 @@ namespace Grpc.Core.Internal
                 Preconditions.CheckState(!started);
                 started = true;
 
-                Initialize(details.Channel.Environment.CompletionQueue);
+                Initialize(environment.CompletionQueue);
 
                 halfcloseRequested = true;
                 readingDone = true;
@@ -152,7 +165,7 @@ namespace Grpc.Core.Internal
                 Preconditions.CheckState(!started);
                 started = true;
 
-                Initialize(details.Channel.Environment.CompletionQueue);
+                Initialize(environment.CompletionQueue);
 
                 readingDone = true;
 
@@ -176,10 +189,9 @@ namespace Grpc.Core.Internal
                 Preconditions.CheckState(!started);
                 started = true;
 
-                Initialize(details.Channel.Environment.CompletionQueue);
+                Initialize(environment.CompletionQueue);
 
                 halfcloseRequested = true;
-                halfclosed = true;  // halfclose not confirmed yet, but it will be once finishedHandler is called.
 
                 byte[] payload = UnsafeSerialize(msg);
 
@@ -187,6 +199,7 @@ namespace Grpc.Core.Internal
                 {
                     call.StartServerStreaming(HandleFinished, payload, metadataArray, GetWriteFlagsForCall());
                 }
+                call.StartReceiveInitialMetadata(HandleReceivedResponseHeaders);
             }
         }
 
@@ -201,12 +214,13 @@ namespace Grpc.Core.Internal
                 Preconditions.CheckState(!started);
                 started = true;
 
-                Initialize(details.Channel.Environment.CompletionQueue);
+                Initialize(environment.CompletionQueue);
 
                 using (var metadataArray = MetadataArraySafeHandle.Create(details.Options.Headers))
                 {
                     call.StartDuplexStreaming(HandleFinished, metadataArray);
                 }
+                call.StartReceiveInitialMetadata(HandleReceivedResponseHeaders);
             }
         }
 
@@ -248,6 +262,28 @@ namespace Grpc.Core.Internal
         }
 
         /// <summary>
+        /// Get the task that completes once if streaming call finishes with ok status and throws RpcException with given status otherwise.
+        /// </summary>
+        public Task StreamingCallFinishedTask
+        {
+            get
+            {
+                return streamingCallFinishedTcs.Task;
+            }
+        }
+
+        /// <summary>
+        /// Get the task that completes once response headers are received.
+        /// </summary>
+        public Task<Metadata> ResponseHeadersAsync
+        {
+            get
+            {
+                return responseHeadersTcs.Task;
+            }
+        }
+
+        /// <summary>
         /// Gets the resulting status if the call has already finished.
         /// Throws InvalidOperationException otherwise.
         /// </summary>
@@ -281,36 +317,6 @@ namespace Grpc.Core.Internal
             }
         }
 
-        /// <summary>
-        /// On client-side, we only fire readCompletionDelegate once all messages have been read 
-        /// and status has been received.
-        /// </summary>
-        protected override void ProcessLastRead(AsyncCompletionDelegate<TResponse> completionDelegate)
-        {
-            if (completionDelegate != null && readingDone && finishedStatus.HasValue)
-            {
-                bool shouldComplete;
-                lock (myLock)
-                {
-                    shouldComplete = !readObserverCompleted;
-                    readObserverCompleted = true;
-                }
-
-                if (shouldComplete)
-                {
-                    var status = finishedStatus.Value.Status;
-                    if (status.StatusCode != StatusCode.OK)
-                    {
-                        FireCompletion(completionDelegate, default(TResponse), new RpcException(status));
-                    }
-                    else
-                    {
-                        FireCompletion(completionDelegate, default(TResponse), null);
-                    }
-                }
-            }
-        }
-
         protected override void OnAfterReleaseResources()
         {
             details.Channel.RemoveCallReference(this);
@@ -318,16 +324,24 @@ namespace Grpc.Core.Internal
 
         private void Initialize(CompletionQueueSafeHandle cq)
         {
+            var call = CreateNativeCall(cq);
+            details.Channel.AddCallReference(this);
+            InitializeInternal(call);
+            RegisterCancellationCallback();
+        }
+
+        private INativeCall CreateNativeCall(CompletionQueueSafeHandle cq)
+        {
+            if (injectedNativeCall != null)
+            {
+                return injectedNativeCall;  // allows injecting a mock INativeCall in tests.
+            }
+
             var parentCall = details.Options.PropagationToken != null ? details.Options.PropagationToken.ParentCall : CallSafeHandle.NullInstance;
 
-            var call = details.Channel.Handle.CreateCall(details.Channel.Environment.CompletionRegistry,
+            return details.Channel.Handle.CreateCall(environment.CompletionRegistry,
                 parentCall, ContextPropagationToken.DefaultMask, cq,
                 details.Method, details.Host, Timespec.FromDateTime(details.Options.Deadline.Value));
-
-            details.Channel.AddCallReference(this);
-
-            InitializeInternal(call);
-            RegisterCancellationCallback();
         }
 
         // Make sure that once cancellationToken for this call is cancelled, Cancel() will be called.
@@ -350,31 +364,31 @@ namespace Grpc.Core.Internal
         }
 
         /// <summary>
-        /// Handler for unary response completion.
+        /// Handles receive status completion for calls with streaming response.
         /// </summary>
-        private void HandleUnaryResponse(bool success, BatchContextSafeHandle ctx)
+        private void HandleReceivedResponseHeaders(bool success, Metadata responseHeaders)
         {
-            var fullStatus = ctx.GetReceivedStatusOnClient();
+            responseHeadersTcs.SetResult(responseHeaders);
+        }
 
+        /// <summary>
+        /// Handler for unary response completion.
+        /// </summary>
+        private void HandleUnaryResponse(bool success, ClientSideStatus receivedStatus, byte[] receivedMessage, Metadata responseHeaders)
+        {
             lock (myLock)
             {
                 finished = true;
-                finishedStatus = fullStatus;
-
-                halfclosed = true;
+                finishedStatus = receivedStatus;
 
                 ReleaseResourcesIfPossible();
             }
 
-            if (!success)
-            {
-                unaryResponseTcs.SetException(new RpcException(new Status(StatusCode.Internal, "Internal error occured.")));
-                return;
-            }
+            responseHeadersTcs.SetResult(responseHeaders);
 
-            var status = fullStatus.Status;
+            var status = receivedStatus.Status;
 
-            if (status.StatusCode != StatusCode.OK)
+            if (!success || status.StatusCode != StatusCode.OK)
             {
                 unaryResponseTcs.SetException(new RpcException(status));
                 return;
@@ -382,7 +396,7 @@ namespace Grpc.Core.Internal
 
             // TODO: handle deserialization error
             TResponse msg;
-            TryDeserialize(ctx.GetReceivedMessage(), out msg);
+            TryDeserialize(receivedMessage, out msg);
 
             unaryResponseTcs.SetResult(msg);
         }
@@ -390,22 +404,25 @@ namespace Grpc.Core.Internal
         /// <summary>
         /// Handles receive status completion for calls with streaming response.
         /// </summary>
-        private void HandleFinished(bool success, BatchContextSafeHandle ctx)
+        private void HandleFinished(bool success, ClientSideStatus receivedStatus)
         {
-            var fullStatus = ctx.GetReceivedStatusOnClient();
-
-            AsyncCompletionDelegate<TResponse> origReadCompletionDelegate = null;
             lock (myLock)
             {
                 finished = true;
-                finishedStatus = fullStatus;
-
-                origReadCompletionDelegate = readCompletionDelegate;
+                finishedStatus = receivedStatus;
 
                 ReleaseResourcesIfPossible();
             }
 
-            ProcessLastRead(origReadCompletionDelegate);
+            var status = receivedStatus.Status;
+
+            if (!success || status.StatusCode != StatusCode.OK)
+            {
+                streamingCallFinishedTcs.SetException(new RpcException(status));
+                return;
+            }
+
+            streamingCallFinishedTcs.SetResult(null);
         }
     }
 }
\ No newline at end of file
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs b/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
index 1808294f43..4d20394644 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
@@ -54,30 +54,30 @@ namespace Grpc.Core.Internal
         readonly Func<TWrite, byte[]> serializer;
         readonly Func<byte[], TRead> deserializer;
 
+        protected readonly GrpcEnvironment environment;
         protected readonly object myLock = new object();
 
-        protected CallSafeHandle call;
+        protected INativeCall call;
         protected bool disposed;
 
         protected bool started;
-        protected bool errorOccured;
         protected bool cancelRequested;
 
         protected AsyncCompletionDelegate<object> sendCompletionDelegate;  // Completion of a pending send or sendclose if not null.
         protected AsyncCompletionDelegate<TRead> readCompletionDelegate;  // Completion of a pending send or sendclose if not null.
 
-        protected bool readingDone;
-        protected bool halfcloseRequested;
-        protected bool halfclosed;
+        protected bool readingDone;  // True if last read (i.e. read with null payload) was already received.
+        protected bool halfcloseRequested;  // True if send close have been initiated.
         protected bool finished;  // True if close has been received from the peer.
 
         protected bool initialMetadataSent;
-        protected long streamingWritesCounter;
+        protected long streamingWritesCounter;  // Number of streaming send operations started so far.
 
-        public AsyncCallBase(Func<TWrite, byte[]> serializer, Func<byte[], TRead> deserializer)
+        public AsyncCallBase(Func<TWrite, byte[]> serializer, Func<byte[], TRead> deserializer, GrpcEnvironment environment)
         {
             this.serializer = Preconditions.CheckNotNull(serializer);
             this.deserializer = Preconditions.CheckNotNull(deserializer);
+            this.environment = Preconditions.CheckNotNull(environment);
         }
 
         /// <summary>
@@ -114,7 +114,7 @@ namespace Grpc.Core.Internal
             }
         }
 
-        protected void InitializeInternal(CallSafeHandle call)
+        protected void InitializeInternal(INativeCall call)
         {
             lock (myLock)
             {
@@ -159,16 +159,6 @@ namespace Grpc.Core.Internal
             }
         }
 
-        // TODO(jtattermusch): find more fitting name for this method.
-        /// <summary>
-        /// Default behavior just completes the read observer, but more sofisticated behavior might be required
-        /// by subclasses.
-        /// </summary>
-        protected virtual void ProcessLastRead(AsyncCompletionDelegate<TRead> completionDelegate)
-        {
-            FireCompletion(completionDelegate, default(TRead), null);
-        }
-
         /// <summary>
         /// If there are no more pending actions and no new actions can be started, releases
         /// the underlying native resources.
@@ -177,7 +167,7 @@ namespace Grpc.Core.Internal
         {
             if (!disposed && call != null)
             {
-                bool noMoreSendCompletions = halfclosed || (cancelRequested && sendCompletionDelegate == null);
+                bool noMoreSendCompletions = sendCompletionDelegate == null && (halfcloseRequested || cancelRequested || finished);
                 if (noMoreSendCompletions && readingDone && finished)
                 {
                     ReleaseResources();
@@ -204,11 +194,11 @@ namespace Grpc.Core.Internal
         protected void CheckSendingAllowed()
         {
             Preconditions.CheckState(started);
-            Preconditions.CheckState(!errorOccured);
             CheckNotCancelled();
             Preconditions.CheckState(!disposed);
 
             Preconditions.CheckState(!halfcloseRequested, "Already halfclosed.");
+            Preconditions.CheckState(!finished, "Already finished.");
             Preconditions.CheckState(sendCompletionDelegate == null, "Only one write can be pending at a time");
         }
 
@@ -216,7 +206,6 @@ namespace Grpc.Core.Internal
         {
             Preconditions.CheckState(started);
             Preconditions.CheckState(!disposed);
-            Preconditions.CheckState(!errorOccured);
 
             Preconditions.CheckState(!readingDone, "Stream has already been closed.");
             Preconditions.CheckState(readCompletionDelegate == null, "Only one read can be pending at a time");
@@ -280,7 +269,7 @@ namespace Grpc.Core.Internal
         /// <summary>
         /// Handles send completion.
         /// </summary>
-        protected void HandleSendFinished(bool success, BatchContextSafeHandle ctx)
+        protected void HandleSendFinished(bool success)
         {
             AsyncCompletionDelegate<object> origCompletionDelegate = null;
             lock (myLock)
@@ -304,12 +293,11 @@ namespace Grpc.Core.Internal
         /// <summary>
         /// Handles halfclose completion.
         /// </summary>
-        protected void HandleHalfclosed(bool success, BatchContextSafeHandle ctx)
+        protected void HandleHalfclosed(bool success)
         {
             AsyncCompletionDelegate<object> origCompletionDelegate = null;
             lock (myLock)
             {
-                halfclosed = true;
                 origCompletionDelegate = sendCompletionDelegate;
                 sendCompletionDelegate = null;
 
@@ -329,23 +317,17 @@ namespace Grpc.Core.Internal
         /// <summary>
         /// Handles streaming read completion.
         /// </summary>
-        protected void HandleReadFinished(bool success, BatchContextSafeHandle ctx)
+        protected void HandleReadFinished(bool success, byte[] receivedMessage)
         {
-            var payload = ctx.GetReceivedMessage();
-
             AsyncCompletionDelegate<TRead> origCompletionDelegate = null;
             lock (myLock)
             {
                 origCompletionDelegate = readCompletionDelegate;
-                if (payload != null)
-                {
-                    readCompletionDelegate = null;
-                }
-                else
+                readCompletionDelegate = null;
+
+                if (receivedMessage == null)
                 {
-                    // This was the last read. Keeping the readCompletionDelegate
-                    // to be either fired by this handler or by client-side finished
-                    // handler.
+                    // This was the last read.
                     readingDone = true;
                 }
 
@@ -354,17 +336,17 @@ namespace Grpc.Core.Internal
 
             // TODO: handle the case when error occured...
 
-            if (payload != null)
+            if (receivedMessage != null)
             {
                 // TODO: handle deserialization error
                 TRead msg;
-                TryDeserialize(payload, out msg);
+                TryDeserialize(receivedMessage, out msg);
 
                 FireCompletion(origCompletionDelegate, msg, null);
             }
             else
             {
-                ProcessLastRead(origCompletionDelegate);
+                FireCompletion(origCompletionDelegate, default(TRead), null);
             }
         }
     }
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs b/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
index 6278c0191e..5c47251030 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
@@ -49,12 +49,10 @@ namespace Grpc.Core.Internal
     {
         readonly TaskCompletionSource<object> finishedServersideTcs = new TaskCompletionSource<object>();
         readonly CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
-        readonly GrpcEnvironment environment;
         readonly Server server;
 
-        public AsyncCallServer(Func<TResponse, byte[]> serializer, Func<byte[], TRequest> deserializer, GrpcEnvironment environment, Server server) : base(serializer, deserializer)
+        public AsyncCallServer(Func<TResponse, byte[]> serializer, Func<byte[], TRequest> deserializer, GrpcEnvironment environment, Server server) : base(serializer, deserializer, environment)
         {
-            this.environment = Preconditions.CheckNotNull(environment);
             this.server = Preconditions.CheckNotNull(server);
         }
 
@@ -185,10 +183,8 @@ namespace Grpc.Core.Internal
         /// <summary>
         /// Handles the server side close completion.
         /// </summary>
-        private void HandleFinishedServerside(bool success, BatchContextSafeHandle ctx)
+        private void HandleFinishedServerside(bool success, bool cancelled)
         {
-            bool cancelled = ctx.GetReceivedCloseOnServerCancelled();
-
             lock (myLock)
             {
                 finished = true;
diff --git a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
index 3cb01e29bd..c3611a7761 100644
--- a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
@@ -38,9 +38,9 @@ using Grpc.Core.Utils;
 namespace Grpc.Core.Internal
 {
     /// <summary>
-    /// grpc_call from <grpc/grpc.h>
+    /// grpc_call from <c>grpc/grpc.h</c>
     /// </summary>
-    internal class CallSafeHandle : SafeHandleZeroIsInvalid
+    internal class CallSafeHandle : SafeHandleZeroIsInvalid, INativeCall
     {
         public static readonly CallSafeHandle NullInstance = new CallSafeHandle();
 
@@ -87,6 +87,10 @@ namespace Grpc.Core.Internal
             BatchContextSafeHandle ctx);
 
         [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_recv_initial_metadata(CallSafeHandle call,
+            BatchContextSafeHandle ctx);
+
+        [DllImport("grpc_csharp_ext.dll")]
         static extern GRPCCallError grpcsharp_call_start_serverside(CallSafeHandle call,
             BatchContextSafeHandle ctx);
 
@@ -109,10 +113,10 @@ namespace Grpc.Core.Internal
             this.completionRegistry = completionRegistry;
         }
 
-        public void StartUnary(BatchCompletionDelegate callback, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
+        public void StartUnary(UnaryResponseClientHandler callback, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
         {
             var ctx = BatchContextSafeHandle.Create();
-            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedStatusOnClient(), context.GetReceivedMessage(), context.GetReceivedInitialMetadata()));
             grpcsharp_call_start_unary(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray, writeFlags)
                 .CheckOk();
         }
@@ -123,66 +127,73 @@ namespace Grpc.Core.Internal
                 .CheckOk();
         }
 
-        public void StartClientStreaming(BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
+        public void StartClientStreaming(UnaryResponseClientHandler callback, MetadataArraySafeHandle metadataArray)
         {
             var ctx = BatchContextSafeHandle.Create();
-            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedStatusOnClient(), context.GetReceivedMessage(), context.GetReceivedInitialMetadata()));
             grpcsharp_call_start_client_streaming(this, ctx, metadataArray).CheckOk();
         }
 
-        public void StartServerStreaming(BatchCompletionDelegate callback, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
+        public void StartServerStreaming(ReceivedStatusOnClientHandler callback, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
         {
             var ctx = BatchContextSafeHandle.Create();
-            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedStatusOnClient()));
             grpcsharp_call_start_server_streaming(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray, writeFlags).CheckOk();
         }
 
-        public void StartDuplexStreaming(BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
+        public void StartDuplexStreaming(ReceivedStatusOnClientHandler callback, MetadataArraySafeHandle metadataArray)
         {
             var ctx = BatchContextSafeHandle.Create();
-            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedStatusOnClient()));
             grpcsharp_call_start_duplex_streaming(this, ctx, metadataArray).CheckOk();
         }
 
-        public void StartSendMessage(BatchCompletionDelegate callback, byte[] payload, WriteFlags writeFlags, bool sendEmptyInitialMetadata)
+        public void StartSendMessage(SendCompletionHandler callback, byte[] payload, WriteFlags writeFlags, bool sendEmptyInitialMetadata)
         {
             var ctx = BatchContextSafeHandle.Create();
-            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success));
             grpcsharp_call_send_message(this, ctx, payload, new UIntPtr((ulong)payload.Length), writeFlags, sendEmptyInitialMetadata).CheckOk();
         }
 
-        public void StartSendCloseFromClient(BatchCompletionDelegate callback)
+        public void StartSendCloseFromClient(SendCompletionHandler callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success));
             grpcsharp_call_send_close_from_client(this, ctx).CheckOk();
         }
 
-        public void StartSendStatusFromServer(BatchCompletionDelegate callback, Status status, MetadataArraySafeHandle metadataArray, bool sendEmptyInitialMetadata)
+        public void StartSendStatusFromServer(SendCompletionHandler callback, Status status, MetadataArraySafeHandle metadataArray, bool sendEmptyInitialMetadata)
         {
             var ctx = BatchContextSafeHandle.Create();
-            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success));
             grpcsharp_call_send_status_from_server(this, ctx, status.StatusCode, status.Detail, metadataArray, sendEmptyInitialMetadata).CheckOk();
         }
 
-        public void StartReceiveMessage(BatchCompletionDelegate callback)
+        public void StartReceiveMessage(ReceivedMessageHandler callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedMessage()));
             grpcsharp_call_recv_message(this, ctx).CheckOk();
         }
 
-        public void StartServerSide(BatchCompletionDelegate callback)
+        public void StartReceiveInitialMetadata(ReceivedResponseHeadersHandler callback)
+        {
+            var ctx = BatchContextSafeHandle.Create();
+            completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedInitialMetadata()));
+            grpcsharp_call_recv_initial_metadata(this, ctx).CheckOk();
+        }
+
+        public void StartServerSide(ReceivedCloseOnServerHandler callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedCloseOnServerCancelled()));
             grpcsharp_call_start_serverside(this, ctx).CheckOk();
         }
 
-        public void StartSendInitialMetadata(BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
+        public void StartSendInitialMetadata(SendCompletionHandler callback, MetadataArraySafeHandle metadataArray)
         {
             var ctx = BatchContextSafeHandle.Create();
-            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success));
             grpcsharp_call_send_initial_metadata(this, ctx, metadataArray).CheckOk();
         }
 
diff --git a/src/csharp/Grpc.Core/Internal/ChannelArgsSafeHandle.cs b/src/csharp/Grpc.Core/Internal/ChannelArgsSafeHandle.cs
index c12aec5a3a..ea5b52374e 100644
--- a/src/csharp/Grpc.Core/Internal/ChannelArgsSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/ChannelArgsSafeHandle.cs
@@ -35,7 +35,7 @@ using System.Threading.Tasks;
 namespace Grpc.Core.Internal
 {
     /// <summary>
-    /// grpc_channel_args from <grpc/grpc.h>
+    /// grpc_channel_args from <c>grpc/grpc.h</c>
     /// </summary>
     internal class ChannelArgsSafeHandle : SafeHandleZeroIsInvalid
     {
diff --git a/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs b/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
index 8cef566c14..7a1c6e3dac 100644
--- a/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
@@ -36,7 +36,7 @@ using System.Threading.Tasks;
 namespace Grpc.Core.Internal
 {
     /// <summary>
-    /// grpc_channel from <grpc/grpc.h>
+    /// grpc_channel from <c>grpc/grpc.h</c>
     /// </summary>
     internal class ChannelSafeHandle : SafeHandleZeroIsInvalid
     {
diff --git a/src/csharp/Grpc.Core/Internal/ClientResponseStream.cs b/src/csharp/Grpc.Core/Internal/ClientResponseStream.cs
index 6c44521038..b4a7335c7c 100644
--- a/src/csharp/Grpc.Core/Internal/ClientResponseStream.cs
+++ b/src/csharp/Grpc.Core/Internal/ClientResponseStream.cs
@@ -72,7 +72,13 @@ namespace Grpc.Core.Internal
             call.StartReadMessage(taskSource.CompletionDelegate);
             var result = await taskSource.Task;
             this.current = result;
-            return result != null;
+
+            if (result == null)
+            {
+                await call.StreamingCallFinishedTask;
+                return false;
+            }
+            return true;
         }
 
         public void Dispose()
diff --git a/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
index f64f3d4175..f7a3471bb4 100644
--- a/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
@@ -35,7 +35,7 @@ using System.Threading.Tasks;
 namespace Grpc.Core.Internal
 {
     /// <summary>
-    /// grpc_completion_queue from <grpc/grpc.h>
+    /// grpc_completion_queue from <c>grpc/grpc.h</c>
     /// </summary>
     internal class CompletionQueueSafeHandle : SafeHandleZeroIsInvalid
     {
diff --git a/src/csharp/Grpc.Core/Internal/CredentialsSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CredentialsSafeHandle.cs
index 8b4fa85e5d..feed335362 100644
--- a/src/csharp/Grpc.Core/Internal/CredentialsSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/CredentialsSafeHandle.cs
@@ -36,7 +36,7 @@ using System.Threading.Tasks;
 namespace Grpc.Core.Internal
 {
     /// <summary>
-    /// grpc_credentials from <grpc/grpc_security.h>
+    /// grpc_credentials from <c>grpc/grpc_security.h</c>
     /// </summary>
     internal class CredentialsSafeHandle : SafeHandleZeroIsInvalid
     {
diff --git a/src/csharp/Grpc.Core/Internal/INativeCall.cs b/src/csharp/Grpc.Core/Internal/INativeCall.cs
new file mode 100644
index 0000000000..cbef599139
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/INativeCall.cs
@@ -0,0 +1,85 @@
+#region Copyright notice and license
+// Copyright 2015, Google Inc.
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+// 
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+
+namespace Grpc.Core.Internal
+{
+    internal delegate void UnaryResponseClientHandler(bool success, ClientSideStatus receivedStatus, byte[] receivedMessage, Metadata responseHeaders);
+
+    // Received status for streaming response calls.
+    internal delegate void ReceivedStatusOnClientHandler(bool success, ClientSideStatus receivedStatus);
+
+    internal delegate void ReceivedMessageHandler(bool success, byte[] receivedMessage);
+
+    internal delegate void ReceivedResponseHeadersHandler(bool success, Metadata responseHeaders);
+
+    internal delegate void SendCompletionHandler(bool success);
+
+    internal delegate void ReceivedCloseOnServerHandler(bool success, bool cancelled);
+
+    /// <summary>
+    /// Abstraction of a native call object.
+    /// </summary>
+    internal interface INativeCall : IDisposable
+    {
+        void Cancel();
+
+        void CancelWithStatus(Grpc.Core.Status status);
+
+        string GetPeer();
+
+        void StartUnary(UnaryResponseClientHandler callback, byte[] payload, MetadataArraySafeHandle metadataArray, Grpc.Core.WriteFlags writeFlags);
+
+        void StartUnary(BatchContextSafeHandle ctx, byte[] payload, MetadataArraySafeHandle metadataArray, Grpc.Core.WriteFlags writeFlags);
+
+        void StartClientStreaming(UnaryResponseClientHandler callback, MetadataArraySafeHandle metadataArray);
+
+        void StartServerStreaming(ReceivedStatusOnClientHandler callback, byte[] payload, MetadataArraySafeHandle metadataArray, Grpc.Core.WriteFlags writeFlags);
+
+        void StartDuplexStreaming(ReceivedStatusOnClientHandler callback, MetadataArraySafeHandle metadataArray);
+
+        void StartReceiveMessage(ReceivedMessageHandler callback);
+
+        void StartReceiveInitialMetadata(ReceivedResponseHeadersHandler callback);
+
+        void StartSendInitialMetadata(SendCompletionHandler callback, MetadataArraySafeHandle metadataArray);
+
+        void StartSendMessage(SendCompletionHandler callback, byte[] payload, Grpc.Core.WriteFlags writeFlags, bool sendEmptyInitialMetadata);
+
+        void StartSendCloseFromClient(SendCompletionHandler callback);
+
+        void StartSendStatusFromServer(SendCompletionHandler callback, Grpc.Core.Status status, MetadataArraySafeHandle metadataArray, bool sendEmptyInitialMetadata);
+
+        void StartServerSide(ReceivedCloseOnServerHandler callback);
+    }
+}
diff --git a/src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs b/src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs
index 83994f6762..31b834c979 100644
--- a/src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs
@@ -35,7 +35,7 @@ using System.Threading.Tasks;
 namespace Grpc.Core.Internal
 {
     /// <summary>
-    /// grpc_metadata_array from <grpc/grpc.h>
+    /// grpc_metadata_array from <c>grpc/grpc.h</c>
     /// </summary>
     internal class MetadataArraySafeHandle : SafeHandleZeroIsInvalid
     {
diff --git a/src/csharp/Grpc.Core/Internal/ServerCredentialsSafeHandle.cs b/src/csharp/Grpc.Core/Internal/ServerCredentialsSafeHandle.cs
index 37a4f5256b..51e352a18b 100644
--- a/src/csharp/Grpc.Core/Internal/ServerCredentialsSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerCredentialsSafeHandle.cs
@@ -37,7 +37,7 @@ using Grpc.Core.Utils;
 namespace Grpc.Core.Internal
 {
     /// <summary>
-    /// grpc_server_credentials from <grpc/grpc_security.h>
+    /// grpc_server_credentials from <c>grpc/grpc_security.h</c>
     /// </summary>
     internal class ServerCredentialsSafeHandle : SafeHandleZeroIsInvalid
     {
diff --git a/src/csharp/Grpc.Core/Metadata.cs b/src/csharp/Grpc.Core/Metadata.cs
index a589b50caa..99fe0b5478 100644
--- a/src/csharp/Grpc.Core/Metadata.cs
+++ b/src/csharp/Grpc.Core/Metadata.cs
@@ -41,7 +41,13 @@ using Grpc.Core.Utils;
 namespace Grpc.Core
 {
     /// <summary>
-    /// Provides access to read and write metadata values to be exchanged during a call.
+    /// A collection of metadata entries that can be exchanged during a call.
+    /// gRPC supports these types of metadata:
+    /// <list type="bullet">
+    /// <item><term>Request headers</term><description>are sent by the client at the beginning of a remote call before any request messages are sent.</description></item>
+    /// <item><term>Response headers</term><description>are sent by the server at the beginning of a remote call handler before any response messages are sent.</description></item>
+    /// <item><term>Response trailers</term><description>are sent by the server at the end of a remote call along with resulting call status.</description></item>
+    /// </list>
     /// </summary>
     public sealed class Metadata : IList<Metadata.Entry>
     {
@@ -58,21 +64,19 @@ namespace Grpc.Core
         readonly List<Entry> entries;
         bool readOnly;
 
+        /// <summary>
+        /// Initializes a new instance of <c>Metadata</c>.
+        /// </summary>
         public Metadata()
         {
             this.entries = new List<Entry>();
         }
 
-        public Metadata(ICollection<Entry> entries)
-        {
-            this.entries = new List<Entry>(entries);
-        }
-
         /// <summary>
         /// Makes this object read-only.
         /// </summary>
         /// <returns>this object</returns>
-        public Metadata Freeze()
+        internal Metadata Freeze()
         {
             this.readOnly = true;
             return this;
@@ -197,7 +201,7 @@ namespace Grpc.Core
             }
 
             /// <summary>
-            /// Initializes a new instance of the <see cref="Grpc.Core.Metadata+Entry"/> struct with a binary value.
+            /// Initializes a new instance of the <see cref="Grpc.Core.Metadata.Entry"/> struct with a binary value.
             /// </summary>
             /// <param name="key">Metadata key, needs to have suffix indicating a binary valued metadata entry.</param>
             /// <param name="valueBytes">Value bytes.</param>
@@ -213,7 +217,7 @@ namespace Grpc.Core
             }
 
             /// <summary>
-            /// Initializes a new instance of the <see cref="Grpc.Core.Metadata+Entry"/> struct holding an ASCII value.
+            /// Initializes a new instance of the <see cref="Grpc.Core.Metadata.Entry"/> struct holding an ASCII value.
             /// </summary>
             /// <param name="key">Metadata key, must not use suffix indicating a binary valued metadata entry.</param>
             /// <param name="value">Value string. Only ASCII characters are allowed.</param>
@@ -280,7 +284,7 @@ namespace Grpc.Core
             }
 
             /// <summary>
-            /// Returns a <see cref="System.String"/> that represents the current <see cref="Grpc.Core.Metadata+Entry"/>.
+            /// Returns a <see cref="System.String"/> that represents the current <see cref="Grpc.Core.Metadata.Entry"/>.
             /// </summary>
             public override string ToString()
             {
diff --git a/src/csharp/Grpc.Core/Method.cs b/src/csharp/Grpc.Core/Method.cs
index 4c53285893..99162a7d5d 100644
--- a/src/csharp/Grpc.Core/Method.cs
+++ b/src/csharp/Grpc.Core/Method.cs
@@ -84,6 +84,8 @@ namespace Grpc.Core
     /// <summary>
     /// A description of a remote method.
     /// </summary>
+    /// <typeparam name="TRequest">Request message type for this method.</typeparam>
+    /// <typeparam name="TResponse">Response message type for this method.</typeparam>
     public class Method<TRequest, TResponse> : IMethod
     {
         readonly MethodType type;
diff --git a/src/csharp/Grpc.Core/Server.cs b/src/csharp/Grpc.Core/Server.cs
index 28f1686e20..7c94d21561 100644
--- a/src/csharp/Grpc.Core/Server.cs
+++ b/src/csharp/Grpc.Core/Server.cs
@@ -44,7 +44,7 @@ using Grpc.Core.Utils;
 namespace Grpc.Core
 {
     /// <summary>
-    /// A gRPC server.
+    /// gRPC server. A single server can server arbitrary number of services and can listen on more than one ports.
     /// </summary>
     public class Server
     {
@@ -324,6 +324,9 @@ namespace Grpc.Core
                 server.AddServiceDefinitionInternal(serviceDefinition);
             }
 
+            /// <summary>
+            /// Gets enumerator for this collection.
+            /// </summary>
             public IEnumerator<ServerServiceDefinition> GetEnumerator()
             {
                 return server.serviceDefinitionsList.GetEnumerator();
@@ -369,6 +372,9 @@ namespace Grpc.Core
                 return Add(new ServerPort(host, port, credentials));
             }
 
+            /// <summary>
+            /// Gets enumerator for this collection.
+            /// </summary>
             public IEnumerator<ServerPort> GetEnumerator()
             {
                 return server.serverPortList.GetEnumerator();
diff --git a/src/csharp/Grpc.Core/ServerCallContext.cs b/src/csharp/Grpc.Core/ServerCallContext.cs
index 75d81c64f3..09a6b882a6 100644
--- a/src/csharp/Grpc.Core/ServerCallContext.cs
+++ b/src/csharp/Grpc.Core/ServerCallContext.cs
@@ -72,6 +72,13 @@ namespace Grpc.Core
             this.writeOptionsHolder = writeOptionsHolder;
         }
 
+        /// <summary>
+        /// Asynchronously sends response headers for the current call to the client. This method may only be invoked once for each call and needs to be invoked
+        /// before any response messages are written. Writing the first response message implicitly sends empty response headers if <c>WriteResponseHeadersAsync</c> haven't
+        /// been called yet.
+        /// </summary>
+        /// <param name="responseHeaders">The response headers to send.</param>
+        /// <returns>The task that finished once response headers have been written.</returns>
         public Task WriteResponseHeadersAsync(Metadata responseHeaders)
         {
             return writeHeadersFunc(responseHeaders);
@@ -186,6 +193,9 @@ namespace Grpc.Core
     /// </summary>
     public interface IHasWriteOptions
     {
+        /// <summary>
+        /// Gets or sets the write options.
+        /// </summary>
         WriteOptions WriteOptions { get; set; }
     }
 }
diff --git a/src/csharp/Grpc.Core/ServerMethods.cs b/src/csharp/Grpc.Core/ServerMethods.cs
index 1f119a80ff..728f77cde5 100644
--- a/src/csharp/Grpc.Core/ServerMethods.cs
+++ b/src/csharp/Grpc.Core/ServerMethods.cs
@@ -38,6 +38,8 @@ namespace Grpc.Core
     /// <summary>
     /// Server-side handler for unary call.
     /// </summary>
+    /// <typeparam name="TRequest">Request message type for this method.</typeparam>
+    /// <typeparam name="TResponse">Response message type for this method.</typeparam>
     public delegate Task<TResponse> UnaryServerMethod<TRequest, TResponse>(TRequest request, ServerCallContext context)
         where TRequest : class
         where TResponse : class;
@@ -45,6 +47,8 @@ namespace Grpc.Core
     /// <summary>
     /// Server-side handler for client streaming call.
     /// </summary>
+    /// <typeparam name="TRequest">Request message type for this method.</typeparam>
+    /// <typeparam name="TResponse">Response message type for this method.</typeparam>
     public delegate Task<TResponse> ClientStreamingServerMethod<TRequest, TResponse>(IAsyncStreamReader<TRequest> requestStream, ServerCallContext context)
         where TRequest : class
         where TResponse : class;
@@ -52,6 +56,8 @@ namespace Grpc.Core
     /// <summary>
     /// Server-side handler for server streaming call.
     /// </summary>
+    /// <typeparam name="TRequest">Request message type for this method.</typeparam>
+    /// <typeparam name="TResponse">Response message type for this method.</typeparam>
     public delegate Task ServerStreamingServerMethod<TRequest, TResponse>(TRequest request, IServerStreamWriter<TResponse> responseStream, ServerCallContext context)
         where TRequest : class
         where TResponse : class;
@@ -59,6 +65,8 @@ namespace Grpc.Core
     /// <summary>
     /// Server-side handler for bidi streaming call.
     /// </summary>
+    /// <typeparam name="TRequest">Request message type for this method.</typeparam>
+    /// <typeparam name="TResponse">Response message type for this method.</typeparam>
     public delegate Task DuplexStreamingServerMethod<TRequest, TResponse>(IAsyncStreamReader<TRequest> requestStream, IServerStreamWriter<TResponse> responseStream, ServerCallContext context)
         where TRequest : class
         where TResponse : class;
diff --git a/src/csharp/Grpc.Core/ServerServiceDefinition.cs b/src/csharp/Grpc.Core/ServerServiceDefinition.cs
index 94b0a320c3..deb1431ca3 100644
--- a/src/csharp/Grpc.Core/ServerServiceDefinition.cs
+++ b/src/csharp/Grpc.Core/ServerServiceDefinition.cs
@@ -40,6 +40,8 @@ namespace Grpc.Core
 {
     /// <summary>
     /// Mapping of method names to server call handlers.
+    /// Normally, the <c>ServerServiceDefinition</c> objects will be created by the <c>BindService</c> factory method 
+    /// that is part of the autogenerated code for a protocol buffers service definition.
     /// </summary>
     public class ServerServiceDefinition
     {
@@ -58,21 +60,41 @@ namespace Grpc.Core
             }
         }
 
+        /// <summary>
+        /// Creates a new builder object for <c>ServerServiceDefinition</c>.
+        /// </summary>
+        /// <param name="serviceName">The service name.</param>
+        /// <returns>The builder object.</returns>
         public static Builder CreateBuilder(string serviceName)
         {
             return new Builder(serviceName);
         }
 
+        /// <summary>
+        /// Builder class for <see cref="ServerServiceDefinition"/>.
+        /// </summary>
         public class Builder
         {
             readonly string serviceName;
             readonly Dictionary<string, IServerCallHandler> callHandlers = new Dictionary<string, IServerCallHandler>();
 
+            /// <summary>
+            /// Creates a new instance of builder.
+            /// </summary>
+            /// <param name="serviceName">The service name.</param>
             public Builder(string serviceName)
             {
                 this.serviceName = serviceName;
             }
 
+            /// <summary>
+            /// Adds a definitions for a single request - single response method.
+            /// </summary>
+            /// <typeparam name="TRequest">The request message class.</typeparam>
+            /// <typeparam name="TResponse">The response message class.</typeparam>
+            /// <param name="method">The method.</param>
+            /// <param name="handler">The method handler.</param>
+            /// <returns>This builder instance.</returns>
             public Builder AddMethod<TRequest, TResponse>(
                 Method<TRequest, TResponse> method,
                 UnaryServerMethod<TRequest, TResponse> handler)
@@ -83,6 +105,14 @@ namespace Grpc.Core
                 return this;
             }
 
+            /// <summary>
+            /// Adds a definitions for a client streaming method.
+            /// </summary>
+            /// <typeparam name="TRequest">The request message class.</typeparam>
+            /// <typeparam name="TResponse">The response message class.</typeparam>
+            /// <param name="method">The method.</param>
+            /// <param name="handler">The method handler.</param>
+            /// <returns>This builder instance.</returns>
             public Builder AddMethod<TRequest, TResponse>(
                 Method<TRequest, TResponse> method,
                 ClientStreamingServerMethod<TRequest, TResponse> handler)
@@ -93,6 +123,14 @@ namespace Grpc.Core
                 return this;
             }
 
+            /// <summary>
+            /// Adds a definitions for a server streaming method.
+            /// </summary>
+            /// <typeparam name="TRequest">The request message class.</typeparam>
+            /// <typeparam name="TResponse">The response message class.</typeparam>
+            /// <param name="method">The method.</param>
+            /// <param name="handler">The method handler.</param>
+            /// <returns>This builder instance.</returns>
             public Builder AddMethod<TRequest, TResponse>(
                 Method<TRequest, TResponse> method,
                 ServerStreamingServerMethod<TRequest, TResponse> handler)
@@ -103,6 +141,14 @@ namespace Grpc.Core
                 return this;
             }
 
+            /// <summary>
+            /// Adds a definitions for a bidirectional streaming method.
+            /// </summary>
+            /// <typeparam name="TRequest">The request message class.</typeparam>
+            /// <typeparam name="TResponse">The response message class.</typeparam>
+            /// <param name="method">The method.</param>
+            /// <param name="handler">The method handler.</param>
+            /// <returns>This builder instance.</returns>
             public Builder AddMethod<TRequest, TResponse>(
                 Method<TRequest, TResponse> method,
                 DuplexStreamingServerMethod<TRequest, TResponse> handler)
@@ -113,6 +159,10 @@ namespace Grpc.Core
                 return this;
             }
 
+            /// <summary>
+            /// Creates an immutable <c>ServerServiceDefinition</c> from this builder.
+            /// </summary>
+            /// <returns>The <c>ServerServiceDefinition</c> object.</returns>
             public ServerServiceDefinition Build()
             {
                 return new ServerServiceDefinition(callHandlers);
diff --git a/src/csharp/Grpc.Core/Utils/Preconditions.cs b/src/csharp/Grpc.Core/Utils/Preconditions.cs
index 374262f87a..a8ab603391 100644
--- a/src/csharp/Grpc.Core/Utils/Preconditions.cs
+++ b/src/csharp/Grpc.Core/Utils/Preconditions.cs
@@ -43,6 +43,7 @@ namespace Grpc.Core.Utils
         /// <summary>
         /// Throws <see cref="ArgumentException"/> if condition is false.
         /// </summary>
+        /// <param name="condition">The condition.</param>
         public static void CheckArgument(bool condition)
         {
             if (!condition)
@@ -54,6 +55,8 @@ namespace Grpc.Core.Utils
         /// <summary>
         /// Throws <see cref="ArgumentException"/> with given message if condition is false.
         /// </summary>
+        /// <param name="condition">The condition.</param>
+        /// <param name="errorMessage">The error message.</param>
         public static void CheckArgument(bool condition, string errorMessage)
         {
             if (!condition)
@@ -65,6 +68,7 @@ namespace Grpc.Core.Utils
         /// <summary>
         /// Throws <see cref="ArgumentNullException"/> if reference is null.
         /// </summary>
+        /// <param name="reference">The reference.</param>
         public static T CheckNotNull<T>(T reference)
         {
             if (reference == null)
@@ -77,6 +81,8 @@ namespace Grpc.Core.Utils
         /// <summary>
         /// Throws <see cref="ArgumentNullException"/> if reference is null.
         /// </summary>
+        /// <param name="reference">The reference.</param>
+        /// <param name="paramName">The parameter name.</param>
         public static T CheckNotNull<T>(T reference, string paramName)
         {
             if (reference == null)
@@ -89,6 +95,7 @@ namespace Grpc.Core.Utils
         /// <summary>
         /// Throws <see cref="InvalidOperationException"/> if condition is false.
         /// </summary>
+        /// <param name="condition">The condition.</param>
         public static void CheckState(bool condition)
         {
             if (!condition)
@@ -100,6 +107,8 @@ namespace Grpc.Core.Utils
         /// <summary>
         /// Throws <see cref="InvalidOperationException"/> with given message if condition is false.
         /// </summary>
+        /// <param name="condition">The condition.</param>
+        /// <param name="errorMessage">The error message.</param>
         public static void CheckState(bool condition, string errorMessage)
         {
             if (!condition)
diff --git a/src/csharp/Grpc.Core/WriteOptions.cs b/src/csharp/Grpc.Core/WriteOptions.cs
index 7ef3189d76..7523ada84a 100644
--- a/src/csharp/Grpc.Core/WriteOptions.cs
+++ b/src/csharp/Grpc.Core/WriteOptions.cs
@@ -66,11 +66,18 @@ namespace Grpc.Core
             
         private WriteFlags flags;
 
+        /// <summary>
+        /// Initializes a new instance of <c>WriteOptions</c> class.
+        /// </summary>
+        /// <param name="flags">The write flags.</param>
         public WriteOptions(WriteFlags flags = default(WriteFlags))
         {
             this.flags = flags;
         }
 
+        /// <summary>
+        /// Gets the write flags.
+        /// </summary>
         public WriteFlags Flags
         {
             get
diff --git a/src/csharp/Grpc.HealthCheck/HealthServiceImpl.cs b/src/csharp/Grpc.HealthCheck/HealthServiceImpl.cs
index 3c3b9c35f1..8c04b43a86 100644
--- a/src/csharp/Grpc.HealthCheck/HealthServiceImpl.cs
+++ b/src/csharp/Grpc.HealthCheck/HealthServiceImpl.cs
@@ -95,6 +95,12 @@ namespace Grpc.HealthCheck
             }
         }
 
+        /// <summary>
+        /// Performs a health status check.
+        /// </summary>
+        /// <param name="request">The check request.</param>
+        /// <param name="context">The call context.</param>
+        /// <returns>The asynchronous response.</returns>
         public Task<HealthCheckResponse> Check(HealthCheckRequest request, ServerCallContext context)
         {
             lock (myLock)
diff --git a/src/csharp/doc/grpc_csharp_public.shfbproj b/src/csharp/doc/grpc_csharp_public.shfbproj
index 05c93f4a13..d9b9749819 100644
--- a/src/csharp/doc/grpc_csharp_public.shfbproj
+++ b/src/csharp/doc/grpc_csharp_public.shfbproj
@@ -18,7 +18,8 @@
     <Language>en-US</Language>
     <DocumentationSources>
       <DocumentationSource sourceFile="..\Grpc.Auth\Grpc.Auth.csproj" />
-<DocumentationSource sourceFile="..\Grpc.Core\Grpc.Core.csproj" /></DocumentationSources>
+      <DocumentationSource sourceFile="..\Grpc.Core\Grpc.Core.csproj" />
+    </DocumentationSources>
     <BuildAssemblerVerbosity>OnlyWarningsAndErrors</BuildAssemblerVerbosity>
     <HelpFileFormat>Website</HelpFileFormat>
     <IndentHtml>False</IndentHtml>
@@ -37,6 +38,15 @@
     <HelpTitle>gRPC C#</HelpTitle>
     <ContentPlacement>AboveNamespaces</ContentPlacement>
     <HtmlHelpName>Documentation</HtmlHelpName>
+    <NamespaceSummaries>
+      <NamespaceSummaryItem name="Grpc.Auth" isDocumented="True">Provides OAuth2 based authentication for gRPC. &lt;c&gt;Grpc.Auth&lt;/c&gt; currently consists of a set of very lightweight wrappers and uses C# &lt;a href="https://www.nuget.org/packages/Google.Apis.Auth/"&gt;Google.Apis.Auth&lt;/a&gt; library.</NamespaceSummaryItem>
+<NamespaceSummaryItem name="Grpc.Core" isDocumented="True">Main namespace for gRPC C# functionality. Contains concepts representing both client side and server side gRPC logic.
+
+&lt;seealso cref="Grpc.Core.Channel"/&gt; 
+&lt;seealso cref="Grpc.Core.Server"/&gt;</NamespaceSummaryItem>
+<NamespaceSummaryItem name="Grpc.Core.Logging" isDocumented="True">Provides functionality to redirect gRPC logs to application-specified destination.</NamespaceSummaryItem>
+<NamespaceSummaryItem name="Grpc.Core.Utils" isDocumented="True">Various utilities for gRPC C#.</NamespaceSummaryItem></NamespaceSummaries>
+    <MissingTags>Summary, Parameter, AutoDocumentCtors, Namespace, TypeParameter, AutoDocumentDispose</MissingTags>
   </PropertyGroup>
   <!-- There are no properties for these groups.  AnyCPU needs to appear in order for Visual Studio to perform
 			 the build.  The others are optional common platform types that may appear. -->
diff --git a/src/csharp/ext/grpc_csharp_ext.c b/src/csharp/ext/grpc_csharp_ext.c
index fc9470f93f..489e219c49 100644
--- a/src/csharp/ext/grpc_csharp_ext.c
+++ b/src/csharp/ext/grpc_csharp_ext.c
@@ -595,7 +595,7 @@ GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_start_server_streaming(
     grpc_call *call, grpcsharp_batch_context *ctx, const char *send_buffer,
     size_t send_buffer_len, grpc_metadata_array *initial_metadata, gpr_uint32 write_flags) {
   /* TODO: don't use magic number */
-  grpc_op ops[5];
+  grpc_op ops[4];
   ops[0].op = GRPC_OP_SEND_INITIAL_METADATA;
   grpcsharp_metadata_array_move(&(ctx->send_initial_metadata),
                                 initial_metadata);
@@ -615,23 +615,18 @@ GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_start_server_streaming(
   ops[2].flags = 0;
   ops[2].reserved = NULL;
 
-  ops[3].op = GRPC_OP_RECV_INITIAL_METADATA;
-  ops[3].data.recv_initial_metadata = &(ctx->recv_initial_metadata);
-  ops[3].flags = 0;
-  ops[3].reserved = NULL;
-
-  ops[4].op = GRPC_OP_RECV_STATUS_ON_CLIENT;
-  ops[4].data.recv_status_on_client.trailing_metadata =
+  ops[3].op = GRPC_OP_RECV_STATUS_ON_CLIENT;
+  ops[3].data.recv_status_on_client.trailing_metadata =
       &(ctx->recv_status_on_client.trailing_metadata);
-  ops[4].data.recv_status_on_client.status =
+  ops[3].data.recv_status_on_client.status =
       &(ctx->recv_status_on_client.status);
   /* not using preallocation for status_details */
-  ops[4].data.recv_status_on_client.status_details =
+  ops[3].data.recv_status_on_client.status_details =
       &(ctx->recv_status_on_client.status_details);
-  ops[4].data.recv_status_on_client.status_details_capacity =
+  ops[3].data.recv_status_on_client.status_details_capacity =
       &(ctx->recv_status_on_client.status_details_capacity);
-  ops[4].flags = 0;
-  ops[4].reserved = NULL;
+  ops[3].flags = 0;
+  ops[3].reserved = NULL;
 
   return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
                                NULL);
@@ -642,7 +637,7 @@ grpcsharp_call_start_duplex_streaming(grpc_call *call,
                                       grpcsharp_batch_context *ctx,
                                       grpc_metadata_array *initial_metadata) {
   /* TODO: don't use magic number */
-  grpc_op ops[3];
+  grpc_op ops[2];
   ops[0].op = GRPC_OP_SEND_INITIAL_METADATA;
   grpcsharp_metadata_array_move(&(ctx->send_initial_metadata),
                                 initial_metadata);
@@ -652,28 +647,36 @@ grpcsharp_call_start_duplex_streaming(grpc_call *call,
   ops[0].flags = 0;
   ops[0].reserved = NULL;
 
-  ops[1].op = GRPC_OP_RECV_INITIAL_METADATA;
-  ops[1].data.recv_initial_metadata = &(ctx->recv_initial_metadata);
-  ops[1].flags = 0;
-  ops[1].reserved = NULL;
-
-  ops[2].op = GRPC_OP_RECV_STATUS_ON_CLIENT;
-  ops[2].data.recv_status_on_client.trailing_metadata =
+  ops[1].op = GRPC_OP_RECV_STATUS_ON_CLIENT;
+  ops[1].data.recv_status_on_client.trailing_metadata =
       &(ctx->recv_status_on_client.trailing_metadata);
-  ops[2].data.recv_status_on_client.status =
+  ops[1].data.recv_status_on_client.status =
       &(ctx->recv_status_on_client.status);
   /* not using preallocation for status_details */
-  ops[2].data.recv_status_on_client.status_details =
+  ops[1].data.recv_status_on_client.status_details =
       &(ctx->recv_status_on_client.status_details);
-  ops[2].data.recv_status_on_client.status_details_capacity =
+  ops[1].data.recv_status_on_client.status_details_capacity =
       &(ctx->recv_status_on_client.status_details_capacity);
-  ops[2].flags = 0;
-  ops[2].reserved = NULL;
+  ops[1].flags = 0;
+  ops[1].reserved = NULL;
 
   return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
                                NULL);
 }
 
+GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_recv_initial_metadata(
+	grpc_call *call, grpcsharp_batch_context *ctx) {
+	/* TODO: don't use magic number */
+	grpc_op ops[1];
+	ops[0].op = GRPC_OP_RECV_INITIAL_METADATA;
+	ops[0].data.recv_initial_metadata = &(ctx->recv_initial_metadata);
+	ops[0].flags = 0;
+	ops[0].reserved = NULL;
+
+	return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
+		NULL);
+}
+
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
 grpcsharp_call_send_message(grpc_call *call, grpcsharp_batch_context *ctx,
                             const char *send_buffer, size_t send_buffer_len,
diff --git a/src/node/ext/server_credentials.cc b/src/node/ext/server_credentials.cc
index 1b8e7b43fb..6e17197e16 100644
--- a/src/node/ext/server_credentials.cc
+++ b/src/node/ext/server_credentials.cc
@@ -41,6 +41,7 @@
 namespace grpc {
 namespace node {
 
+using v8::Array;
 using v8::Exception;
 using v8::External;
 using v8::Function;
@@ -52,6 +53,7 @@ using v8::Local;
 using v8::Object;
 using v8::ObjectTemplate;
 using v8::Persistent;
+using v8::String;
 using v8::Value;
 
 NanCallback *ServerCredentials::constructor;
@@ -122,25 +124,66 @@ NAN_METHOD(ServerCredentials::CreateSsl) {
   // TODO: have the node API support multiple key/cert pairs.
   NanScope();
   char *root_certs = NULL;
-  grpc_ssl_pem_key_cert_pair key_cert_pair;
   if (::node::Buffer::HasInstance(args[0])) {
     root_certs = ::node::Buffer::Data(args[0]);
   } else if (!(args[0]->IsNull() || args[0]->IsUndefined())) {
     return NanThrowTypeError(
         "createSSl's first argument must be a Buffer if provided");
   }
-  if (!::node::Buffer::HasInstance(args[1])) {
-    return NanThrowTypeError("createSsl's second argument must be a Buffer");
+  if (!args[1]->IsArray()) {
+    return NanThrowTypeError(
+        "createSsl's second argument must be a list of objects");
+  }
+  int force_client_auth = 0;
+  if (args[2]->IsBoolean()) {
+    force_client_auth = (int)args[2]->BooleanValue();
+  } else if (!(args[2]->IsUndefined() || args[2]->IsNull())) {
+    return NanThrowTypeError(
+        "createSsl's third argument must be a boolean if provided");
   }
-  key_cert_pair.private_key = ::node::Buffer::Data(args[1]);
-  if (!::node::Buffer::HasInstance(args[2])) {
-    return NanThrowTypeError("createSsl's third argument must be a Buffer");
+  Handle<Array> pair_list = Local<Array>::Cast(args[1]);
+  uint32_t key_cert_pair_count = pair_list->Length();
+  grpc_ssl_pem_key_cert_pair *key_cert_pairs = new grpc_ssl_pem_key_cert_pair[
+      key_cert_pair_count];
+
+  Handle<String> key_key = NanNew("private_key");
+  Handle<String> cert_key = NanNew("cert_chain");
+
+  for(uint32_t i = 0; i < key_cert_pair_count; i++) {
+    if (!pair_list->Get(i)->IsObject()) {
+      delete key_cert_pairs;
+      return NanThrowTypeError("Key/cert pairs must be objects");
+    }
+    Handle<Object> pair_obj = pair_list->Get(i)->ToObject();
+    if (!pair_obj->HasOwnProperty(key_key)) {
+      delete key_cert_pairs;
+      return NanThrowTypeError(
+          "Key/cert pairs must have a private_key and a cert_chain");
+    }
+    if (!pair_obj->HasOwnProperty(cert_key)) {
+      delete key_cert_pairs;
+      return NanThrowTypeError(
+          "Key/cert pairs must have a private_key and a cert_chain");
+    }
+    if (!::node::Buffer::HasInstance(pair_obj->Get(key_key))) {
+      delete key_cert_pairs;
+      return NanThrowTypeError("private_key must be a Buffer");
+    }
+    if (!::node::Buffer::HasInstance(pair_obj->Get(cert_key))) {
+      delete key_cert_pairs;
+      return NanThrowTypeError("cert_chain must be a Buffer");
+    }
+    key_cert_pairs[i].private_key = ::node::Buffer::Data(
+        pair_obj->Get(key_key));
+    key_cert_pairs[i].cert_chain = ::node::Buffer::Data(
+        pair_obj->Get(cert_key));
   }
-  key_cert_pair.cert_chain = ::node::Buffer::Data(args[2]);
-  // TODO Add a force_client_auth parameter and pass it as the last parameter
-  // here.
   grpc_server_credentials *creds =
-      grpc_ssl_server_credentials_create(root_certs, &key_cert_pair, 1, 0);
+      grpc_ssl_server_credentials_create(root_certs,
+                                         key_cert_pairs,
+                                         key_cert_pair_count,
+                                         force_client_auth);
+  delete key_cert_pairs;
   if (creds == NULL) {
     NanReturnNull();
   }
diff --git a/src/node/health_check/health.js b/src/node/health_check/health.js
index 87e00197fe..84d7e0568e 100644
--- a/src/node/health_check/health.js
+++ b/src/node/health_check/health.js
@@ -45,17 +45,13 @@ 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.setStatus = function(service, status) {
+  this.statusMap[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);
+  var status = _.get(this.statusMap, service, null);
   if (status === null) {
     callback({code:grpc.status.NOT_FOUND});
   } else {
diff --git a/src/node/health_check/health.proto b/src/node/health_check/health.proto
index d31df1e0a7..57f4aaa9c0 100644
--- a/src/node/health_check/health.proto
+++ b/src/node/health_check/health.proto
@@ -32,8 +32,7 @@ syntax = "proto3";
 package grpc.health.v1alpha;
 
 message HealthCheckRequest {
-  string host = 1;
-  string service = 2;
+  string service = 1;
 }
 
 message HealthCheckResponse {
@@ -47,4 +46,4 @@ message HealthCheckResponse {
 
 service Health {
   rpc Check(HealthCheckRequest) returns (HealthCheckResponse);
-}
\ No newline at end of file
+}
diff --git a/src/node/interop/interop_server.js b/src/node/interop/interop_server.js
index 1242a0f939..99155e9958 100644
--- a/src/node/interop/interop_server.js
+++ b/src/node/interop/interop_server.js
@@ -169,8 +169,8 @@ function getServer(port, tls) {
     var key_data = fs.readFileSync(key_path);
     var pem_data = fs.readFileSync(pem_path);
     server_creds = grpc.ServerCredentials.createSsl(null,
-                                                    key_data,
-                                                    pem_data);
+                                                    [{private_key: key_data,
+                                                      cert_chain: pem_data}]);
   } else {
     server_creds = grpc.ServerCredentials.createInsecure();
   }
diff --git a/src/node/test/health_test.js b/src/node/test/health_test.js
index be4ef1d251..04959f5f55 100644
--- a/src/node/test/health_test.js
+++ b/src/node/test/health_test.js
@@ -41,13 +41,9 @@ var grpc = require('../');
 
 describe('Health Checking', function() {
   var statusMap = {
-    '': {
-      '': 'SERVING',
-      'grpc.test.TestService': 'NOT_SERVING',
-    },
-    virtual_host: {
-      'grpc.test.TestService': 'SERVING'
-    }
+    '': 'SERVING',
+    'grpc.test.TestServiceNotServing': 'NOT_SERVING',
+    'grpc.test.TestServiceServing': 'SERVING'
   };
   var healthServer = new grpc.Server();
   healthServer.addProtoService(health.service,
@@ -71,15 +67,15 @@ describe('Health Checking', function() {
     });
   });
   it('should say that a disabled service is NOT_SERVING', function(done) {
-    healthClient.check({service: 'grpc.test.TestService'},
+    healthClient.check({service: 'grpc.test.TestServiceNotServing'},
                        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'},
+  it('should say that an enabled service is SERVING', function(done) {
+    healthClient.check({service: 'grpc.test.TestServiceServing'},
                        function(err, response) {
                          assert.ifError(err);
                          assert.strictEqual(response.status, 'SERVING');
@@ -93,12 +89,4 @@ describe('Health Checking', function() {
       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/node/test/server_test.js b/src/node/test/server_test.js
index 20c9a07ffa..78bac8da29 100644
--- a/src/node/test/server_test.js
+++ b/src/node/test/server_test.js
@@ -70,7 +70,9 @@ describe('server', function() {
       var pem_path = path.join(__dirname, '../test/data/server1.pem');
       var key_data = fs.readFileSync(key_path);
       var pem_data = fs.readFileSync(pem_path);
-      var creds = grpc.ServerCredentials.createSsl(null, key_data, pem_data);
+      var creds = grpc.ServerCredentials.createSsl(null,
+                                                   [{private_key: key_data,
+                                                     cert_chain: pem_data}]);
       assert.doesNotThrow(function() {
         port = server.addHttp2Port('0.0.0.0:0', creds);
       });
diff --git a/src/objective-c/tests/GRPCClientTests.m b/src/objective-c/tests/GRPCClientTests.m
index 06581e7599..09a55e0704 100644
--- a/src/objective-c/tests/GRPCClientTests.m
+++ b/src/objective-c/tests/GRPCClientTests.m
@@ -53,6 +53,37 @@ static ProtoMethod *kInexistentMethod;
 static ProtoMethod *kEmptyCallMethod;
 static ProtoMethod *kUnaryCallMethod;
 
+// This is an observer class for testing that responseMetadata is KVO-compliant
+
+@interface PassthroughObserver : NSObject
+
+- (instancetype) initWithCallback:(void (^)(NSString*, id, NSDictionary*))callback;
+
+- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change
+                       context:(void *)context;
+@end
+
+@implementation PassthroughObserver {
+  void (^_callback)(NSString*, id, NSDictionary*);
+}
+
+- (instancetype)initWithCallback:(void (^)(NSString *, id, NSDictionary *))callback {
+  self = [super init];
+  if (self) {
+    _callback = callback;
+  }
+  return self;
+  
+}
+
+- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
+{
+  _callback(keyPath, object, change);
+  [object removeObserver:self forKeyPath:keyPath];
+}
+
+@end
+
 @interface GRPCClientTests : XCTestCase
 @end
 
@@ -183,4 +214,35 @@ static ProtoMethod *kUnaryCallMethod;
   [self waitForExpectationsWithTimeout:4 handler:nil];
 }
 
+- (void)testResponseMetadataKVO {
+  __weak XCTestExpectation *response = [self expectationWithDescription:@"Empty response received."];
+  __weak XCTestExpectation *completion = [self expectationWithDescription:@"Empty RPC completed."];
+  __weak XCTestExpectation *metadata = [self expectationWithDescription:@"Metadata changed."];
+  
+  GRPCCall *call = [[GRPCCall alloc] initWithHost:kHostAddress
+                                             path:kEmptyCallMethod.HTTPPath
+                                   requestsWriter:[GRXWriter writerWithValue:[NSData data]]];
+  
+  PassthroughObserver *observer = [[PassthroughObserver alloc] initWithCallback:^(NSString *keypath, id object, NSDictionary * change) {
+    if ([keypath isEqual: @"responseHeaders"]) {
+      [metadata fulfill];
+    }
+  }];
+  
+  [call addObserver:observer forKeyPath:@"responseHeaders" options:0 context:NULL];
+  
+  id<GRXWriteable> responsesWriteable = [[GRXWriteable alloc] initWithValueHandler:^(NSData *value) {
+    XCTAssertNotNil(value, @"nil value received as response.");
+    XCTAssertEqual([value length], 0, @"Non-empty response received: %@", value);
+    [response fulfill];
+  } completionHandler:^(NSError *errorOrNil) {
+    XCTAssertNil(errorOrNil, @"Finished with unexpected error: %@", errorOrNil);
+    [completion fulfill];
+  }];
+  
+  [call startWithWriteable:responsesWriteable];
+  
+  [self waitForExpectationsWithTimeout:8 handler:nil];
+}
+
 @end
diff --git a/src/python/grpcio/grpc/_adapter/_c/types.h b/src/python/grpcio/grpc/_adapter/_c/types.h
index f646465c63..f6ff957baa 100644
--- a/src/python/grpcio/grpc/_adapter/_c/types.h
+++ b/src/python/grpcio/grpc/_adapter/_c/types.h
@@ -146,6 +146,7 @@ typedef struct Server {
   PyObject_HEAD
   grpc_server *c_serv;
   CompletionQueue *cq;
+  int shutdown_called;
 } Server;
 Server *pygrpc_Server_new(PyTypeObject *type, PyObject *args, PyObject *kwargs);
 void pygrpc_Server_dealloc(Server *self);
@@ -156,6 +157,7 @@ PyObject *pygrpc_Server_add_http2_port(
 PyObject *pygrpc_Server_start(Server *self, PyObject *ignored);
 PyObject *pygrpc_Server_shutdown(
     Server *self, PyObject *args, PyObject *kwargs);
+PyObject *pygrpc_Server_cancel_all_calls(Server *self, PyObject *unused);
 extern PyTypeObject pygrpc_Server_type;
 
 /*=========*/
diff --git a/src/python/grpcio/grpc/_adapter/_c/types/server.c b/src/python/grpcio/grpc/_adapter/_c/types/server.c
index 15c98f28eb..8feab8aab1 100644
--- a/src/python/grpcio/grpc/_adapter/_c/types/server.c
+++ b/src/python/grpcio/grpc/_adapter/_c/types/server.c
@@ -45,6 +45,8 @@ PyMethodDef pygrpc_Server_methods[] = {
      METH_KEYWORDS, ""},
     {"start", (PyCFunction)pygrpc_Server_start, METH_NOARGS, ""},
     {"shutdown", (PyCFunction)pygrpc_Server_shutdown, METH_KEYWORDS, ""},
+    {"cancel_all_calls", (PyCFunction)pygrpc_Server_cancel_all_calls,
+     METH_NOARGS, ""},
     {NULL}
 };
 const char pygrpc_Server_doc[] = "See grpc._adapter._types.Server.";
@@ -109,6 +111,7 @@ Server *pygrpc_Server_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
   pygrpc_discard_channel_args(c_args);
   self->cq = cq;
   Py_INCREF(self->cq);
+  self->shutdown_called = 0;
   return self;
 }
 
@@ -163,6 +166,7 @@ PyObject *pygrpc_Server_add_http2_port(
 
 PyObject *pygrpc_Server_start(Server *self, PyObject *ignored) {
   grpc_server_start(self->c_serv);
+  self->shutdown_called = 0;
   Py_RETURN_NONE;
 }
 
@@ -176,5 +180,17 @@ PyObject *pygrpc_Server_shutdown(
   }
   tag = pygrpc_produce_server_shutdown_tag(user_tag);
   grpc_server_shutdown_and_notify(self->c_serv, self->cq->c_cq, tag);
+  self->shutdown_called = 1;
+  Py_RETURN_NONE;
+}
+
+PyObject *pygrpc_Server_cancel_all_calls(Server *self, PyObject *unused) {
+  if (!self->shutdown_called) {
+    PyErr_SetString(
+        PyExc_RuntimeError,
+        "shutdown must have been called prior to calling cancel_all_calls!");
+    return NULL;
+  }
+  grpc_server_cancel_all_calls(self->c_serv);
   Py_RETURN_NONE;
 }
diff --git a/src/python/grpcio/grpc/_adapter/_low.py b/src/python/grpcio/grpc/_adapter/_low.py
index 147086e725..3859ebb0e2 100644
--- a/src/python/grpcio/grpc/_adapter/_low.py
+++ b/src/python/grpcio/grpc/_adapter/_low.py
@@ -124,3 +124,6 @@ class Server(_types.Server):
 
   def request_call(self, completion_queue, tag):
     return self.server.request_call(completion_queue.completion_queue, tag)
+
+  def cancel_all_calls(self):
+    return self.server.cancel_all_calls()
diff --git a/src/python/grpcio/grpc/_links/invocation.py b/src/python/grpcio/grpc/_links/invocation.py
index 0058ae91f8..ee3d72fdbc 100644
--- a/src/python/grpcio/grpc/_links/invocation.py
+++ b/src/python/grpcio/grpc/_links/invocation.py
@@ -101,7 +101,7 @@ class _Kernel(object):
     else:
       ticket = links.Ticket(
           operation_id, rpc_state.sequence_number, None, None, None, None, 1,
-          None, None, None, None, None, None)
+          None, None, None, None, None, None, None)
       rpc_state.sequence_number += 1
       self._relay.add_value(ticket)
       rpc_state.low_write = _LowWrite.OPEN
@@ -118,7 +118,7 @@ class _Kernel(object):
       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)
+          None, None)
       rpc_state.sequence_number += 1
       self._relay.add_value(ticket)
 
@@ -129,7 +129,7 @@ class _Kernel(object):
     ticket = links.Ticket(
         operation_id, rpc_state.sequence_number, None, None,
         links.Ticket.Subscription.FULL, None, None, event.metadata, None, None,
-        None, None, None)
+        None, None, None, None)
     rpc_state.sequence_number += 1
     self._relay.add_value(ticket)
 
@@ -141,12 +141,14 @@ class _Kernel(object):
       termination = links.Ticket.Termination.CANCELLATION
     elif event.status.code is _intermediary_low.Code.DEADLINE_EXCEEDED:
       termination = links.Ticket.Termination.EXPIRATION
+    elif event.status.code is _intermediary_low.Code.UNKNOWN:
+      termination = links.Ticket.Termination.LOCAL_FAILURE
     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)
+        termination, None)
     rpc_state.sequence_number += 1
     self._relay.add_value(ticket)
 
@@ -349,7 +351,7 @@ def invocation_link(channel, host, request_serializers, response_deserializers):
   """Creates an InvocationLink.
 
   Args:
-    channel: A channel for use by the link.
+    channel: An _intermediary_low.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.
diff --git a/src/python/grpcio/grpc/_links/service.py b/src/python/grpcio/grpc/_links/service.py
index 5c636d61ab..43c4c0e80c 100644
--- a/src/python/grpcio/grpc/_links/service.py
+++ b/src/python/grpcio/grpc/_links/service.py
@@ -40,6 +40,19 @@ from grpc.framework.foundation import logging_pool
 from grpc.framework.foundation import relay
 from grpc.framework.interfaces.links import links
 
+_TERMINATION_KIND_TO_CODE = {
+    links.Ticket.Termination.COMPLETION: _intermediary_low.Code.OK,
+    links.Ticket.Termination.CANCELLATION: _intermediary_low.Code.CANCELLED,
+    links.Ticket.Termination.EXPIRATION:
+        _intermediary_low.Code.DEADLINE_EXCEEDED,
+    links.Ticket.Termination.SHUTDOWN: _intermediary_low.Code.UNAVAILABLE,
+    links.Ticket.Termination.RECEPTION_FAILURE: _intermediary_low.Code.INTERNAL,
+    links.Ticket.Termination.TRANSMISSION_FAILURE:
+        _intermediary_low.Code.INTERNAL,
+    links.Ticket.Termination.LOCAL_FAILURE: _intermediary_low.Code.UNKNOWN,
+    links.Ticket.Termination.REMOTE_FAILURE: _intermediary_low.Code.UNKNOWN,
+}
+
 
 @enum.unique
 class _Read(enum.Enum):
@@ -93,6 +106,15 @@ def _metadatafy(call, metadata):
     call.add_metadata(metadata_key, metadata_value)
 
 
+def _status(termination_kind, code, details):
+  effective_details = b'' if details is None else details
+  if code is None:
+    effective_code = _TERMINATION_KIND_TO_CODE[termination_kind]
+  else:
+    effective_code = code
+  return _intermediary_low.Status(effective_code, effective_details)
+
+
 class _Kernel(object):
 
   def __init__(self, request_deserializers, response_serializers, ticket_relay):
@@ -131,7 +153,7 @@ class _Kernel(object):
     ticket = links.Ticket(
         call, 0, group, method, links.Ticket.Subscription.FULL,
         service_acceptance.deadline - time.time(), None, event.metadata, None,
-        None, None, None, None)
+        None, None, None, None, 'TODO: Service Context Object!')
     self._relay.add_value(ticket)
 
   def _on_read_event(self, event):
@@ -157,7 +179,7 @@ class _Kernel(object):
         # rpc_state.read = _Read.AWAITING_ALLOWANCE
     ticket = links.Ticket(
         call, rpc_state.sequence_number, None, None, None, None, None, None,
-        payload, None, None, None, termination)
+        payload, None, None, None, termination, None)
     rpc_state.sequence_number += 1
     self._relay.add_value(ticket)
 
@@ -170,13 +192,15 @@ class _Kernel(object):
     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)
+      status = _status(
+          links.Ticket.Termination.COMPLETION, rpc_state.code,
+          rpc_state.message)
+      call.status(status, 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)
+          None, None, None, None, None, None)
       rpc_state.sequence_number += 1
       self._relay.add_value(ticket)
       rpc_state.low_write = _LowWrite.OPEN
@@ -198,7 +222,7 @@ class _Kernel(object):
       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)
+        None, None, None, None, termination, None)
     rpc_state.sequence_number += 1
     self._relay.add_value(ticket)
 
@@ -239,7 +263,7 @@ class _Kernel(object):
       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.termination is not None or
             ticket.code is not None or
             ticket.message is not None):
           call.premetadata()
@@ -257,11 +281,11 @@ class _Kernel(object):
             termination = None
           else:
             termination = links.Ticket.Termination.COMPLETION
-          ticket = links.Ticket(
+          early_read_ticket = links.Ticket(
               call, rpc_state.sequence_number, None, None, None, None, None,
-              None, payload, None, None, None, termination)
+              None, payload, None, None, None, termination, None)
           rpc_state.sequence_number += 1
-          self._relay.add_value(ticket)
+          self._relay.add_value(early_read_ticket)
 
       if ticket.payload is not None:
         call.write(rpc_state.response_serializer(ticket.payload), call)
@@ -279,14 +303,17 @@ class _Kernel(object):
         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)
+          status = _status(
+              links.Ticket.Termination.COMPLETION, rpc_state.code,
+              rpc_state.message)
           call.status(status, call)
           rpc_state.low_write = _LowWrite.CLOSED
       elif ticket.termination is not None:
-        call.cancel()
+        if rpc_state.terminal_metadata is not None:
+          _metadatafy(call, rpc_state.terminal_metadata)
+        status = _status(
+            ticket.termination, rpc_state.code, rpc_state.message)
+        call.status(status, call)
         self._rpc_states.pop(call, None)
 
   def add_port(self, port, server_credentials):
diff --git a/src/python/grpcio/grpc/framework/core/__init__.py b/src/python/grpcio/grpc/framework/core/__init__.py
new file mode 100644
index 0000000000..7086519106
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/__init__.py
@@ -0,0 +1,30 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
diff --git a/src/python/grpcio/grpc/framework/core/_constants.py b/src/python/grpcio/grpc/framework/core/_constants.py
new file mode 100644
index 0000000000..d3be3a4c4a
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/_constants.py
@@ -0,0 +1,59 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Private constants for the package."""
+
+from grpc.framework.interfaces.base import base
+from grpc.framework.interfaces.links import links
+
+TICKET_SUBSCRIPTION_FOR_BASE_SUBSCRIPTION_KIND = {
+    base.Subscription.Kind.NONE: links.Ticket.Subscription.NONE,
+    base.Subscription.Kind.TERMINATION_ONLY:
+        links.Ticket.Subscription.TERMINATION,
+    base.Subscription.Kind.FULL: links.Ticket.Subscription.FULL,
+    }
+
+# Mapping from abortive operation outcome to ticket termination to be
+# sent to the other side of the operation, or None to indicate that no
+# ticket should be sent to the other side in the event of such an
+# outcome.
+ABORTION_OUTCOME_TO_TICKET_TERMINATION = {
+    base.Outcome.CANCELLED: links.Ticket.Termination.CANCELLATION,
+    base.Outcome.EXPIRED: links.Ticket.Termination.EXPIRATION,
+    base.Outcome.LOCAL_SHUTDOWN: links.Ticket.Termination.SHUTDOWN,
+    base.Outcome.REMOTE_SHUTDOWN: None,
+    base.Outcome.RECEPTION_FAILURE: links.Ticket.Termination.RECEPTION_FAILURE,
+    base.Outcome.TRANSMISSION_FAILURE: None,
+    base.Outcome.LOCAL_FAILURE: links.Ticket.Termination.LOCAL_FAILURE,
+    base.Outcome.REMOTE_FAILURE: links.Ticket.Termination.REMOTE_FAILURE,
+}
+
+INTERNAL_ERROR_LOG_MESSAGE = ':-( RPC Framework (Core) internal error! )-:'
+TERMINATION_CALLBACK_EXCEPTION_LOG_MESSAGE = (
+    'Exception calling termination callback!')
diff --git a/src/python/grpcio/grpc/framework/core/_context.py b/src/python/grpcio/grpc/framework/core/_context.py
new file mode 100644
index 0000000000..24a12b612e
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/_context.py
@@ -0,0 +1,92 @@
+# 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 for operation context."""
+
+import time
+
+# _interfaces is referenced from specification in this module.
+from grpc.framework.core import _interfaces  # pylint: disable=unused-import
+from grpc.framework.interfaces.base import base
+
+
+class OperationContext(base.OperationContext):
+  """An implementation of interfaces.OperationContext."""
+
+  def __init__(
+      self, lock, termination_manager, transmission_manager,
+      expiration_manager):
+    """Constructor.
+
+    Args:
+      lock: The operation-wide lock.
+      termination_manager: The _interfaces.TerminationManager for the operation.
+      transmission_manager: The _interfaces.TransmissionManager for the
+        operation.
+      expiration_manager: The _interfaces.ExpirationManager for the operation.
+    """
+    self._lock = lock
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._expiration_manager = expiration_manager
+
+  def _abort(self, outcome):
+    with self._lock:
+      if self._termination_manager.outcome is None:
+        self._termination_manager.abort(outcome)
+        self._transmission_manager.abort(outcome)
+        self._expiration_manager.terminate()
+
+  def outcome(self):
+    """See base.OperationContext.outcome for specification."""
+    with self._lock:
+      return self._termination_manager.outcome
+
+  def add_termination_callback(self, callback):
+    """See base.OperationContext.add_termination_callback."""
+    with self._lock:
+      if self._termination_manager.outcome is None:
+        self._termination_manager.add_callback(callback)
+        return None
+      else:
+        return self._termination_manager.outcome
+
+  def time_remaining(self):
+    """See base.OperationContext.time_remaining for specification."""
+    with self._lock:
+      deadline = self._expiration_manager.deadline()
+    return max(0.0, deadline - time.time())
+
+  def cancel(self):
+    """See base.OperationContext.cancel for specification."""
+    self._abort(base.Outcome.CANCELLED)
+
+  def fail(self, exception):
+    """See base.OperationContext.fail for specification."""
+    self._abort(base.Outcome.LOCAL_FAILURE)
diff --git a/src/python/grpcio/grpc/framework/core/_emission.py b/src/python/grpcio/grpc/framework/core/_emission.py
new file mode 100644
index 0000000000..7c702ab2ce
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/_emission.py
@@ -0,0 +1,97 @@
+# 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 for handling emitted values."""
+
+from grpc.framework.core import _interfaces
+from grpc.framework.interfaces.base import base
+
+
+class EmissionManager(_interfaces.EmissionManager):
+  """An EmissionManager implementation."""
+
+  def __init__(
+      self, lock, termination_manager, transmission_manager,
+      expiration_manager):
+    """Constructor.
+
+    Args:
+      lock: The operation-wide lock.
+      termination_manager: The _interfaces.TerminationManager for the operation.
+      transmission_manager: The _interfaces.TransmissionManager for the
+        operation.
+      expiration_manager: The _interfaces.ExpirationManager for the operation.
+    """
+    self._lock = lock
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._expiration_manager = expiration_manager
+    self._ingestion_manager = None
+
+    self._initial_metadata_seen = False
+    self._payload_seen = False
+    self._completion_seen = False
+
+  def set_ingestion_manager(self, ingestion_manager):
+    """Sets the ingestion manager with which this manager will cooperate.
+
+    Args:
+      ingestion_manager: The _interfaces.IngestionManager for the operation.
+    """
+    self._ingestion_manager = ingestion_manager
+
+  def advance(
+      self, initial_metadata=None, payload=None, completion=None,
+      allowance=None):
+    initial_metadata_present = initial_metadata is not None
+    payload_present = payload is not None
+    completion_present = completion is not None
+    allowance_present = allowance is not None
+    with self._lock:
+      if self._termination_manager.outcome is None:
+        if (initial_metadata_present and (
+                self._initial_metadata_seen or self._payload_seen or
+                self._completion_seen) or
+            payload_present and self._completion_seen or
+            completion_present and self._completion_seen or
+            allowance_present and allowance <= 0):
+          self._termination_manager.abort(base.Outcome.LOCAL_FAILURE)
+          self._transmission_manager.abort(base.Outcome.LOCAL_FAILURE)
+          self._expiration_manager.terminate()
+        else:
+          self._initial_metadata_seen |= initial_metadata_present
+          self._payload_seen |= payload_present
+          self._completion_seen |= completion_present
+          if completion_present:
+            self._termination_manager.emission_complete()
+            self._ingestion_manager.local_emissions_done()
+          self._transmission_manager.advance(
+              initial_metadata, payload, completion, allowance)
+          if allowance_present:
+            self._ingestion_manager.add_local_allowance(allowance)
diff --git a/src/python/grpcio/grpc/framework/core/_end.py b/src/python/grpcio/grpc/framework/core/_end.py
new file mode 100644
index 0000000000..fb2c532df6
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/_end.py
@@ -0,0 +1,251 @@
+# 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.
+
+"""Implementation of base.End."""
+
+import abc
+import enum
+import threading
+import uuid
+
+from grpc.framework.core import _operation
+from grpc.framework.core import _utilities
+from grpc.framework.foundation import callable_util
+from grpc.framework.foundation import later
+from grpc.framework.foundation import logging_pool
+from grpc.framework.interfaces.base import base
+from grpc.framework.interfaces.links import links
+from grpc.framework.interfaces.links import utilities
+
+_IDLE_ACTION_EXCEPTION_LOG_MESSAGE = 'Exception calling idle action!'
+
+
+class End(base.End, links.Link):
+  """A bridge between base.End and links.Link.
+
+  Implementations of this interface translate arriving tickets into
+  calls on application objects implementing base interfaces and
+  translate calls from application objects implementing base interfaces
+  into tickets sent to a joined link.
+  """
+  __metaclass__ = abc.ABCMeta
+
+
+class _Cycle(object):
+  """State for a single start-stop End lifecycle."""
+
+  def __init__(self, pool):
+    self.pool = pool
+    self.grace = False
+    self.futures = []
+    self.operations = {}
+    self.idle_actions = []
+
+
+def _abort(operations):
+  for operation in operations:
+    operation.abort(base.Outcome.LOCAL_SHUTDOWN)
+
+
+def _cancel_futures(futures):
+  for future in futures:
+    futures.cancel()
+
+
+def _future_shutdown(lock, cycle, event):
+  def in_future():
+    with lock:
+      _abort(cycle.operations.values())
+      _cancel_futures(cycle.futures)
+      pool = cycle.pool
+    cycle.pool.shutdown(wait=True)
+  return in_future
+
+
+def _termination_action(lock, stats, operation_id, cycle):
+  """Constructs the termination action for a single operation.
+
+  Args:
+    lock: A lock to hold during the termination action.
+    states: A mapping from base.Outcome values to integers to increment with
+      the outcome given to the termination action.
+    operation_id: The operation ID for the termination action.
+    cycle: A _Cycle value to be updated during the termination action.
+
+  Returns:
+    A callable that takes an operation outcome as its sole parameter and that
+      should be used as the termination action for the operation associated
+      with the given operation ID.
+  """
+  def termination_action(outcome):
+    with lock:
+      stats[outcome] += 1
+      cycle.operations.pop(operation_id, None)
+      if not cycle.operations:
+        for action in cycle.idle_actions:
+          cycle.pool.submit(action)
+        cycle.idle_actions = []
+        if cycle.grace:
+          _cancel_futures(cycle.futures)
+  return termination_action
+
+
+class _End(End):
+  """An End implementation."""
+
+  def __init__(self, servicer_package):
+    """Constructor.
+
+    Args:
+      servicer_package: A _ServicerPackage for servicing operations or None if
+        this end will not be used to service operations.
+    """
+    self._lock = threading.Condition()
+    self._servicer_package = servicer_package
+
+    self._stats = {outcome: 0 for outcome in base.Outcome}
+
+    self._mate = None
+
+    self._cycle = None
+
+  def start(self):
+    """See base.End.start for specification."""
+    with self._lock:
+      if self._cycle is not None:
+        raise ValueError('Tried to start a not-stopped End!')
+      else:
+        self._cycle = _Cycle(logging_pool.pool(1))
+
+  def stop(self, grace):
+    """See base.End.stop for specification."""
+    with self._lock:
+      if self._cycle is None:
+        event = threading.Event()
+        event.set()
+        return event
+      elif not self._cycle.operations:
+        event = threading.Event()
+        self._cycle.pool.submit(event.set)
+        self._cycle.pool.shutdown(wait=False)
+        self._cycle = None
+        return event
+      else:
+        self._cycle.grace = True
+        event = threading.Event()
+        self._cycle.idle_actions.append(event.set)
+        if 0 < grace:
+          future = later.later(
+              grace, _future_shutdown(self._lock, self._cycle, event))
+          self._cycle.futures.append(future)
+        else:
+          _abort(self._cycle.operations.values())
+        return event
+
+  def operate(
+      self, group, method, subscription, timeout, initial_metadata=None,
+      payload=None, completion=None):
+    """See base.End.operate for specification."""
+    operation_id = uuid.uuid4()
+    with self._lock:
+      if self._cycle is None or self._cycle.grace:
+        raise ValueError('Can\'t operate on stopped or stopping End!')
+      termination_action = _termination_action(
+          self._lock, self._stats, operation_id, self._cycle)
+      operation = _operation.invocation_operate(
+          operation_id, group, method, subscription, timeout, initial_metadata,
+          payload, completion, self._mate.accept_ticket, termination_action,
+          self._cycle.pool)
+      self._cycle.operations[operation_id] = operation
+      return operation.context, operation.operator
+
+  def operation_stats(self):
+    """See base.End.operation_stats for specification."""
+    with self._lock:
+      return dict(self._stats)
+
+  def add_idle_action(self, action):
+    """See base.End.add_idle_action for specification."""
+    with self._lock:
+      if self._cycle is None:
+        raise ValueError('Can\'t add idle action to stopped End!')
+      action_with_exceptions_logged = callable_util.with_exceptions_logged(
+          action, _IDLE_ACTION_EXCEPTION_LOG_MESSAGE)
+      if self._cycle.operations:
+        self._cycle.idle_actions.append(action_with_exceptions_logged)
+      else:
+        self._cycle.pool.submit(action_with_exceptions_logged)
+
+  def accept_ticket(self, ticket):
+    """See links.Link.accept_ticket for specification."""
+    with self._lock:
+      if self._cycle is not None and not self._cycle.grace:
+        operation = self._cycle.operations.get(ticket.operation_id)
+        if operation is not None:
+          operation.handle_ticket(ticket)
+        elif self._servicer_package is not None:
+          termination_action = _termination_action(
+              self._lock, self._stats, ticket.operation_id, self._cycle)
+          operation = _operation.service_operate(
+              self._servicer_package, ticket, self._mate.accept_ticket,
+              termination_action, self._cycle.pool)
+          if operation is not None:
+            self._cycle.operations[ticket.operation_id] = operation
+
+  def join_link(self, link):
+    """See links.Link.join_link for specification."""
+    with self._lock:
+      self._mate = utilities.NULL_LINK if link is None else link
+
+
+def serviceless_end_link():
+  """Constructs an End usable only for invoking operations.
+
+  Returns:
+    An End usable for translating operations into ticket exchange.
+  """
+  return _End(None)
+
+
+def serviceful_end_link(servicer, default_timeout, maximum_timeout):
+  """Constructs an End capable of servicing operations.
+
+  Args:
+    servicer: An interfaces.Servicer for servicing operations.
+    default_timeout: A length of time in seconds to be used as the default
+      time alloted for a single operation.
+    maximum_timeout: A length of time in seconds to be used as the maximum
+      time alloted for a single operation.
+
+  Returns:
+    An End capable of servicing the operations requested of it through ticket
+      exchange.
+  """
+  return _End(
+      _utilities.ServicerPackage(servicer, default_timeout, maximum_timeout))
diff --git a/src/python/grpcio/grpc/framework/core/_expiration.py b/src/python/grpcio/grpc/framework/core/_expiration.py
new file mode 100644
index 0000000000..d94bdf2d2b
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/_expiration.py
@@ -0,0 +1,152 @@
+# 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 for operation expiration."""
+
+import time
+
+from grpc.framework.core import _interfaces
+from grpc.framework.foundation import later
+from grpc.framework.interfaces.base import base
+
+
+class _ExpirationManager(_interfaces.ExpirationManager):
+  """An implementation of _interfaces.ExpirationManager."""
+
+  def __init__(
+      self, commencement, timeout, maximum_timeout, lock, termination_manager,
+      transmission_manager):
+    """Constructor.
+
+    Args:
+      commencement: The time in seconds since the epoch at which the operation
+        began.
+      timeout: A length of time in seconds to allow for the operation to run.
+      maximum_timeout: The maximum length of time in seconds to allow for the
+        operation to run despite what is requested via this object's
+        change_timout method.
+      lock: The operation-wide lock.
+      termination_manager: The _interfaces.TerminationManager for the operation.
+      transmission_manager: The _interfaces.TransmissionManager for the
+        operation.
+    """
+    self._lock = lock
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._commencement = commencement
+    self._maximum_timeout = maximum_timeout
+
+    self._timeout = timeout
+    self._deadline = commencement + timeout
+    self._index = None
+    self._future = None
+
+  def _expire(self, index):
+    def expire():
+      with self._lock:
+        if self._future is not None and index == self._index:
+          self._future = None
+          self._termination_manager.expire()
+          self._transmission_manager.abort(base.Outcome.EXPIRED)
+    return expire
+
+  def start(self):
+    self._index = 0
+    self._future = later.later(self._timeout, self._expire(0))
+
+  def change_timeout(self, timeout):
+    if self._future is not None and timeout != self._timeout:
+      self._future.cancel()
+      new_timeout = min(timeout, self._maximum_timeout)
+      new_index = self._index + 1
+      self._timeout = new_timeout
+      self._deadline = self._commencement + new_timeout
+      self._index = new_index
+      delay = self._deadline - time.time()
+      self._future = later.later(delay, self._expire(new_index))
+      if new_timeout != timeout:
+        self._transmission_manager.timeout(new_timeout)
+
+  def deadline(self):
+    return self._deadline
+
+  def terminate(self):
+    if self._future:
+      self._future.cancel()
+      self._future = None
+    self._deadline_index = None
+
+
+def invocation_expiration_manager(
+    timeout, lock, termination_manager, transmission_manager):
+  """Creates an _interfaces.ExpirationManager appropriate for front-side use.
+
+  Args:
+    timeout: A length of time in seconds to allow for the operation to run.
+    lock: The operation-wide lock.
+    termination_manager: The _interfaces.TerminationManager for the operation.
+    transmission_manager: The _interfaces.TransmissionManager for the
+      operation.
+
+  Returns:
+    An _interfaces.ExpirationManager appropriate for invocation-side use.
+  """
+  expiration_manager = _ExpirationManager(
+      time.time(), timeout, timeout, lock, termination_manager,
+      transmission_manager)
+  expiration_manager.start()
+  return expiration_manager
+
+
+def service_expiration_manager(
+    timeout, default_timeout, maximum_timeout, lock, termination_manager,
+    transmission_manager):
+  """Creates an _interfaces.ExpirationManager appropriate for back-side use.
+
+  Args:
+    timeout: A length of time in seconds to allow for the operation to run. May
+      be None in which case default_timeout will be used.
+    default_timeout: The default length of time in seconds to allow for the
+      operation to run if the front-side customer has not specified such a value
+      (or if the value they specified is not yet known).
+    maximum_timeout: The maximum length of time in seconds to allow for the
+      operation to run.
+    lock: The operation-wide lock.
+    termination_manager: The _interfaces.TerminationManager for the operation.
+    transmission_manager: The _interfaces.TransmissionManager for the
+      operation.
+
+  Returns:
+    An _interfaces.ExpirationManager appropriate for service-side use.
+  """
+  expiration_manager = _ExpirationManager(
+      time.time(), default_timeout if timeout is None else timeout,
+      maximum_timeout, lock, termination_manager, transmission_manager)
+  expiration_manager.start()
+  return expiration_manager
diff --git a/src/python/grpcio/grpc/framework/core/_ingestion.py b/src/python/grpcio/grpc/framework/core/_ingestion.py
new file mode 100644
index 0000000000..59f7f8adc8
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/_ingestion.py
@@ -0,0 +1,410 @@
+# 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 for ingestion during an operation."""
+
+import abc
+import collections
+
+from grpc.framework.core import _constants
+from grpc.framework.core import _interfaces
+from grpc.framework.foundation import abandonment
+from grpc.framework.foundation import callable_util
+from grpc.framework.interfaces.base import base
+
+_CREATE_SUBSCRIPTION_EXCEPTION_LOG_MESSAGE = 'Exception initializing ingestion!'
+_INGESTION_EXCEPTION_LOG_MESSAGE = 'Exception during ingestion!'
+
+
+class _SubscriptionCreation(collections.namedtuple(
+    '_SubscriptionCreation', ('subscription', 'remote_error', 'abandoned'))):
+  """A sum type for the outcome of ingestion initialization.
+
+  Either subscription will be non-None, remote_error will be True, or abandoned
+  will be True.
+
+  Attributes:
+    subscription: A base.Subscription describing the customer's interest in
+      operation values from the other side.
+    remote_error: A boolean indicating that the subscription could not be
+      created due to an error on the remote side of the operation.
+    abandoned: A boolean indicating that subscription creation was abandoned.
+  """
+
+
+class _SubscriptionCreator(object):
+  """Common specification of subscription-creating behavior."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def create(self, group, method):
+    """Creates the base.Subscription of the local customer.
+
+    Any exceptions raised by this method should be attributed to and treated as
+    defects in the customer code called by this method.
+
+    Args:
+      group: The group identifier of the operation.
+      method: The method identifier of the operation.
+
+    Returns:
+      A _SubscriptionCreation describing the result of subscription creation.
+    """
+    raise NotImplementedError()
+
+
+class _ServiceSubscriptionCreator(_SubscriptionCreator):
+  """A _SubscriptionCreator appropriate for service-side use."""
+
+  def __init__(self, servicer, operation_context, output_operator):
+    """Constructor.
+
+    Args:
+      servicer: The base.Servicer that will service the operation.
+      operation_context: A base.OperationContext for the operation to be passed
+        to the customer.
+      output_operator: A base.Operator for the operation to be passed to the
+        customer and to be called by the customer to accept operation data
+        emitted by the customer.
+    """
+    self._servicer = servicer
+    self._operation_context = operation_context
+    self._output_operator = output_operator
+
+  def create(self, group, method):
+    try:
+      subscription = self._servicer.service(
+          group, method, self._operation_context, self._output_operator)
+    except base.NoSuchMethodError:
+      return _SubscriptionCreation(None, True, False)
+    except abandonment.Abandoned:
+      return _SubscriptionCreation(None, False, True)
+    else:
+      return _SubscriptionCreation(subscription, False, False)
+
+
+def _wrap(behavior):
+  def wrapped(*args, **kwargs):
+    try:
+      behavior(*args, **kwargs)
+    except abandonment.Abandoned:
+      return False
+    else:
+      return True
+  return wrapped
+
+
+class _IngestionManager(_interfaces.IngestionManager):
+  """An implementation of _interfaces.IngestionManager."""
+
+  def __init__(
+      self, lock, pool, subscription, subscription_creator, termination_manager,
+      transmission_manager, expiration_manager):
+    """Constructor.
+
+    Args:
+      lock: The operation-wide lock.
+      pool: A thread pool in which to execute customer code.
+      subscription: A base.Subscription describing the customer's interest in
+        operation values from the other side. May be None if
+        subscription_creator is not None.
+      subscription_creator: A _SubscriptionCreator wrapping the portion of
+        customer code that when called returns the base.Subscription describing
+        the customer's interest in operation values from the other side. May be
+        None if subscription is not None.
+      termination_manager: The _interfaces.TerminationManager for the operation.
+      transmission_manager: The _interfaces.TransmissionManager for the
+        operation.
+      expiration_manager: The _interfaces.ExpirationManager for the operation.
+    """
+    self._lock = lock
+    self._pool = pool
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._expiration_manager = expiration_manager
+
+    if subscription is None:
+      self._subscription_creator = subscription_creator
+      self._wrapped_operator = None
+    elif subscription.kind is base.Subscription.Kind.FULL:
+      self._subscription_creator = None
+      self._wrapped_operator = _wrap(subscription.operator.advance)
+    else:
+      # TODO(nathaniel): Support other subscriptions.
+      raise ValueError('Unsupported subscription "%s"!' % subscription.kind)
+    self._pending_initial_metadata = None
+    self._pending_payloads = []
+    self._pending_completion = None
+    self._local_allowance = 1
+    # A nonnegative integer or None, with None indicating that the local
+    # customer is done emitting anyway so there's no need to bother it by
+    # informing it that the remote customer has granted it further permission to
+    # emit.
+    self._remote_allowance = 0
+    self._processing = False
+
+  def _abort_internal_only(self):
+    self._subscription_creator = None
+    self._wrapped_operator = None
+    self._pending_initial_metadata = None
+    self._pending_payloads = None
+    self._pending_completion = None
+
+  def _abort_and_notify(self, outcome):
+    self._abort_internal_only()
+    self._termination_manager.abort(outcome)
+    self._transmission_manager.abort(outcome)
+    self._expiration_manager.terminate()
+
+  def _operator_next(self):
+    """Computes the next step for full-subscription ingestion.
+
+    Returns:
+      An initial_metadata, payload, completion, allowance, continue quintet
+        indicating what operation values (if any) are available to pass into
+        customer code and whether or not there is anything immediately
+        actionable to call customer code to do.
+    """
+    if self._wrapped_operator is None:
+      return None, None, None, None, False
+    else:
+      initial_metadata, payload, completion, allowance, action = [None] * 5
+      if self._pending_initial_metadata is not None:
+        initial_metadata = self._pending_initial_metadata
+        self._pending_initial_metadata = None
+        action = True
+      if self._pending_payloads and 0 < self._local_allowance:
+        payload = self._pending_payloads.pop(0)
+        self._local_allowance -= 1
+        action = True
+      if not self._pending_payloads and self._pending_completion is not None:
+        completion = self._pending_completion
+        self._pending_completion = None
+        action = True
+      if self._remote_allowance is not None and 0 < self._remote_allowance:
+        allowance = self._remote_allowance
+        self._remote_allowance = 0
+        action = True
+      return initial_metadata, payload, completion, allowance, bool(action)
+
+  def _operator_process(
+      self, wrapped_operator, initial_metadata, payload,
+      completion, allowance):
+    while True:
+      advance_outcome = callable_util.call_logging_exceptions(
+          wrapped_operator, _INGESTION_EXCEPTION_LOG_MESSAGE,
+          initial_metadata=initial_metadata, payload=payload,
+          completion=completion, allowance=allowance)
+      if advance_outcome.exception is None:
+        if advance_outcome.return_value:
+          with self._lock:
+            if self._termination_manager.outcome is not None:
+              return
+            if completion is not None:
+              self._termination_manager.ingestion_complete()
+            initial_metadata, payload, completion, allowance, moar = (
+                self._operator_next())
+            if not moar:
+              self._processing = False
+              return
+        else:
+          with self._lock:
+            if self._termination_manager.outcome is None:
+              self._abort_and_notify(base.Outcome.LOCAL_FAILURE)
+            return
+      else:
+        with self._lock:
+          if self._termination_manager.outcome is None:
+            self._abort_and_notify(base.Outcome.LOCAL_FAILURE)
+          return
+
+  def _operator_post_create(self, subscription):
+    wrapped_operator = _wrap(subscription.operator.advance)
+    with self._lock:
+      if self._termination_manager.outcome is not None:
+        return
+      self._wrapped_operator = wrapped_operator
+      self._subscription_creator = None
+      metadata, payload, completion, allowance, moar = self._operator_next()
+      if not moar:
+        self._processing = False
+        return
+    self._operator_process(
+        wrapped_operator, metadata, payload, completion, allowance)
+
+  def _create(self, subscription_creator, group, name):
+    outcome = callable_util.call_logging_exceptions(
+        subscription_creator.create, _CREATE_SUBSCRIPTION_EXCEPTION_LOG_MESSAGE,
+        group, name)
+    if outcome.return_value is None:
+      with self._lock:
+        if self._termination_manager.outcome is None:
+          self._abort_and_notify(base.Outcome.LOCAL_FAILURE)
+    elif outcome.return_value.abandoned:
+      with self._lock:
+        if self._termination_manager.outcome is None:
+          self._abort_and_notify(base.Outcome.LOCAL_FAILURE)
+    elif outcome.return_value.remote_error:
+      with self._lock:
+        if self._termination_manager.outcome is None:
+          self._abort_and_notify(base.Outcome.REMOTE_FAILURE)
+    elif outcome.return_value.subscription.kind is base.Subscription.Kind.FULL:
+      self._operator_post_create(outcome.return_value.subscription)
+    else:
+      # TODO(nathaniel): Support other subscriptions.
+      raise ValueError(
+          'Unsupported "%s"!' % outcome.return_value.subscription.kind)
+
+  def _store_advance(self, initial_metadata, payload, completion, allowance):
+    if initial_metadata is not None:
+      self._pending_initial_metadata = initial_metadata
+    if payload is not None:
+      self._pending_payloads.append(payload)
+    if completion is not None:
+      self._pending_completion = completion
+    if allowance is not None and self._remote_allowance is not None:
+      self._remote_allowance += allowance
+
+  def _operator_advance(self, initial_metadata, payload, completion, allowance):
+    if self._processing:
+      self._store_advance(initial_metadata, payload, completion, allowance)
+    else:
+      action = False
+      if initial_metadata is not None:
+        action = True
+      if payload is not None:
+        if 0 < self._local_allowance:
+          self._local_allowance -= 1
+          action = True
+        else:
+          self._pending_payloads.append(payload)
+          payload = False
+      if completion is not None:
+        if self._pending_payloads:
+          self._pending_completion = completion
+        else:
+          action = True
+      if allowance is not None and self._remote_allowance is not None:
+        allowance += self._remote_allowance
+        self._remote_allowance = 0
+        action = True
+      if action:
+        self._pool.submit(
+            callable_util.with_exceptions_logged(
+                self._operator_process, _constants.INTERNAL_ERROR_LOG_MESSAGE),
+            self._wrapped_operator, initial_metadata, payload, completion,
+            allowance)
+
+  def set_group_and_method(self, group, method):
+    """See _interfaces.IngestionManager.set_group_and_method for spec."""
+    if self._subscription_creator is not None and not self._processing:
+      self._pool.submit(
+          callable_util.with_exceptions_logged(
+              self._create, _constants.INTERNAL_ERROR_LOG_MESSAGE),
+          self._subscription_creator, group, method)
+      self._processing = True
+
+  def add_local_allowance(self, allowance):
+    """See _interfaces.IngestionManager.add_local_allowance for spec."""
+    if any((self._subscription_creator, self._wrapped_operator,)):
+      self._local_allowance += allowance
+      if not self._processing:
+        initial_metadata, payload, completion, allowance, moar = (
+            self._operator_next())
+        if moar:
+          self._pool.submit(
+              callable_util.with_exceptions_logged(
+                  self._operator_process,
+                  _constants.INTERNAL_ERROR_LOG_MESSAGE),
+              initial_metadata, payload, completion, allowance)
+
+  def local_emissions_done(self):
+    self._remote_allowance = None
+
+  def advance(self, initial_metadata, payload, completion, allowance):
+    """See _interfaces.IngestionManager.advance for specification."""
+    if self._subscription_creator is not None:
+      self._store_advance(initial_metadata, payload, completion, allowance)
+    elif self._wrapped_operator is not None:
+      self._operator_advance(initial_metadata, payload, completion, allowance)
+
+
+def invocation_ingestion_manager(
+    subscription, lock, pool, termination_manager, transmission_manager,
+    expiration_manager):
+  """Creates an IngestionManager appropriate for invocation-side use.
+
+  Args:
+    subscription: A base.Subscription indicating the customer's interest in the
+      data and results from the service-side of the operation.
+    lock: The operation-wide lock.
+    pool: A thread pool in which to execute customer code.
+    termination_manager: The _interfaces.TerminationManager for the operation.
+    transmission_manager: The _interfaces.TransmissionManager for the
+      operation.
+    expiration_manager: The _interfaces.ExpirationManager for the operation.
+
+  Returns:
+    An IngestionManager appropriate for invocation-side use.
+  """
+  return _IngestionManager(
+      lock, pool, subscription, None, termination_manager, transmission_manager,
+      expiration_manager)
+
+
+def service_ingestion_manager(
+    servicer, operation_context, output_operator, lock, pool,
+    termination_manager, transmission_manager, expiration_manager):
+  """Creates an IngestionManager appropriate for service-side use.
+
+  The returned IngestionManager will require its set_group_and_name method to be
+  called before its advance method may be called.
+
+  Args:
+    servicer: A base.Servicer for servicing the operation.
+    operation_context: A base.OperationContext for the operation to be passed to
+      the customer.
+    output_operator: A base.Operator for the operation to be passed to the
+      customer and to be called by the customer to accept operation data output
+      by the customer.
+    lock: The operation-wide lock.
+    pool: A thread pool in which to execute customer code.
+    termination_manager: The _interfaces.TerminationManager for the operation.
+    transmission_manager: The _interfaces.TransmissionManager for the
+      operation.
+    expiration_manager: The _interfaces.ExpirationManager for the operation.
+
+  Returns:
+    An IngestionManager appropriate for service-side use.
+  """
+  subscription_creator = _ServiceSubscriptionCreator(
+      servicer, operation_context, output_operator)
+  return _IngestionManager(
+      lock, pool, None, subscription_creator, termination_manager,
+      transmission_manager, expiration_manager)
diff --git a/src/python/grpcio/grpc/framework/core/_interfaces.py b/src/python/grpcio/grpc/framework/core/_interfaces.py
new file mode 100644
index 0000000000..a626b9f767
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/_interfaces.py
@@ -0,0 +1,308 @@
+# 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.
+
+"""Package-internal interfaces."""
+
+import abc
+
+from grpc.framework.interfaces.base import base
+
+
+class TerminationManager(object):
+  """An object responsible for handling the termination of an operation.
+
+  Attributes:
+    outcome: None if the operation is active or a base.Outcome value if it has
+      terminated.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def add_callback(self, callback):
+    """Registers a callback to be called on operation termination.
+
+    If the operation has already terminated the callback will not be called.
+
+    Args:
+      callback: A callable that will be passed an interfaces.Outcome value.
+
+    Returns:
+      None if the operation has not yet terminated and the passed callback will
+        be called when it does, or a base.Outcome value describing the operation
+        termination if the operation has terminated and the callback will not be
+        called as a result of this method call.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def emission_complete(self):
+    """Indicates that emissions from customer code have completed."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def transmission_complete(self):
+    """Indicates that transmissions to the remote end are complete.
+
+    Returns:
+      True if the operation has terminated or False if the operation remains
+        ongoing.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def reception_complete(self):
+    """Indicates that reception from the other side is complete."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def ingestion_complete(self):
+    """Indicates that customer code ingestion of received values is complete."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def expire(self):
+    """Indicates that the operation must abort because it has taken too long."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def abort(self, outcome):
+    """Indicates that the operation must abort for the indicated reason.
+
+    Args:
+      outcome: An interfaces.Outcome indicating operation abortion.
+    """
+    raise NotImplementedError()
+
+
+class TransmissionManager(object):
+  """A manager responsible for transmitting to the other end of an operation."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def kick_off(
+      self, group, method, timeout, initial_metadata, payload, completion,
+      allowance):
+    """Transmits the values associated with operation invocation."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def advance(self, initial_metadata, payload, completion, allowance):
+    """Accepts values for transmission to the other end of the operation.
+
+    Args:
+      initial_metadata: An initial metadata value to be transmitted to the other
+        side of the operation. May only ever be non-None once.
+      payload: A payload value.
+      completion: A base.Completion value. May only ever be non-None in the last
+        transmission to be made to the other side.
+      allowance: A positive integer communicating the number of additional
+        payloads allowed to be transmitted from the other side to this side of
+        the operation, or None if no additional allowance is being granted in
+        this call.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def timeout(self, timeout):
+    """Accepts for transmission to the other side a new timeout value.
+
+    Args:
+      timeout: A positive float used as the new timeout value for the operation
+        to be transmitted to the other side.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def allowance(self, allowance):
+    """Indicates to this manager that the remote customer is allowing payloads.
+
+    Args:
+      allowance: A positive integer indicating the number of additional payloads
+        the remote customer is allowing to be transmitted from this side of the
+        operation.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def remote_complete(self):
+    """Indicates to this manager that data from the remote side is complete."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def abort(self, outcome):
+    """Indicates that the operation has aborted.
+
+    Args:
+      outcome: An interfaces.Outcome for the operation. If None, indicates that
+        the operation abortion should not be communicated to the other side of
+        the operation.
+    """
+    raise NotImplementedError()
+
+
+class ExpirationManager(object):
+  """A manager responsible for aborting the operation if it runs out of time."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def change_timeout(self, timeout):
+    """Changes the timeout allotted for the operation.
+
+    Operation duration is always measure from the beginning of the operation;
+    calling this method changes the operation's allotted time to timeout total
+    seconds, not timeout seconds from the time of this method call.
+
+    Args:
+      timeout: A length of time in seconds to allow for the operation.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def deadline(self):
+    """Returns the time until which the operation is allowed to run.
+
+    Returns:
+      The time (seconds since the epoch) at which the operation will expire.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def terminate(self):
+    """Indicates to this manager that the operation has terminated."""
+    raise NotImplementedError()
+
+
+class EmissionManager(base.Operator):
+  """A manager of values emitted by customer code."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def advance(
+      self, initial_metadata=None, payload=None, completion=None,
+      allowance=None):
+    """Accepts a value emitted by customer code.
+
+    This method should only be called by customer code.
+
+    Args:
+      initial_metadata: An initial metadata value emitted by the local customer
+        to be sent to the other side of the operation.
+      payload: A payload value emitted by the local customer to be sent to the
+        other side of the operation.
+      completion: A Completion value emitted by the local customer to be sent to
+        the other side of the operation.
+      allowance: A positive integer indicating an additional number of payloads
+        that the local customer is willing to accept from the other side of the
+        operation.
+    """
+    raise NotImplementedError()
+
+
+class IngestionManager(object):
+  """A manager responsible for executing customer code.
+
+  This name of this manager comes from its responsibility to pass successive
+  values from the other side of the operation into the code of the local
+  customer.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def set_group_and_method(self, group, method):
+    """Communicates to this IngestionManager the operation group and method.
+
+    Args:
+      group: The group identifier of the operation.
+      method: The method identifier of the operation.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def add_local_allowance(self, allowance):
+    """Communicates to this IngestionManager that more payloads may be ingested.
+
+    Args:
+      allowance: A positive integer indicating an additional number of payloads
+        that the local customer is willing to ingest.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def local_emissions_done(self):
+    """Indicates to this manager that local emissions are done."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def advance(self, initial_metadata, payload, completion, allowance):
+    """Advances the operation by passing values to the local customer."""
+    raise NotImplementedError()
+
+
+class ReceptionManager(object):
+  """A manager responsible for receiving tickets from the other end."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def receive_ticket(self, ticket):
+    """Handle a ticket from the other side of the operation.
+
+    Args:
+      ticket: An interfaces.BackToFrontTicket or interfaces.FrontToBackTicket
+        appropriate to this end of the operation and this object.
+    """
+    raise NotImplementedError()
+
+
+class Operation(object):
+  """An ongoing operation.
+
+  Attributes:
+    context: A base.OperationContext object for the operation.
+    operator: A base.Operator object for the operation for use by the customer
+      of the operation.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def handle_ticket(self, ticket):
+    """Handle a ticket from the other side of the operation.
+
+    Args:
+      ticket: A links.Ticket from the other side of the operation.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def abort(self, outcome):
+    """Aborts the operation.
+
+    Args:
+      outcome: A base.Outcome value indicating operation abortion.
+    """
+    raise NotImplementedError()
diff --git a/src/python/grpcio/grpc/framework/core/_operation.py b/src/python/grpcio/grpc/framework/core/_operation.py
new file mode 100644
index 0000000000..d20e40a53d
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/_operation.py
@@ -0,0 +1,192 @@
+# 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.
+
+"""Implementation of operations."""
+
+import threading
+
+# _utilities is referenced from specification in this module.
+from grpc.framework.core import _context
+from grpc.framework.core import _emission
+from grpc.framework.core import _expiration
+from grpc.framework.core import _ingestion
+from grpc.framework.core import _interfaces
+from grpc.framework.core import _reception
+from grpc.framework.core import _termination
+from grpc.framework.core import _transmission
+from grpc.framework.core import _utilities  # pylint: disable=unused-import
+
+
+class _EasyOperation(_interfaces.Operation):
+  """A trivial implementation of interfaces.Operation."""
+
+  def __init__(
+      self, lock, termination_manager, transmission_manager, expiration_manager,
+      context, operator, reception_manager):
+    """Constructor.
+
+    Args:
+      lock: The operation-wide lock.
+      termination_manager: The _interfaces.TerminationManager for the operation.
+      transmission_manager: The _interfaces.TransmissionManager for the
+        operation.
+      expiration_manager: The _interfaces.ExpirationManager for the operation.
+      context: A base.OperationContext for use by the customer during the
+        operation.
+      operator: A base.Operator for use by the customer during the operation.
+      reception_manager: The _interfaces.ReceptionManager for the operation.
+    """
+    self._lock = lock
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._expiration_manager = expiration_manager
+    self._reception_manager = reception_manager
+
+    self.context = context
+    self.operator = operator
+
+  def handle_ticket(self, ticket):
+    with self._lock:
+      self._reception_manager.receive_ticket(ticket)
+
+  def abort(self, outcome):
+    with self._lock:
+      if self._termination_manager.outcome is None:
+        self._termination_manager.abort(outcome)
+        self._transmission_manager.abort(outcome)
+        self._expiration_manager.terminate()
+
+
+def invocation_operate(
+    operation_id, group, method, subscription, timeout, initial_metadata,
+    payload, completion, ticket_sink, termination_action, pool):
+  """Constructs objects necessary for front-side operation management.
+
+  Args:
+    operation_id: An object identifying the operation.
+    group: The group identifier of the operation.
+    method: The method identifier of the operation.
+    subscription: A base.Subscription describing the customer's interest in the
+      results of the operation.
+    timeout: A length of time in seconds to allow for the operation.
+    initial_metadata: An initial metadata value to be sent to the other side of
+      the operation. May be None if the initial metadata will be passed later or
+      if there will be no initial metadata passed at all.
+    payload: The first payload value to be transmitted to the other side. May be
+      None if there is no such value or if the customer chose not to pass it at
+      operation invocation.
+    completion: A base.Completion value indicating the end of values passed to
+      the other side of the operation.
+    ticket_sink: A callable that accepts links.Tickets and delivers them to the
+      other side of the operation.
+    termination_action: A callable that accepts the outcome of the operation as
+      a base.Outcome value to be called on operation completion.
+    pool: A thread pool with which to do the work of the operation.
+
+  Returns:
+    An _interfaces.Operation for the operation.
+  """
+  lock = threading.Lock()
+  with lock:
+    termination_manager = _termination.invocation_termination_manager(
+        termination_action, pool)
+    transmission_manager = _transmission.TransmissionManager(
+        operation_id, ticket_sink, lock, pool, termination_manager)
+    expiration_manager = _expiration.invocation_expiration_manager(
+        timeout, lock, termination_manager, transmission_manager)
+    operation_context = _context.OperationContext(
+        lock, termination_manager, transmission_manager, expiration_manager)
+    emission_manager = _emission.EmissionManager(
+        lock, termination_manager, transmission_manager, expiration_manager)
+    ingestion_manager = _ingestion.invocation_ingestion_manager(
+        subscription, lock, pool, termination_manager, transmission_manager,
+        expiration_manager)
+    reception_manager = _reception.ReceptionManager(
+        termination_manager, transmission_manager, expiration_manager,
+        ingestion_manager)
+
+    termination_manager.set_expiration_manager(expiration_manager)
+    transmission_manager.set_expiration_manager(expiration_manager)
+    emission_manager.set_ingestion_manager(ingestion_manager)
+
+    transmission_manager.kick_off(
+        group, method, timeout, initial_metadata, payload, completion, None)
+
+  return _EasyOperation(
+      lock, termination_manager, transmission_manager, expiration_manager,
+      operation_context, emission_manager, reception_manager)
+
+
+def service_operate(
+    servicer_package, ticket, ticket_sink, termination_action, pool):
+  """Constructs an Operation for service of an operation.
+
+  Args:
+    servicer_package: A _utilities.ServicerPackage to be used servicing the
+      operation.
+    ticket: The first links.Ticket received for the operation.
+    ticket_sink: A callable that accepts links.Tickets and delivers them to the
+      other side of the operation.
+    termination_action: A callable that accepts the outcome of the operation as
+      a base.Outcome value to be called on operation completion.
+    pool: A thread pool with which to do the work of the operation.
+
+  Returns:
+    An _interfaces.Operation for the operation.
+  """
+  lock = threading.Lock()
+  with lock:
+    termination_manager = _termination.service_termination_manager(
+        termination_action, pool)
+    transmission_manager = _transmission.TransmissionManager(
+        ticket.operation_id, ticket_sink, lock, pool, termination_manager)
+    expiration_manager = _expiration.service_expiration_manager(
+        ticket.timeout, servicer_package.default_timeout,
+        servicer_package.maximum_timeout, lock, termination_manager,
+        transmission_manager)
+    operation_context = _context.OperationContext(
+        lock, termination_manager, transmission_manager, expiration_manager)
+    emission_manager = _emission.EmissionManager(
+        lock, termination_manager, transmission_manager, expiration_manager)
+    ingestion_manager = _ingestion.service_ingestion_manager(
+        servicer_package.servicer, operation_context, emission_manager, lock,
+        pool, termination_manager, transmission_manager, expiration_manager)
+    reception_manager = _reception.ReceptionManager(
+        termination_manager, transmission_manager, expiration_manager,
+        ingestion_manager)
+
+    termination_manager.set_expiration_manager(expiration_manager)
+    transmission_manager.set_expiration_manager(expiration_manager)
+    emission_manager.set_ingestion_manager(ingestion_manager)
+
+    reception_manager.receive_ticket(ticket)
+
+  return _EasyOperation(
+      lock, termination_manager, transmission_manager, expiration_manager,
+      operation_context, emission_manager, reception_manager)
diff --git a/src/python/grpcio/grpc/framework/core/_reception.py b/src/python/grpcio/grpc/framework/core/_reception.py
new file mode 100644
index 0000000000..0858f64ff6
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/_reception.py
@@ -0,0 +1,139 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""State and behavior for ticket reception."""
+
+from grpc.framework.core import _interfaces
+from grpc.framework.interfaces.base import base
+from grpc.framework.interfaces.base import utilities
+from grpc.framework.interfaces.links import links
+
+_REMOTE_TICKET_TERMINATION_TO_LOCAL_OUTCOME = {
+    links.Ticket.Termination.CANCELLATION: base.Outcome.CANCELLED,
+    links.Ticket.Termination.EXPIRATION: base.Outcome.EXPIRED,
+    links.Ticket.Termination.SHUTDOWN: base.Outcome.REMOTE_SHUTDOWN,
+    links.Ticket.Termination.RECEPTION_FAILURE: base.Outcome.RECEPTION_FAILURE,
+    links.Ticket.Termination.TRANSMISSION_FAILURE:
+        base.Outcome.TRANSMISSION_FAILURE,
+    links.Ticket.Termination.LOCAL_FAILURE: base.Outcome.REMOTE_FAILURE,
+    links.Ticket.Termination.REMOTE_FAILURE: base.Outcome.LOCAL_FAILURE,
+}
+
+
+class ReceptionManager(_interfaces.ReceptionManager):
+  """A ReceptionManager based around a _Receiver passed to it."""
+
+  def __init__(
+      self, termination_manager, transmission_manager, expiration_manager,
+      ingestion_manager):
+    """Constructor.
+
+    Args:
+      termination_manager: The operation's _interfaces.TerminationManager.
+      transmission_manager: The operation's _interfaces.TransmissionManager.
+      expiration_manager: The operation's _interfaces.ExpirationManager.
+      ingestion_manager: The operation's _interfaces.IngestionManager.
+    """
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._expiration_manager = expiration_manager
+    self._ingestion_manager = ingestion_manager
+
+    self._lowest_unseen_sequence_number = 0
+    self._out_of_sequence_tickets = {}
+    self._aborted = False
+
+  def _abort(self, outcome):
+    self._aborted = True
+    if self._termination_manager.outcome is None:
+      self._termination_manager.abort(outcome)
+      self._transmission_manager.abort(None)
+      self._expiration_manager.terminate()
+
+  def _sequence_failure(self, ticket):
+    """Determines a just-arrived ticket's sequential legitimacy.
+
+    Args:
+      ticket: A just-arrived ticket.
+
+    Returns:
+      True if the ticket is sequentially legitimate; False otherwise.
+    """
+    if ticket.sequence_number < self._lowest_unseen_sequence_number:
+      return True
+    elif ticket.sequence_number in self._out_of_sequence_tickets:
+      return True
+    else:
+      return False
+
+  def _process_one(self, ticket):
+    if ticket.sequence_number == 0:
+      self._ingestion_manager.set_group_and_method(ticket.group, ticket.method)
+    if ticket.timeout is not None:
+      self._expiration_manager.change_timeout(ticket.timeout)
+    if ticket.termination is None:
+      completion = None
+    else:
+      completion = utilities.completion(
+          ticket.terminal_metadata, ticket.code, ticket.message)
+    self._ingestion_manager.advance(
+        ticket.initial_metadata, ticket.payload, completion, ticket.allowance)
+    if ticket.allowance is not None:
+      self._transmission_manager.allowance(ticket.allowance)
+
+  def _process(self, ticket):
+    """Process those tickets ready to be processed.
+
+    Args:
+      ticket: A just-arrived ticket the sequence number of which matches this
+        _ReceptionManager's _lowest_unseen_sequence_number field.
+    """
+    while True:
+      self._process_one(ticket)
+      next_ticket = self._out_of_sequence_tickets.pop(
+          ticket.sequence_number + 1, None)
+      if next_ticket is None:
+        self._lowest_unseen_sequence_number = ticket.sequence_number + 1
+        return
+      else:
+        ticket = next_ticket
+
+  def receive_ticket(self, ticket):
+    """See _interfaces.ReceptionManager.receive_ticket for specification."""
+    if self._aborted:
+      return
+    elif self._sequence_failure(ticket):
+      self._abort(base.Outcome.RECEPTION_FAILURE)
+    elif ticket.termination not in (None, links.Ticket.Termination.COMPLETION):
+      outcome = _REMOTE_TICKET_TERMINATION_TO_LOCAL_OUTCOME[ticket.termination]
+      self._abort(outcome)
+    elif ticket.sequence_number == self._lowest_unseen_sequence_number:
+      self._process(ticket)
+    else:
+      self._out_of_sequence_tickets[ticket.sequence_number] = ticket
diff --git a/src/python/grpcio/grpc/framework/core/_termination.py b/src/python/grpcio/grpc/framework/core/_termination.py
new file mode 100644
index 0000000000..ad9f6123d8
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/_termination.py
@@ -0,0 +1,212 @@
+# 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 for operation termination."""
+
+import abc
+
+from grpc.framework.core import _constants
+from grpc.framework.core import _interfaces
+from grpc.framework.foundation import callable_util
+from grpc.framework.interfaces.base import base
+
+
+def _invocation_completion_predicate(
+    unused_emission_complete, unused_transmission_complete,
+    unused_reception_complete, ingestion_complete):
+  return ingestion_complete
+
+
+def _service_completion_predicate(
+    unused_emission_complete, transmission_complete, unused_reception_complete,
+    unused_ingestion_complete):
+  return transmission_complete
+
+
+class TerminationManager(_interfaces.TerminationManager):
+  """A _interfaces.TransmissionManager on which another manager may be set."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def set_expiration_manager(self, expiration_manager):
+    """Sets the expiration manager with which this manager will interact.
+
+    Args:
+      expiration_manager: The _interfaces.ExpirationManager associated with the
+        current operation.
+    """
+    raise NotImplementedError()
+
+
+class _TerminationManager(TerminationManager):
+  """An implementation of TerminationManager."""
+
+  def __init__(self, predicate, action, pool):
+    """Constructor.
+
+    Args:
+      predicate: One of _invocation_completion_predicate or
+        _service_completion_predicate to be used to determine when the operation
+        has completed.
+      action: A behavior to pass the operation outcome on operation termination.
+      pool: A thread pool.
+    """
+    self._predicate = predicate
+    self._action = action
+    self._pool = pool
+    self._expiration_manager = None
+
+    self.outcome = None
+    self._callbacks = []
+
+    self._emission_complete = False
+    self._transmission_complete = False
+    self._reception_complete = False
+    self._ingestion_complete = False
+
+  def set_expiration_manager(self, expiration_manager):
+    self._expiration_manager = expiration_manager
+
+  def _terminate_internal_only(self, outcome):
+    """Terminates the operation.
+
+    Args:
+      outcome: A base.Outcome describing the outcome of the operation.
+    """
+    self.outcome = outcome
+    callbacks = list(self._callbacks)
+    self._callbacks = None
+
+    act = callable_util.with_exceptions_logged(
+        self._action, _constants.INTERNAL_ERROR_LOG_MESSAGE)
+
+    if outcome is base.Outcome.LOCAL_FAILURE:
+      self._pool.submit(act, outcome)
+    else:
+      def call_callbacks_and_act(callbacks, outcome):
+        for callback in callbacks:
+          callback_outcome = callable_util.call_logging_exceptions(
+              callback, _constants.TERMINATION_CALLBACK_EXCEPTION_LOG_MESSAGE,
+              outcome)
+          if callback_outcome.exception is not None:
+            outcome = base.Outcome.LOCAL_FAILURE
+            break
+        act(outcome)
+
+      self._pool.submit(
+          callable_util.with_exceptions_logged(
+              call_callbacks_and_act, _constants.INTERNAL_ERROR_LOG_MESSAGE),
+          callbacks, outcome)
+
+  def _terminate_and_notify(self, outcome):
+    self._terminate_internal_only(outcome)
+    self._expiration_manager.terminate()
+
+  def _perhaps_complete(self):
+    if self._predicate(
+        self._emission_complete, self._transmission_complete,
+        self._reception_complete, self._ingestion_complete):
+      self._terminate_and_notify(base.Outcome.COMPLETED)
+      return True
+    else:
+      return False
+
+  def is_active(self):
+    """See _interfaces.TerminationManager.is_active for specification."""
+    return self.outcome is None
+
+  def add_callback(self, callback):
+    """See _interfaces.TerminationManager.add_callback for specification."""
+    if self.outcome is None:
+      self._callbacks.append(callback)
+      return None
+    else:
+      return self.outcome
+
+  def emission_complete(self):
+    """See superclass method for specification."""
+    if self.outcome is None:
+      self._emission_complete = True
+      self._perhaps_complete()
+
+  def transmission_complete(self):
+    """See superclass method for specification."""
+    if self.outcome is None:
+      self._transmission_complete = True
+      return self._perhaps_complete()
+    else:
+      return False
+
+  def reception_complete(self):
+    """See superclass method for specification."""
+    if self.outcome is None:
+      self._reception_complete = True
+      self._perhaps_complete()
+
+  def ingestion_complete(self):
+    """See superclass method for specification."""
+    if self.outcome is None:
+      self._ingestion_complete = True
+      self._perhaps_complete()
+
+  def expire(self):
+    """See _interfaces.TerminationManager.expire for specification."""
+    self._terminate_internal_only(base.Outcome.EXPIRED)
+
+  def abort(self, outcome):
+    """See _interfaces.TerminationManager.abort for specification."""
+    self._terminate_and_notify(outcome)
+
+
+def invocation_termination_manager(action, pool):
+  """Creates a TerminationManager appropriate for invocation-side use.
+
+  Args:
+    action: An action to call on operation termination.
+    pool: A thread pool in which to execute the passed action and any
+      termination callbacks that are registered during the operation.
+
+  Returns:
+    A TerminationManager appropriate for invocation-side use.
+  """
+  return _TerminationManager(_invocation_completion_predicate, action, pool)
+
+
+def service_termination_manager(action, pool):
+  """Creates a TerminationManager appropriate for service-side use.
+
+  Args:
+    action: An action to call on operation termination.
+    pool: A thread pool in which to execute the passed action and any
+      termination callbacks that are registered during the operation.
+
+  Returns:
+    A TerminationManager appropriate for service-side use.
+  """
+  return _TerminationManager(_service_completion_predicate, action, pool)
diff --git a/src/python/grpcio/grpc/framework/core/_transmission.py b/src/python/grpcio/grpc/framework/core/_transmission.py
new file mode 100644
index 0000000000..03644f4d49
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/_transmission.py
@@ -0,0 +1,294 @@
+# 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 for ticket transmission during an operation."""
+
+from grpc.framework.core import _constants
+from grpc.framework.core import _interfaces
+from grpc.framework.foundation import callable_util
+from grpc.framework.interfaces.base import base
+from grpc.framework.interfaces.links import links
+
+_TRANSMISSION_EXCEPTION_LOG_MESSAGE = 'Exception during transmission!'
+
+
+def _explode_completion(completion):
+  if completion is None:
+    return None, None, None, None
+  else:
+    return (
+        completion.terminal_metadata, completion.code, completion.message,
+        links.Ticket.Termination.COMPLETION)
+
+
+class TransmissionManager(_interfaces.TransmissionManager):
+  """An _interfaces.TransmissionManager that sends links.Tickets."""
+
+  def __init__(
+      self, operation_id, ticket_sink, lock, pool, termination_manager):
+    """Constructor.
+
+    Args:
+      operation_id: The operation's ID.
+      ticket_sink: A callable that accepts tickets and sends them to the other
+        side of the operation.
+      lock: The operation-servicing-wide lock object.
+      pool: A thread pool in which the work of transmitting tickets will be
+        performed.
+      termination_manager: The _interfaces.TerminationManager associated with
+        this operation.
+    """
+    self._lock = lock
+    self._pool = pool
+    self._ticket_sink = ticket_sink
+    self._operation_id = operation_id
+    self._termination_manager = termination_manager
+    self._expiration_manager = None
+
+    self._lowest_unused_sequence_number = 0
+    self._remote_allowance = 1
+    self._remote_complete = False
+    self._timeout = None
+    self._local_allowance = 0
+    self._initial_metadata = None
+    self._payloads = []
+    self._completion = None
+    self._aborted = False
+    self._abortion_outcome = None
+    self._transmitting = False
+
+  def set_expiration_manager(self, expiration_manager):
+    """Sets the ExpirationManager with which this manager will cooperate."""
+    self._expiration_manager = expiration_manager
+
+  def _next_ticket(self):
+    """Creates the next ticket to be transmitted.
+
+    Returns:
+      A links.Ticket to be sent to the other side of the operation or None if
+        there is nothing to be sent at this time.
+    """
+    if self._aborted:
+      if self._abortion_outcome is None:
+        return None
+      else:
+        termination = _constants.ABORTION_OUTCOME_TO_TICKET_TERMINATION[
+            self._abortion_outcome]
+        if termination is None:
+          return None
+        else:
+          self._abortion_outcome = None
+          return links.Ticket(
+              self._operation_id, self._lowest_unused_sequence_number, None,
+              None, None, None, None, None, None, None, None, None,
+              termination, None)
+
+    action = False
+    # TODO(nathaniel): Support other subscriptions.
+    local_subscription = links.Ticket.Subscription.FULL
+    timeout = self._timeout
+    if timeout is not None:
+      self._timeout = None
+      action = True
+    if self._local_allowance <= 0:
+      allowance = None
+    else:
+      allowance = self._local_allowance
+      self._local_allowance = 0
+      action = True
+    initial_metadata = self._initial_metadata
+    if initial_metadata is not None:
+      self._initial_metadata = None
+      action = True
+    if not self._payloads or self._remote_allowance <= 0:
+      payload = None
+    else:
+      payload = self._payloads.pop(0)
+      self._remote_allowance -= 1
+      action = True
+    if self._completion is None or self._payloads:
+      terminal_metadata, code, message, termination = None, None, None, None
+    else:
+      terminal_metadata, code, message, termination = _explode_completion(
+          self._completion)
+      self._completion = None
+      action = True
+
+    if action:
+      ticket = links.Ticket(
+          self._operation_id, self._lowest_unused_sequence_number, None, None,
+          local_subscription, timeout, allowance, initial_metadata, payload,
+          terminal_metadata, code, message, termination, None)
+      self._lowest_unused_sequence_number += 1
+      return ticket
+    else:
+      return None
+
+  def _transmit(self, ticket):
+    """Commences the transmission loop sending tickets.
+
+    Args:
+      ticket: A links.Ticket to be sent to the other side of the operation.
+    """
+    def transmit(ticket):
+      while True:
+        transmission_outcome = callable_util.call_logging_exceptions(
+            self._ticket_sink, _TRANSMISSION_EXCEPTION_LOG_MESSAGE, ticket)
+        if transmission_outcome.exception is None:
+          with self._lock:
+            if ticket.termination is links.Ticket.Termination.COMPLETION:
+              self._termination_manager.transmission_complete()
+            ticket = self._next_ticket()
+            if ticket is None:
+              self._transmitting = False
+              return
+        else:
+          with self._lock:
+            if self._termination_manager.outcome is None:
+              self._termination_manager.abort(base.Outcome.TRANSMISSION_FAILURE)
+              self._expiration_manager.terminate()
+            return
+
+    self._pool.submit(callable_util.with_exceptions_logged(
+        transmit, _constants.INTERNAL_ERROR_LOG_MESSAGE), ticket)
+    self._transmitting = True
+
+  def kick_off(
+      self, group, method, timeout, initial_metadata, payload, completion,
+      allowance):
+    """See _interfaces.TransmissionManager.kickoff for specification."""
+    # TODO(nathaniel): Support other subscriptions.
+    subscription = links.Ticket.Subscription.FULL
+    terminal_metadata, code, message, termination = _explode_completion(
+        completion)
+    self._remote_allowance = 1 if payload is None else 0
+    ticket = links.Ticket(
+        self._operation_id, 0, group, method, subscription, timeout, allowance,
+        initial_metadata, payload, terminal_metadata, code, message,
+        termination, None)
+    self._lowest_unused_sequence_number = 1
+    self._transmit(ticket)
+
+  def advance(self, initial_metadata, payload, completion, allowance):
+    """See _interfaces.TransmissionManager.advance for specification."""
+    effective_initial_metadata = initial_metadata
+    effective_payload = payload
+    effective_completion = completion
+    if allowance is not None and not self._remote_complete:
+      effective_allowance = allowance
+    else:
+      effective_allowance = None
+    if self._transmitting:
+      if effective_initial_metadata is not None:
+        self._initial_metadata = effective_initial_metadata
+      if effective_payload is not None:
+        self._payloads.append(effective_payload)
+      if effective_completion is not None:
+        self._completion = effective_completion
+      if effective_allowance is not None:
+        self._local_allowance += effective_allowance
+    else:
+      if effective_payload is not None:
+        if 0 < self._remote_allowance:
+          ticket_payload = effective_payload
+          self._remote_allowance -= 1
+        else:
+          self._payloads.append(effective_payload)
+          ticket_payload = None
+      else:
+        ticket_payload = None
+      if effective_completion is not None and not self._payloads:
+        ticket_completion = effective_completion
+      else:
+        self._completion = effective_completion
+        ticket_completion = None
+      if any(
+          (effective_initial_metadata, ticket_payload, ticket_completion,
+           effective_allowance)):
+        terminal_metadata, code, message, termination = _explode_completion(
+            completion)
+        ticket = links.Ticket(
+            self._operation_id, self._lowest_unused_sequence_number, None, None,
+            None, None, allowance, effective_initial_metadata, ticket_payload,
+            terminal_metadata, code, message, termination, None)
+        self._lowest_unused_sequence_number += 1
+        self._transmit(ticket)
+
+  def timeout(self, timeout):
+    """See _interfaces.TransmissionManager.timeout for specification."""
+    if self._transmitting:
+      self._timeout = timeout
+    else:
+      ticket = links.Ticket(
+          self._operation_id, self._lowest_unused_sequence_number, None, None,
+          None, timeout, None, None, None, None, None, None, None, None)
+      self._lowest_unused_sequence_number += 1
+      self._transmit(ticket)
+
+  def allowance(self, allowance):
+    """See _interfaces.TransmissionManager.allowance for specification."""
+    if self._transmitting or not self._payloads:
+      self._remote_allowance += allowance
+    else:
+      self._remote_allowance += allowance - 1
+      payload = self._payloads.pop(0)
+      if self._payloads:
+        completion = None
+      else:
+        completion = self._completion
+        self._completion = None
+      terminal_metadata, code, message, termination = _explode_completion(
+          completion)
+      ticket = links.Ticket(
+          self._operation_id, self._lowest_unused_sequence_number, None, None,
+          None, None, None, None, payload, terminal_metadata, code, message,
+          termination, None)
+      self._lowest_unused_sequence_number += 1
+      self._transmit(ticket)
+
+  def remote_complete(self):
+    """See _interfaces.TransmissionManager.remote_complete for specification."""
+    self._remote_complete = True
+    self._local_allowance = 0
+
+  def abort(self, outcome):
+    """See _interfaces.TransmissionManager.abort for specification."""
+    if self._transmitting:
+      self._aborted, self._abortion_outcome = True, outcome
+    else:
+      self._aborted = True
+      if outcome is not None:
+        termination = _constants.ABORTION_OUTCOME_TO_TICKET_TERMINATION[
+            outcome]
+        if termination is not None:
+          ticket = links.Ticket(
+              self._operation_id, self._lowest_unused_sequence_number, None,
+              None, None, None, None, None, None, None, None, None,
+              termination, None)
+          self._transmit(ticket)
diff --git a/src/python/grpcio/grpc/framework/core/_utilities.py b/src/python/grpcio/grpc/framework/core/_utilities.py
new file mode 100644
index 0000000000..5b0d798751
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/_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.
+
+"""Package-internal utilities."""
+
+import collections
+
+
+class ServicerPackage(
+    collections.namedtuple(
+        'ServicerPackage', ('servicer', 'default_timeout', 'maximum_timeout'))):
+  """A trivial bundle class.
+
+  Attributes:
+    servicer: A base.Servicer.
+    default_timeout: A float indicating the length of time in seconds to allow
+      for an operation invoked without a timeout.
+    maximum_timeout: A float indicating the maximum length of time in seconds to
+      allow for an operation.
+  """
diff --git a/src/python/grpcio/grpc/framework/core/implementations.py b/src/python/grpcio/grpc/framework/core/implementations.py
new file mode 100644
index 0000000000..364a7faed4
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/core/implementations.py
@@ -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.
+
+"""Entry points into the ticket-exchange-based base layer implementation."""
+
+# base and links are referenced from specification in this module.
+from grpc.framework.core import _end
+from grpc.framework.interfaces.base import base  # pylint: disable=unused-import
+from grpc.framework.interfaces.links import links  # pylint: disable=unused-import
+
+
+def invocation_end_link():
+  """Creates a base.End-links.Link suitable for operation invocation.
+
+  Returns:
+    An object that is both a base.End and a links.Link, that supports operation
+      invocation, and that translates operation invocation into ticket exchange.
+  """
+  return _end.serviceless_end_link()
+
+
+def service_end_link(servicer, default_timeout, maximum_timeout):
+  """Creates a base.End-links.Link suitable for operation service.
+
+  Args:
+    servicer: A base.Servicer for servicing operations.
+    default_timeout: A length of time in seconds to be used as the default
+      time alloted for a single operation.
+    maximum_timeout: A length of time in seconds to be used as the maximum
+      time alloted for a single operation.
+
+  Returns:
+    An object that is both a base.End and a links.Link and that services
+      operations that arrive at it through ticket exchange.
+  """
+  return _end.serviceful_end_link(servicer, default_timeout, maximum_timeout)
diff --git a/src/python/grpcio/grpc/framework/interfaces/base/base.py b/src/python/grpcio/grpc/framework/interfaces/base/base.py
index 9d1651daac..76e0a5bdae 100644
--- a/src/python/grpcio/grpc/framework/interfaces/base/base.py
+++ b/src/python/grpcio/grpc/framework/interfaces/base/base.py
@@ -27,10 +27,20 @@
 # (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 base interface of RPC Framework."""
+"""The base interface of RPC Framework.
 
+Implementations of this interface support the conduct of "operations":
+exchanges between two distinct ends of an arbitrary number of data payloads
+and metadata such as a name for the operation, initial and terminal metadata
+in each direction, and flow control. These operations may be used for transfers
+of data, remote procedure calls, status indication, or anything else
+applications choose.
+"""
+
+# threading is referenced from specification in this module.
 import abc
 import enum
+import threading
 
 # abandonment is referenced from specification in this module.
 from grpc.framework.foundation import abandonment  # pylint: disable=unused-import
@@ -208,19 +218,26 @@ class End(object):
     raise NotImplementedError()
 
   @abc.abstractmethod
-  def stop_gracefully(self):
-    """Gracefully stops this object's service of operations.
+  def stop(self, grace):
+    """Stops this object's service of operations.
 
-    Operations in progress will be allowed to complete, and this method blocks
-    until all of them have.
-    """
-    raise NotImplementedError()
+    This object will refuse service of new operations as soon as this method is
+    called but operations under way at the time of the call may be given a
+    grace period during which they are allowed to finish.
 
-  @abc.abstractmethod
-  def stop_immediately(self):
-    """Immediately stops this object's service of operations.
+    Args:
+      grace: A duration of time in seconds to allow ongoing operations to
+        terminate before being forcefully terminated by the stopping of this
+        End. May be zero to terminate all ongoing operations and immediately
+        stop.
 
-    Operations in progress will not be allowed to complete.
+    Returns:
+      A threading.Event that will be set to indicate all operations having
+        terminated and this End having completely stopped. The returned event
+        may not be set until after the full grace period (if some ongoing
+        operation continues for the full length of the period) or it may be set
+        much sooner (if for example this End had no operations in progress at
+        the time its stop method was called).
     """
     raise NotImplementedError()
 
diff --git a/src/python/grpcio/grpc/framework/interfaces/face/__init__.py b/src/python/grpcio/grpc/framework/interfaces/face/__init__.py
new file mode 100644
index 0000000000..7086519106
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/interfaces/face/__init__.py
@@ -0,0 +1,30 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
diff --git a/src/python/grpcio/grpc/framework/interfaces/face/face.py b/src/python/grpcio/grpc/framework/interfaces/face/face.py
new file mode 100644
index 0000000000..948e7505b6
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/interfaces/face/face.py
@@ -0,0 +1,933 @@
+# 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.
+
+"""Interfaces defining the Face layer of RPC Framework."""
+
+import abc
+import collections
+import enum
+
+# cardinality, style, abandonment, future, and stream are
+# referenced from specification in this module.
+from grpc.framework.common import cardinality  # pylint: disable=unused-import
+from grpc.framework.common import style  # pylint: disable=unused-import
+from grpc.framework.foundation import abandonment  # pylint: disable=unused-import
+from grpc.framework.foundation import future  # pylint: disable=unused-import
+from grpc.framework.foundation import stream  # pylint: disable=unused-import
+
+
+class NoSuchMethodError(Exception):
+  """Raised by customer code to indicate an unrecognized method.
+
+  Attributes:
+    group: The group of the unrecognized method.
+    name: The name of the unrecognized method.
+  """
+
+  def __init__(self, group, method):
+    """Constructor.
+
+    Args:
+      group: The group identifier of the unrecognized RPC name.
+      method: The method identifier of the unrecognized RPC name.
+    """
+    super(NoSuchMethodError, self).__init__()
+    self.group = group
+    self.method = method
+
+  def __repr__(self):
+    return 'face.NoSuchMethodError(%s, %s)' % (self.group, self.method,)
+
+
+class Abortion(
+    collections.namedtuple(
+        'Abortion',
+        ('kind', 'initial_metadata', 'terminal_metadata', 'code', 'details',))):
+  """A value describing RPC abortion.
+
+  Attributes:
+    kind: A Kind value identifying how the RPC failed.
+    initial_metadata: The initial metadata from the other side of the RPC or
+      None if no initial metadata value was received.
+    terminal_metadata: The terminal metadata from the other side of the RPC or
+      None if no terminal metadata value was received.
+    code: The code value from the other side of the RPC or None if no code value
+      was received.
+    details: The details value from the other side of the RPC or None if no
+      details value was received.
+  """
+
+  @enum.unique
+  class Kind(enum.Enum):
+    """Types of RPC abortion."""
+
+    CANCELLED = 'cancelled'
+    EXPIRED = 'expired'
+    LOCAL_SHUTDOWN = 'local shutdown'
+    REMOTE_SHUTDOWN = 'remote shutdown'
+    NETWORK_FAILURE = 'network failure'
+    LOCAL_FAILURE = 'local failure'
+    REMOTE_FAILURE = 'remote failure'
+
+
+class AbortionError(Exception):
+  """Common super type for exceptions indicating RPC abortion.
+
+    initial_metadata: The initial metadata from the other side of the RPC or
+      None if no initial metadata value was received.
+    terminal_metadata: The terminal metadata from the other side of the RPC or
+      None if no terminal metadata value was received.
+    code: The code value from the other side of the RPC or None if no code value
+      was received.
+    details: The details value from the other side of the RPC or None if no
+      details value was received.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  def __init__(self, initial_metadata, terminal_metadata, code, details):
+    super(AbortionError, self).__init__()
+    self.initial_metadata = initial_metadata
+    self.terminal_metadata = terminal_metadata
+    self.code = code
+    self.details = details
+
+
+class CancellationError(AbortionError):
+  """Indicates that an RPC has been cancelled."""
+
+
+class ExpirationError(AbortionError):
+  """Indicates that an RPC has expired ("timed out")."""
+
+
+class LocalShutdownError(AbortionError):
+  """Indicates that an RPC has terminated due to local shutdown of RPCs."""
+
+
+class RemoteShutdownError(AbortionError):
+  """Indicates that an RPC has terminated due to remote shutdown of RPCs."""
+
+
+class NetworkError(AbortionError):
+  """Indicates that some error occurred on the network."""
+
+
+class LocalError(AbortionError):
+  """Indicates that an RPC has terminated due to a local defect."""
+
+
+class RemoteError(AbortionError):
+  """Indicates that an RPC has terminated due to a remote defect."""
+
+
+class RpcContext(object):
+  """Provides RPC-related information and action."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def is_active(self):
+    """Describes whether the RPC is active or has terminated."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def time_remaining(self):
+    """Describes the length of allowed time remaining for the RPC.
+
+    Returns:
+      A nonnegative float indicating the length of allowed time in seconds
+      remaining for the RPC to complete before it is considered to have timed
+      out.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def add_abortion_callback(self, abortion_callback):
+    """Registers a callback to be called if the RPC is aborted.
+
+    Args:
+      abortion_callback: A callable to be called and passed an Abortion value
+        in the event of RPC abortion.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def cancel(self):
+    """Cancels the RPC.
+
+    Idempotent and has no effect if the RPC has already terminated.
+    """
+    raise NotImplementedError()
+
+
+class Call(RpcContext):
+  """Invocation-side utility object for an RPC."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def initial_metadata(self):
+    """Accesses the initial metadata from the service-side of the RPC.
+
+    This method blocks until the value is available or is known not to have been
+    emitted from the service-side of the RPC.
+
+    Returns:
+      The initial metadata object emitted by the service-side of the RPC, or
+        None if there was no such value.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def terminal_metadata(self):
+    """Accesses the terminal metadata from the service-side of the RPC.
+
+    This method blocks until the value is available or is known not to have been
+    emitted from the service-side of the RPC.
+
+    Returns:
+      The terminal metadata object emitted by the service-side of the RPC, or
+        None if there was no such value.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def code(self):
+    """Accesses the code emitted by the service-side of the RPC.
+
+    This method blocks until the value is available or is known not to have been
+    emitted from the service-side of the RPC.
+
+    Returns:
+      The code object emitted by the service-side of the RPC, or None if there
+        was no such value.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def details(self):
+    """Accesses the details value emitted by the service-side of the RPC.
+
+    This method blocks until the value is available or is known not to have been
+    emitted from the service-side of the RPC.
+
+    Returns:
+      The details value emitted by the service-side of the RPC, or None if there
+        was no such value.
+    """
+    raise NotImplementedError()
+
+
+class ServicerContext(RpcContext):
+  """A context object passed to method implementations."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def invocation_metadata(self):
+    """Accesses the metadata from the invocation-side of the RPC.
+
+    This method blocks until the value is available or is known not to have been
+    emitted from the invocation-side of the RPC.
+
+    Returns:
+      The metadata object emitted by the invocation-side of the RPC, or None if
+        there was no such value.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def initial_metadata(self, initial_metadata):
+    """Accepts the service-side initial metadata value of the RPC.
+
+    This method need not be called by method implementations if they have no
+    service-side initial metadata to transmit.
+
+    Args:
+      initial_metadata: The service-side initial metadata value of the RPC to
+        be transmitted to the invocation side of the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def terminal_metadata(self, terminal_metadata):
+    """Accepts the service-side terminal metadata value of the RPC.
+
+    This method need not be called by method implementations if they have no
+    service-side terminal metadata to transmit.
+
+    Args:
+      terminal_metadata: The service-side terminal metadata value of the RPC to
+        be transmitted to the invocation side of the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def code(self, code):
+    """Accepts the service-side code of the RPC.
+
+    This method need not be called by method implementations if they have no
+    code to transmit.
+
+    Args:
+      code: The code of the RPC to be transmitted to the invocation side of the
+        RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def details(self, details):
+    """Accepts the service-side details of the RPC.
+
+    This method need not be called by method implementations if they have no
+    service-side details to transmit.
+
+    Args:
+      details: The service-side details value of the RPC to be transmitted to
+        the invocation side of the RPC.
+    """
+    raise NotImplementedError()
+
+
+class ResponseReceiver(object):
+  """Invocation-side object used to accept the output of an RPC."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def initial_metadata(self, initial_metadata):
+    """Receives the initial metadata from the service-side of the RPC.
+
+    Args:
+      initial_metadata: The initial metadata object emitted from the
+        service-side of the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def response(self, response):
+    """Receives a response from the service-side of the RPC.
+
+    Args:
+      response: A response object emitted from the service-side of the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def complete(self, terminal_metadata, code, details):
+    """Receives the completion values emitted from the service-side of the RPC.
+
+    Args:
+      terminal_metadata: The terminal metadata object emitted from the
+        service-side of the RPC.
+      code: The code object emitted from the service-side of the RPC.
+      details: The details object emitted from the service-side of the RPC.
+    """
+    raise NotImplementedError()
+
+
+class UnaryUnaryMultiCallable(object):
+  """Affords invoking a unary-unary RPC in any call style."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def __call__(
+      self, request, timeout, metadata=None, with_call=False):
+    """Synchronously invokes the underlying RPC.
+
+    Args:
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+      with_call: Whether or not to include return a Call for the RPC in addition
+        to the reponse.
+
+    Returns:
+      The response value for the RPC, and a Call for the RPC if with_call was
+        set to True at invocation.
+
+    Raises:
+      AbortionError: Indicating that the RPC was aborted.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def future(self, request, timeout, metadata=None):
+    """Asynchronously invokes the underlying RPC.
+
+    Args:
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+
+    Returns:
+      An object that is both a Call for the RPC and a future.Future. In the
+        event of RPC completion, the return Future's result value will be the
+        response value of the RPC. In the event of RPC abortion, the returned
+        Future's exception value will be an AbortionError.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event(
+      self, request, receiver, abortion_callback, timeout,
+      metadata=None):
+    """Asynchronously invokes the underlying RPC.
+
+    Args:
+      request: The request value for the RPC.
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+
+    Returns:
+      A Call for the RPC.
+    """
+    raise NotImplementedError()
+
+
+class UnaryStreamMultiCallable(object):
+  """Affords invoking a unary-stream RPC in any call style."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def __call__(self, request, timeout, metadata=None):
+    """Invokes the underlying RPC.
+
+    Args:
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+
+    Returns:
+      An object that is both a Call for the RPC and an iterator of response
+        values. Drawing response values from the returned iterator may raise
+        AbortionError indicating abortion of the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event(
+      self, request, receiver, abortion_callback, timeout,
+      metadata=None):
+    """Asynchronously invokes the underlying RPC.
+
+    Args:
+      request: The request value for the RPC.
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+
+    Returns:
+      A Call object for the RPC.
+    """
+    raise NotImplementedError()
+
+
+class StreamUnaryMultiCallable(object):
+  """Affords invoking a stream-unary RPC in any call style."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def __call__(
+      self, request_iterator, timeout, metadata=None,
+      with_call=False):
+    """Synchronously invokes the underlying RPC.
+
+    Args:
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+      with_call: Whether or not to include return a Call for the RPC in addition
+        to the reponse.
+
+    Returns:
+      The response value for the RPC, and a Call for the RPC if with_call was
+        set to True at invocation.
+
+    Raises:
+      AbortionError: Indicating that the RPC was aborted.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def future(self, request_iterator, timeout, metadata=None):
+    """Asynchronously invokes the underlying RPC.
+
+    Args:
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+
+    Returns:
+      An object that is both a Call for the RPC and a future.Future. In the
+        event of RPC completion, the return Future's result value will be the
+        response value of the RPC. In the event of RPC abortion, the returned
+        Future's exception value will be an AbortionError.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event(
+      self, receiver, abortion_callback, timeout, metadata=None):
+    """Asynchronously invokes the underlying RPC.
+
+    Args:
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+
+    Returns:
+      A single object that is both a Call object for the RPC and a
+        stream.Consumer to which the request values of the RPC should be passed.
+    """
+    raise NotImplementedError()
+
+
+class StreamStreamMultiCallable(object):
+  """Affords invoking a stream-stream RPC in any call style."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def __call__(self, request_iterator, timeout, metadata=None):
+    """Invokes the underlying RPC.
+
+    Args:
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+
+    Returns:
+      An object that is both a Call for the RPC and an iterator of response
+        values. Drawing response values from the returned iterator may raise
+        AbortionError indicating abortion of the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event(
+      self, receiver, abortion_callback, timeout, metadata=None):
+    """Asynchronously invokes the underlying RPC.
+
+    Args:
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+
+    Returns:
+      A single object that is both a Call object for the RPC and a
+        stream.Consumer to which the request values of the RPC should be passed.
+    """
+    raise NotImplementedError()
+
+
+class MethodImplementation(object):
+  """A sum type that describes a method implementation.
+
+  Attributes:
+    cardinality: A cardinality.Cardinality value.
+    style: A style.Service value.
+    unary_unary_inline: The implementation of the method as a callable value
+      that takes a request value and a ServicerContext object and returns a
+      response value. Only non-None if cardinality is
+      cardinality.Cardinality.UNARY_UNARY and style is style.Service.INLINE.
+    unary_stream_inline: The implementation of the method as a callable value
+      that takes a request value and a ServicerContext object and returns an
+      iterator of response values. Only non-None if cardinality is
+      cardinality.Cardinality.UNARY_STREAM and style is style.Service.INLINE.
+    stream_unary_inline: The implementation of the method as a callable value
+      that takes an iterator of request values and a ServicerContext object and
+      returns a response value. Only non-None if cardinality is
+      cardinality.Cardinality.STREAM_UNARY and style is style.Service.INLINE.
+    stream_stream_inline: The implementation of the method as a callable value
+      that takes an iterator of request values and a ServicerContext object and
+      returns an iterator of response values. Only non-None if cardinality is
+      cardinality.Cardinality.STREAM_STREAM and style is style.Service.INLINE.
+    unary_unary_event: The implementation of the method as a callable value that
+      takes a request value, a response callback to which to pass the response
+      value of the RPC, and a ServicerContext. Only non-None if cardinality is
+      cardinality.Cardinality.UNARY_UNARY and style is style.Service.EVENT.
+    unary_stream_event: The implementation of the method as a callable value
+      that takes a request value, a stream.Consumer to which to pass the
+      response values of the RPC, and a ServicerContext. Only non-None if
+      cardinality is cardinality.Cardinality.UNARY_STREAM and style is
+      style.Service.EVENT.
+    stream_unary_event: The implementation of the method as a callable value
+      that takes a response callback to which to pass the response value of the
+      RPC and a ServicerContext and returns a stream.Consumer to which the
+      request values of the RPC should be passed. Only non-None if cardinality
+      is cardinality.Cardinality.STREAM_UNARY and style is style.Service.EVENT.
+    stream_stream_event: The implementation of the method as a callable value
+      that takes a stream.Consumer to which to pass the response values of the
+      RPC and a ServicerContext and returns a stream.Consumer to which the
+      request values of the RPC should be passed. Only non-None if cardinality
+      is cardinality.Cardinality.STREAM_STREAM and style is
+      style.Service.EVENT.
+  """
+  __metaclass__ = abc.ABCMeta
+
+
+class MultiMethodImplementation(object):
+  """A general type able to service many methods."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, group, method, response_consumer, context):
+    """Services an RPC.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      response_consumer: A stream.Consumer to be called to accept the response
+        values of the RPC.
+      context: a ServicerContext object.
+
+    Returns:
+      A stream.Consumer with which to accept the request values of the RPC. The
+        consumer returned from this method may or may not be invoked to
+        completion: in the case of RPC abortion, RPC Framework will simply stop
+        passing values to this object. Implementations must not assume that this
+        object will be called to completion of the request stream or even called
+        at all.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+      NoSuchMethodError: If this MultiMethod does not recognize the given group
+        and name for the RPC and is not able to service the RPC.
+    """
+    raise NotImplementedError()
+
+
+class GenericStub(object):
+  """Affords RPC invocation via generic methods."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def blocking_unary_unary(
+      self, group, method, request, timeout, metadata=None,
+      with_call=False):
+    """Invokes a unary-request-unary-response method.
+
+    This method blocks until either returning the response value of the RPC
+    (in the event of RPC completion) or raising an exception (in the event of
+    RPC abortion).
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+      with_call: Whether or not to include return a Call for the RPC in addition
+        to the reponse.
+
+    Returns:
+      The response value for the RPC, and a Call for the RPC if with_call was
+        set to True at invocation.
+
+    Raises:
+      AbortionError: Indicating that the RPC was aborted.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def future_unary_unary(
+      self, group, method, request, timeout, metadata=None):
+    """Invokes a unary-request-unary-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+
+    Returns:
+      An object that is both a Call for the RPC and a future.Future. In the
+        event of RPC completion, the return Future's result value will be the
+        response value of the RPC. In the event of RPC abortion, the returned
+        Future's exception value will be an AbortionError.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def inline_unary_stream(
+      self, group, method, request, timeout, metadata=None):
+    """Invokes a unary-request-stream-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+
+    Returns:
+      An object that is both a Call for the RPC and an iterator of response
+        values. Drawing response values from the returned iterator may raise
+        AbortionError indicating abortion of the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def blocking_stream_unary(
+      self, group, method, request_iterator, timeout, metadata=None,
+      with_call=False):
+    """Invokes a stream-request-unary-response method.
+
+    This method blocks until either returning the response value of the RPC
+    (in the event of RPC completion) or raising an exception (in the event of
+    RPC abortion).
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+      with_call: Whether or not to include return a Call for the RPC in addition
+        to the reponse.
+
+    Returns:
+      The response value for the RPC, and a Call for the RPC if with_call was
+        set to True at invocation.
+
+    Raises:
+      AbortionError: Indicating that the RPC was aborted.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def future_stream_unary(
+      self, group, method, request_iterator, timeout, metadata=None):
+    """Invokes a stream-request-unary-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+
+    Returns:
+      An object that is both a Call for the RPC and a future.Future. In the
+        event of RPC completion, the return Future's result value will be the
+        response value of the RPC. In the event of RPC abortion, the returned
+        Future's exception value will be an AbortionError.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def inline_stream_stream(
+      self, group, method, request_iterator, timeout, metadata=None):
+    """Invokes a stream-request-stream-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+
+    Returns:
+      An object that is both a Call for the RPC and an iterator of response
+        values. Drawing response values from the returned iterator may raise
+        AbortionError indicating abortion of the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event_unary_unary(
+      self, group, method, request, receiver, abortion_callback, timeout,
+      metadata=None):
+    """Event-driven invocation of a unary-request-unary-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request: The request value for the RPC.
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+
+    Returns:
+      A Call for the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event_unary_stream(
+      self, group, method, request, receiver, abortion_callback, timeout,
+      metadata=None):
+    """Event-driven invocation of a unary-request-stream-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request: The request value for the RPC.
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+
+    Returns:
+      A Call for the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event_stream_unary(
+      self, group, method, receiver, abortion_callback, timeout,
+      metadata=None):
+    """Event-driven invocation of a unary-request-unary-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+
+    Returns:
+      A pair of a Call object for the RPC and a stream.Consumer to which the
+        request values of the RPC should be passed.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event_stream_stream(
+      self, group, method, receiver, abortion_callback, timeout,
+      metadata=None):
+    """Event-driven invocation of a unary-request-stream-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+
+    Returns:
+      A pair of a Call object for the RPC and a stream.Consumer to which the
+        request values of the RPC should be passed.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def unary_unary(self, group, method):
+    """Creates a UnaryUnaryMultiCallable for a unary-unary method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+
+    Returns:
+      A UnaryUnaryMultiCallable value for the named unary-unary method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def unary_stream(self, group, method):
+    """Creates a UnaryStreamMultiCallable for a unary-stream method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+
+    Returns:
+      A UnaryStreamMultiCallable value for the name unary-stream method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def stream_unary(self, group, method):
+    """Creates a StreamUnaryMultiCallable for a stream-unary method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+
+    Returns:
+      A StreamUnaryMultiCallable value for the named stream-unary method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def stream_stream(self, group, method):
+    """Creates a StreamStreamMultiCallable for a stream-stream method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+
+    Returns:
+      A StreamStreamMultiCallable value for the named stream-stream method.
+    """
+    raise NotImplementedError()
+
+
+class DynamicStub(object):
+  """Affords RPC invocation via attributes corresponding to afforded methods.
+
+  Instances of this type may be scoped to a single group so that attribute
+  access is unambiguous.
+
+  Instances of this type respond to attribute access as follows: if the
+  requested attribute is the name of a unary-unary method, the value of the
+  attribute will be a UnaryUnaryMultiCallable with which to invoke an RPC; if
+  the requested attribute is the name of a unary-stream method, the value of the
+  attribute will be a UnaryStreamMultiCallable with which to invoke an RPC; if
+  the requested attribute is the name of a stream-unary method, the value of the
+  attribute will be a StreamUnaryMultiCallable with which to invoke an RPC; and
+  if the requested attribute is the name of a stream-stream method, the value of
+  the attribute will be a StreamStreamMultiCallable with which to invoke an RPC.
+  """
+  __metaclass__ = abc.ABCMeta
diff --git a/src/python/grpcio/grpc/framework/interfaces/face/utilities.py b/src/python/grpcio/grpc/framework/interfaces/face/utilities.py
new file mode 100644
index 0000000000..db2ec6ed87
--- /dev/null
+++ b/src/python/grpcio/grpc/framework/interfaces/face/utilities.py
@@ -0,0 +1,178 @@
+# 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 for RPC Framework's Face interface."""
+
+import collections
+
+# stream is referenced from specification in this module.
+from grpc.framework.common import cardinality
+from grpc.framework.common import style
+from grpc.framework.foundation import stream  # pylint: disable=unused-import
+from grpc.framework.interfaces.face import face
+
+
+class _MethodImplementation(
+    face.MethodImplementation,
+    collections.namedtuple(
+        '_MethodImplementation',
+        ['cardinality', 'style', 'unary_unary_inline', 'unary_stream_inline',
+         'stream_unary_inline', 'stream_stream_inline', 'unary_unary_event',
+         'unary_stream_event', 'stream_unary_event', 'stream_stream_event',])):
+  pass
+
+
+def unary_unary_inline(behavior):
+  """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a unary-unary RPC method as a callable value
+      that takes a request value and an face.ServicerContext object and
+      returns a response value.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+  return _MethodImplementation(
+      cardinality.Cardinality.UNARY_UNARY, style.Service.INLINE, behavior,
+      None, None, None, None, None, None, None)
+
+
+def unary_stream_inline(behavior):
+  """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a unary-stream RPC method as a callable
+      value that takes a request value and an face.ServicerContext object and
+      returns an iterator of response values.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+  return _MethodImplementation(
+      cardinality.Cardinality.UNARY_STREAM, style.Service.INLINE, None,
+      behavior, None, None, None, None, None, None)
+
+
+def stream_unary_inline(behavior):
+  """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a stream-unary RPC method as a callable
+      value that takes an iterator of request values and an
+      face.ServicerContext object and returns a response value.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+  return _MethodImplementation(
+      cardinality.Cardinality.STREAM_UNARY, style.Service.INLINE, None, None,
+      behavior, None, None, None, None, None)
+
+
+def stream_stream_inline(behavior):
+  """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a stream-stream RPC method as a callable
+      value that takes an iterator of request values and an
+      face.ServicerContext object and returns an iterator of response values.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+  return _MethodImplementation(
+      cardinality.Cardinality.STREAM_STREAM, style.Service.INLINE, None, None,
+      None, behavior, None, None, None, None)
+
+
+def unary_unary_event(behavior):
+  """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a unary-unary RPC method as a callable
+      value that takes a request value, a response callback to which to pass
+      the response value of the RPC, and an face.ServicerContext.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+  return _MethodImplementation(
+      cardinality.Cardinality.UNARY_UNARY, style.Service.EVENT, None, None,
+      None, None, behavior, None, None, None)
+
+
+def unary_stream_event(behavior):
+  """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a unary-stream RPC method as a callable
+      value that takes a request value, a stream.Consumer to which to pass the
+      the response values of the RPC, and an face.ServicerContext.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+  return _MethodImplementation(
+      cardinality.Cardinality.UNARY_STREAM, style.Service.EVENT, None, None,
+      None, None, None, behavior, None, None)
+
+
+def stream_unary_event(behavior):
+  """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a stream-unary RPC method as a callable
+      value that takes a response callback to which to pass the response value
+      of the RPC and an face.ServicerContext and returns a stream.Consumer to
+      which the request values of the RPC should be passed.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+  return _MethodImplementation(
+      cardinality.Cardinality.STREAM_UNARY, style.Service.EVENT, None, None,
+      None, None, None, None, behavior, None)
+
+
+def stream_stream_event(behavior):
+  """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a stream-stream RPC method as a callable
+      value that takes a stream.Consumer to which to pass the response values
+      of the RPC and an face.ServicerContext and returns a stream.Consumer to
+      which the request values of the RPC should be passed.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+  return _MethodImplementation(
+      cardinality.Cardinality.STREAM_STREAM, style.Service.EVENT, None, None,
+      None, None, None, None, None, behavior)
diff --git a/src/python/grpcio/grpc/framework/interfaces/links/links.py b/src/python/grpcio/grpc/framework/interfaces/links/links.py
index 5ebbac8a6f..b98a30a399 100644
--- a/src/python/grpcio/grpc/framework/interfaces/links/links.py
+++ b/src/python/grpcio/grpc/framework/interfaces/links/links.py
@@ -34,12 +34,30 @@ import collections
 import enum
 
 
+class Transport(collections.namedtuple('Transport', ('kind', 'value',))):
+  """A sum type for handles to an underlying transport system.
+
+  Attributes:
+    kind: A Kind value identifying the kind of value being passed to or from
+      the underlying transport.
+    value: The value being passed through RPC Framework between the high-level
+      application and the underlying transport.
+  """
+
+  @enum.unique
+  class Kind(enum.Enum):
+    CALL_OPTION = 'call option'
+    SERVICER_CONTEXT = 'servicer context'
+    INVOCATION_CONTEXT = 'invocation context'
+
+
 class Ticket(
     collections.namedtuple(
         'Ticket',
-        ['operation_id', 'sequence_number', 'group', 'method', 'subscription',
+        ('operation_id', 'sequence_number', 'group', 'method', 'subscription',
          'timeout', 'allowance', 'initial_metadata', 'payload',
-         'terminal_metadata', 'code', 'message', 'termination'])):
+         'terminal_metadata', 'code', 'message', 'termination',
+         'transport',))):
   """A sum type for all values sent from a front to a back.
 
   Attributes:
@@ -81,6 +99,8 @@ class Ticket(
     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.
+    transport: A Transport value or None, with further semantics being a matter
+      between high-level application and underlying transport.
   """
 
   @enum.unique
@@ -98,7 +118,7 @@ class Ticket(
     COMPLETION = 'completion'
     CANCELLATION = 'cancellation'
     EXPIRATION = 'expiration'
-    LOCAL_SHUTDOWN = 'local shutdown'
+    SHUTDOWN = 'shutdown'
     RECEPTION_FAILURE = 'reception failure'
     TRANSMISSION_FAILURE = 'transmission failure'
     LOCAL_FAILURE = 'local failure'
diff --git a/src/python/grpcio_test/grpc_test/_adapter/_low_test.py b/src/python/grpcio_test/grpc_test/_adapter/_low_test.py
index 44fe760fbc..70149127da 100644
--- a/src/python/grpcio_test/grpc_test/_adapter/_low_test.py
+++ b/src/python/grpcio_test/grpc_test/_adapter/_low_test.py
@@ -52,7 +52,6 @@ def wait_for_events(completion_queues, deadline):
   def set_ith_result(i, completion_queue):
     result = completion_queue.next(deadline)
     with lock:
-      print i, completion_queue, result, time.time() - deadline
       results[i] = result
   for i, completion_queue in enumerate(completion_queues):
     thread = threading.Thread(target=set_ith_result,
@@ -80,10 +79,12 @@ class InsecureServerInsecureClient(unittest.TestCase):
     del self.client_channel
 
     self.client_completion_queue.shutdown()
-    while self.client_completion_queue.next().type != _types.EventType.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:
+    while (self.server_completion_queue.next().type !=
+           _types.EventType.QUEUE_SHUTDOWN):
       pass
 
     del self.client_completion_queue
@@ -91,58 +92,68 @@ class InsecureServerInsecureClient(unittest.TestCase):
     del self.server
 
   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'
+    deadline = time.time() + 5
+    event_time_tolerance = 2
+    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 = 'blarghaflargh'
+    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)
+    request_call_result = self.server.request_call(self.server_completion_queue,
+                                                   server_request_tag)
 
-    self.assertEquals(_types.CallError.OK, request_call_result)
+    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_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, 0),
+        _types.OpArgs.send_message(request, 0),
         _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.assertEquals(_types.CallError.OK, client_start_batch_result)
+    self.assertEqual(_types.CallError.OK, client_start_batch_result)
 
-    client_no_event, request_event, = wait_for_events([self.client_completion_queue, self.server_completion_queue], time.time() + 2)
-    self.assertEquals(client_no_event, None)
-    self.assertEquals(_types.EventType.OP_COMPLETE, request_event.type)
+    client_no_event, request_event, = wait_for_events(
+        [self.client_completion_queue, self.server_completion_queue],
+        time.time() + event_time_tolerance)
+    self.assertEqual(client_no_event, None)
+    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.assertEquals(1, len(request_event.results))
+    self.assertEqual(1, len(request_event.results))
     received_initial_metadata = dict(request_event.results[0].initial_metadata)
     # Check that our metadata were transmitted
-    self.assertEquals(
+    self.assertEqual(
         dict(client_initial_metadata),
-        dict((x, received_initial_metadata[x]) for x in zip(*client_initial_metadata)[0]))
+        dict((x, received_initial_metadata[x])
+             for x in zip(*client_initial_metadata)[0]))
     # Check that Python's user agent string is a part of the full user agent
     # string
     self.assertIn('Python-gRPC-{}'.format(_grpcio_metadata.__version__),
                   received_initial_metadata['user-agent'])
-    self.assertEquals(METHOD, request_event.call_details.method)
-    self.assertEquals(HOST, request_event.call_details.host)
-    self.assertLess(abs(DEADLINE - request_event.call_details.deadline), DEADLINE_TOLERANCE)
+    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)
 
     # Check that the channel is connected, and that both it and the call have
     # the proper target and peer; do this after the first flurry of messages to
@@ -155,33 +166,43 @@ class InsecureServerInsecureClient(unittest.TestCase):
 
     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_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, 0),
+        _types.OpArgs.send_message(response, 0),
         _types.OpArgs.recv_close_on_server(),
-        _types.OpArgs.send_status_from_server(server_trailing_metadata, SERVER_STATUS_CODE, SERVER_STATUS_DETAILS)
+        _types.OpArgs.send_status_from_server(
+            server_trailing_metadata, server_status_code, server_status_details)
     ], server_call_tag)
-    self.assertEquals(_types.CallError.OK, server_start_batch_result)
+    self.assertEqual(_types.CallError.OK, server_start_batch_result)
 
-    client_event, server_event, = wait_for_events([self.client_completion_queue, self.server_completion_queue], time.time() + 1)
+    client_event, server_event, = wait_for_events(
+        [self.client_completion_queue, self.server_completion_queue],
+        time.time() + event_time_tolerance)
 
-    self.assertEquals(6, len(client_event.results))
+    self.assertEqual(6, len(client_event.results))
     found_client_op_types = set()
     for client_result in client_event.results:
-      self.assertNotIn(client_result.type, found_client_op_types)  # we expect each op type to be unique
+      # 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.assertEquals(dict(server_initial_metadata), dict(client_result.initial_metadata))
+        self.assertEqual(dict(server_initial_metadata),
+                         dict(client_result.initial_metadata))
       elif client_result.type == _types.OpType.RECV_MESSAGE:
-        self.assertEquals(RESPONSE, client_result.message)
+        self.assertEqual(response, client_result.message)
       elif client_result.type == _types.OpType.RECV_STATUS_ON_CLIENT:
-        self.assertEquals(dict(server_trailing_metadata), dict(client_result.trailing_metadata))
-        self.assertEquals(SERVER_STATUS_DETAILS, client_result.status.details)
-        self.assertEquals(SERVER_STATUS_CODE, client_result.status.code)
-    self.assertEquals(set([
+        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,
@@ -190,16 +211,16 @@ class InsecureServerInsecureClient(unittest.TestCase):
           _types.OpType.RECV_STATUS_ON_CLIENT
       ]), found_client_op_types)
 
-    self.assertEquals(5, len(server_event.results))
+    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.assertEquals(REQUEST, server_result.message)
+        self.assertEqual(request, server_result.message)
       elif server_result.type == _types.OpType.RECV_CLOSE_ON_SERVER:
         self.assertFalse(server_result.cancelled)
-    self.assertEquals(set([
+    self.assertEqual(set([
           _types.OpType.SEND_INITIAL_METADATA,
           _types.OpType.RECV_MESSAGE,
           _types.OpType.SEND_MESSAGE,
@@ -211,5 +232,81 @@ class InsecureServerInsecureClient(unittest.TestCase):
     del server_call
 
 
+class HangingServerShutdown(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()
+    self.server_completion_queue.shutdown()
+    while True:
+      client_event, server_event = wait_for_events(
+          [self.client_completion_queue, self.server_completion_queue],
+          float("+inf"))
+      if (client_event.type == _types.EventType.QUEUE_SHUTDOWN and
+          server_event.type == _types.EventType.QUEUE_SHUTDOWN):
+        break
+
+    del self.client_completion_queue
+    del self.server_completion_queue
+    del self.server
+
+  def testHangingServerCall(self):
+    deadline = time.time() + 5
+    deadline_tolerance = 0.25
+    event_time_tolerance = 2
+    cancel_all_calls_time_tolerance = 0.5
+    request = 'blarghaflargh'
+    method = 'twinkies'
+    host = 'hostess'
+    server_request_tag = object()
+    request_call_result = self.server.request_call(self.server_completion_queue,
+                                                   server_request_tag)
+
+    client_call_tag = object()
+    client_call = self.client_channel.create_call(self.client_completion_queue,
+                                                  method, host, deadline)
+    client_start_batch_result = client_call.start_batch([
+        _types.OpArgs.send_initial_metadata([]),
+        _types.OpArgs.send_message(request, 0),
+        _types.OpArgs.send_close_from_client(),
+        _types.OpArgs.recv_initial_metadata(),
+        _types.OpArgs.recv_message(),
+        _types.OpArgs.recv_status_on_client()
+    ], client_call_tag)
+
+    client_no_event, request_event, = wait_for_events(
+        [self.client_completion_queue, self.server_completion_queue],
+        time.time() + event_time_tolerance)
+
+    # Now try to shutdown the server and expect that we see server shutdown
+    # almost immediately after calling cancel_all_calls.
+    with self.assertRaises(RuntimeError):
+      self.server.cancel_all_calls()
+    shutdown_tag = object()
+    self.server.shutdown(shutdown_tag)
+    pre_cancel_timestamp = time.time()
+    self.server.cancel_all_calls()
+    finish_shutdown_timestamp = None
+    client_call_event, server_shutdown_event = wait_for_events(
+        [self.client_completion_queue, self.server_completion_queue],
+        time.time() + event_time_tolerance)
+    self.assertIs(shutdown_tag, server_shutdown_event.tag)
+    self.assertGreater(pre_cancel_timestamp + cancel_all_calls_time_tolerance,
+                       time.time())
+
+    del client_call
+
+
 if __name__ == '__main__':
   unittest.main(verbosity=2)
diff --git a/src/python/grpcio_test/grpc_test/_core_over_links_base_interface_test.py b/src/python/grpcio_test/grpc_test/_core_over_links_base_interface_test.py
new file mode 100644
index 0000000000..72b1ae5642
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/_core_over_links_base_interface_test.py
@@ -0,0 +1,165 @@
+# 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 the RPC Framework Core's implementation of the Base interface."""
+
+import collections
+import logging
+import random
+import time
+import unittest
+
+from grpc._adapter import _intermediary_low
+from grpc._links import invocation
+from grpc._links import service
+from grpc.framework.core import implementations
+from grpc.framework.interfaces.base import utilities
+from grpc_test import test_common as grpc_test_common
+from grpc_test.framework.common import test_constants
+from grpc_test.framework.interfaces.base import test_cases
+from grpc_test.framework.interfaces.base import test_interfaces
+
+_INVOCATION_INITIAL_METADATA = ((b'0', b'abc'), (b'1', b'def'), (b'2', b'ghi'),)
+_SERVICE_INITIAL_METADATA = ((b'3', b'jkl'), (b'4', b'mno'), (b'5', b'pqr'),)
+_SERVICE_TERMINAL_METADATA = ((b'6', b'stu'), (b'7', b'vwx'), (b'8', b'yza'),)
+_CODE = _intermediary_low.Code.OK
+_MESSAGE = b'test message'
+
+
+class _SerializationBehaviors(
+    collections.namedtuple(
+        '_SerializationBehaviors',
+        ('request_serializers', 'request_deserializers', 'response_serializers',
+         'response_deserializers',))):
+  pass
+
+
+class _Links(
+    collections.namedtuple(
+        '_Links',
+        ('invocation_end_link', 'invocation_grpc_link', 'service_grpc_link',
+         'service_end_link'))):
+  pass
+
+
+def _serialization_behaviors_from_serializations(serializations):
+  request_serializers = {}
+  request_deserializers = {}
+  response_serializers = {}
+  response_deserializers = {}
+  for (group, method), serialization in serializations.iteritems():
+    request_serializers[group, method] = serialization.serialize_request
+    request_deserializers[group, method] = serialization.deserialize_request
+    response_serializers[group, method] = serialization.serialize_response
+    response_deserializers[group, method] = serialization.deserialize_response
+  return _SerializationBehaviors(
+      request_serializers, request_deserializers, response_serializers,
+      response_deserializers)
+
+
+class _Implementation(test_interfaces.Implementation):
+
+  def instantiate(self, serializations, servicer):
+    serialization_behaviors = _serialization_behaviors_from_serializations(
+        serializations)
+    invocation_end_link = implementations.invocation_end_link()
+    service_end_link = implementations.service_end_link(
+        servicer, test_constants.DEFAULT_TIMEOUT,
+        test_constants.MAXIMUM_TIMEOUT)
+    service_grpc_link = service.service_link(
+        serialization_behaviors.request_deserializers,
+        serialization_behaviors.response_serializers)
+    port = service_grpc_link.add_port(0, None)
+    channel = _intermediary_low.Channel('localhost:%d' % port, None)
+    invocation_grpc_link = invocation.invocation_link(
+        channel, b'localhost',
+        serialization_behaviors.request_serializers,
+        serialization_behaviors.response_deserializers)
+
+    invocation_end_link.join_link(invocation_grpc_link)
+    invocation_grpc_link.join_link(invocation_end_link)
+    service_end_link.join_link(service_grpc_link)
+    service_grpc_link.join_link(service_end_link)
+    invocation_grpc_link.start()
+    service_grpc_link.start()
+    return invocation_end_link, service_end_link, (
+        invocation_grpc_link, service_grpc_link)
+
+  def destantiate(self, memo):
+    invocation_grpc_link, service_grpc_link = memo
+    invocation_grpc_link.stop()
+    service_grpc_link.stop_gracefully()
+
+  def invocation_initial_metadata(self):
+    return _INVOCATION_INITIAL_METADATA
+
+  def service_initial_metadata(self):
+    return _SERVICE_INITIAL_METADATA
+
+  def invocation_completion(self):
+    return utilities.completion(None, None, None)
+
+  def service_completion(self):
+    return utilities.completion(_SERVICE_TERMINAL_METADATA, _CODE, _MESSAGE)
+
+  def metadata_transmitted(self, original_metadata, transmitted_metadata):
+    return original_metadata is None or grpc_test_common.metadata_transmitted(
+        original_metadata, transmitted_metadata)
+
+  def completion_transmitted(self, original_completion, transmitted_completion):
+    if (original_completion.terminal_metadata is not None and
+        not grpc_test_common.metadata_transmitted(
+            original_completion.terminal_metadata,
+            transmitted_completion.terminal_metadata)):
+        return False
+    elif original_completion.code is not transmitted_completion.code:
+      return False
+    elif original_completion.message != transmitted_completion.message:
+      return False
+    else:
+      return True
+
+
+def setUpModule():
+  logging.warn('setUpModule!')
+
+
+def tearDownModule():
+  logging.warn('tearDownModule!')
+
+
+def load_tests(loader, tests, pattern):
+  return unittest.TestSuite(
+      tests=tuple(
+          loader.loadTestsFromTestCase(test_case_class)
+          for test_case_class in test_cases.test_cases(_Implementation())))
+
+
+if __name__ == '__main__':
+  unittest.main(verbosity=2)
diff --git a/src/python/grpcio_test/grpc_test/_links/_lonely_invocation_link_test.py b/src/python/grpcio_test/grpc_test/_links/_lonely_invocation_link_test.py
index abe240e07a..373a2b2a1f 100644
--- a/src/python/grpcio_test/grpc_test/_links/_lonely_invocation_link_test.py
+++ b/src/python/grpcio_test/grpc_test/_links/_lonely_invocation_link_test.py
@@ -66,7 +66,7 @@ class LonelyInvocationLinkTest(unittest.TestCase):
     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)
+        None, None, None, None, termination, None)
     invocation_link.accept_ticket(ticket)
     invocation_link_mate.block_until_tickets_satisfy(test_cases.terminated)
 
diff --git a/src/python/grpcio_test/grpc_test/_links/_transmission_test.py b/src/python/grpcio_test/grpc_test/_links/_transmission_test.py
index 9cdc9620f0..02ddd512c2 100644
--- a/src/python/grpcio_test/grpc_test/_links/_transmission_test.py
+++ b/src/python/grpcio_test/grpc_test/_links/_transmission_test.py
@@ -128,14 +128,14 @@ class RoundTripTest(unittest.TestCase):
     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)
+        None, None, None, None, links.Ticket.Termination.COMPLETION, None)
     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)
+        links.Ticket.Termination.COMPLETION, None)
     service_link.accept_ticket(service_ticket)
     invocation_mate.block_until_tickets_satisfy(test_cases.terminated)
 
@@ -174,33 +174,34 @@ class RoundTripTest(unittest.TestCase):
     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)
+        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)
+          request, None, 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)
+          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)
+        None, None, None, None, None, links.Ticket.Termination.COMPLETION,
+        None)
     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)
+        links.Ticket.Termination.COMPLETION, None)
     service_link.accept_ticket(service_completion_ticket)
     invocation_mate.block_until_tickets_satisfy(test_cases.terminated)
 
diff --git a/src/python/grpcio_test/grpc_test/framework/common/test_control.py b/src/python/grpcio_test/grpc_test/framework/common/test_control.py
index 3960c4e649..8d6eba5c2c 100644
--- a/src/python/grpcio_test/grpc_test/framework/common/test_control.py
+++ b/src/python/grpcio_test/grpc_test/framework/common/test_control.py
@@ -34,6 +34,14 @@ import contextlib
 import threading
 
 
+class Defect(Exception):
+  """Simulates a programming defect raised into in a system under test.
+
+  Use of a standard exception type is too easily misconstrued as an actual
+  defect in either the test infrastructure or the system under test.
+  """
+
+
 class Control(object):
   """An object that accepts program control from a system under test.
 
@@ -62,7 +70,7 @@ class PauseFailControl(Control):
   def control(self):
     with self._condition:
       if self._fail:
-        raise ValueError()
+        raise Defect()
 
       while self._paused:
         self._condition.wait()
diff --git a/src/python/grpcio_test/grpc_test/framework/core/__init__.py b/src/python/grpcio_test/grpc_test/framework/core/__init__.py
new file mode 100644
index 0000000000..7086519106
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/core/__init__.py
@@ -0,0 +1,30 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
diff --git a/src/python/grpcio_test/grpc_test/framework/core/_base_interface_test.py b/src/python/grpcio_test/grpc_test/framework/core/_base_interface_test.py
new file mode 100644
index 0000000000..8d72f131d5
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/core/_base_interface_test.py
@@ -0,0 +1,96 @@
+# 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 the RPC Framework Core's implementation of the Base interface."""
+
+import logging
+import random
+import time
+import unittest
+
+from grpc.framework.core import implementations
+from grpc.framework.interfaces.base import utilities
+from grpc_test.framework.common import test_constants
+from grpc_test.framework.interfaces.base import test_cases
+from grpc_test.framework.interfaces.base import test_interfaces
+
+
+class _Implementation(test_interfaces.Implementation):
+
+  def __init__(self):
+    self._invocation_initial_metadata = object()
+    self._service_initial_metadata = object()
+    self._invocation_terminal_metadata = object()
+    self._service_terminal_metadata = object()
+
+  def instantiate(self, serializations, servicer):
+    invocation = implementations.invocation_end_link()
+    service = implementations.service_end_link(
+        servicer, test_constants.DEFAULT_TIMEOUT,
+        test_constants.MAXIMUM_TIMEOUT)
+    invocation.join_link(service)
+    service.join_link(invocation)
+    return invocation, service, None
+
+  def destantiate(self, memo):
+    pass
+
+  def invocation_initial_metadata(self):
+    return self._invocation_initial_metadata
+
+  def service_initial_metadata(self):
+    return self._service_initial_metadata
+
+  def invocation_completion(self):
+    return utilities.completion(self._invocation_terminal_metadata, None, None)
+
+  def service_completion(self):
+    return utilities.completion(self._service_terminal_metadata, None, None)
+
+  def metadata_transmitted(self, original_metadata, transmitted_metadata):
+    return transmitted_metadata is original_metadata
+
+  def completion_transmitted(self, original_completion, transmitted_completion):
+    return (
+        (original_completion.terminal_metadata is
+         transmitted_completion.terminal_metadata) and
+        original_completion.code is transmitted_completion.code and
+        original_completion.message is transmitted_completion.message
+    )
+
+
+def load_tests(loader, tests, pattern):
+  return unittest.TestSuite(
+      tests=tuple(
+          loader.loadTestsFromTestCase(test_case_class)
+          for test_case_class in test_cases.test_cases(_Implementation())))
+
+
+if __name__ == '__main__':
+  unittest.main(verbosity=2)
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/base/test_cases.py b/src/python/grpcio_test/grpc_test/framework/interfaces/base/test_cases.py
index dd332fe5dd..5c8b176da4 100644
--- a/src/python/grpcio_test/grpc_test/framework/interfaces/base/test_cases.py
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/base/test_cases.py
@@ -211,8 +211,10 @@ class _OperationTest(unittest.TestCase):
       elif instruction.kind is _control.Instruction.Kind.CONCLUDE:
         break
 
-    invocation_end.stop_gracefully()
-    service_end.stop_gracefully()
+    invocation_stop_event = invocation_end.stop(0)
+    service_stop_event = service_end.stop(0)
+    invocation_stop_event.wait()
+    service_stop_event.wait()
     invocation_stats = invocation_end.operation_stats()
     service_stats = service_end.operation_stats()
 
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/face/__init__.py b/src/python/grpcio_test/grpc_test/framework/interfaces/face/__init__.py
new file mode 100644
index 0000000000..7086519106
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/face/__init__.py
@@ -0,0 +1,30 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/face/_blocking_invocation_inline_service.py b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_blocking_invocation_inline_service.py
new file mode 100644
index 0000000000..857ad5cf3e
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_blocking_invocation_inline_service.py
@@ -0,0 +1,250 @@
+# 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 code for the Face layer of RPC Framework."""
+
+import abc
+import unittest
+
+# test_interfaces is referenced from specification in this module.
+from grpc.framework.interfaces.face import face
+from grpc_test.framework.common import test_constants
+from grpc_test.framework.common import test_control
+from grpc_test.framework.common import test_coverage
+from grpc_test.framework.interfaces.face import _digest
+from grpc_test.framework.interfaces.face import _stock_service
+from grpc_test.framework.interfaces.face import test_interfaces  # pylint: disable=unused-import
+
+
+class TestCase(test_coverage.Coverage, unittest.TestCase):
+  """A test of the Face layer of RPC Framework.
+
+  Concrete subclasses must have an "implementation" attribute of type
+  test_interfaces.Implementation and an "invoker_constructor" attribute of type
+  _invocation.InvokerConstructor.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  NAME = 'BlockingInvocationInlineServiceTest'
+
+  def setUp(self):
+    """See unittest.TestCase.setUp for full specification.
+
+    Overriding implementations must call this implementation.
+    """
+    self._control = test_control.PauseFailControl()
+    self._digest = _digest.digest(
+        _stock_service.STOCK_TEST_SERVICE, self._control, None)
+
+    generic_stub, dynamic_stubs, self._memo = self.implementation.instantiate(
+        self._digest.methods, self._digest.inline_method_implementations, None)
+    self._invoker = self.invoker_constructor.construct_invoker(
+        generic_stub, dynamic_stubs, self._digest.methods)
+
+  def tearDown(self):
+    """See unittest.TestCase.tearDown for full specification.
+
+    Overriding implementations must call this implementation.
+    """
+    self.implementation.destantiate(self._memo)
+
+  def testSuccessfulUnaryRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        response = self._invoker.blocking(group, method)(
+            request, test_constants.LONG_TIMEOUT)
+
+        test_messages.verify(request, response, self)
+
+  def testSuccessfulUnaryRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        response_iterator = self._invoker.blocking(group, method)(
+            request, test_constants.LONG_TIMEOUT)
+        responses = list(response_iterator)
+
+        test_messages.verify(request, responses, self)
+
+  def testSuccessfulStreamRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        response = self._invoker.blocking(group, method)(
+            iter(requests), test_constants.LONG_TIMEOUT)
+
+        test_messages.verify(requests, response, self)
+
+  def testSuccessfulStreamRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        response_iterator = self._invoker.blocking(group, method)(
+            iter(requests), test_constants.LONG_TIMEOUT)
+        responses = list(response_iterator)
+
+        test_messages.verify(requests, responses, self)
+
+  def testSequentialInvocations(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        first_request = test_messages.request()
+        second_request = test_messages.request()
+
+        first_response = self._invoker.blocking(group, method)(
+            first_request, test_constants.LONG_TIMEOUT)
+
+        test_messages.verify(first_request, first_response, self)
+
+        second_response = self._invoker.blocking(group, method)(
+            second_request, test_constants.LONG_TIMEOUT)
+
+        test_messages.verify(second_request, second_response, self)
+
+  @unittest.skip('Parallel invocations impossible with blocking control flow!')
+  def testParallelInvocations(self):
+    raise NotImplementedError()
+
+  @unittest.skip('Parallel invocations impossible with blocking control flow!')
+  def testWaitingForSomeButNotAllParallelInvocations(self):
+    raise NotImplementedError()
+
+  @unittest.skip('Cancellation impossible with blocking control flow!')
+  def testCancelledUnaryRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @unittest.skip('Cancellation impossible with blocking control flow!')
+  def testCancelledUnaryRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @unittest.skip('Cancellation impossible with blocking control flow!')
+  def testCancelledStreamRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @unittest.skip('Cancellation impossible with blocking control flow!')
+  def testCancelledStreamRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  def testExpiredUnaryRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self._control.pause(), self.assertRaises(
+            face.ExpirationError):
+          self._invoker.blocking(group, method)(
+              request, test_constants.SHORT_TIMEOUT)
+
+  def testExpiredUnaryRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self._control.pause(), self.assertRaises(
+            face.ExpirationError):
+          response_iterator = self._invoker.blocking(group, method)(
+              request, test_constants.SHORT_TIMEOUT)
+          list(response_iterator)
+
+  def testExpiredStreamRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self._control.pause(), self.assertRaises(
+            face.ExpirationError):
+          self._invoker.blocking(group, method)(
+              iter(requests), test_constants.SHORT_TIMEOUT)
+
+  def testExpiredStreamRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self._control.pause(), self.assertRaises(
+            face.ExpirationError):
+          response_iterator = self._invoker.blocking(group, method)(
+              iter(requests), test_constants.SHORT_TIMEOUT)
+          list(response_iterator)
+
+  def testFailedUnaryRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self._control.fail(), self.assertRaises(face.RemoteError):
+          self._invoker.blocking(group, method)(
+              request, test_constants.LONG_TIMEOUT)
+
+  def testFailedUnaryRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self._control.fail(), self.assertRaises(face.RemoteError):
+          response_iterator = self._invoker.blocking(group, method)(
+              request, test_constants.LONG_TIMEOUT)
+          list(response_iterator)
+
+  def testFailedStreamRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self._control.fail(), self.assertRaises(face.RemoteError):
+          self._invoker.blocking(group, method)(
+              iter(requests), test_constants.LONG_TIMEOUT)
+
+  def testFailedStreamRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self._control.fail(), self.assertRaises(face.RemoteError):
+          response_iterator = self._invoker.blocking(group, method)(
+              iter(requests), test_constants.LONG_TIMEOUT)
+          list(response_iterator)
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/face/_digest.py b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_digest.py
new file mode 100644
index 0000000000..da56ed7b27
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_digest.py
@@ -0,0 +1,444 @@
+# 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 making a service.TestService more amenable to use in tests."""
+
+import collections
+import threading
+
+# test_control, _service, and test_interfaces are referenced from specification
+# in this module.
+from grpc.framework.common import cardinality
+from grpc.framework.common import style
+from grpc.framework.foundation import stream
+from grpc.framework.foundation import stream_util
+from grpc.framework.interfaces.face import face
+from grpc_test.framework.common import test_control  # pylint: disable=unused-import
+from grpc_test.framework.interfaces.face import _service  # pylint: disable=unused-import
+from grpc_test.framework.interfaces.face import test_interfaces  # pylint: disable=unused-import
+
+_IDENTITY = lambda x: x
+
+
+class TestServiceDigest(
+    collections.namedtuple(
+        'TestServiceDigest',
+        ('methods',
+         'inline_method_implementations',
+         'event_method_implementations',
+         'multi_method_implementation',
+         'unary_unary_messages_sequences',
+         'unary_stream_messages_sequences',
+         'stream_unary_messages_sequences',
+         'stream_stream_messages_sequences',))):
+  """A transformation of a service.TestService.
+
+  Attributes:
+    methods: A dict from method group-name pair to test_interfaces.Method object
+      describing the RPC methods that may be called during the test.
+    inline_method_implementations: A dict from method group-name pair to
+      face.MethodImplementation object to be used in tests of in-line calls to
+      behaviors under test.
+    event_method_implementations: A dict from method group-name pair to
+      face.MethodImplementation object to be used in tests of event-driven calls
+      to behaviors under test.
+    multi_method_implementation: A face.MultiMethodImplementation to be used in
+      tests of generic calls to behaviors under test.
+    unary_unary_messages_sequences: A dict from method group-name pair to
+      sequence of service.UnaryUnaryTestMessages objects to be used to test the
+      identified method.
+    unary_stream_messages_sequences: A dict from method group-name pair to
+      sequence of service.UnaryStreamTestMessages objects to be used to test the
+      identified method.
+    stream_unary_messages_sequences: A dict from method group-name pair to
+      sequence of service.StreamUnaryTestMessages objects to be used to test the
+      identified method.
+    stream_stream_messages_sequences: A dict from method group-name pair to
+      sequence of service.StreamStreamTestMessages objects to be used to test
+      the identified method.
+  """
+
+
+class _BufferingConsumer(stream.Consumer):
+  """A trivial Consumer that dumps what it consumes in a user-mutable buffer."""
+
+  def __init__(self):
+    self.consumed = []
+    self.terminated = False
+
+  def consume(self, value):
+    self.consumed.append(value)
+
+  def terminate(self):
+    self.terminated = True
+
+  def consume_and_terminate(self, value):
+    self.consumed.append(value)
+    self.terminated = True
+
+
+class _InlineUnaryUnaryMethod(face.MethodImplementation):
+
+  def __init__(self, unary_unary_test_method, control):
+    self._test_method = unary_unary_test_method
+    self._control = control
+
+    self.cardinality = cardinality.Cardinality.UNARY_UNARY
+    self.style = style.Service.INLINE
+
+  def unary_unary_inline(self, request, context):
+    response_list = []
+    self._test_method.service(
+        request, response_list.append, context, self._control)
+    return response_list.pop(0)
+
+
+class _EventUnaryUnaryMethod(face.MethodImplementation):
+
+  def __init__(self, unary_unary_test_method, control, pool):
+    self._test_method = unary_unary_test_method
+    self._control = control
+    self._pool = pool
+
+    self.cardinality = cardinality.Cardinality.UNARY_UNARY
+    self.style = style.Service.EVENT
+
+  def unary_unary_event(self, request, response_callback, context):
+    if self._pool is None:
+      self._test_method.service(
+          request, response_callback, context, self._control)
+    else:
+      self._pool.submit(
+          self._test_method.service, request, response_callback, context,
+          self._control)
+
+
+class _InlineUnaryStreamMethod(face.MethodImplementation):
+
+  def __init__(self, unary_stream_test_method, control):
+    self._test_method = unary_stream_test_method
+    self._control = control
+
+    self.cardinality = cardinality.Cardinality.UNARY_STREAM
+    self.style = style.Service.INLINE
+
+  def unary_stream_inline(self, request, context):
+    response_consumer = _BufferingConsumer()
+    self._test_method.service(
+        request, response_consumer, context, self._control)
+    for response in response_consumer.consumed:
+      yield response
+
+
+class _EventUnaryStreamMethod(face.MethodImplementation):
+
+  def __init__(self, unary_stream_test_method, control, pool):
+    self._test_method = unary_stream_test_method
+    self._control = control
+    self._pool = pool
+
+    self.cardinality = cardinality.Cardinality.UNARY_STREAM
+    self.style = style.Service.EVENT
+
+  def unary_stream_event(self, request, response_consumer, context):
+    if self._pool is None:
+      self._test_method.service(
+          request, response_consumer, context, self._control)
+    else:
+      self._pool.submit(
+          self._test_method.service, request, response_consumer, context,
+          self._control)
+
+
+class _InlineStreamUnaryMethod(face.MethodImplementation):
+
+  def __init__(self, stream_unary_test_method, control):
+    self._test_method = stream_unary_test_method
+    self._control = control
+
+    self.cardinality = cardinality.Cardinality.STREAM_UNARY
+    self.style = style.Service.INLINE
+
+  def stream_unary_inline(self, request_iterator, context):
+    response_list = []
+    request_consumer = self._test_method.service(
+        response_list.append, context, self._control)
+    for request in request_iterator:
+      request_consumer.consume(request)
+    request_consumer.terminate()
+    return response_list.pop(0)
+
+
+class _EventStreamUnaryMethod(face.MethodImplementation):
+
+  def __init__(self, stream_unary_test_method, control, pool):
+    self._test_method = stream_unary_test_method
+    self._control = control
+    self._pool = pool
+
+    self.cardinality = cardinality.Cardinality.STREAM_UNARY
+    self.style = style.Service.EVENT
+
+  def stream_unary_event(self, response_callback, context):
+    request_consumer = self._test_method.service(
+        response_callback, context, self._control)
+    if self._pool is None:
+      return request_consumer
+    else:
+      return stream_util.ThreadSwitchingConsumer(request_consumer, self._pool)
+
+
+class _InlineStreamStreamMethod(face.MethodImplementation):
+
+  def __init__(self, stream_stream_test_method, control):
+    self._test_method = stream_stream_test_method
+    self._control = control
+
+    self.cardinality = cardinality.Cardinality.STREAM_STREAM
+    self.style = style.Service.INLINE
+
+  def stream_stream_inline(self, request_iterator, context):
+    response_consumer = _BufferingConsumer()
+    request_consumer = self._test_method.service(
+        response_consumer, context, self._control)
+
+    for request in request_iterator:
+      request_consumer.consume(request)
+      while response_consumer.consumed:
+        yield response_consumer.consumed.pop(0)
+    response_consumer.terminate()
+
+
+class _EventStreamStreamMethod(face.MethodImplementation):
+
+  def __init__(self, stream_stream_test_method, control, pool):
+    self._test_method = stream_stream_test_method
+    self._control = control
+    self._pool = pool
+
+    self.cardinality = cardinality.Cardinality.STREAM_STREAM
+    self.style = style.Service.EVENT
+
+  def stream_stream_event(self, response_consumer, context):
+    request_consumer = self._test_method.service(
+        response_consumer, context, self._control)
+    if self._pool is None:
+      return request_consumer
+    else:
+      return stream_util.ThreadSwitchingConsumer(request_consumer, self._pool)
+
+
+class _UnaryConsumer(stream.Consumer):
+  """A Consumer that only allows consumption of exactly one value."""
+
+  def __init__(self, action):
+    self._lock = threading.Lock()
+    self._action = action
+    self._consumed = False
+    self._terminated = False
+
+  def consume(self, value):
+    with self._lock:
+      if self._consumed:
+        raise ValueError('Unary consumer already consumed!')
+      elif self._terminated:
+        raise ValueError('Unary consumer already terminated!')
+      else:
+        self._consumed = True
+
+    self._action(value)
+
+  def terminate(self):
+    with self._lock:
+      if not self._consumed:
+        raise ValueError('Unary consumer hasn\'t yet consumed!')
+      elif self._terminated:
+        raise ValueError('Unary consumer already terminated!')
+      else:
+        self._terminated = True
+
+  def consume_and_terminate(self, value):
+    with self._lock:
+      if self._consumed:
+        raise ValueError('Unary consumer already consumed!')
+      elif self._terminated:
+        raise ValueError('Unary consumer already terminated!')
+      else:
+        self._consumed = True
+        self._terminated = True
+
+    self._action(value)
+
+
+class _UnaryUnaryAdaptation(object):
+
+  def __init__(self, unary_unary_test_method):
+    self._method = unary_unary_test_method
+
+  def service(self, response_consumer, context, control):
+    def action(request):
+      self._method.service(
+          request, response_consumer.consume_and_terminate, context, control)
+    return _UnaryConsumer(action)
+
+
+class _UnaryStreamAdaptation(object):
+
+  def __init__(self, unary_stream_test_method):
+    self._method = unary_stream_test_method
+
+  def service(self, response_consumer, context, control):
+    def action(request):
+      self._method.service(request, response_consumer, context, control)
+    return _UnaryConsumer(action)
+
+
+class _StreamUnaryAdaptation(object):
+
+  def __init__(self, stream_unary_test_method):
+    self._method = stream_unary_test_method
+
+  def service(self, response_consumer, context, control):
+    return self._method.service(
+        response_consumer.consume_and_terminate, context, control)
+
+
+class _MultiMethodImplementation(face.MultiMethodImplementation):
+
+  def __init__(self, methods, control, pool):
+    self._methods = methods
+    self._control = control
+    self._pool = pool
+
+  def service(self, group, name, response_consumer, context):
+    method = self._methods.get(group, name, None)
+    if method is None:
+      raise face.NoSuchMethodError(group, name)
+    elif self._pool is None:
+      return method(response_consumer, context, self._control)
+    else:
+      request_consumer = method(response_consumer, context, self._control)
+      return stream_util.ThreadSwitchingConsumer(request_consumer, self._pool)
+
+
+class _Assembly(
+    collections.namedtuple(
+        '_Assembly',
+        ['methods', 'inlines', 'events', 'adaptations', 'messages'])):
+  """An intermediate structure created when creating a TestServiceDigest."""
+
+
+def _assemble(
+    scenarios, identifiers, inline_method_constructor, event_method_constructor,
+    adapter, control, pool):
+  """Creates an _Assembly from the given scenarios."""
+  methods = {}
+  inlines = {}
+  events = {}
+  adaptations = {}
+  messages = {}
+  for identifier, scenario in scenarios.iteritems():
+    if identifier in identifiers:
+      raise ValueError('Repeated identifier "(%s, %s)"!' % identifier)
+
+    test_method = scenario[0]
+    inline_method = inline_method_constructor(test_method, control)
+    event_method = event_method_constructor(test_method, control, pool)
+    adaptation = adapter(test_method)
+
+    methods[identifier] = test_method
+    inlines[identifier] = inline_method
+    events[identifier] = event_method
+    adaptations[identifier] = adaptation
+    messages[identifier] = scenario[1]
+
+  return _Assembly(methods, inlines, events, adaptations, messages)
+
+
+def digest(service, control, pool):
+  """Creates a TestServiceDigest from a TestService.
+
+  Args:
+    service: A _service.TestService.
+    control: A test_control.Control.
+    pool: If RPC methods should be serviced in a separate thread, a thread pool.
+      None if RPC methods should be serviced in the thread belonging to the
+      run-time that calls for their service.
+
+  Returns:
+    A TestServiceDigest synthesized from the given service.TestService.
+  """
+  identifiers = set()
+
+  unary_unary = _assemble(
+      service.unary_unary_scenarios(), identifiers, _InlineUnaryUnaryMethod,
+      _EventUnaryUnaryMethod, _UnaryUnaryAdaptation, control, pool)
+  identifiers.update(unary_unary.inlines)
+
+  unary_stream = _assemble(
+      service.unary_stream_scenarios(), identifiers, _InlineUnaryStreamMethod,
+      _EventUnaryStreamMethod, _UnaryStreamAdaptation, control, pool)
+  identifiers.update(unary_stream.inlines)
+
+  stream_unary = _assemble(
+      service.stream_unary_scenarios(), identifiers, _InlineStreamUnaryMethod,
+      _EventStreamUnaryMethod, _StreamUnaryAdaptation, control, pool)
+  identifiers.update(stream_unary.inlines)
+
+  stream_stream = _assemble(
+      service.stream_stream_scenarios(), identifiers, _InlineStreamStreamMethod,
+      _EventStreamStreamMethod, _IDENTITY, control, pool)
+  identifiers.update(stream_stream.inlines)
+
+  methods = dict(unary_unary.methods)
+  methods.update(unary_stream.methods)
+  methods.update(stream_unary.methods)
+  methods.update(stream_stream.methods)
+  adaptations = dict(unary_unary.adaptations)
+  adaptations.update(unary_stream.adaptations)
+  adaptations.update(stream_unary.adaptations)
+  adaptations.update(stream_stream.adaptations)
+  inlines = dict(unary_unary.inlines)
+  inlines.update(unary_stream.inlines)
+  inlines.update(stream_unary.inlines)
+  inlines.update(stream_stream.inlines)
+  events = dict(unary_unary.events)
+  events.update(unary_stream.events)
+  events.update(stream_unary.events)
+  events.update(stream_stream.events)
+
+  return TestServiceDigest(
+      methods,
+      inlines,
+      events,
+      _MultiMethodImplementation(adaptations, control, pool),
+      unary_unary.messages,
+      unary_stream.messages,
+      stream_unary.messages,
+      stream_stream.messages)
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/face/_event_invocation_synchronous_event_service.py b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_event_invocation_synchronous_event_service.py
new file mode 100644
index 0000000000..ea5cdeaea3
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_event_invocation_synchronous_event_service.py
@@ -0,0 +1,377 @@
+# 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 code for the Face layer of RPC Framework."""
+
+import abc
+import unittest
+
+# test_interfaces is referenced from specification in this module.
+from grpc.framework.interfaces.face import face
+from grpc_test.framework.common import test_constants
+from grpc_test.framework.common import test_control
+from grpc_test.framework.common import test_coverage
+from grpc_test.framework.interfaces.face import _digest
+from grpc_test.framework.interfaces.face import _receiver
+from grpc_test.framework.interfaces.face import _stock_service
+from grpc_test.framework.interfaces.face import test_interfaces  # pylint: disable=unused-import
+
+
+class TestCase(test_coverage.Coverage, unittest.TestCase):
+  """A test of the Face layer of RPC Framework.
+
+  Concrete subclasses must have an "implementation" attribute of type
+  test_interfaces.Implementation and an "invoker_constructor" attribute of type
+  _invocation.InvokerConstructor.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  NAME = 'EventInvocationSynchronousEventServiceTest'
+
+  def setUp(self):
+    """See unittest.TestCase.setUp for full specification.
+
+    Overriding implementations must call this implementation.
+    """
+    self._control = test_control.PauseFailControl()
+    self._digest = _digest.digest(
+        _stock_service.STOCK_TEST_SERVICE, self._control, None)
+
+    generic_stub, dynamic_stubs, self._memo = self.implementation.instantiate(
+        self._digest.methods, self._digest.event_method_implementations, None)
+    self._invoker = self.invoker_constructor.construct_invoker(
+        generic_stub, dynamic_stubs, self._digest.methods)
+
+  def tearDown(self):
+    """See unittest.TestCase.tearDown for full specification.
+
+    Overriding implementations must call this implementation.
+    """
+    self.implementation.destantiate(self._memo)
+
+  def testSuccessfulUnaryRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        receiver = _receiver.Receiver()
+
+        self._invoker.event(group, method)(
+            request, receiver, receiver.abort, test_constants.LONG_TIMEOUT)
+        receiver.block_until_terminated()
+        response = receiver.unary_response()
+
+        test_messages.verify(request, response, self)
+
+  def testSuccessfulUnaryRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        receiver = _receiver.Receiver()
+
+        self._invoker.event(group, method)(
+            request, receiver, receiver.abort, test_constants.LONG_TIMEOUT)
+        receiver.block_until_terminated()
+        responses = receiver.stream_responses()
+
+        test_messages.verify(request, responses, self)
+
+  def testSuccessfulStreamRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        receiver = _receiver.Receiver()
+
+        call_consumer = self._invoker.event(group, method)(
+            receiver, receiver.abort, test_constants.LONG_TIMEOUT)
+        for request in requests:
+          call_consumer.consume(request)
+        call_consumer.terminate()
+        receiver.block_until_terminated()
+        response = receiver.unary_response()
+
+        test_messages.verify(requests, response, self)
+
+  def testSuccessfulStreamRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        receiver = _receiver.Receiver()
+
+        call_consumer = self._invoker.event(group, method)(
+            receiver, receiver.abort, test_constants.LONG_TIMEOUT)
+        for request in requests:
+          call_consumer.consume(request)
+        call_consumer.terminate()
+        receiver.block_until_terminated()
+        responses = receiver.stream_responses()
+
+        test_messages.verify(requests, responses, self)
+
+  def testSequentialInvocations(self):
+    # pylint: disable=cell-var-from-loop
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        first_request = test_messages.request()
+        second_request = test_messages.request()
+        second_receiver = _receiver.Receiver()
+
+        def make_second_invocation():
+          self._invoker.event(group, method)(
+              second_request, second_receiver, second_receiver.abort,
+              test_constants.LONG_TIMEOUT)
+
+        class FirstReceiver(_receiver.Receiver):
+
+          def complete(self, terminal_metadata, code, details):
+            super(FirstReceiver, self).complete(
+                terminal_metadata, code, details)
+            make_second_invocation()
+
+        first_receiver = FirstReceiver()
+
+        self._invoker.event(group, method)(
+            first_request, first_receiver, first_receiver.abort,
+            test_constants.LONG_TIMEOUT)
+        second_receiver.block_until_terminated()
+
+        first_response = first_receiver.unary_response()
+        second_response = second_receiver.unary_response()
+        test_messages.verify(first_request, first_response, self)
+        test_messages.verify(second_request, second_response, self)
+
+  def testParallelInvocations(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        first_request = test_messages.request()
+        first_receiver = _receiver.Receiver()
+        second_request = test_messages.request()
+        second_receiver = _receiver.Receiver()
+
+        self._invoker.event(group, method)(
+            first_request, first_receiver, first_receiver.abort,
+            test_constants.LONG_TIMEOUT)
+        self._invoker.event(group, method)(
+            second_request, second_receiver, second_receiver.abort,
+            test_constants.LONG_TIMEOUT)
+        first_receiver.block_until_terminated()
+        second_receiver.block_until_terminated()
+
+        first_response = first_receiver.unary_response()
+        second_response = second_receiver.unary_response()
+        test_messages.verify(first_request, first_response, self)
+        test_messages.verify(second_request, second_response, self)
+
+  @unittest.skip('TODO(nathaniel): implement.')
+  def testWaitingForSomeButNotAllParallelInvocations(self):
+    raise NotImplementedError()
+
+  def testCancelledUnaryRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        receiver = _receiver.Receiver()
+
+        with self._control.pause():
+          call = self._invoker.event(group, method)(
+              request, receiver, receiver.abort, test_constants.LONG_TIMEOUT)
+          call.cancel()
+          receiver.block_until_terminated()
+
+        self.assertIs(face.Abortion.Kind.CANCELLED, receiver.abortion().kind)
+
+  def testCancelledUnaryRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        receiver = _receiver.Receiver()
+
+        call = self._invoker.event(group, method)(
+            request, receiver, receiver.abort, test_constants.LONG_TIMEOUT)
+        call.cancel()
+        receiver.block_until_terminated()
+
+        self.assertIs(face.Abortion.Kind.CANCELLED, receiver.abortion().kind)
+
+  def testCancelledStreamRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        receiver = _receiver.Receiver()
+
+        call_consumer = self._invoker.event(group, method)(
+            receiver, receiver.abort, test_constants.LONG_TIMEOUT)
+        for request in requests:
+          call_consumer.consume(request)
+        call_consumer.cancel()
+        receiver.block_until_terminated()
+
+        self.assertIs(face.Abortion.Kind.CANCELLED, receiver.abortion().kind)
+
+  def testCancelledStreamRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_stream_messages_sequences.iteritems()):
+      for unused_test_messages in test_messages_sequence:
+        receiver = _receiver.Receiver()
+
+        call_consumer = self._invoker.event(group, method)(
+            receiver, receiver.abort, test_constants.LONG_TIMEOUT)
+        call_consumer.cancel()
+        receiver.block_until_terminated()
+
+        self.assertIs(face.Abortion.Kind.CANCELLED, receiver.abortion().kind)
+
+  def testExpiredUnaryRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        receiver = _receiver.Receiver()
+
+        with self._control.pause():
+          self._invoker.event(group, method)(
+              request, receiver, receiver.abort, test_constants.SHORT_TIMEOUT)
+          receiver.block_until_terminated()
+
+        self.assertIs(face.Abortion.Kind.EXPIRED, receiver.abortion().kind)
+
+  def testExpiredUnaryRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        receiver = _receiver.Receiver()
+
+        with self._control.pause():
+          self._invoker.event(group, method)(
+              request, receiver, receiver.abort, test_constants.SHORT_TIMEOUT)
+          receiver.block_until_terminated()
+
+        self.assertIs(face.Abortion.Kind.EXPIRED, receiver.abortion().kind)
+
+  def testExpiredStreamRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_unary_messages_sequences.iteritems()):
+      for unused_test_messages in test_messages_sequence:
+        receiver = _receiver.Receiver()
+
+        self._invoker.event(group, method)(
+            receiver, receiver.abort, test_constants.SHORT_TIMEOUT)
+        receiver.block_until_terminated()
+
+        self.assertIs(face.Abortion.Kind.EXPIRED, receiver.abortion().kind)
+
+  def testExpiredStreamRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        receiver = _receiver.Receiver()
+
+        call_consumer = self._invoker.event(group, method)(
+            receiver, receiver.abort, test_constants.SHORT_TIMEOUT)
+        for request in requests:
+          call_consumer.consume(request)
+        receiver.block_until_terminated()
+
+        self.assertIs(face.Abortion.Kind.EXPIRED, receiver.abortion().kind)
+
+  def testFailedUnaryRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        receiver = _receiver.Receiver()
+
+        with self._control.fail():
+          self._invoker.event(group, method)(
+              request, receiver, receiver.abort, test_constants.LONG_TIMEOUT)
+          receiver.block_until_terminated()
+
+        self.assertIs(
+            face.Abortion.Kind.REMOTE_FAILURE, receiver.abortion().kind)
+
+  def testFailedUnaryRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        receiver = _receiver.Receiver()
+
+        with self._control.fail():
+          self._invoker.event(group, method)(
+              request, receiver, receiver.abort, test_constants.LONG_TIMEOUT)
+          receiver.block_until_terminated()
+
+        self.assertIs(
+            face.Abortion.Kind.REMOTE_FAILURE, receiver.abortion().kind)
+
+  def testFailedStreamRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        receiver = _receiver.Receiver()
+
+        with self._control.fail():
+          call_consumer = self._invoker.event(group, method)(
+              receiver, receiver.abort, test_constants.LONG_TIMEOUT)
+          for request in requests:
+            call_consumer.consume(request)
+          call_consumer.terminate()
+          receiver.block_until_terminated()
+
+        self.assertIs(
+            face.Abortion.Kind.REMOTE_FAILURE, receiver.abortion().kind)
+
+  def testFailedStreamRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        receiver = _receiver.Receiver()
+
+        with self._control.fail():
+          call_consumer = self._invoker.event(group, method)(
+              receiver, receiver.abort, test_constants.LONG_TIMEOUT)
+          for request in requests:
+            call_consumer.consume(request)
+          call_consumer.terminate()
+          receiver.block_until_terminated()
+
+        self.assertIs(
+            face.Abortion.Kind.REMOTE_FAILURE, receiver.abortion().kind)
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/face/_future_invocation_asynchronous_event_service.py b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_future_invocation_asynchronous_event_service.py
new file mode 100644
index 0000000000..a649362cef
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_future_invocation_asynchronous_event_service.py
@@ -0,0 +1,378 @@
+# 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 code for the Face layer of RPC Framework."""
+
+import abc
+import contextlib
+import threading
+import unittest
+
+# test_interfaces is referenced from specification in this module.
+from grpc.framework.foundation import logging_pool
+from grpc.framework.interfaces.face import face
+from grpc_test.framework.common import test_constants
+from grpc_test.framework.common import test_control
+from grpc_test.framework.common import test_coverage
+from grpc_test.framework.interfaces.face import _digest
+from grpc_test.framework.interfaces.face import _stock_service
+from grpc_test.framework.interfaces.face import test_interfaces  # pylint: disable=unused-import
+
+
+class _PauseableIterator(object):
+
+  def __init__(self, upstream):
+    self._upstream = upstream
+    self._condition = threading.Condition()
+    self._paused = False
+
+  @contextlib.contextmanager
+  def pause(self):
+    with self._condition:
+      self._paused = True
+    yield
+    with self._condition:
+      self._paused = False
+      self._condition.notify_all()
+
+  def __iter__(self):
+    return self
+
+  def next(self):
+    with self._condition:
+      while self._paused:
+        self._condition.wait()
+    return next(self._upstream)
+
+
+class TestCase(test_coverage.Coverage, unittest.TestCase):
+  """A test of the Face layer of RPC Framework.
+
+  Concrete subclasses must have an "implementation" attribute of type
+  test_interfaces.Implementation and an "invoker_constructor" attribute of type
+  _invocation.InvokerConstructor.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  NAME = 'FutureInvocationAsynchronousEventServiceTest'
+
+  def setUp(self):
+    """See unittest.TestCase.setUp for full specification.
+
+    Overriding implementations must call this implementation.
+    """
+    self._control = test_control.PauseFailControl()
+    self._digest_pool = logging_pool.pool(test_constants.POOL_SIZE)
+    self._digest = _digest.digest(
+        _stock_service.STOCK_TEST_SERVICE, self._control, self._digest_pool)
+
+    generic_stub, dynamic_stubs, self._memo = self.implementation.instantiate(
+        self._digest.methods, self._digest.event_method_implementations, None)
+    self._invoker = self.invoker_constructor.construct_invoker(
+        generic_stub, dynamic_stubs, self._digest.methods)
+
+  def tearDown(self):
+    """See unittest.TestCase.tearDown for full specification.
+
+    Overriding implementations must call this implementation.
+    """
+    self.implementation.destantiate(self._memo)
+    self._digest_pool.shutdown(wait=True)
+
+  def testSuccessfulUnaryRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        response_future = self._invoker.future(group, method)(
+            request, test_constants.LONG_TIMEOUT)
+        response = response_future.result()
+
+        test_messages.verify(request, response, self)
+
+  def testSuccessfulUnaryRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        response_iterator = self._invoker.future(group, method)(
+            request, test_constants.LONG_TIMEOUT)
+        responses = list(response_iterator)
+
+        test_messages.verify(request, responses, self)
+
+  def testSuccessfulStreamRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        request_iterator = _PauseableIterator(iter(requests))
+
+        # Use of a paused iterator of requests allows us to test that control is
+        # returned to calling code before the iterator yields any requests.
+        with request_iterator.pause():
+          response_future = self._invoker.future(group, method)(
+              request_iterator, test_constants.LONG_TIMEOUT)
+        response = response_future.result()
+
+        test_messages.verify(requests, response, self)
+
+  def testSuccessfulStreamRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        request_iterator = _PauseableIterator(iter(requests))
+
+        # Use of a paused iterator of requests allows us to test that control is
+        # returned to calling code before the iterator yields any requests.
+        with request_iterator.pause():
+          response_iterator = self._invoker.future(group, method)(
+              request_iterator, test_constants.LONG_TIMEOUT)
+        responses = list(response_iterator)
+
+        test_messages.verify(requests, responses, self)
+
+  def testSequentialInvocations(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        first_request = test_messages.request()
+        second_request = test_messages.request()
+
+        first_response_future = self._invoker.future(group, method)(
+            first_request, test_constants.LONG_TIMEOUT)
+        first_response = first_response_future.result()
+
+        test_messages.verify(first_request, first_response, self)
+
+        second_response_future = self._invoker.future(group, method)(
+            second_request, test_constants.LONG_TIMEOUT)
+        second_response = second_response_future.result()
+
+        test_messages.verify(second_request, second_response, self)
+
+  def testParallelInvocations(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        first_request = test_messages.request()
+        second_request = test_messages.request()
+
+        first_response_future = self._invoker.future(group, method)(
+            first_request, test_constants.LONG_TIMEOUT)
+        second_response_future = self._invoker.future(group, method)(
+            second_request, test_constants.LONG_TIMEOUT)
+        first_response = first_response_future.result()
+        second_response = second_response_future.result()
+
+        test_messages.verify(first_request, first_response, self)
+        test_messages.verify(second_request, second_response, self)
+
+  @unittest.skip('TODO(nathaniel): implement.')
+  def testWaitingForSomeButNotAllParallelInvocations(self):
+    raise NotImplementedError()
+
+  def testCancelledUnaryRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self._control.pause():
+          response_future = self._invoker.future(group, method)(
+              request, test_constants.LONG_TIMEOUT)
+          cancel_method_return_value = response_future.cancel()
+
+        self.assertFalse(cancel_method_return_value)
+        self.assertTrue(response_future.cancelled())
+
+  def testCancelledUnaryRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self._control.pause():
+          response_iterator = self._invoker.future(group, method)(
+              request, test_constants.LONG_TIMEOUT)
+          response_iterator.cancel()
+
+        with self.assertRaises(face.CancellationError):
+          next(response_iterator)
+
+  def testCancelledStreamRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self._control.pause():
+          response_future = self._invoker.future(group, method)(
+              iter(requests), test_constants.LONG_TIMEOUT)
+          cancel_method_return_value = response_future.cancel()
+
+        self.assertFalse(cancel_method_return_value)
+        self.assertTrue(response_future.cancelled())
+
+  def testCancelledStreamRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self._control.pause():
+          response_iterator = self._invoker.future(group, method)(
+              iter(requests), test_constants.LONG_TIMEOUT)
+          response_iterator.cancel()
+
+        with self.assertRaises(face.CancellationError):
+          next(response_iterator)
+
+  def testExpiredUnaryRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self._control.pause():
+          response_future = self._invoker.future(
+              group, method)(request, test_constants.SHORT_TIMEOUT)
+          self.assertIsInstance(
+              response_future.exception(), face.ExpirationError)
+          with self.assertRaises(face.ExpirationError):
+            response_future.result()
+
+  def testExpiredUnaryRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self._control.pause():
+          response_iterator = self._invoker.future(group, method)(
+              request, test_constants.SHORT_TIMEOUT)
+          with self.assertRaises(face.ExpirationError):
+            list(response_iterator)
+
+  def testExpiredStreamRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self._control.pause():
+          response_future = self._invoker.future(group, method)(
+              iter(requests), test_constants.SHORT_TIMEOUT)
+          self.assertIsInstance(
+              response_future.exception(), face.ExpirationError)
+          with self.assertRaises(face.ExpirationError):
+            response_future.result()
+
+  def testExpiredStreamRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self._control.pause():
+          response_iterator = self._invoker.future(group, method)(
+              iter(requests), test_constants.SHORT_TIMEOUT)
+          with self.assertRaises(face.ExpirationError):
+            list(response_iterator)
+
+  def testFailedUnaryRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self._control.fail():
+          response_future = self._invoker.future(group, method)(
+              request, test_constants.SHORT_TIMEOUT)
+
+          # Because the servicer fails outside of the thread from which the
+          # servicer-side runtime called into it its failure is
+          # indistinguishable from simply not having called its
+          # response_callback before the expiration of the RPC.
+          self.assertIsInstance(
+              response_future.exception(), face.ExpirationError)
+          with self.assertRaises(face.ExpirationError):
+            response_future.result()
+
+  def testFailedUnaryRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        # Because the servicer fails outside of the thread from which the
+        # servicer-side runtime called into it its failure is indistinguishable
+        # from simply not having called its response_consumer before the
+        # expiration of the RPC.
+        with self._control.fail(), self.assertRaises(face.ExpirationError):
+          response_iterator = self._invoker.future(group, method)(
+              request, test_constants.SHORT_TIMEOUT)
+          list(response_iterator)
+
+  def testFailedStreamRequestUnaryResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self._control.fail():
+          response_future = self._invoker.future(group, method)(
+              iter(requests), test_constants.SHORT_TIMEOUT)
+
+          # Because the servicer fails outside of the thread from which the
+          # servicer-side runtime called into it its failure is
+          # indistinguishable from simply not having called its
+          # response_callback before the expiration of the RPC.
+          self.assertIsInstance(
+              response_future.exception(), face.ExpirationError)
+          with self.assertRaises(face.ExpirationError):
+            response_future.result()
+
+  def testFailedStreamRequestStreamResponse(self):
+    for (group, method), test_messages_sequence in (
+        self._digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        # Because the servicer fails outside of the thread from which the
+        # servicer-side runtime called into it its failure is indistinguishable
+        # from simply not having called its response_consumer before the
+        # expiration of the RPC.
+        with self._control.fail(), self.assertRaises(face.ExpirationError):
+          response_iterator = self._invoker.future(group, method)(
+              iter(requests), test_constants.SHORT_TIMEOUT)
+          list(response_iterator)
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/face/_invocation.py b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_invocation.py
new file mode 100644
index 0000000000..448e845a08
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_invocation.py
@@ -0,0 +1,213 @@
+# 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.
+
+"""Coverage across the Face layer's generic-to-dynamic range for invocation."""
+
+import abc
+
+from grpc.framework.common import cardinality
+
+_CARDINALITY_TO_GENERIC_BLOCKING_BEHAVIOR = {
+    cardinality.Cardinality.UNARY_UNARY: 'blocking_unary_unary',
+    cardinality.Cardinality.UNARY_STREAM: 'inline_unary_stream',
+    cardinality.Cardinality.STREAM_UNARY: 'blocking_stream_unary',
+    cardinality.Cardinality.STREAM_STREAM: 'inline_stream_stream',
+}
+
+_CARDINALITY_TO_GENERIC_FUTURE_BEHAVIOR = {
+    cardinality.Cardinality.UNARY_UNARY: 'future_unary_unary',
+    cardinality.Cardinality.UNARY_STREAM: 'inline_unary_stream',
+    cardinality.Cardinality.STREAM_UNARY: 'future_stream_unary',
+    cardinality.Cardinality.STREAM_STREAM: 'inline_stream_stream',
+}
+
+_CARDINALITY_TO_GENERIC_EVENT_BEHAVIOR = {
+    cardinality.Cardinality.UNARY_UNARY: 'event_unary_unary',
+    cardinality.Cardinality.UNARY_STREAM: 'event_unary_stream',
+    cardinality.Cardinality.STREAM_UNARY: 'event_stream_unary',
+    cardinality.Cardinality.STREAM_STREAM: 'event_stream_stream',
+}
+
+_CARDINALITY_TO_MULTI_CALLABLE_ATTRIBUTE = {
+    cardinality.Cardinality.UNARY_UNARY: 'unary_unary',
+    cardinality.Cardinality.UNARY_STREAM: 'unary_stream',
+    cardinality.Cardinality.STREAM_UNARY: 'stream_unary',
+    cardinality.Cardinality.STREAM_STREAM: 'stream_stream',
+}
+
+
+class Invoker(object):
+  """A type used to invoke test RPCs."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def blocking(self, group, name):
+    """Invokes an RPC with blocking control flow."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def future(self, group, name):
+    """Invokes an RPC with future control flow."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event(self, group, name):
+    """Invokes an RPC with event control flow."""
+    raise NotImplementedError()
+
+
+class InvokerConstructor(object):
+  """A type used to create Invokers."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def name(self):
+    """Specifies the name of the Invoker constructed by this object."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def construct_invoker(self, generic_stub, dynamic_stubs, methods):
+    """Constructs an Invoker for the given stubs and methods."""
+    raise NotImplementedError()
+
+
+class _GenericInvoker(Invoker):
+
+  def __init__(self, generic_stub, methods):
+    self._stub = generic_stub
+    self._methods = methods
+
+  def _behavior(self, group, name, cardinality_to_generic_method):
+    method_cardinality = self._methods[group, name].cardinality()
+    behavior = getattr(
+        self._stub, cardinality_to_generic_method[method_cardinality])
+    return lambda *args, **kwargs: behavior(group, name, *args, **kwargs)
+
+  def blocking(self, group, name):
+    return self._behavior(
+        group, name, _CARDINALITY_TO_GENERIC_BLOCKING_BEHAVIOR)
+
+  def future(self, group, name):
+    return self._behavior(group, name, _CARDINALITY_TO_GENERIC_FUTURE_BEHAVIOR)
+
+  def event(self, group, name):
+    return self._behavior(group, name, _CARDINALITY_TO_GENERIC_EVENT_BEHAVIOR)
+
+
+class _GenericInvokerConstructor(InvokerConstructor):
+
+  def name(self):
+    return 'GenericInvoker'
+
+  def construct_invoker(self, generic_stub, dynamic_stub, methods):
+    return _GenericInvoker(generic_stub, methods)
+
+
+class _MultiCallableInvoker(Invoker):
+
+  def __init__(self, generic_stub, methods):
+    self._stub = generic_stub
+    self._methods = methods
+
+  def _multi_callable(self, group, name):
+    method_cardinality = self._methods[group, name].cardinality()
+    behavior = getattr(
+        self._stub,
+        _CARDINALITY_TO_MULTI_CALLABLE_ATTRIBUTE[method_cardinality])
+    return behavior(group, name)
+
+  def blocking(self, group, name):
+    return self._multi_callable(group, name)
+
+  def future(self, group, name):
+    method_cardinality = self._methods[group, name].cardinality()
+    behavior = getattr(
+        self._stub,
+        _CARDINALITY_TO_MULTI_CALLABLE_ATTRIBUTE[method_cardinality])
+    if method_cardinality in (
+        cardinality.Cardinality.UNARY_UNARY,
+        cardinality.Cardinality.STREAM_UNARY):
+      return behavior(group, name).future
+    else:
+      return behavior(group, name)
+
+  def event(self, group, name):
+    return self._multi_callable(group, name).event
+
+
+class _MultiCallableInvokerConstructor(InvokerConstructor):
+
+  def name(self):
+    return 'MultiCallableInvoker'
+
+  def construct_invoker(self, generic_stub, dynamic_stub, methods):
+    return _MultiCallableInvoker(generic_stub, methods)
+
+
+class _DynamicInvoker(Invoker):
+
+  def __init__(self, dynamic_stubs, methods):
+    self._stubs = dynamic_stubs
+    self._methods = methods
+
+  def blocking(self, group, name):
+    return getattr(self._stubs[group], name)
+
+  def future(self, group, name):
+    if self._methods[group, name].cardinality() in (
+        cardinality.Cardinality.UNARY_UNARY,
+        cardinality.Cardinality.STREAM_UNARY):
+      return getattr(self._stubs[group], name).future
+    else:
+      return getattr(self._stubs[group], name)
+
+  def event(self, group, name):
+    return getattr(self._stubs[group], name).event
+
+
+class _DynamicInvokerConstructor(InvokerConstructor):
+
+  def name(self):
+    return 'DynamicInvoker'
+
+  def construct_invoker(self, generic_stub, dynamic_stubs, methods):
+    return _DynamicInvoker(dynamic_stubs, methods)
+
+
+def invoker_constructors():
+  """Creates a sequence of InvokerConstructors to use in tests of RPCs.
+
+  Returns:
+    A sequence of InvokerConstructors.
+  """
+  return (
+      _GenericInvokerConstructor(),
+      _MultiCallableInvokerConstructor(),
+      _DynamicInvokerConstructor(),
+  )
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/face/_receiver.py b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_receiver.py
new file mode 100644
index 0000000000..2e444ff09d
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_receiver.py
@@ -0,0 +1,95 @@
+# 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 utility useful in tests of asynchronous, event-driven interfaces."""
+
+import threading
+
+from grpc.framework.interfaces.face import face
+
+
+class Receiver(face.ResponseReceiver):
+  """A utility object useful in tests of asynchronous code."""
+
+  def __init__(self):
+    self._condition = threading.Condition()
+    self._initial_metadata = None
+    self._responses = []
+    self._terminal_metadata = None
+    self._code = None
+    self._details = None
+    self._completed = False
+    self._abortion = None
+
+  def abort(self, abortion):
+    with self._condition:
+      self._abortion = abortion
+      self._condition.notify_all()
+
+  def initial_metadata(self, initial_metadata):
+    with self._condition:
+      self._initial_metadata = initial_metadata
+
+  def response(self, response):
+    with self._condition:
+      self._responses.append(response)
+
+  def complete(self, terminal_metadata, code, details):
+    with self._condition:
+      self._terminal_metadata = terminal_metadata
+      self._code = code
+      self._details = details
+      self._completed = True
+      self._condition.notify_all()
+
+  def block_until_terminated(self):
+    with self._condition:
+      while self._abortion is None and not self._completed:
+        self._condition.wait()
+
+  def unary_response(self):
+    with self._condition:
+      if self._abortion is not None:
+        raise AssertionError('Aborted with abortion "%s"!' % self._abortion)
+      elif len(self._responses) != 1:
+        raise AssertionError(
+            '%d responses received, not exactly one!', len(self._responses))
+      else:
+        return self._responses[0]
+
+  def stream_responses(self):
+    with self._condition:
+      if self._abortion is None:
+        return list(self._responses)
+      else:
+        raise AssertionError('Aborted with abortion "%s"!' % self._abortion)
+
+  def abortion(self):
+    with self._condition:
+      return self._abortion
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/face/_service.py b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_service.py
new file mode 100644
index 0000000000..e25b8a038c
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_service.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.
+
+"""Private interfaces implemented by data sets used in Face-layer tests."""
+
+import abc
+
+# face is referenced from specification in this module.
+from grpc.framework.interfaces.face import face  # pylint: disable=unused-import
+from grpc_test.framework.interfaces.face import test_interfaces
+
+
+class UnaryUnaryTestMethodImplementation(test_interfaces.Method):
+  """A controllable implementation of a unary-unary method."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, request, response_callback, context, control):
+    """Services an RPC that accepts one message and produces one message.
+
+    Args:
+      request: The single request message for the RPC.
+      response_callback: A callback to be called to accept the response message
+        of the RPC.
+      context: An face.ServicerContext object.
+      control: A test_control.Control to control execution of this method.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+    """
+    raise NotImplementedError()
+
+
+class UnaryUnaryTestMessages(object):
+  """A type for unary-request-unary-response message pairings."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def request(self):
+    """Affords a request message.
+
+    Implementations of this method should return a different message with each
+    call so that multiple test executions of the test method may be made with
+    different inputs.
+
+    Returns:
+      A request message.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def verify(self, request, response, test_case):
+    """Verifies that the computed response matches the given request.
+
+    Args:
+      request: A request message.
+      response: A response message.
+      test_case: A unittest.TestCase object affording useful assertion methods.
+
+    Raises:
+      AssertionError: If the request and response do not match, indicating that
+        there was some problem executing the RPC under test.
+    """
+    raise NotImplementedError()
+
+
+class UnaryStreamTestMethodImplementation(test_interfaces.Method):
+  """A controllable implementation of a unary-stream method."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, request, response_consumer, context, control):
+    """Services an RPC that takes one message and produces a stream of messages.
+
+    Args:
+      request: The single request message for the RPC.
+      response_consumer: A stream.Consumer to be called to accept the response
+        messages of the RPC.
+      context: A face.ServicerContext object.
+      control: A test_control.Control to control execution of this method.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+    """
+    raise NotImplementedError()
+
+
+class UnaryStreamTestMessages(object):
+  """A type for unary-request-stream-response message pairings."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def request(self):
+    """Affords a request message.
+
+    Implementations of this method should return a different message with each
+    call so that multiple test executions of the test method may be made with
+    different inputs.
+
+    Returns:
+      A request message.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def verify(self, request, responses, test_case):
+    """Verifies that the computed responses match the given request.
+
+    Args:
+      request: A request message.
+      responses: A sequence of response messages.
+      test_case: A unittest.TestCase object affording useful assertion methods.
+
+    Raises:
+      AssertionError: If the request and responses do not match, indicating that
+        there was some problem executing the RPC under test.
+    """
+    raise NotImplementedError()
+
+
+class StreamUnaryTestMethodImplementation(test_interfaces.Method):
+  """A controllable implementation of a stream-unary method."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, response_callback, context, control):
+    """Services an RPC that takes a stream of messages and produces one message.
+
+    Args:
+      response_callback: A callback to be called to accept the response message
+        of the RPC.
+      context: A face.ServicerContext object.
+      control: A test_control.Control to control execution of this method.
+
+    Returns:
+      A stream.Consumer with which to accept the request messages of the RPC.
+        The consumer returned from this method may or may not be invoked to
+        completion: in the case of RPC abortion, RPC Framework will simply stop
+        passing messages to this object. Implementations must not assume that
+        this object will be called to completion of the request stream or even
+        called at all.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+    """
+    raise NotImplementedError()
+
+
+class StreamUnaryTestMessages(object):
+  """A type for stream-request-unary-response message pairings."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def requests(self):
+    """Affords a sequence of request messages.
+
+    Implementations of this method should return a different sequences with each
+    call so that multiple test executions of the test method may be made with
+    different inputs.
+
+    Returns:
+      A sequence of request messages.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def verify(self, requests, response, test_case):
+    """Verifies that the computed response matches the given requests.
+
+    Args:
+      requests: A sequence of request messages.
+      response: A response message.
+      test_case: A unittest.TestCase object affording useful assertion methods.
+
+    Raises:
+      AssertionError: If the requests and response do not match, indicating that
+        there was some problem executing the RPC under test.
+    """
+    raise NotImplementedError()
+
+
+class StreamStreamTestMethodImplementation(test_interfaces.Method):
+  """A controllable implementation of a stream-stream method."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, response_consumer, context, control):
+    """Services an RPC that accepts and produces streams of messages.
+
+    Args:
+      response_consumer: A stream.Consumer to be called to accept the response
+        messages of the RPC.
+      context: A face.ServicerContext object.
+      control: A test_control.Control to control execution of this method.
+
+    Returns:
+      A stream.Consumer with which to accept the request messages of the RPC.
+        The consumer returned from this method may or may not be invoked to
+        completion: in the case of RPC abortion, RPC Framework will simply stop
+        passing messages to this object. Implementations must not assume that
+        this object will be called to completion of the request stream or even
+        called at all.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+    """
+    raise NotImplementedError()
+
+
+class StreamStreamTestMessages(object):
+  """A type for stream-request-stream-response message pairings."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def requests(self):
+    """Affords a sequence of request messages.
+
+    Implementations of this method should return a different sequences with each
+    call so that multiple test executions of the test method may be made with
+    different inputs.
+
+    Returns:
+      A sequence of request messages.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def verify(self, requests, responses, test_case):
+    """Verifies that the computed response matches the given requests.
+
+    Args:
+      requests: A sequence of request messages.
+      responses: A sequence of response messages.
+      test_case: A unittest.TestCase object affording useful assertion methods.
+
+    Raises:
+      AssertionError: If the requests and responses do not match, indicating
+        that there was some problem executing the RPC under test.
+    """
+    raise NotImplementedError()
+
+
+class TestService(object):
+  """A specification of implemented methods to use in tests."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def unary_unary_scenarios(self):
+    """Affords unary-request-unary-response test methods and their messages.
+
+    Returns:
+      A dict from method group-name pair to implementation/messages pair. The
+        first element of the pair is a UnaryUnaryTestMethodImplementation object
+        and the second element is a sequence of UnaryUnaryTestMethodMessages
+        objects.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def unary_stream_scenarios(self):
+    """Affords unary-request-stream-response test methods and their messages.
+
+    Returns:
+      A dict from method group-name pair to implementation/messages pair. The
+        first element of the pair is a UnaryStreamTestMethodImplementation
+        object and the second element is a sequence of
+        UnaryStreamTestMethodMessages objects.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def stream_unary_scenarios(self):
+    """Affords stream-request-unary-response test methods and their messages.
+
+    Returns:
+      A dict from method group-name pair to implementation/messages pair. The
+        first element of the pair is a StreamUnaryTestMethodImplementation
+        object and the second element is a sequence of
+        StreamUnaryTestMethodMessages objects.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def stream_stream_scenarios(self):
+    """Affords stream-request-stream-response test methods and their messages.
+
+    Returns:
+      A dict from method group-name pair to implementation/messages pair. The
+        first element of the pair is a StreamStreamTestMethodImplementation
+        object and the second element is a sequence of
+        StreamStreamTestMethodMessages objects.
+    """
+    raise NotImplementedError()
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/face/_stock_service.py b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_stock_service.py
new file mode 100644
index 0000000000..1dd2ec3633
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/face/_stock_service.py
@@ -0,0 +1,396 @@
+B# 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.
+
+"""Examples of Python implementations of the stock.proto Stock service."""
+
+from grpc.framework.common import cardinality
+from grpc.framework.foundation import abandonment
+from grpc.framework.foundation import stream
+from grpc_test.framework.common import test_constants
+from grpc_test.framework.interfaces.face import _service
+from grpc_test._junkdrawer import stock_pb2
+
+_STOCK_GROUP_NAME = 'Stock'
+_SYMBOL_FORMAT = 'test symbol:%03d'
+
+# A test-appropriate security-pricing function. :-P
+_price = lambda symbol_name: float(hash(symbol_name) % 4096)
+
+
+def _get_last_trade_price(stock_request, stock_reply_callback, control, active):
+  """A unary-request, unary-response test method."""
+  control.control()
+  if active():
+    stock_reply_callback(
+        stock_pb2.StockReply(
+            symbol=stock_request.symbol, price=_price(stock_request.symbol)))
+  else:
+    raise abandonment.Abandoned()
+
+
+def _get_last_trade_price_multiple(stock_reply_consumer, control, active):
+  """A stream-request, stream-response test method."""
+  def stock_reply_for_stock_request(stock_request):
+    control.control()
+    if active():
+      return stock_pb2.StockReply(
+          symbol=stock_request.symbol, price=_price(stock_request.symbol))
+    else:
+      raise abandonment.Abandoned()
+
+  class StockRequestConsumer(stream.Consumer):
+
+    def consume(self, stock_request):
+      stock_reply_consumer.consume(stock_reply_for_stock_request(stock_request))
+
+    def terminate(self):
+      control.control()
+      stock_reply_consumer.terminate()
+
+    def consume_and_terminate(self, stock_request):
+      stock_reply_consumer.consume_and_terminate(
+          stock_reply_for_stock_request(stock_request))
+
+  return StockRequestConsumer()
+
+
+def _watch_future_trades(stock_request, stock_reply_consumer, control, active):
+  """A unary-request, stream-response test method."""
+  base_price = _price(stock_request.symbol)
+  for index in range(stock_request.num_trades_to_watch):
+    control.control()
+    if active():
+      stock_reply_consumer.consume(
+          stock_pb2.StockReply(
+              symbol=stock_request.symbol, price=base_price + index))
+    else:
+      raise abandonment.Abandoned()
+  stock_reply_consumer.terminate()
+
+
+def _get_highest_trade_price(stock_reply_callback, control, active):
+  """A stream-request, unary-response test method."""
+
+  class StockRequestConsumer(stream.Consumer):
+    """Keeps an ongoing record of the most valuable symbol yet consumed."""
+
+    def __init__(self):
+      self._symbol = None
+      self._price = None
+
+    def consume(self, stock_request):
+      control.control()
+      if active():
+        if self._price is None:
+          self._symbol = stock_request.symbol
+          self._price = _price(stock_request.symbol)
+        else:
+          candidate_price = _price(stock_request.symbol)
+          if self._price < candidate_price:
+            self._symbol = stock_request.symbol
+            self._price = candidate_price
+
+    def terminate(self):
+      control.control()
+      if active():
+        if self._symbol is None:
+          raise ValueError()
+        else:
+          stock_reply_callback(
+              stock_pb2.StockReply(symbol=self._symbol, price=self._price))
+          self._symbol = None
+          self._price = None
+
+    def consume_and_terminate(self, stock_request):
+      control.control()
+      if active():
+        if self._price is None:
+          stock_reply_callback(
+              stock_pb2.StockReply(
+                  symbol=stock_request.symbol,
+                  price=_price(stock_request.symbol)))
+        else:
+          candidate_price = _price(stock_request.symbol)
+          if self._price < candidate_price:
+            stock_reply_callback(
+                stock_pb2.StockReply(
+                    symbol=stock_request.symbol, price=candidate_price))
+          else:
+            stock_reply_callback(
+                stock_pb2.StockReply(
+                    symbol=self._symbol, price=self._price))
+
+        self._symbol = None
+        self._price = None
+
+  return StockRequestConsumer()
+
+
+class GetLastTradePrice(_service.UnaryUnaryTestMethodImplementation):
+  """GetLastTradePrice for use in tests."""
+
+  def group(self):
+    return _STOCK_GROUP_NAME
+
+  def name(self):
+    return 'GetLastTradePrice'
+
+  def cardinality(self):
+    return cardinality.Cardinality.UNARY_UNARY
+
+  def request_class(self):
+    return stock_pb2.StockRequest
+
+  def response_class(self):
+    return stock_pb2.StockReply
+
+  def serialize_request(self, request):
+    return request.SerializeToString()
+
+  def deserialize_request(self, serialized_request):
+    return stock_pb2.StockRequest.FromString(serialized_request)
+
+  def serialize_response(self, response):
+    return response.SerializeToString()
+
+  def deserialize_response(self, serialized_response):
+    return stock_pb2.StockReply.FromString(serialized_response)
+
+  def service(self, request, response_callback, context, control):
+    _get_last_trade_price(
+        request, response_callback, control, context.is_active)
+
+
+class GetLastTradePriceMessages(_service.UnaryUnaryTestMessages):
+
+  def __init__(self):
+    self._index = 0
+
+  def request(self):
+    symbol = _SYMBOL_FORMAT % self._index
+    self._index += 1
+    return stock_pb2.StockRequest(symbol=symbol)
+
+  def verify(self, request, response, test_case):
+    test_case.assertEqual(request.symbol, response.symbol)
+    test_case.assertEqual(_price(request.symbol), response.price)
+
+
+class GetLastTradePriceMultiple(_service.StreamStreamTestMethodImplementation):
+  """GetLastTradePriceMultiple for use in tests."""
+
+  def group(self):
+    return _STOCK_GROUP_NAME
+
+  def name(self):
+    return 'GetLastTradePriceMultiple'
+
+  def cardinality(self):
+    return cardinality.Cardinality.STREAM_STREAM
+
+  def request_class(self):
+    return stock_pb2.StockRequest
+
+  def response_class(self):
+    return stock_pb2.StockReply
+
+  def serialize_request(self, request):
+    return request.SerializeToString()
+
+  def deserialize_request(self, serialized_request):
+    return stock_pb2.StockRequest.FromString(serialized_request)
+
+  def serialize_response(self, response):
+    return response.SerializeToString()
+
+  def deserialize_response(self, serialized_response):
+    return stock_pb2.StockReply.FromString(serialized_response)
+
+  def service(self, response_consumer, context, control):
+    return _get_last_trade_price_multiple(
+        response_consumer, control, context.is_active)
+
+
+class GetLastTradePriceMultipleMessages(_service.StreamStreamTestMessages):
+  """Pairs of message streams for use with GetLastTradePriceMultiple."""
+
+  def __init__(self):
+    self._index = 0
+
+  def requests(self):
+    base_index = self._index
+    self._index += 1
+    return [
+        stock_pb2.StockRequest(symbol=_SYMBOL_FORMAT % (base_index + index))
+        for index in range(test_constants.STREAM_LENGTH)]
+
+  def verify(self, requests, responses, test_case):
+    test_case.assertEqual(len(requests), len(responses))
+    for stock_request, stock_reply in zip(requests, responses):
+      test_case.assertEqual(stock_request.symbol, stock_reply.symbol)
+      test_case.assertEqual(_price(stock_request.symbol), stock_reply.price)
+
+
+class WatchFutureTrades(_service.UnaryStreamTestMethodImplementation):
+  """WatchFutureTrades for use in tests."""
+
+  def group(self):
+    return _STOCK_GROUP_NAME
+
+  def name(self):
+    return 'WatchFutureTrades'
+
+  def cardinality(self):
+    return cardinality.Cardinality.UNARY_STREAM
+
+  def request_class(self):
+    return stock_pb2.StockRequest
+
+  def response_class(self):
+    return stock_pb2.StockReply
+
+  def serialize_request(self, request):
+    return request.SerializeToString()
+
+  def deserialize_request(self, serialized_request):
+    return stock_pb2.StockRequest.FromString(serialized_request)
+
+  def serialize_response(self, response):
+    return response.SerializeToString()
+
+  def deserialize_response(self, serialized_response):
+    return stock_pb2.StockReply.FromString(serialized_response)
+
+  def service(self, request, response_consumer, context, control):
+    _watch_future_trades(request, response_consumer, control, context.is_active)
+
+
+class WatchFutureTradesMessages(_service.UnaryStreamTestMessages):
+  """Pairs of a single request message and a sequence of response messages."""
+
+  def __init__(self):
+    self._index = 0
+
+  def request(self):
+    symbol = _SYMBOL_FORMAT % self._index
+    self._index += 1
+    return stock_pb2.StockRequest(
+        symbol=symbol, num_trades_to_watch=test_constants.STREAM_LENGTH)
+
+  def verify(self, request, responses, test_case):
+    test_case.assertEqual(test_constants.STREAM_LENGTH, len(responses))
+    base_price = _price(request.symbol)
+    for index, response in enumerate(responses):
+      test_case.assertEqual(base_price + index, response.price)
+
+
+class GetHighestTradePrice(_service.StreamUnaryTestMethodImplementation):
+  """GetHighestTradePrice for use in tests."""
+
+  def group(self):
+    return _STOCK_GROUP_NAME
+
+  def name(self):
+    return 'GetHighestTradePrice'
+
+  def cardinality(self):
+    return cardinality.Cardinality.STREAM_UNARY
+
+  def request_class(self):
+    return stock_pb2.StockRequest
+
+  def response_class(self):
+    return stock_pb2.StockReply
+
+  def serialize_request(self, request):
+    return request.SerializeToString()
+
+  def deserialize_request(self, serialized_request):
+    return stock_pb2.StockRequest.FromString(serialized_request)
+
+  def serialize_response(self, response):
+    return response.SerializeToString()
+
+  def deserialize_response(self, serialized_response):
+    return stock_pb2.StockReply.FromString(serialized_response)
+
+  def service(self, response_callback, context, control):
+    return _get_highest_trade_price(
+        response_callback, control, context.is_active)
+
+
+class GetHighestTradePriceMessages(_service.StreamUnaryTestMessages):
+
+  def requests(self):
+    return [
+        stock_pb2.StockRequest(symbol=_SYMBOL_FORMAT % index)
+        for index in range(test_constants.STREAM_LENGTH)]
+
+  def verify(self, requests, response, test_case):
+    price = None
+    symbol = None
+    for stock_request in requests:
+      current_symbol = stock_request.symbol
+      current_price = _price(current_symbol)
+      if price is None or price < current_price:
+        price = current_price
+        symbol = current_symbol
+    test_case.assertEqual(price, response.price)
+    test_case.assertEqual(symbol, response.symbol)
+
+
+class StockTestService(_service.TestService):
+  """A corpus of test data with one method of each RPC cardinality."""
+
+  def unary_unary_scenarios(self):
+    return {
+        (_STOCK_GROUP_NAME, 'GetLastTradePrice'): (
+            GetLastTradePrice(), [GetLastTradePriceMessages()]),
+    }
+
+  def unary_stream_scenarios(self):
+    return {
+        (_STOCK_GROUP_NAME, 'WatchFutureTrades'): (
+            WatchFutureTrades(), [WatchFutureTradesMessages()]),
+    }
+
+  def stream_unary_scenarios(self):
+    return {
+        (_STOCK_GROUP_NAME, 'GetHighestTradePrice'): (
+            GetHighestTradePrice(), [GetHighestTradePriceMessages()])
+    }
+
+  def stream_stream_scenarios(self):
+    return {
+        (_STOCK_GROUP_NAME, 'GetLastTradePriceMultiple'): (
+            GetLastTradePriceMultiple(), [GetLastTradePriceMultipleMessages()]),
+    }
+
+
+STOCK_TEST_SERVICE = StockTestService()
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/face/test_cases.py b/src/python/grpcio_test/grpc_test/framework/interfaces/face/test_cases.py
new file mode 100644
index 0000000000..ca623662f7
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/face/test_cases.py
@@ -0,0 +1,67 @@
+# 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.
+
+"""Tools for creating tests of implementations of the Face layer."""
+
+# unittest is referenced from specification in this module.
+import unittest  # pylint: disable=unused-import
+
+# test_interfaces is referenced from specification in this module.
+from grpc_test.framework.interfaces.face import _blocking_invocation_inline_service
+from grpc_test.framework.interfaces.face import _event_invocation_synchronous_event_service
+from grpc_test.framework.interfaces.face import _future_invocation_asynchronous_event_service
+from grpc_test.framework.interfaces.face import _invocation
+from grpc_test.framework.interfaces.face import test_interfaces  # pylint: disable=unused-import
+
+_TEST_CASE_SUPERCLASSES = (
+    _blocking_invocation_inline_service.TestCase,
+    _event_invocation_synchronous_event_service.TestCase,
+    _future_invocation_asynchronous_event_service.TestCase,
+)
+
+
+def test_cases(implementation):
+  """Creates unittest.TestCase classes for a given Face layer implementation.
+
+  Args:
+    implementation: A test_interfaces.Implementation specifying creation and
+      destruction of a given Face layer implementation.
+
+  Returns:
+    A sequence of subclasses of unittest.TestCase defining tests of the
+      specified Face layer implementation.
+  """
+  test_case_classes = []
+  for invoker_constructor in _invocation.invoker_constructors():
+    for super_class in _TEST_CASE_SUPERCLASSES:
+      test_case_classes.append(
+          type(invoker_constructor.name() + super_class.NAME, (super_class,),
+               {'implementation': implementation,
+                'invoker_constructor': invoker_constructor}))
+  return test_case_classes
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/face/test_interfaces.py b/src/python/grpcio_test/grpc_test/framework/interfaces/face/test_interfaces.py
new file mode 100644
index 0000000000..b2b5c10fa6
--- /dev/null
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/face/test_interfaces.py
@@ -0,0 +1,229 @@
+# 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.
+
+"""Interfaces used in tests of implementations of the Face layer."""
+
+import abc
+
+from grpc.framework.common import cardinality  # pylint: disable=unused-import
+from grpc.framework.interfaces.face import face  # pylint: disable=unused-import
+
+
+class Method(object):
+  """Specifies a method to be used in tests."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def group(self):
+    """Identify the group of the method.
+
+    Returns:
+      The group of the method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def name(self):
+    """Identify the name of the method.
+
+    Returns:
+      The name of the method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def cardinality(self):
+    """Identify the cardinality of the method.
+
+    Returns:
+      A cardinality.Cardinality value describing the streaming semantics of the
+        method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def request_class(self):
+    """Identify the class used for the method's request objects.
+
+    Returns:
+      The class object of the class to which the method's request objects
+        belong.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def response_class(self):
+    """Identify the class used for the method's response objects.
+
+    Returns:
+      The class object of the class to which the method's response objects
+        belong.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def serialize_request(self, request):
+    """Serialize the given request object.
+
+    Args:
+      request: A request object appropriate for this method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def deserialize_request(self, serialized_request):
+    """Synthesize a request object from a given bytestring.
+
+    Args:
+      serialized_request: A bytestring deserializable into a request object
+        appropriate for this method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def serialize_response(self, response):
+    """Serialize the given response object.
+
+    Args:
+      response: A response object appropriate for this method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def deserialize_response(self, serialized_response):
+    """Synthesize a response object from a given bytestring.
+
+    Args:
+      serialized_response: A bytestring deserializable into a response object
+        appropriate for this method.
+    """
+    raise NotImplementedError()
+
+
+class Implementation(object):
+  """Specifies an implementation of the Face layer."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def instantiate(
+      self, methods, method_implementations,
+      multi_method_implementation):
+    """Instantiates the Face layer implementation to be used in a test.
+
+    Args:
+      methods: A sequence of Method objects describing the methods available to
+        be called during the test.
+      method_implementations: A dictionary from group-name pair to
+        face.MethodImplementation object specifying implementation of a method.
+      multi_method_implementation: A face.MultiMethodImplementation or None.
+
+    Returns:
+      A sequence of length three the first element of which is a
+        face.GenericStub, the second element of which is dictionary from groups
+        to face.DynamicStubs affording invocation of the group's methods, and
+        the third element of which is an arbitrary memo object to be kept and
+        passed to destantiate at the conclusion of the test. The returned stubs
+        must be backed by the provided implementations.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def destantiate(self, memo):
+    """Destroys the Face layer implementation under test.
+
+    Args:
+      memo: The object from the third position of the return value of a call to
+        instantiate.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def invocation_metadata(self):
+    """Provides the metadata to be used when invoking a test RPC.
+
+    Returns:
+      An object to use as the supplied-at-invocation-time metadata in a test
+        RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def initial_metadata(self):
+    """Provides the metadata for use as a test RPC's first servicer metadata.
+
+    Returns:
+      An object to use as the from-the-servicer-before-responses metadata in a
+        test RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def terminal_metadata(self):
+    """Provides the metadata for use as a test RPC's second servicer metadata.
+
+    Returns:
+      An object to use as the from-the-servicer-after-all-responses metadata in
+        a test RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def code(self):
+    """Provides the value for use as a test RPC's code.
+
+    Returns:
+      An object to use as the from-the-servicer code in a test RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def details(self):
+    """Provides the value for use as a test RPC's details.
+
+    Returns:
+      An object to use as the from-the-servicer details in a test RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def metadata_transmitted(self, original_metadata, transmitted_metadata):
+    """Identifies whether or not metadata was properly transmitted.
+
+    Args:
+      original_metadata: A metadata value passed to the Face interface
+        implementation under test.
+      transmitted_metadata: The same metadata value after having been
+        transmitted via an RPC performed by the Face interface implementation
+          under test.
+
+    Returns:
+      Whether or not the metadata was properly transmitted by the Face interface
+        implementation under test.
+    """
+    raise NotImplementedError()
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/links/test_cases.py b/src/python/grpcio_test/grpc_test/framework/interfaces/links/test_cases.py
index 1e575d1a9e..ecf49d9cdb 100644
--- a/src/python/grpcio_test/grpc_test/framework/interfaces/links/test_cases.py
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/links/test_cases.py
@@ -300,7 +300,7 @@ class TransmissionTest(object):
         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)
+        invocation_message, links.Ticket.Termination.COMPLETION, None)
     self._invocation_link.accept_ticket(original_invocation_ticket)
 
     self._service_mate.block_until_tickets_satisfy(
@@ -317,7 +317,7 @@ class TransmissionTest(object):
         service_operation_id, 0, None, None, links.Ticket.Subscription.FULL,
         timeout, 0, service_initial_metadata, service_payload,
         service_terminal_metadata, service_code, service_message,
-        links.Ticket.Termination.COMPLETION)
+        links.Ticket.Termination.COMPLETION, None)
     self._service_link.accept_ticket(original_service_ticket)
     self._invocation_mate.block_until_tickets_satisfy(terminated)
     self._assert_is_valid_service_sequence(
diff --git a/src/python/grpcio_test/grpc_test/framework/interfaces/links/test_utilities.py b/src/python/grpcio_test/grpc_test/framework/interfaces/links/test_utilities.py
index 6c2e3346aa..39c7f2fc63 100644
--- a/src/python/grpcio_test/grpc_test/framework/interfaces/links/test_utilities.py
+++ b/src/python/grpcio_test/grpc_test/framework/interfaces/links/test_utilities.py
@@ -29,9 +29,42 @@
 
 """State and behavior appropriate for use in tests."""
 
+import logging
 import threading
+import time
 
 from grpc.framework.interfaces.links import links
+from grpc.framework.interfaces.links import utilities
+
+# A more-or-less arbitrary limit on the length of raw data values to be logged.
+_UNCOMFORTABLY_LONG = 48
+
+
+def _safe_for_log_ticket(ticket):
+  """Creates a safe-for-printing-to-the-log ticket for a given ticket.
+
+  Args:
+    ticket: Any links.Ticket.
+
+  Returns:
+    A links.Ticket that is as much as can be equal to the given ticket but
+      possibly features values like the string "<payload of length 972321>" in
+      place of the actual values of the given ticket.
+  """
+  if isinstance(ticket.payload, (basestring,)):
+    payload_length = len(ticket.payload)
+  else:
+    payload_length = -1
+  if payload_length < _UNCOMFORTABLY_LONG:
+    return ticket
+  else:
+    return links.Ticket(
+        ticket.operation_id, ticket.sequence_number,
+        ticket.group, ticket.method, ticket.subscription, ticket.timeout,
+        ticket.allowance, ticket.initial_metadata,
+        '<payload of length {}>'.format(payload_length),
+        ticket.terminal_metadata, ticket.code, ticket.message,
+        ticket.termination, None)
 
 
 class RecordingLink(links.Link):
@@ -64,3 +97,71 @@ class RecordingLink(links.Link):
     """Returns a copy of the list of all tickets received by this Link."""
     with self._condition:
       return tuple(self._tickets)
+
+
+class _Pipe(object):
+  """A conduit that logs all tickets passed through it."""
+
+  def __init__(self, name):
+    self._lock = threading.Lock()
+    self._name = name
+    self._left_mate = utilities.NULL_LINK
+    self._right_mate = utilities.NULL_LINK
+
+  def accept_left_to_right_ticket(self, ticket):
+    with self._lock:
+      logging.warning(
+          '%s: moving left to right through %s: %s', time.time(), self._name,
+          _safe_for_log_ticket(ticket))
+      try:
+        self._right_mate.accept_ticket(ticket)
+      except Exception as e:  # pylint: disable=broad-except
+        logging.exception(e)
+
+  def accept_right_to_left_ticket(self, ticket):
+    with self._lock:
+      logging.warning(
+          '%s: moving right to left through %s: %s', time.time(), self._name,
+          _safe_for_log_ticket(ticket))
+      try:
+        self._left_mate.accept_ticket(ticket)
+      except Exception as e:  # pylint: disable=broad-except
+        logging.exception(e)
+
+  def join_left_mate(self, left_mate):
+    with self._lock:
+      self._left_mate = utilities.NULL_LINK if left_mate is None else left_mate
+
+  def join_right_mate(self, right_mate):
+    with self._lock:
+      self._right_mate = (
+          utilities.NULL_LINK if right_mate is None else right_mate)
+
+
+class _Facade(links.Link):
+
+  def __init__(self, accept, join):
+    self._accept = accept
+    self._join = join
+
+  def accept_ticket(self, ticket):
+    self._accept(ticket)
+
+  def join_link(self, link):
+    self._join(link)
+
+
+def logging_links(name):
+  """Creates a conduit that logs all tickets passed through it.
+
+  Args:
+    name: A name to use for the conduit to identify itself in logging output.
+
+  Returns:
+    Two links.Links, the first of which is the "left" side of the conduit
+      and the second of which is the "right" side of the conduit.
+  """
+  pipe = _Pipe(name)
+  left_facade = _Facade(pipe.accept_left_to_right_ticket, pipe.join_left_mate)
+  right_facade = _Facade(pipe.accept_right_to_left_ticket, pipe.join_right_mate)
+  return left_facade, right_facade
diff --git a/src/python/grpcio_test/setup.py b/src/python/grpcio_test/setup.py
index a6203cae2d..898ea204ac 100644
--- a/src/python/grpcio_test/setup.py
+++ b/src/python/grpcio_test/setup.py
@@ -61,6 +61,7 @@ _SETUP_REQUIRES = (
     'pytest>=2.6',
     'pytest-cov>=2.0',
     'pytest-xdist>=1.11',
+    'pytest-timeout>=0.5',
 )
 
 _INSTALL_REQUIRES = (