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

63 files changed, 959 insertions, 691 deletions

diff --git a/src/csharp/Grpc.Core.Tests/ClientServerTest.cs b/src/csharp/Grpc.Core.Tests/ClientServerTest.cs
index d92addbf54..dcdddc769e 100644
--- a/src/csharp/Grpc.Core.Tests/ClientServerTest.cs
+++ b/src/csharp/Grpc.Core.Tests/ClientServerTest.cs
@@ -235,8 +235,16 @@ namespace Grpc.Core.Tests
             await barrier.Task;  // make sure the handler has started.
             cts.Cancel();
 
-            var ex = Assert.ThrowsAsync<RpcException>(async () => await call.ResponseAsync);
-            Assert.AreEqual(StatusCode.Cancelled, ex.Status.StatusCode);
+            try
+            {
+                // cannot use Assert.ThrowsAsync because it uses Task.Wait and would deadlock.
+                await call.ResponseAsync;
+                Assert.Fail();
+            }
+            catch (RpcException ex)
+            {
+                Assert.AreEqual(StatusCode.Cancelled, ex.Status.StatusCode);
+            }
         }
 
         [Test]
@@ -265,9 +273,15 @@ namespace Grpc.Core.Tests
             await handlerStartedBarrier.Task;
             cts.Cancel();
 
-            var ex = Assert.ThrowsAsync<RpcException>(async () => await call.ResponseAsync);
-            Assert.AreEqual(StatusCode.Cancelled, ex.Status.StatusCode);
-
+            try
+            {
+                await call.ResponseAsync;
+                Assert.Fail();
+            }
+            catch (RpcException ex)
+            {
+                Assert.AreEqual(StatusCode.Cancelled, ex.Status.StatusCode);
+            }
             Assert.AreEqual("SUCCESS", await successTcs.Task);
         }
 
diff --git a/src/csharp/Grpc.Core.Tests/ContextPropagationTest.cs b/src/csharp/Grpc.Core.Tests/ContextPropagationTest.cs
index cec8c7ce6b..6a156293ad 100644
--- a/src/csharp/Grpc.Core.Tests/ContextPropagationTest.cs
+++ b/src/csharp/Grpc.Core.Tests/ContextPropagationTest.cs
@@ -105,7 +105,15 @@ namespace Grpc.Core.Tests
             var parentCall = Calls.AsyncClientStreamingCall(helper.CreateClientStreamingCall(new CallOptions(cancellationToken: cts.Token)));
             await readyToCancelTcs.Task;
             cts.Cancel();
-            Assert.ThrowsAsync(typeof(RpcException), async () => await parentCall);
+            try
+            {
+                // cannot use Assert.ThrowsAsync because it uses Task.Wait and would deadlock.
+                await parentCall;
+                Assert.Fail();
+            }
+            catch (RpcException)
+            {
+            }
             Assert.AreEqual("CHILD_CALL_CANCELLED", await successTcs.Task);
         }
 
diff --git a/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs b/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs
index ab12c120cb..6fe382751a 100644
--- a/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs
+++ b/src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs
@@ -32,7 +32,7 @@
 #endregion
 
 using System;
-using System.Threading;
+using System.Linq;
 using Grpc.Core;
 using NUnit.Framework;
 
@@ -44,7 +44,11 @@ namespace Grpc.Core.Tests
         public void InitializeAndShutdownGrpcEnvironment()
         {
             var env = GrpcEnvironment.AddRef();
-            Assert.IsNotNull(env.CompletionQueue);
+            Assert.IsTrue(env.CompletionQueues.Count > 0);
+            for (int i = 0; i < env.CompletionQueues.Count; i++)
+            {
+                Assert.IsNotNull(env.CompletionQueues.ElementAt(i));
+            }
             GrpcEnvironment.Release();
         }
 
diff --git a/src/csharp/Grpc.Core.Tests/Internal/AsyncCallServerTest.cs b/src/csharp/Grpc.Core.Tests/Internal/AsyncCallServerTest.cs
index 0e204761f6..c35aaf680f 100644
--- a/src/csharp/Grpc.Core.Tests/Internal/AsyncCallServerTest.cs
+++ b/src/csharp/Grpc.Core.Tests/Internal/AsyncCallServerTest.cs
@@ -53,8 +53,6 @@ namespace Grpc.Core.Internal.Tests
         [SetUp]
         public void Init()
         {
-            var environment = GrpcEnvironment.AddRef();
-
             // Create a fake server just so we have an instance to refer to.
             // The server won't actually be used at all.
             server = new Server()
@@ -66,7 +64,6 @@ namespace Grpc.Core.Internal.Tests
             fakeCall = new FakeNativeCall();
             asyncCallServer = new AsyncCallServer<string, string>(
                 Marshallers.StringMarshaller.Serializer, Marshallers.StringMarshaller.Deserializer,
-                environment,
                 server);
             asyncCallServer.InitializeForTesting(fakeCall);
         }
@@ -75,7 +72,6 @@ namespace Grpc.Core.Internal.Tests
         public void Cleanup()
         {
             server.ShutdownAsync().Wait();
-            GrpcEnvironment.Release();
         }
 
         [Test]
@@ -136,7 +132,6 @@ namespace Grpc.Core.Internal.Tests
         public void WriteAfterCancelNotificationFails()
         {
             var finishedTask = asyncCallServer.ServerSideCallAsync();
-            var requestStream = new ServerRequestStream<string, string>(asyncCallServer);
             var responseStream = new ServerResponseStream<string, string>(asyncCallServer);
 
             fakeCall.ReceivedCloseOnServerHandler(true, cancelled: true);
@@ -181,6 +176,21 @@ namespace Grpc.Core.Internal.Tests
             AssertFinished(asyncCallServer, fakeCall, finishedTask);
         }
 
+        [Test]
+        public void WriteAfterWriteStatusThrowsInvalidOperationException()
+        {
+            var finishedTask = asyncCallServer.ServerSideCallAsync();
+            var responseStream = new ServerResponseStream<string, string>(asyncCallServer);
+
+            asyncCallServer.SendStatusFromServerAsync(Status.DefaultSuccess, new Metadata(), null);
+            Assert.ThrowsAsync(typeof(InvalidOperationException), async () => await responseStream.WriteAsync("request1"));
+
+            fakeCall.SendStatusFromServerHandler(true);
+            fakeCall.ReceivedCloseOnServerHandler(true, cancelled: true);
+
+            AssertFinished(asyncCallServer, fakeCall, finishedTask);
+        }
+
         static void AssertFinished(AsyncCallServer<string, string> asyncCallServer, FakeNativeCall fakeCall, Task finishedTask)
         {
             Assert.IsTrue(fakeCall.IsDisposed);
diff --git a/src/csharp/Grpc.Core.Tests/Internal/AsyncCallTest.cs b/src/csharp/Grpc.Core.Tests/Internal/AsyncCallTest.cs
index 777a1c8c50..81897f8c77 100644
--- a/src/csharp/Grpc.Core.Tests/Internal/AsyncCallTest.cs
+++ b/src/csharp/Grpc.Core.Tests/Internal/AsyncCallTest.cs
@@ -33,7 +33,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 
 using Grpc.Core.Internal;
@@ -82,7 +81,7 @@ namespace Grpc.Core.Internal.Tests
             Assert.ThrowsAsync(typeof(InvalidOperationException),
                 async () => await asyncCall.ReadMessageAsync());
             Assert.Throws(typeof(InvalidOperationException),
-                () => asyncCall.StartSendMessage("abc", new WriteFlags(), (x,y) => {}));
+                () => asyncCall.SendMessageAsync("abc", new WriteFlags()));
         }
 
         [Test]
@@ -103,7 +102,7 @@ namespace Grpc.Core.Internal.Tests
             var resultTask = asyncCall.UnaryCallAsync("request1");
             fakeCall.UnaryResponseClientHandler(true,
                 CreateClientSideStatus(StatusCode.InvalidArgument),
-                CreateResponsePayload(),
+                null,
                 new Metadata());
 
             AssertUnaryResponseError(asyncCall, fakeCall, resultTask, StatusCode.InvalidArgument);
@@ -148,7 +147,7 @@ namespace Grpc.Core.Internal.Tests
             var resultTask = asyncCall.ClientStreamingCallAsync();
             fakeCall.UnaryResponseClientHandler(true,
                 CreateClientSideStatus(StatusCode.InvalidArgument),
-                CreateResponsePayload(),
+                null,
                 new Metadata());
 
             AssertUnaryResponseError(asyncCall, fakeCall, resultTask, StatusCode.InvalidArgument);
@@ -193,7 +192,7 @@ namespace Grpc.Core.Internal.Tests
 
             fakeCall.UnaryResponseClientHandler(true,
                 CreateClientSideStatus(StatusCode.Internal),
-                CreateResponsePayload(),
+                null,
                 new Metadata());
 
             AssertUnaryResponseError(asyncCall, fakeCall, resultTask, StatusCode.Internal);
@@ -211,7 +210,9 @@ namespace Grpc.Core.Internal.Tests
                 new Metadata());
 
             AssertUnaryResponseSuccess(asyncCall, fakeCall, resultTask);
-            var ex = Assert.Throws<RpcException>(() => requestStream.WriteAsync("request1"));
+
+            var writeTask = requestStream.WriteAsync("request1");
+            var ex = Assert.ThrowsAsync<RpcException>(async () => await writeTask);
             Assert.AreEqual(Status.DefaultSuccess, ex.Status);
         }
 
@@ -223,11 +224,13 @@ namespace Grpc.Core.Internal.Tests
 
             fakeCall.UnaryResponseClientHandler(true,
                 new ClientSideStatus(new Status(StatusCode.OutOfRange, ""), new Metadata()),
-                CreateResponsePayload(),
+                null,
                 new Metadata());
 
             AssertUnaryResponseError(asyncCall, fakeCall, resultTask, StatusCode.OutOfRange);
-            var ex = Assert.Throws<RpcException>(() => requestStream.WriteAsync("request1"));
+
+            var writeTask = requestStream.WriteAsync("request1");
+            var ex = Assert.ThrowsAsync<RpcException>(async () => await writeTask);
             Assert.AreEqual(StatusCode.OutOfRange, ex.Status.StatusCode);
         }
 
@@ -267,7 +270,7 @@ namespace Grpc.Core.Internal.Tests
         }
 
         [Test]
-        public void ClientStreaming_WriteAfterCancellationRequestThrowsOperationCancelledException()
+        public void ClientStreaming_WriteAfterCancellationRequestThrowsTaskCanceledException()
         {
             var resultTask = asyncCall.ClientStreamingCallAsync();
             var requestStream = new ClientRequestStream<string, string>(asyncCall);
@@ -275,11 +278,12 @@ namespace Grpc.Core.Internal.Tests
             asyncCall.Cancel();
             Assert.IsTrue(fakeCall.IsCancelled);
 
-            Assert.Throws(typeof(OperationCanceledException), () => requestStream.WriteAsync("request1"));
+            var writeTask = requestStream.WriteAsync("request1");
+            Assert.ThrowsAsync(typeof(TaskCanceledException), async () => await writeTask);
 
             fakeCall.UnaryResponseClientHandler(true,
                 CreateClientSideStatus(StatusCode.Cancelled),
-                CreateResponsePayload(),
+                null,
                 new Metadata());
 
             AssertUnaryResponseError(asyncCall, fakeCall, resultTask, StatusCode.Cancelled);
@@ -290,7 +294,7 @@ namespace Grpc.Core.Internal.Tests
         {
             asyncCall.StartServerStreamingCall("request1");
             Assert.Throws(typeof(InvalidOperationException),
-                () => asyncCall.StartSendMessage("abc", new WriteFlags(), (x,y) => {}));
+                () => asyncCall.SendMessageAsync("abc", new WriteFlags()));
         }
 
         [Test]
@@ -390,12 +394,13 @@ namespace Grpc.Core.Internal.Tests
 
             AssertStreamingResponseSuccess(asyncCall, fakeCall, readTask);
 
-            var ex = Assert.ThrowsAsync<RpcException>(async () => await requestStream.WriteAsync("request1"));
+            var writeTask = requestStream.WriteAsync("request1");
+            var ex = Assert.ThrowsAsync<RpcException>(async () => await writeTask);
             Assert.AreEqual(Status.DefaultSuccess, ex.Status);
         }
 
         [Test]
-        public void DuplexStreaming_CompleteAfterReceivingStatusFails()
+        public void DuplexStreaming_CompleteAfterReceivingStatusSuceeds()
         {
             asyncCall.StartDuplexStreamingCall();
             var requestStream = new ClientRequestStream<string, string>(asyncCall);
@@ -411,7 +416,7 @@ namespace Grpc.Core.Internal.Tests
         }
 
         [Test]
-        public void DuplexStreaming_WriteAfterCancellationRequestThrowsOperationCancelledException()
+        public void DuplexStreaming_WriteAfterCancellationRequestThrowsTaskCanceledException()
         {
             asyncCall.StartDuplexStreamingCall();
             var requestStream = new ClientRequestStream<string, string>(asyncCall);
@@ -419,7 +424,9 @@ namespace Grpc.Core.Internal.Tests
 
             asyncCall.Cancel();
             Assert.IsTrue(fakeCall.IsCancelled);
-            Assert.Throws(typeof(OperationCanceledException), () => requestStream.WriteAsync("request1"));
+
+            var writeTask = requestStream.WriteAsync("request1");
+            Assert.ThrowsAsync(typeof(TaskCanceledException), async () => await writeTask);
 
             var readTask = responseStream.MoveNext();
             fakeCall.ReceivedMessageHandler(true, null);
diff --git a/src/csharp/Grpc.Core.Tests/Internal/CompletionQueueSafeHandleTest.cs b/src/csharp/Grpc.Core.Tests/Internal/CompletionQueueSafeHandleTest.cs
index c6843f10af..195119f920 100644
--- a/src/csharp/Grpc.Core.Tests/Internal/CompletionQueueSafeHandleTest.cs
+++ b/src/csharp/Grpc.Core.Tests/Internal/CompletionQueueSafeHandleTest.cs
@@ -60,7 +60,7 @@ namespace Grpc.Core.Internal.Tests
             var ev = cq.Next();
             cq.Dispose();
             GrpcEnvironment.Release();
-            Assert.AreEqual(GRPCCompletionType.Shutdown, ev.type);
+            Assert.AreEqual(CompletionQueueEvent.CompletionType.Shutdown, ev.type);
             Assert.AreNotEqual(IntPtr.Zero, ev.success);
             Assert.AreEqual(IntPtr.Zero, ev.tag);
         }
diff --git a/src/csharp/Grpc.Core.Tests/Internal/TimespecTest.cs b/src/csharp/Grpc.Core.Tests/Internal/TimespecTest.cs
index 74f7f2497a..c124ea29af 100644
--- a/src/csharp/Grpc.Core.Tests/Internal/TimespecTest.cs
+++ b/src/csharp/Grpc.Core.Tests/Internal/TimespecTest.cs
@@ -61,15 +61,15 @@ namespace Grpc.Core.Internal.Tests
         }
 
         [Test]
-        public void InfFuture()
+        public void InfFutureMatchesNativeValue()
         {
-            var timespec = Timespec.InfFuture;
+            Assert.AreEqual(Timespec.NativeInfFuture, Timespec.InfFuture);
         }
 
         [Test]
-        public void InfPast()
+        public void InfPastMatchesNativeValue()
         {
-            var timespec = Timespec.InfPast;
+            Assert.AreEqual(Timespec.NativeInfPast, Timespec.InfPast);
         }
 
         [Test]
@@ -108,7 +108,7 @@ namespace Grpc.Core.Internal.Tests
             Assert.Throws(typeof(InvalidOperationException),
                 () => new Timespec(0, 1000 * 1000 * 1000).ToDateTime());
             Assert.Throws(typeof(InvalidOperationException),
-                () => new Timespec(0, 0, GPRClockType.Monotonic).ToDateTime());
+                () => new Timespec(0, 0, ClockType.Monotonic).ToDateTime());
         }
 
         [Test]
diff --git a/src/csharp/Grpc.Core.Tests/MarshallingErrorsTest.cs b/src/csharp/Grpc.Core.Tests/MarshallingErrorsTest.cs
index 0663e77d1e..d770f82390 100644
--- a/src/csharp/Grpc.Core.Tests/MarshallingErrorsTest.cs
+++ b/src/csharp/Grpc.Core.Tests/MarshallingErrorsTest.cs
@@ -134,7 +134,15 @@ namespace Grpc.Core.Tests
         {
             helper.ClientStreamingHandler = new ClientStreamingServerMethod<string, string>(async (requestStream, context) =>
             {
-                Assert.ThrowsAsync<IOException>(async () => await requestStream.MoveNext());
+                try
+                {
+                    // cannot use Assert.ThrowsAsync because it uses Task.Wait and would deadlock.
+                    await requestStream.MoveNext();
+                    Assert.Fail();
+                }
+                catch (IOException)
+                {
+                }
                 return "RESPONSE";
             });
 
diff --git a/src/csharp/Grpc.Core/Channel.cs b/src/csharp/Grpc.Core/Channel.cs
index 93a6e6a3d9..886adfec33 100644
--- a/src/csharp/Grpc.Core/Channel.cs
+++ b/src/csharp/Grpc.Core/Channel.cs
@@ -31,7 +31,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -56,6 +55,7 @@ namespace Grpc.Core
 
         readonly string target;
         readonly GrpcEnvironment environment;
+        readonly CompletionQueueSafeHandle completionQueue;
         readonly ChannelSafeHandle handle;
         readonly Dictionary<string, ChannelOption> options;
 
@@ -75,6 +75,7 @@ namespace Grpc.Core
             EnsureUserAgentChannelOption(this.options);
             this.environment = GrpcEnvironment.AddRef();
 
+            this.completionQueue = this.environment.PickCompletionQueue();
             using (var nativeCredentials = credentials.ToNativeCredentials())
             using (var nativeChannelArgs = ChannelOptions.CreateChannelArgs(this.options.Values))
             {
@@ -135,7 +136,7 @@ namespace Grpc.Core
                     tcs.SetCanceled();
                 }
             });
-            handle.WatchConnectivityState(lastObservedState, deadlineTimespec, environment.CompletionQueue, environment.CompletionRegistry, handler);
+            handle.WatchConnectivityState(lastObservedState, deadlineTimespec, completionQueue, handler);
             return tcs.Task;
         }
 
@@ -231,6 +232,14 @@ namespace Grpc.Core
             }
         }
 
+        internal CompletionQueueSafeHandle CompletionQueue
+        {
+            get
+            {
+                return this.completionQueue;
+            }
+        }
+
         internal void AddCallReference(object call)
         {
             activeCallCounter.Increment();
diff --git a/src/csharp/Grpc.Core/Grpc.Core.csproj b/src/csharp/Grpc.Core/Grpc.Core.csproj
index 95077a6ca5..a8b7b5f00d 100644
--- a/src/csharp/Grpc.Core/Grpc.Core.csproj
+++ b/src/csharp/Grpc.Core/Grpc.Core.csproj
@@ -74,7 +74,6 @@
     <Compile Include="Internal\CallSafeHandle.cs" />
     <Compile Include="Internal\ChannelSafeHandle.cs" />
     <Compile Include="Internal\CompletionQueueSafeHandle.cs" />
-    <Compile Include="Internal\Enums.cs" />
     <Compile Include="Internal\SafeHandleZeroIsInvalid.cs" />
     <Compile Include="Internal\Timespec.cs" />
     <Compile Include="Internal\GrpcThreadPool.cs" />
@@ -87,7 +86,6 @@
     <Compile Include="Utils\BenchmarkUtil.cs" />
     <Compile Include="ChannelCredentials.cs" />
     <Compile Include="Internal\ChannelArgsSafeHandle.cs" />
-    <Compile Include="Internal\AsyncCompletion.cs" />
     <Compile Include="Internal\AsyncCallBase.cs" />
     <Compile Include="Internal\AsyncCallServer.cs" />
     <Compile Include="Internal\AsyncCall.cs" />
@@ -134,6 +132,10 @@
     <Compile Include="DefaultCallInvoker.cs" />
     <Compile Include="Internal\UnimplementedCallInvoker.cs" />
     <Compile Include="Internal\InterceptingCallInvoker.cs" />
+    <Compile Include="Internal\ServerRpcNew.cs" />
+    <Compile Include="Internal\ClientSideStatus.cs" />
+    <Compile Include="Internal\ClockType.cs" />
+    <Compile Include="Internal\CallError.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="Grpc.Core.nuspec" />
diff --git a/src/csharp/Grpc.Core/GrpcEnvironment.cs b/src/csharp/Grpc.Core/GrpcEnvironment.cs
index bee0ef1d62..18af1099f1 100644
--- a/src/csharp/Grpc.Core/GrpcEnvironment.cs
+++ b/src/csharp/Grpc.Core/GrpcEnvironment.cs
@@ -32,8 +32,9 @@
 #endregion
 
 using System;
+using System.Collections.Generic;
+using System.Linq;
 using System.Runtime.InteropServices;
-using System.Threading.Tasks;
 using Grpc.Core.Internal;
 using Grpc.Core.Logging;
 using Grpc.Core.Utils;
@@ -51,12 +52,13 @@ namespace Grpc.Core
         static GrpcEnvironment instance;
         static int refCount;
         static int? customThreadPoolSize;
+        static int? customCompletionQueueCount;
 
         static ILogger logger = new ConsoleLogger();
 
         readonly GrpcThreadPool threadPool;
-        readonly CompletionRegistry completionRegistry;
         readonly DebugStats debugStats = new DebugStats();
+        readonly AtomicCounter cqPickerCounter = new AtomicCounter();
         bool isClosed;
 
         /// <summary>
@@ -141,36 +143,51 @@ namespace Grpc.Core
         }
 
         /// <summary>
+        /// Sets the number of completion queues in the  gRPC thread pool that polls for internal RPC events.
+        /// Can be only invoke before the <c>GrpcEnviroment</c> is started and cannot be changed afterwards.
+        /// Setting the number of completions queues is an advanced setting and you should only use it if you know what you are doing.
+        /// Most users should rely on the default value provided by gRPC library.
+        /// Note: this method is part of an experimental API that can change or be removed without any prior notice.
+        /// </summary>
+        public static void SetCompletionQueueCount(int completionQueueCount)
+        {
+            lock (staticLock)
+            {
+                GrpcPreconditions.CheckState(instance == null, "Can only be set before GrpcEnvironment is initialized");
+                GrpcPreconditions.CheckArgument(completionQueueCount > 0, "threadCount needs to be a positive number");
+                customCompletionQueueCount = completionQueueCount;
+            }
+        }
+
+        /// <summary>
         /// Creates gRPC environment.
         /// </summary>
         private GrpcEnvironment()
         {
             GrpcNativeInit();
-            completionRegistry = new CompletionRegistry(this);
-            threadPool = new GrpcThreadPool(this, GetThreadPoolSizeOrDefault());
+            threadPool = new GrpcThreadPool(this, GetThreadPoolSizeOrDefault(), GetCompletionQueueCountOrDefault());
             threadPool.Start();
         }
 
         /// <summary>
-        /// Gets the completion registry used by this gRPC environment.
+        /// Gets the completion queues used by this gRPC environment.
         /// </summary>
-        internal CompletionRegistry CompletionRegistry
+        internal IReadOnlyCollection<CompletionQueueSafeHandle> CompletionQueues
         {
             get
             {
-                return this.completionRegistry;
+                return this.threadPool.CompletionQueues;
             }
         }
 
         /// <summary>
-        /// Gets the completion queue used by this gRPC environment.
+        /// Picks a completion queue in a round-robin fashion.
+        /// Shouldn't be invoked on a per-call basis (used at per-channel basis).
         /// </summary>
-        internal CompletionQueueSafeHandle CompletionQueue
+        internal CompletionQueueSafeHandle PickCompletionQueue()
         {
-            get
-            {
-                return this.threadPool.CompletionQueue;
-            }
+            var cqIndex = (int) ((cqPickerCounter.Increment() - 1) % this.threadPool.CompletionQueues.Count);
+            return this.threadPool.CompletionQueues.ElementAt(cqIndex);
         }
 
         /// <summary>
@@ -230,5 +247,15 @@ namespace Grpc.Core
             // more work, but seems to work reasonably well for a start.
             return Math.Max(MinDefaultThreadPoolSize, Environment.ProcessorCount / 2);
         }
+
+        private int GetCompletionQueueCountOrDefault()
+        {
+            if (customCompletionQueueCount.HasValue)
+            {
+                return customCompletionQueueCount.Value;
+            }
+            // by default, create a completion queue for each thread
+            return GetThreadPoolSizeOrDefault();
+        }
     }
 }
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCall.cs b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
index 55351869b5..895be690a5 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCall.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
@@ -32,12 +32,7 @@
 #endregion
 
 using System;
-using System.Diagnostics;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-using System.Threading;
 using System.Threading.Tasks;
-using Grpc.Core.Internal;
 using Grpc.Core.Logging;
 using Grpc.Core.Profiling;
 using Grpc.Core.Utils;
@@ -57,9 +52,11 @@ namespace Grpc.Core.Internal
         // Completion of a pending unary response if not null.
         TaskCompletionSource<TResponse> unaryResponseTcs;
 
+        // TODO(jtattermusch): this field doesn't need to be initialized for unary response calls.
         // Indicates that response streaming call has finished.
         TaskCompletionSource<object> streamingCallFinishedTcs = new TaskCompletionSource<object>();
 
+        // TODO(jtattermusch): this field could be lazy-initialized (only if someone requests the response headers).
         // Response headers set here once received.
         TaskCompletionSource<Metadata> responseHeadersTcs = new TaskCompletionSource<Metadata>();
 
@@ -67,7 +64,7 @@ namespace Grpc.Core.Internal
         ClientSideStatus? finishedStatus;
 
         public AsyncCall(CallInvocationDetails<TRequest, TResponse> callDetails)
-            : base(callDetails.RequestMarshaller.Serializer, callDetails.ResponseMarshaller.Deserializer, callDetails.Channel.Environment)
+            : base(callDetails.RequestMarshaller.Serializer, callDetails.ResponseMarshaller.Deserializer)
         {
             this.details = callDetails.WithOptions(callDetails.Options.Normalize());
             this.initialMetadataSent = true;  // we always send metadata at the very beginning of the call.
@@ -144,7 +141,7 @@ namespace Grpc.Core.Internal
                 GrpcPreconditions.CheckState(!started);
                 started = true;
 
-                Initialize(environment.CompletionQueue);
+                Initialize(details.Channel.CompletionQueue);
 
                 halfcloseRequested = true;
                 readingDone = true;
@@ -171,7 +168,7 @@ namespace Grpc.Core.Internal
                 GrpcPreconditions.CheckState(!started);
                 started = true;
 
-                Initialize(environment.CompletionQueue);
+                Initialize(details.Channel.CompletionQueue);
 
                 readingDone = true;
 
@@ -195,7 +192,7 @@ namespace Grpc.Core.Internal
                 GrpcPreconditions.CheckState(!started);
                 started = true;
 
-                Initialize(environment.CompletionQueue);
+                Initialize(details.Channel.CompletionQueue);
 
                 halfcloseRequested = true;
 
@@ -220,7 +217,7 @@ namespace Grpc.Core.Internal
                 GrpcPreconditions.CheckState(!started);
                 started = true;
 
-                Initialize(environment.CompletionQueue);
+                Initialize(details.Channel.CompletionQueue);
 
                 using (var metadataArray = MetadataArraySafeHandle.Create(details.Options.Headers))
                 {
@@ -232,11 +229,10 @@ namespace Grpc.Core.Internal
 
         /// <summary>
         /// Sends a streaming request. Only one pending send action is allowed at any given time.
-        /// completionDelegate is called when the operation finishes.
         /// </summary>
-        public void StartSendMessage(TRequest msg, WriteFlags writeFlags, AsyncCompletionDelegate<object> completionDelegate)
+        public Task SendMessageAsync(TRequest msg, WriteFlags writeFlags)
         {
-            StartSendMessageInternal(msg, writeFlags, completionDelegate);
+            return SendMessageInternalAsync(msg, writeFlags);
         }
 
         /// <summary>
@@ -250,29 +246,32 @@ namespace Grpc.Core.Internal
         /// <summary>
         /// Sends halfclose, indicating client is done with streaming requests.
         /// Only one pending send action is allowed at any given time.
-        /// completionDelegate is called when the operation finishes.
         /// </summary>
-        public void StartSendCloseFromClient(AsyncCompletionDelegate<object> completionDelegate)
+        public Task SendCloseFromClientAsync()
         {
             lock (myLock)
             {
-                GrpcPreconditions.CheckNotNull(completionDelegate, "Completion delegate cannot be null");
-                CheckSendingAllowed(allowFinished: true);
+                GrpcPreconditions.CheckState(started);
 
-                if (!disposed && !finished)
+                var earlyResult = CheckSendPreconditionsClientSide();
+                if (earlyResult != null)
                 {
-                    call.StartSendCloseFromClient(HandleSendCloseFromClientFinished);
+                    return earlyResult;
                 }
-                else
+
+                if (disposed || finished)
                 {
                     // In case the call has already been finished by the serverside,
-                    // the halfclose has already been done implicitly, so we only
-                    // emit the notification for the completion delegate.
-                    Task.Run(() => HandleSendCloseFromClientFinished(true));
+                    // the halfclose has already been done implicitly, so just return
+                    // completed task here.
+                    halfcloseRequested = true;
+                    return Task.FromResult<object>(null);
                 }
+                call.StartSendCloseFromClient(HandleSendCloseFromClientFinished);
 
                 halfcloseRequested = true;
-                sendCompletionDelegate = completionDelegate;
+                streamingWriteTcs = new TaskCompletionSource<object>();
+                return streamingWriteTcs.Task;
             }
         }
 
@@ -342,6 +341,45 @@ namespace Grpc.Core.Internal
             get { return true; }
         }
 
+        protected override Task CheckSendAllowedOrEarlyResult()
+        {
+            var earlyResult = CheckSendPreconditionsClientSide();
+            if (earlyResult != null)
+            {
+                return earlyResult;
+            }
+
+            if (finishedStatus.HasValue)
+            {
+                // throwing RpcException if we already received status on client
+                // side makes the most sense.
+                // Note that this throws even for StatusCode.OK.
+                // Writing after the call has finished is not a programming error because server can close
+                // the call anytime, so don't throw directly, but let the write task finish with an error.
+                var tcs = new TaskCompletionSource<object>();
+                tcs.SetException(new RpcException(finishedStatus.Value.Status));
+                return tcs.Task;
+            }
+
+            return null;
+        }
+
+        private Task CheckSendPreconditionsClientSide()
+        {
+            GrpcPreconditions.CheckState(!halfcloseRequested, "Request stream has already been completed.");
+            GrpcPreconditions.CheckState(streamingWriteTcs == null, "Only one write can be pending at a time.");
+
+            if (cancelRequested)
+            {
+                // Return a cancelled task.
+                var tcs = new TaskCompletionSource<object>();
+                tcs.SetCanceled();
+                return tcs.Task;
+            }
+
+            return null;
+        }
+
         private void Initialize(CompletionQueueSafeHandle cq)
         {
             using (Profilers.ForCurrentThread().NewScope("AsyncCall.Initialize"))
@@ -368,7 +406,7 @@ namespace Grpc.Core.Internal
                 var credentials = details.Options.Credentials;
                 using (var nativeCredentials = credentials != null ? credentials.ToNativeCredentials() : null)
                 {
-                    var result = details.Channel.Handle.CreateCall(environment.CompletionRegistry,
+                    var result = details.Channel.Handle.CreateCall(
                                  parentCall, ContextPropagationToken.DefaultMask, cq,
                                  details.Method, details.Host, Timespec.FromDateTime(details.Options.Deadline.Value), nativeCredentials);
                     return result;
@@ -400,6 +438,7 @@ namespace Grpc.Core.Internal
         /// </summary>
         private void HandleReceivedResponseHeaders(bool success, Metadata responseHeaders)
         {
+            // TODO(jtattermusch): handle success==false
             responseHeadersTcs.SetResult(responseHeaders);
         }
 
@@ -443,19 +482,6 @@ namespace Grpc.Core.Internal
             }
         }
 
-        protected override void CheckSendingAllowed(bool allowFinished)
-        {
-            base.CheckSendingAllowed(true);
-
-            // throwing RpcException if we already received status on client
-            // side makes the most sense.
-            // Note that this throws even for StatusCode.OK.
-            if (!allowFinished && finishedStatus.HasValue)
-            {
-                throw new RpcException(finishedStatus.Value.Status);
-            }
-        }
-
         /// <summary>
         /// Handles receive status completion for calls with streaming response.
         /// </summary>
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs b/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
index 4de23706b2..cb8366c216 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
@@ -58,7 +58,6 @@ 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 INativeCall call;
@@ -67,8 +66,8 @@ namespace Grpc.Core.Internal
         protected bool started;
         protected bool cancelRequested;
 
-        protected AsyncCompletionDelegate<object> sendCompletionDelegate;  // Completion of a pending send or sendclose if not null.
         protected TaskCompletionSource<TRead> streamingReadTcs;  // Completion of a pending streaming read if not null.
+        protected TaskCompletionSource<object> streamingWriteTcs;  // Completion of a pending streaming write or send close from client if not null.
         protected TaskCompletionSource<object> sendStatusFromServerTcs;
 
         protected bool readingDone;  // True if last read (i.e. read with null payload) was already received.
@@ -78,11 +77,10 @@ namespace Grpc.Core.Internal
         protected bool initialMetadataSent;
         protected long streamingWritesCounter;  // Number of streaming send operations started so far.
 
-        public AsyncCallBase(Func<TWrite, byte[]> serializer, Func<byte[], TRead> deserializer, GrpcEnvironment environment)
+        public AsyncCallBase(Func<TWrite, byte[]> serializer, Func<byte[], TRead> deserializer)
         {
             this.serializer = GrpcPreconditions.CheckNotNull(serializer);
             this.deserializer = GrpcPreconditions.CheckNotNull(deserializer);
-            this.environment = GrpcPreconditions.CheckNotNull(environment);
         }
 
         /// <summary>
@@ -128,28 +126,31 @@ namespace Grpc.Core.Internal
 
         /// <summary>
         /// Initiates sending a message. Only one send operation can be active at a time.
-        /// completionDelegate is invoked upon completion.
         /// </summary>
-        protected void StartSendMessageInternal(TWrite msg, WriteFlags writeFlags, AsyncCompletionDelegate<object> completionDelegate)
+        protected Task SendMessageInternalAsync(TWrite msg, WriteFlags writeFlags)
         {
             byte[] payload = UnsafeSerialize(msg);
 
             lock (myLock)
             {
-                GrpcPreconditions.CheckNotNull(completionDelegate, "Completion delegate cannot be null");
-                CheckSendingAllowed(allowFinished: false);
+                GrpcPreconditions.CheckState(started);
+                var earlyResult = CheckSendAllowedOrEarlyResult();
+                if (earlyResult != null)
+                {
+                    return earlyResult;
+                }
 
                 call.StartSendMessage(HandleSendFinished, payload, writeFlags, !initialMetadataSent);
 
-                sendCompletionDelegate = completionDelegate;
                 initialMetadataSent = true;
                 streamingWritesCounter++;
+                streamingWriteTcs = new TaskCompletionSource<object>();
+                return streamingWriteTcs.Task;
             }
         }
 
         /// <summary>
         /// Initiates reading a message. Only one read operation can be active at a time.
-        /// completionDelegate is invoked upon completion.
         /// </summary>
         protected Task<TRead> ReadMessageInternalAsync()
         {
@@ -159,7 +160,7 @@ namespace Grpc.Core.Internal
                 if (readingDone)
                 {
                     // the last read that returns null or throws an exception is idempotent
-                    // and maintain its state.
+                    // and maintains its state.
                     GrpcPreconditions.CheckState(streamingReadTcs != null, "Call does not support streaming reads.");
                     return streamingReadTcs.Task;
                 }
@@ -183,7 +184,7 @@ namespace Grpc.Core.Internal
             {
                 if (!disposed && call != null)
                 {
-                    bool noMoreSendCompletions = sendCompletionDelegate == null && (halfcloseRequested || cancelRequested || finished);
+                    bool noMoreSendCompletions = streamingWriteTcs == null && (halfcloseRequested || cancelRequested || finished);
                     if (noMoreSendCompletions && readingDone && finished)
                     {
                         ReleaseResources();
@@ -213,24 +214,11 @@ namespace Grpc.Core.Internal
         {
         }
 
-        protected virtual void CheckSendingAllowed(bool allowFinished)
-        {
-            GrpcPreconditions.CheckState(started);
-            CheckNotCancelled();
-            GrpcPreconditions.CheckState(!disposed || allowFinished);
-
-            GrpcPreconditions.CheckState(!halfcloseRequested, "Already halfclosed.");
-            GrpcPreconditions.CheckState(!finished || allowFinished, "Already finished.");
-            GrpcPreconditions.CheckState(sendCompletionDelegate == null, "Only one write can be pending at a time");
-        }
-
-        protected void CheckNotCancelled()
-        {
-            if (cancelRequested)
-            {
-                throw new OperationCanceledException("Remote call has been cancelled.");
-            }
-        }
+        /// <summary>
+        /// Checks if sending is allowed and possibly returns a Task that allows short-circuiting the send
+        /// logic by directly returning the write operation result task. Normally, null is returned.
+        /// </summary>
+        protected abstract Task CheckSendAllowedOrEarlyResult();
 
         protected byte[] UnsafeSerialize(TWrite msg)
         {
@@ -259,39 +247,27 @@ namespace Grpc.Core.Internal
             }
         }
 
-        protected void FireCompletion<T>(AsyncCompletionDelegate<T> completionDelegate, T value, Exception error)
-        {
-            try
-            {
-                completionDelegate(value, error);
-            }
-            catch (Exception e)
-            {
-                Logger.Error(e, "Exception occured while invoking completion delegate.");
-            }
-        }
-
         /// <summary>
         /// Handles send completion.
         /// </summary>
         protected void HandleSendFinished(bool success)
         {
-            AsyncCompletionDelegate<object> origCompletionDelegate = null;
+            TaskCompletionSource<object> origTcs = null;
             lock (myLock)
             {
-                origCompletionDelegate = sendCompletionDelegate;
-                sendCompletionDelegate = null;
+                origTcs = streamingWriteTcs;
+                streamingWriteTcs = null;
 
                 ReleaseResourcesIfPossible();
             }
 
             if (!success)
             {
-                FireCompletion(origCompletionDelegate, null, new InvalidOperationException("Send failed"));
+                origTcs.SetException(new InvalidOperationException("Send failed"));
             }
             else
             {
-                FireCompletion(origCompletionDelegate, null, null);
+                origTcs.SetResult(null);
             }
         }
 
@@ -300,22 +276,23 @@ namespace Grpc.Core.Internal
         /// </summary>
         protected void HandleSendCloseFromClientFinished(bool success)
         {
-            AsyncCompletionDelegate<object> origCompletionDelegate = null;
+            TaskCompletionSource<object> origTcs = null;
             lock (myLock)
             {
-                origCompletionDelegate = sendCompletionDelegate;
-                sendCompletionDelegate = null;
+                origTcs = streamingWriteTcs;
+                streamingWriteTcs = null;
 
                 ReleaseResourcesIfPossible();
             }
 
             if (!success)
             {
-                FireCompletion(origCompletionDelegate, null, new InvalidOperationException("Sending close from client has failed."));
+                // TODO(jtattermusch): this method is same as HandleSendFinished (only the error message differs).
+                origTcs.SetException(new InvalidOperationException("Sending close from client has failed."));
             }
             else
             {
-                FireCompletion(origCompletionDelegate, null, null);
+                origTcs.SetResult(null);
             }
         }
 
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs b/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
index b1566b44a7..56c23ba3ef 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
@@ -51,14 +51,14 @@ namespace Grpc.Core.Internal
         readonly CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
         readonly Server server;
 
-        public AsyncCallServer(Func<TResponse, byte[]> serializer, Func<byte[], TRequest> deserializer, GrpcEnvironment environment, Server server) : base(serializer, deserializer, environment)
+        public AsyncCallServer(Func<TResponse, byte[]> serializer, Func<byte[], TRequest> deserializer, Server server) : base(serializer, deserializer)
         {
             this.server = GrpcPreconditions.CheckNotNull(server);
         }
 
-        public void Initialize(CallSafeHandle call)
+        public void Initialize(CallSafeHandle call, CompletionQueueSafeHandle completionQueue)
         {
-            call.Initialize(environment.CompletionRegistry, environment.CompletionQueue);
+            call.Initialize(completionQueue);
 
             server.AddCallReference(this);
             InitializeInternal(call);
@@ -91,11 +91,10 @@ namespace Grpc.Core.Internal
 
         /// <summary>
         /// Sends a streaming response. Only one pending send action is allowed at any given time.
-        /// completionDelegate is called when the operation finishes.
         /// </summary>
-        public void StartSendMessage(TResponse msg, WriteFlags writeFlags, AsyncCompletionDelegate<object> completionDelegate)
+        public Task SendMessageAsync(TResponse msg, WriteFlags writeFlags)
         {
-            StartSendMessageInternal(msg, writeFlags, completionDelegate);
+            return SendMessageInternalAsync(msg, writeFlags);
         }
 
         /// <summary>
@@ -110,20 +109,22 @@ namespace Grpc.Core.Internal
         /// Initiates sending a initial metadata. 
         /// Even though C-core allows sending metadata in parallel to sending messages, we will treat sending metadata as a send message operation
         /// to make things simpler.
-        /// completionDelegate is invoked upon completion.
         /// </summary>
-        public void StartSendInitialMetadata(Metadata headers, AsyncCompletionDelegate<object> completionDelegate)
+        public Task SendInitialMetadataAsync(Metadata headers)
         {
             lock (myLock)
             {
                 GrpcPreconditions.CheckNotNull(headers, "metadata");
-                GrpcPreconditions.CheckNotNull(completionDelegate, "Completion delegate cannot be null");
 
+                GrpcPreconditions.CheckState(started);
                 GrpcPreconditions.CheckState(!initialMetadataSent, "Response headers can only be sent once per call.");
                 GrpcPreconditions.CheckState(streamingWritesCounter == 0, "Response headers can only be sent before the first write starts.");
-                CheckSendingAllowed(allowFinished: false);
 
-                GrpcPreconditions.CheckNotNull(completionDelegate, "Completion delegate cannot be null");
+                var earlyResult = CheckSendAllowedOrEarlyResult();
+                if (earlyResult != null)
+                {
+                    return earlyResult;
+                }
 
                 using (var metadataArray = MetadataArraySafeHandle.Create(headers))
                 {
@@ -131,7 +132,8 @@ namespace Grpc.Core.Internal
                 }
 
                 this.initialMetadataSent = true;
-                sendCompletionDelegate = completionDelegate;
+                streamingWriteTcs = new TaskCompletionSource<object>();
+                return streamingWriteTcs.Task;
             }
         }
 
@@ -196,6 +198,16 @@ namespace Grpc.Core.Internal
             server.RemoveCallReference(this);
         }
 
+        protected override Task CheckSendAllowedOrEarlyResult()
+        {
+            GrpcPreconditions.CheckState(!halfcloseRequested, "Response stream has already been completed.");
+            GrpcPreconditions.CheckState(!finished, "Already finished.");
+            GrpcPreconditions.CheckState(streamingWriteTcs == null, "Only one write can be pending at a time");
+            GrpcPreconditions.CheckState(!disposed);
+
+            return null;
+        }
+
         /// <summary>
         /// Handles the server side close completion.
         /// </summary>
diff --git a/src/csharp/Grpc.Core/Internal/BatchContextSafeHandle.cs b/src/csharp/Grpc.Core/Internal/BatchContextSafeHandle.cs
index 66d2a66f99..c28a6f64d3 100644
--- a/src/csharp/Grpc.Core/Internal/BatchContextSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/BatchContextSafeHandle.cs
@@ -120,107 +120,4 @@ namespace Grpc.Core.Internal
             return true;
         }
     }
-
-    /// <summary>
-    /// Status + metadata received on client side when call finishes.
-    /// (when receive_status_on_client operation finishes).
-    /// </summary>
-    internal struct ClientSideStatus
-    {
-        readonly Status status;
-        readonly Metadata trailers;
-
-        public ClientSideStatus(Status status, Metadata trailers)
-        {
-            this.status = status;
-            this.trailers = trailers;
-        }
-
-        public Status Status
-        {
-            get
-            {
-                return this.status;
-            }    
-        }
-
-        public Metadata Trailers
-        {
-            get
-            {
-                return this.trailers;
-            }
-        }
-    }
-
-    /// <summary>
-    /// Details of a newly received RPC.
-    /// </summary>
-    internal struct ServerRpcNew
-    {
-        readonly Server server;
-        readonly CallSafeHandle call;
-        readonly string method;
-        readonly string host;
-        readonly Timespec deadline;
-        readonly Metadata requestMetadata;
-
-        public ServerRpcNew(Server server, CallSafeHandle call, string method, string host, Timespec deadline, Metadata requestMetadata)
-        {
-            this.server = server;
-            this.call = call;
-            this.method = method;
-            this.host = host;
-            this.deadline = deadline;
-            this.requestMetadata = requestMetadata;
-        }
-
-        public Server Server
-        {
-            get
-            {
-                return this.server;
-            }
-        }
-
-        public CallSafeHandle Call
-        {
-            get
-            {
-                return this.call;
-            }
-        }
-
-        public string Method
-        {
-            get
-            {
-                return this.method;
-            }
-        }
-
-        public string Host
-        {
-            get
-            {
-                return this.host;
-            }
-        }
-
-        public Timespec Deadline
-        {
-            get
-            {
-                return this.deadline;
-            }
-        }
-
-        public Metadata RequestMetadata
-        {
-            get
-            {
-                return this.requestMetadata;
-            }
-        }
-    }
 }
diff --git a/src/csharp/Grpc.Core/Internal/Enums.cs b/src/csharp/Grpc.Core/Internal/CallError.cs
index 74f86d2a30..541575f5e6 100644
--- a/src/csharp/Grpc.Core/Internal/Enums.cs
+++ b/src/csharp/Grpc.Core/Internal/CallError.cs
@@ -40,7 +40,7 @@ namespace Grpc.Core.Internal
     /// <summary>
     /// grpc_call_error from grpc/grpc.h
     /// </summary>
-    internal enum GRPCCallError
+    internal enum CallError
     {
         /* everything went ok */
         OK = 0,
@@ -70,42 +70,9 @@ namespace Grpc.Core.Internal
         /// <summary>
         /// Checks the call API invocation's result is OK.
         /// </summary>
-        public static void CheckOk(this GRPCCallError callError)
+        public static void CheckOk(this CallError callError)
         {
-            GrpcPreconditions.CheckState(callError == GRPCCallError.OK, "Call error: " + callError);
+            GrpcPreconditions.CheckState(callError == CallError.OK, "Call error: " + callError);
         }
     }
-
-    /// <summary>
-    /// grpc_completion_type from grpc/grpc.h
-    /// </summary>
-    internal enum GRPCCompletionType
-    {
-        /* Shutting down */
-        Shutdown, 
-
-        /* No event before timeout */
-        Timeout,  
-
-        /* operation completion */
-        OpComplete
-    }
-
-    /// <summary>
-    /// gpr_clock_type from grpc/support/time.h
-    /// </summary>
-    internal enum GPRClockType
-    {
-        /* Monotonic clock */
-        Monotonic,
-
-        /* Realtime clock */
-        Realtime,
-
-        /* Precise clock good for performance profiling. */
-        Precise,
-
-        /* Timespan - the distance between two time points */
-        Timespan
-    }
 }
diff --git a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
index 244b97d4a4..82361f5797 100644
--- a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
@@ -47,16 +47,14 @@ namespace Grpc.Core.Internal
         static readonly NativeMethods Native = NativeMethods.Get();
 
         const uint GRPC_WRITE_BUFFER_HINT = 1;
-        CompletionRegistry completionRegistry;
         CompletionQueueSafeHandle completionQueue;
 
         private CallSafeHandle()
         {
         }
 
-        public void Initialize(CompletionRegistry completionRegistry, CompletionQueueSafeHandle completionQueue)
+        public void Initialize(CompletionQueueSafeHandle completionQueue)
         {
-            this.completionRegistry = completionRegistry;
             this.completionQueue = completionQueue;
         }
 
@@ -70,7 +68,7 @@ namespace Grpc.Core.Internal
             using (completionQueue.NewScope())
             {
                 var ctx = BatchContextSafeHandle.Create();
-                completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedStatusOnClient(), context.GetReceivedMessage(), context.GetReceivedInitialMetadata()));
+                completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedStatusOnClient(), context.GetReceivedMessage(), context.GetReceivedInitialMetadata()));
                 Native.grpcsharp_call_start_unary(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray, writeFlags)
                     .CheckOk();
             }
@@ -90,7 +88,7 @@ namespace Grpc.Core.Internal
             using (completionQueue.NewScope())
             {
                 var ctx = BatchContextSafeHandle.Create();
-                completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedStatusOnClient(), context.GetReceivedMessage(), context.GetReceivedInitialMetadata()));
+                completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedStatusOnClient(), context.GetReceivedMessage(), context.GetReceivedInitialMetadata()));
                 Native.grpcsharp_call_start_client_streaming(this, ctx, metadataArray).CheckOk();
             }
         }
@@ -100,7 +98,7 @@ namespace Grpc.Core.Internal
             using (completionQueue.NewScope())
             {
                 var ctx = BatchContextSafeHandle.Create();
-                completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedStatusOnClient()));
+                completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedStatusOnClient()));
                 Native.grpcsharp_call_start_server_streaming(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray, writeFlags).CheckOk();
             }
         }
@@ -110,7 +108,7 @@ namespace Grpc.Core.Internal
             using (completionQueue.NewScope())
             {
                 var ctx = BatchContextSafeHandle.Create();
-                completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedStatusOnClient()));
+                completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedStatusOnClient()));
                 Native.grpcsharp_call_start_duplex_streaming(this, ctx, metadataArray).CheckOk();
             }
         }
@@ -120,7 +118,7 @@ namespace Grpc.Core.Internal
             using (completionQueue.NewScope())
             {
                 var ctx = BatchContextSafeHandle.Create();
-                completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success));
+                completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success));
                 Native.grpcsharp_call_send_message(this, ctx, payload, new UIntPtr((ulong)payload.Length), writeFlags, sendEmptyInitialMetadata).CheckOk();
             }
         }
@@ -130,7 +128,7 @@ namespace Grpc.Core.Internal
             using (completionQueue.NewScope())
             {
                 var ctx = BatchContextSafeHandle.Create();
-                completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success));
+                completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success));
                 Native.grpcsharp_call_send_close_from_client(this, ctx).CheckOk();
             }
         }
@@ -142,7 +140,7 @@ namespace Grpc.Core.Internal
             {
                 var ctx = BatchContextSafeHandle.Create();
                 var optionalPayloadLength = optionalPayload != null ? new UIntPtr((ulong)optionalPayload.Length) : UIntPtr.Zero;
-                completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success));
+                completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success));
                 Native.grpcsharp_call_send_status_from_server(this, ctx, status.StatusCode, status.Detail, metadataArray, sendEmptyInitialMetadata,
                     optionalPayload, optionalPayloadLength, writeFlags).CheckOk();
             }
@@ -153,7 +151,7 @@ namespace Grpc.Core.Internal
             using (completionQueue.NewScope())
             {
                 var ctx = BatchContextSafeHandle.Create();
-                completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedMessage()));
+                completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedMessage()));
                 Native.grpcsharp_call_recv_message(this, ctx).CheckOk();
             }
         }
@@ -163,7 +161,7 @@ namespace Grpc.Core.Internal
             using (completionQueue.NewScope())
             {
                 var ctx = BatchContextSafeHandle.Create();
-                completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedInitialMetadata()));
+                completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedInitialMetadata()));
                 Native.grpcsharp_call_recv_initial_metadata(this, ctx).CheckOk();
             }
         }
@@ -173,7 +171,7 @@ namespace Grpc.Core.Internal
             using (completionQueue.NewScope())
             {
                 var ctx = BatchContextSafeHandle.Create();
-                completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedCloseOnServerCancelled()));
+                completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success, context.GetReceivedCloseOnServerCancelled()));
                 Native.grpcsharp_call_start_serverside(this, ctx).CheckOk();
             }
         }
@@ -183,7 +181,7 @@ namespace Grpc.Core.Internal
             using (completionQueue.NewScope())
             {
                 var ctx = BatchContextSafeHandle.Create();
-                completionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success));
+                completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, (success, context) => callback(success));
                 Native.grpcsharp_call_send_initial_metadata(this, ctx, metadataArray).CheckOk();
             }
         }
diff --git a/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs b/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
index 1dbd1f4e34..62864dff0c 100644
--- a/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
@@ -63,7 +63,7 @@ namespace Grpc.Core.Internal
             return Native.grpcsharp_secure_channel_create(credentials, target, channelArgs);
         }
 
-        public CallSafeHandle CreateCall(CompletionRegistry registry, CallSafeHandle parentCall, ContextPropagationFlags propagationMask, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline, CallCredentialsSafeHandle credentials)
+        public CallSafeHandle CreateCall(CallSafeHandle parentCall, ContextPropagationFlags propagationMask, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline, CallCredentialsSafeHandle credentials)
         {
             using (Profilers.ForCurrentThread().NewScope("ChannelSafeHandle.CreateCall"))
             {
@@ -72,7 +72,7 @@ namespace Grpc.Core.Internal
                 {
                     result.SetCredentials(credentials);
                 }
-                result.Initialize(registry, cq);
+                result.Initialize(cq);
                 return result;
             }
         }
@@ -82,11 +82,10 @@ namespace Grpc.Core.Internal
             return Native.grpcsharp_channel_check_connectivity_state(this, tryToConnect ? 1 : 0);
         }
 
-        public void WatchConnectivityState(ChannelState lastObservedState, Timespec deadline, CompletionQueueSafeHandle cq,
-            CompletionRegistry completionRegistry, BatchCompletionDelegate callback)
+        public void WatchConnectivityState(ChannelState lastObservedState, Timespec deadline, CompletionQueueSafeHandle cq, BatchCompletionDelegate callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            completionRegistry.RegisterBatchCompletion(ctx, callback);
+            cq.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
             Native.grpcsharp_channel_watch_connectivity_state(this, lastObservedState, deadline, cq, ctx);
         }
 
diff --git a/src/csharp/Grpc.Core/Internal/ClientRequestStream.cs b/src/csharp/Grpc.Core/Internal/ClientRequestStream.cs
index 013f00ff6f..924de028f5 100644
--- a/src/csharp/Grpc.Core/Internal/ClientRequestStream.cs
+++ b/src/csharp/Grpc.Core/Internal/ClientRequestStream.cs
@@ -50,16 +50,12 @@ namespace Grpc.Core.Internal
 
         public Task WriteAsync(TRequest message)
         {
-            var taskSource = new AsyncCompletionTaskSource<object>();
-            call.StartSendMessage(message, GetWriteFlags(), taskSource.CompletionDelegate);
-            return taskSource.Task;
+            return call.SendMessageAsync(message, GetWriteFlags());
         }
 
         public Task CompleteAsync()
         {
-            var taskSource = new AsyncCompletionTaskSource<object>();
-            call.StartSendCloseFromClient(taskSource.CompletionDelegate);
-            return taskSource.Task;
+            return call.SendCloseFromClientAsync();
         }
 
         public WriteOptions WriteOptions
diff --git a/src/csharp/Grpc.Core/Internal/ClientSideStatus.cs b/src/csharp/Grpc.Core/Internal/ClientSideStatus.cs
new file mode 100644
index 0000000000..5727e3f11f
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/ClientSideStatus.cs
@@ -0,0 +1,70 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+// 
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using Grpc.Core;
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// Status + metadata received on client side when call finishes.
+    /// (when receive_status_on_client operation finishes).
+    /// </summary>
+    internal struct ClientSideStatus
+    {
+        readonly Status status;
+        readonly Metadata trailers;
+
+        public ClientSideStatus(Status status, Metadata trailers)
+        {
+            this.status = status;
+            this.trailers = trailers;
+        }
+
+        public Status Status
+        {
+            get
+            {
+                return this.status;
+            }
+        }
+
+        public Metadata Trailers
+        {
+            get
+            {
+                return this.trailers;
+            }
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core/Internal/ClockType.cs b/src/csharp/Grpc.Core/Internal/ClockType.cs
new file mode 100644
index 0000000000..57533c9d2f
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/ClockType.cs
@@ -0,0 +1,53 @@
+#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
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// gpr_clock_type from grpc/support/time.h
+    /// </summary>
+    internal enum ClockType
+    {
+        /* Monotonic clock */
+        Monotonic,
+
+        /* Realtime clock */
+        Realtime,
+
+        /* Precise clock good for performance profiling. */
+        Precise,
+
+        /* Timespan - the distance between two time points */
+        Timespan
+    }
+}
diff --git a/src/csharp/Grpc.Core/Internal/CompletionQueueEvent.cs b/src/csharp/Grpc.Core/Internal/CompletionQueueEvent.cs
index 288680792a..a78e9b70f3 100644
--- a/src/csharp/Grpc.Core/Internal/CompletionQueueEvent.cs
+++ b/src/csharp/Grpc.Core/Internal/CompletionQueueEvent.cs
@@ -44,7 +44,7 @@ namespace Grpc.Core.Internal
     {
         static readonly NativeMethods Native = NativeMethods.Get();
 
-        public GRPCCompletionType type;
+        public CompletionType type;
         public int success;
         public IntPtr tag;
 
@@ -55,5 +55,20 @@ namespace Grpc.Core.Internal
                 return Native.grpcsharp_sizeof_grpc_event();
             }
         }
+
+        /// <summary>
+        /// grpc_completion_type from grpc/grpc.h
+        /// </summary>
+        internal enum CompletionType
+        {
+            /* Shutting down */
+            Shutdown, 
+
+            /* No event before timeout */
+            Timeout,  
+
+            /* operation completion */
+            OpComplete
+        }
     }
 }
diff --git a/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
index 91364cdc70..46f5624223 100644
--- a/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
@@ -45,6 +45,7 @@ namespace Grpc.Core.Internal
         static readonly NativeMethods Native = NativeMethods.Get();
 
         AtomicCounter shutdownRefcount = new AtomicCounter(1);
+        CompletionRegistry completionRegistry;
 
         private CompletionQueueSafeHandle()
         {
@@ -53,7 +54,13 @@ namespace Grpc.Core.Internal
         public static CompletionQueueSafeHandle Create()
         {
             return Native.grpcsharp_completion_queue_create();
+        }
 
+        public static CompletionQueueSafeHandle Create(CompletionRegistry completionRegistry)
+        {
+            var cq = Native.grpcsharp_completion_queue_create();
+            cq.completionRegistry = completionRegistry;
+            return cq;
         }
 
         public CompletionQueueEvent Next()
@@ -83,6 +90,15 @@ namespace Grpc.Core.Internal
             DecrementShutdownRefcount();
         }
 
+        /// <summary>
+        /// Completion registry associated with this completion queue.
+        /// Doesn't need to be set if only using Pluck() operations.
+        /// </summary>
+        public CompletionRegistry CompletionRegistry
+        {
+            get { return completionRegistry; }
+        }
+
         protected override bool ReleaseHandle()
         {
             Native.grpcsharp_completion_queue_destroy(handle);
diff --git a/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs b/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
index 4b7124ee74..4de543bef7 100644
--- a/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
+++ b/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
@@ -33,15 +33,15 @@
 
 using System;
 using System.Collections.Generic;
-using System.Runtime.InteropServices;
+using System.Linq;
 using System.Threading;
-using System.Threading.Tasks;
 using Grpc.Core.Logging;
+using Grpc.Core.Utils;
 
 namespace Grpc.Core.Internal
 {
     /// <summary>
-    /// Pool of threads polling on the same completion queue.
+    /// Pool of threads polling on a set of completions queues.
     /// </summary>
     internal class GrpcThreadPool
     {
@@ -51,25 +51,31 @@ namespace Grpc.Core.Internal
         readonly object myLock = new object();
         readonly List<Thread> threads = new List<Thread>();
         readonly int poolSize;
+        readonly int completionQueueCount;
 
-        CompletionQueueSafeHandle cq;
+        IReadOnlyCollection<CompletionQueueSafeHandle> completionQueues;
 
-        public GrpcThreadPool(GrpcEnvironment environment, int poolSize)
+        /// <summary>
+        /// Creates a thread pool threads polling on a set of completions queues.
+        /// </summary>
+        /// <param name="environment">Environment.</param>
+        /// <param name="poolSize">Pool size.</param>
+        /// <param name="completionQueueCount">Completion queue count.</param>
+        public GrpcThreadPool(GrpcEnvironment environment, int poolSize, int completionQueueCount)
         {
             this.environment = environment;
             this.poolSize = poolSize;
+            this.completionQueueCount = completionQueueCount;
+            GrpcPreconditions.CheckArgument(poolSize >= completionQueueCount,
+                "Thread pool size cannot be smaller than the number of completion queues used.");
         }
 
         public void Start()
         {
             lock (myLock)
             {
-                if (cq != null)
-                {
-                    throw new InvalidOperationException("Already started.");
-                }
-
-                cq = CompletionQueueSafeHandle.Create();
+                GrpcPreconditions.CheckState(completionQueues == null, "Already started.");
+                completionQueues = CreateCompletionQueueList(environment, completionQueueCount);
 
                 for (int i = 0; i < poolSize; i++)
                 {
@@ -82,49 +88,60 @@ namespace Grpc.Core.Internal
         {
             lock (myLock)
             {
-                cq.Shutdown();
+                foreach (var cq in completionQueues)
+                {
+                    cq.Shutdown();
+                }
+
                 foreach (var thread in threads)
                 {
                     thread.Join();
                 }
 
-                cq.Dispose();
+                foreach (var cq in completionQueues)
+                {
+                    cq.Dispose();
+                }
             }
         }
 
-        internal CompletionQueueSafeHandle CompletionQueue
+        internal IReadOnlyCollection<CompletionQueueSafeHandle> CompletionQueues
         {
             get
             {
-                return cq;
+                return completionQueues;
             }
         }
 
-        private Thread CreateAndStartThread(int i)
+        private Thread CreateAndStartThread(int threadIndex)
         {
-            var thread = new Thread(new ThreadStart(RunHandlerLoop));
+            var cqIndex = threadIndex % completionQueues.Count;
+            var cq = completionQueues.ElementAt(cqIndex);
+
+            var thread = new Thread(new ThreadStart(() => RunHandlerLoop(cq)));
             thread.IsBackground = false;
+            thread.Name = string.Format("grpc {0} (cq {1})", threadIndex, cqIndex);
             thread.Start();
-            thread.Name = "grpc " + i;
+
             return thread;
         }
 
         /// <summary>
         /// Body of the polling thread.
         /// </summary>
-        private void RunHandlerLoop()
+        private void RunHandlerLoop(CompletionQueueSafeHandle cq)
         {
             CompletionQueueEvent ev;
             do
             {
                 ev = cq.Next();
-                if (ev.type == GRPCCompletionType.OpComplete)
+                if (ev.type == CompletionQueueEvent.CompletionType.OpComplete)
                 {
                     bool success = (ev.success != 0);
                     IntPtr tag = ev.tag;
                     try
                     {
-                        var callback = environment.CompletionRegistry.Extract(tag);
+                        var callback = cq.CompletionRegistry.Extract(tag);
                         callback(success);
                     }
                     catch (Exception e)
@@ -133,7 +150,18 @@ namespace Grpc.Core.Internal
                     }
                 }
             }
-            while (ev.type != GRPCCompletionType.Shutdown);
+            while (ev.type != CompletionQueueEvent.CompletionType.Shutdown);
+        }
+
+        private static IReadOnlyCollection<CompletionQueueSafeHandle> CreateCompletionQueueList(GrpcEnvironment environment, int completionQueueCount)
+        {
+            var list = new List<CompletionQueueSafeHandle>();
+            for (int i = 0; i < completionQueueCount; i++)
+            {
+                var completionRegistry = new CompletionRegistry(environment);
+                list.Add(CompletionQueueSafeHandle.Create(completionRegistry));
+            }
+            return list.AsReadOnly();
         }
     }
 }
diff --git a/src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs b/src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs
index 25735d5262..dc9f62fdab 100644
--- a/src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs
@@ -50,6 +50,11 @@ namespace Grpc.Core.Internal
         {
             using (Profilers.ForCurrentThread().NewScope("MetadataArraySafeHandle.Create"))
             {
+                if (metadata.Count == 0)
+                {
+                    return new MetadataArraySafeHandle();
+                }
+
                 // TODO(jtattermusch): we might wanna check that the metadata is readonly 
                 var metadataArray = Native.grpcsharp_metadata_array_create(new UIntPtr((ulong)metadata.Count));
                 for (int i = 0; i < metadata.Count; i++)
diff --git a/src/csharp/Grpc.Core/Internal/NativeMethods.cs b/src/csharp/Grpc.Core/Internal/NativeMethods.cs
index c277c73ef0..65607ed120 100644
--- a/src/csharp/Grpc.Core/Internal/NativeMethods.cs
+++ b/src/csharp/Grpc.Core/Internal/NativeMethods.cs
@@ -137,6 +137,7 @@ namespace Grpc.Core.Internal
         public readonly Delegates.grpcsharp_server_credentials_release_delegate grpcsharp_server_credentials_release;
 
         public readonly Delegates.grpcsharp_server_create_delegate grpcsharp_server_create;
+        public readonly Delegates.grpcsharp_server_register_completion_queue_delegate grpcsharp_server_register_completion_queue;
         public readonly Delegates.grpcsharp_server_add_insecure_http2_port_delegate grpcsharp_server_add_insecure_http2_port;
         public readonly Delegates.grpcsharp_server_add_secure_http2_port_delegate grpcsharp_server_add_secure_http2_port;
         public readonly Delegates.grpcsharp_server_start_delegate grpcsharp_server_start;
@@ -244,6 +245,7 @@ namespace Grpc.Core.Internal
                 this.grpcsharp_server_credentials_release = GetMethodDelegate<Delegates.grpcsharp_server_credentials_release_delegate>(library);
 
                 this.grpcsharp_server_create = GetMethodDelegate<Delegates.grpcsharp_server_create_delegate>(library);
+                this.grpcsharp_server_register_completion_queue = GetMethodDelegate<Delegates.grpcsharp_server_register_completion_queue_delegate>(library);
                 this.grpcsharp_server_add_insecure_http2_port = GetMethodDelegate<Delegates.grpcsharp_server_add_insecure_http2_port_delegate>(library);
                 this.grpcsharp_server_add_secure_http2_port = GetMethodDelegate<Delegates.grpcsharp_server_add_secure_http2_port_delegate>(library);
                 this.grpcsharp_server_start = GetMethodDelegate<Delegates.grpcsharp_server_start_delegate>(library);
@@ -348,6 +350,7 @@ namespace Grpc.Core.Internal
                 this.grpcsharp_server_credentials_release = PInvokeMethods.grpcsharp_server_credentials_release;
 
                 this.grpcsharp_server_create = PInvokeMethods.grpcsharp_server_create;
+                this.grpcsharp_server_register_completion_queue = PInvokeMethods.grpcsharp_server_register_completion_queue;
                 this.grpcsharp_server_add_insecure_http2_port = PInvokeMethods.grpcsharp_server_add_insecure_http2_port;
                 this.grpcsharp_server_add_secure_http2_port = PInvokeMethods.grpcsharp_server_add_secure_http2_port;
                 this.grpcsharp_server_start = PInvokeMethods.grpcsharp_server_start;
@@ -418,33 +421,33 @@ namespace Grpc.Core.Internal
             public delegate CallCredentialsSafeHandle grpcsharp_composite_call_credentials_create_delegate(CallCredentialsSafeHandle creds1, CallCredentialsSafeHandle creds2);
             public delegate void grpcsharp_call_credentials_release_delegate(IntPtr credentials);
 
-            public delegate GRPCCallError grpcsharp_call_cancel_delegate(CallSafeHandle call);
-            public delegate GRPCCallError grpcsharp_call_cancel_with_status_delegate(CallSafeHandle call, StatusCode status, string description);
-            public delegate GRPCCallError grpcsharp_call_start_unary_delegate(CallSafeHandle call,
+            public delegate CallError grpcsharp_call_cancel_delegate(CallSafeHandle call);
+            public delegate CallError grpcsharp_call_cancel_with_status_delegate(CallSafeHandle call, StatusCode status, string description);
+            public delegate CallError grpcsharp_call_start_unary_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx, byte[] sendBuffer, UIntPtr sendBufferLen, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags);
-            public delegate GRPCCallError grpcsharp_call_start_client_streaming_delegate(CallSafeHandle call,
+            public delegate CallError grpcsharp_call_start_client_streaming_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx, MetadataArraySafeHandle metadataArray);
-            public delegate GRPCCallError grpcsharp_call_start_server_streaming_delegate(CallSafeHandle call,
+            public delegate CallError grpcsharp_call_start_server_streaming_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx, byte[] sendBuffer, UIntPtr sendBufferLen,
                 MetadataArraySafeHandle metadataArray, WriteFlags writeFlags);
-            public delegate GRPCCallError grpcsharp_call_start_duplex_streaming_delegate(CallSafeHandle call,
+            public delegate CallError grpcsharp_call_start_duplex_streaming_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx, MetadataArraySafeHandle metadataArray);
-            public delegate GRPCCallError grpcsharp_call_send_message_delegate(CallSafeHandle call,
+            public delegate CallError grpcsharp_call_send_message_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx, byte[] sendBuffer, UIntPtr sendBufferLen, WriteFlags writeFlags, bool sendEmptyInitialMetadata);
-            public delegate GRPCCallError grpcsharp_call_send_close_from_client_delegate(CallSafeHandle call,
+            public delegate CallError grpcsharp_call_send_close_from_client_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx);
-            public delegate GRPCCallError grpcsharp_call_send_status_from_server_delegate(CallSafeHandle call,
+            public delegate CallError grpcsharp_call_send_status_from_server_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx, StatusCode statusCode, string statusMessage, MetadataArraySafeHandle metadataArray, bool sendEmptyInitialMetadata,
                 byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags);
-            public delegate GRPCCallError grpcsharp_call_recv_message_delegate(CallSafeHandle call,
+            public delegate CallError grpcsharp_call_recv_message_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx);
-            public delegate GRPCCallError grpcsharp_call_recv_initial_metadata_delegate(CallSafeHandle call,
+            public delegate CallError grpcsharp_call_recv_initial_metadata_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx);
-            public delegate GRPCCallError grpcsharp_call_start_serverside_delegate(CallSafeHandle call,
+            public delegate CallError grpcsharp_call_start_serverside_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx);
-            public delegate GRPCCallError grpcsharp_call_send_initial_metadata_delegate(CallSafeHandle call,
+            public delegate CallError grpcsharp_call_send_initial_metadata_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx, MetadataArraySafeHandle metadataArray);
-            public delegate GRPCCallError grpcsharp_call_set_credentials_delegate(CallSafeHandle call, CallCredentialsSafeHandle credentials);
+            public delegate CallError grpcsharp_call_set_credentials_delegate(CallSafeHandle call, CallCredentialsSafeHandle credentials);
             public delegate CStringSafeHandle grpcsharp_call_get_peer_delegate(CallSafeHandle call);
             public delegate void grpcsharp_call_destroy_delegate(IntPtr call);
 
@@ -493,23 +496,24 @@ namespace Grpc.Core.Internal
             public delegate ServerCredentialsSafeHandle grpcsharp_ssl_server_credentials_create_delegate(string pemRootCerts, string[] keyCertPairCertChainArray, string[] keyCertPairPrivateKeyArray, UIntPtr numKeyCertPairs, bool forceClientAuth);
             public delegate void grpcsharp_server_credentials_release_delegate(IntPtr credentials);
 
-            public delegate ServerSafeHandle grpcsharp_server_create_delegate(CompletionQueueSafeHandle cq, ChannelArgsSafeHandle args);
+            public delegate ServerSafeHandle grpcsharp_server_create_delegate(ChannelArgsSafeHandle args);
+            public delegate void grpcsharp_server_register_completion_queue_delegate(ServerSafeHandle server, CompletionQueueSafeHandle cq);
             public delegate int grpcsharp_server_add_insecure_http2_port_delegate(ServerSafeHandle server, string addr);
             public delegate int grpcsharp_server_add_secure_http2_port_delegate(ServerSafeHandle server, string addr, ServerCredentialsSafeHandle creds);
             public delegate void grpcsharp_server_start_delegate(ServerSafeHandle server);
-            public delegate GRPCCallError grpcsharp_server_request_call_delegate(ServerSafeHandle server, CompletionQueueSafeHandle cq, BatchContextSafeHandle ctx);
+            public delegate CallError grpcsharp_server_request_call_delegate(ServerSafeHandle server, CompletionQueueSafeHandle cq, BatchContextSafeHandle ctx);
             public delegate void grpcsharp_server_cancel_all_calls_delegate(ServerSafeHandle server);
             public delegate void grpcsharp_server_shutdown_and_notify_callback_delegate(ServerSafeHandle server, CompletionQueueSafeHandle cq, BatchContextSafeHandle ctx);
             public delegate void grpcsharp_server_destroy_delegate(IntPtr server);
 
-            public delegate Timespec gprsharp_now_delegate(GPRClockType clockType);
-            public delegate Timespec gprsharp_inf_future_delegate(GPRClockType clockType);
-            public delegate Timespec gprsharp_inf_past_delegate(GPRClockType clockType);
+            public delegate Timespec gprsharp_now_delegate(ClockType clockType);
+            public delegate Timespec gprsharp_inf_future_delegate(ClockType clockType);
+            public delegate Timespec gprsharp_inf_past_delegate(ClockType clockType);
 
-            public delegate Timespec gprsharp_convert_clock_type_delegate(Timespec t, GPRClockType targetClock);
+            public delegate Timespec gprsharp_convert_clock_type_delegate(Timespec t, ClockType targetClock);
             public delegate int gprsharp_sizeof_timespec_delegate();
 
-            public delegate GRPCCallError grpcsharp_test_callback_delegate([MarshalAs(UnmanagedType.FunctionPtr)] OpCompletionDelegate callback);
+            public delegate CallError grpcsharp_test_callback_delegate([MarshalAs(UnmanagedType.FunctionPtr)] OpCompletionDelegate callback);
             public delegate IntPtr grpcsharp_test_nop_delegate(IntPtr ptr);
         }
 
@@ -587,59 +591,59 @@ namespace Grpc.Core.Internal
             // CallSafeHandle
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_cancel(CallSafeHandle call);
+            public static extern CallError grpcsharp_call_cancel(CallSafeHandle call);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_cancel_with_status(CallSafeHandle call, StatusCode status, string description);
+            public static extern CallError grpcsharp_call_cancel_with_status(CallSafeHandle call, StatusCode status, string description);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_start_unary(CallSafeHandle call,
+            public static extern CallError grpcsharp_call_start_unary(CallSafeHandle call,
                 BatchContextSafeHandle ctx, byte[] sendBuffer, UIntPtr sendBufferLen, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_start_client_streaming(CallSafeHandle call,
+            public static extern CallError grpcsharp_call_start_client_streaming(CallSafeHandle call,
                 BatchContextSafeHandle ctx, MetadataArraySafeHandle metadataArray);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_start_server_streaming(CallSafeHandle call,
+            public static extern CallError grpcsharp_call_start_server_streaming(CallSafeHandle call,
                 BatchContextSafeHandle ctx, byte[] sendBuffer, UIntPtr sendBufferLen,
                 MetadataArraySafeHandle metadataArray, WriteFlags writeFlags);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_start_duplex_streaming(CallSafeHandle call,
+            public static extern CallError grpcsharp_call_start_duplex_streaming(CallSafeHandle call,
                 BatchContextSafeHandle ctx, MetadataArraySafeHandle metadataArray);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_send_message(CallSafeHandle call,
+            public static extern CallError grpcsharp_call_send_message(CallSafeHandle call,
                 BatchContextSafeHandle ctx, byte[] sendBuffer, UIntPtr sendBufferLen, WriteFlags writeFlags, bool sendEmptyInitialMetadata);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_send_close_from_client(CallSafeHandle call,
+            public static extern CallError grpcsharp_call_send_close_from_client(CallSafeHandle call,
                 BatchContextSafeHandle ctx);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_send_status_from_server(CallSafeHandle call,
+            public static extern CallError grpcsharp_call_send_status_from_server(CallSafeHandle call,
                 BatchContextSafeHandle ctx, StatusCode statusCode, string statusMessage, MetadataArraySafeHandle metadataArray, bool sendEmptyInitialMetadata,
                 byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_recv_message(CallSafeHandle call,
+            public static extern CallError grpcsharp_call_recv_message(CallSafeHandle call,
                 BatchContextSafeHandle ctx);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_recv_initial_metadata(CallSafeHandle call,
+            public static extern CallError grpcsharp_call_recv_initial_metadata(CallSafeHandle call,
                 BatchContextSafeHandle ctx);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_start_serverside(CallSafeHandle call,
+            public static extern CallError grpcsharp_call_start_serverside(CallSafeHandle call,
                 BatchContextSafeHandle ctx);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_send_initial_metadata(CallSafeHandle call,
+            public static extern CallError grpcsharp_call_send_initial_metadata(CallSafeHandle call,
                 BatchContextSafeHandle ctx, MetadataArraySafeHandle metadataArray);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_call_set_credentials(CallSafeHandle call, CallCredentialsSafeHandle credentials);
+            public static extern CallError grpcsharp_call_set_credentials(CallSafeHandle call, CallCredentialsSafeHandle credentials);
 
             [DllImport("grpc_csharp_ext.dll")]
             public static extern CStringSafeHandle grpcsharp_call_get_peer(CallSafeHandle call);
@@ -773,7 +777,10 @@ namespace Grpc.Core.Internal
             // ServerSafeHandle
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern ServerSafeHandle grpcsharp_server_create(CompletionQueueSafeHandle cq, ChannelArgsSafeHandle args);
+            public static extern ServerSafeHandle grpcsharp_server_create(ChannelArgsSafeHandle args);
+
+            [DllImport("grpc_csharp_ext.dll")]
+            public static extern void grpcsharp_server_register_completion_queue(ServerSafeHandle server, CompletionQueueSafeHandle cq);
 
             [DllImport("grpc_csharp_ext.dll")]
             public static extern int grpcsharp_server_add_insecure_http2_port(ServerSafeHandle server, string addr);
@@ -785,7 +792,7 @@ namespace Grpc.Core.Internal
             public static extern void grpcsharp_server_start(ServerSafeHandle server);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_server_request_call(ServerSafeHandle server, CompletionQueueSafeHandle cq, BatchContextSafeHandle ctx);
+            public static extern CallError grpcsharp_server_request_call(ServerSafeHandle server, CompletionQueueSafeHandle cq, BatchContextSafeHandle ctx);
 
             [DllImport("grpc_csharp_ext.dll")]
             public static extern void grpcsharp_server_cancel_all_calls(ServerSafeHandle server);
@@ -799,16 +806,16 @@ namespace Grpc.Core.Internal
             // Timespec
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern Timespec gprsharp_now(GPRClockType clockType);
+            public static extern Timespec gprsharp_now(ClockType clockType);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern Timespec gprsharp_inf_future(GPRClockType clockType);
+            public static extern Timespec gprsharp_inf_future(ClockType clockType);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern Timespec gprsharp_inf_past(GPRClockType clockType);
+            public static extern Timespec gprsharp_inf_past(ClockType clockType);
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern Timespec gprsharp_convert_clock_type(Timespec t, GPRClockType targetClock);
+            public static extern Timespec gprsharp_convert_clock_type(Timespec t, ClockType targetClock);
 
             [DllImport("grpc_csharp_ext.dll")]
             public static extern int gprsharp_sizeof_timespec();
@@ -816,7 +823,7 @@ namespace Grpc.Core.Internal
             // Testing
 
             [DllImport("grpc_csharp_ext.dll")]
-            public static extern GRPCCallError grpcsharp_test_callback([MarshalAs(UnmanagedType.FunctionPtr)] OpCompletionDelegate callback);
+            public static extern CallError grpcsharp_test_callback([MarshalAs(UnmanagedType.FunctionPtr)] OpCompletionDelegate callback);
 
             [DllImport("grpc_csharp_ext.dll")]
             public static extern IntPtr grpcsharp_test_nop(IntPtr ptr);
diff --git a/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs b/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
index 85b7a4b01e..6a2f520163 100644
--- a/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
@@ -44,7 +44,7 @@ namespace Grpc.Core.Internal
 {
     internal interface IServerCallHandler
     {
-        Task HandleCall(ServerRpcNew newRpc, GrpcEnvironment environment);
+        Task HandleCall(ServerRpcNew newRpc, CompletionQueueSafeHandle cq);
     }
 
     internal class UnaryServerCallHandler<TRequest, TResponse> : IServerCallHandler
@@ -62,14 +62,14 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(ServerRpcNew newRpc, GrpcEnvironment environment)
+        public async Task HandleCall(ServerRpcNew newRpc, CompletionQueueSafeHandle cq)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
                 method.RequestMarshaller.Deserializer,
-                environment, newRpc.Server);
+                newRpc.Server);
 
-            asyncCall.Initialize(newRpc.Call);
+            asyncCall.Initialize(newRpc.Call, cq);
             var finishedTask = asyncCall.ServerSideCallAsync();
             var requestStream = new ServerRequestStream<TRequest, TResponse>(asyncCall);
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
@@ -121,14 +121,14 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(ServerRpcNew newRpc, GrpcEnvironment environment)
+        public async Task HandleCall(ServerRpcNew newRpc, CompletionQueueSafeHandle cq)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
                 method.RequestMarshaller.Deserializer,
-                environment, newRpc.Server);
+                newRpc.Server);
 
-            asyncCall.Initialize(newRpc.Call);
+            asyncCall.Initialize(newRpc.Call, cq);
             var finishedTask = asyncCall.ServerSideCallAsync();
             var requestStream = new ServerRequestStream<TRequest, TResponse>(asyncCall);
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
@@ -179,14 +179,14 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(ServerRpcNew newRpc, GrpcEnvironment environment)
+        public async Task HandleCall(ServerRpcNew newRpc, CompletionQueueSafeHandle cq)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
                 method.RequestMarshaller.Deserializer,
-                environment, newRpc.Server);
+                newRpc.Server);
 
-            asyncCall.Initialize(newRpc.Call);
+            asyncCall.Initialize(newRpc.Call, cq);
             var finishedTask = asyncCall.ServerSideCallAsync();
             var requestStream = new ServerRequestStream<TRequest, TResponse>(asyncCall);
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
@@ -237,14 +237,14 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(ServerRpcNew newRpc, GrpcEnvironment environment)
+        public async Task HandleCall(ServerRpcNew newRpc, CompletionQueueSafeHandle cq)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
                 method.RequestMarshaller.Deserializer,
-                environment, newRpc.Server);
+                newRpc.Server);
 
-            asyncCall.Initialize(newRpc.Call);
+            asyncCall.Initialize(newRpc.Call, cq);
             var finishedTask = asyncCall.ServerSideCallAsync();
             var requestStream = new ServerRequestStream<TRequest, TResponse>(asyncCall);
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
@@ -281,13 +281,13 @@ namespace Grpc.Core.Internal
     {
         public static readonly NoSuchMethodCallHandler Instance = new NoSuchMethodCallHandler();
 
-        public async Task HandleCall(ServerRpcNew newRpc, GrpcEnvironment environment)
+        public async Task HandleCall(ServerRpcNew newRpc, CompletionQueueSafeHandle cq)
         {
             // We don't care about the payload type here.
             var asyncCall = new AsyncCallServer<byte[], byte[]>(
-                (payload) => payload, (payload) => payload, environment, newRpc.Server);
+                (payload) => payload, (payload) => payload, newRpc.Server);
             
-            asyncCall.Initialize(newRpc.Call);
+            asyncCall.Initialize(newRpc.Call, cq);
             var finishedTask = asyncCall.ServerSideCallAsync();
             await asyncCall.SendStatusFromServerAsync(new Status(StatusCode.Unimplemented, ""), Metadata.Empty, null).ConfigureAwait(false);
             await finishedTask.ConfigureAwait(false);
@@ -317,7 +317,7 @@ namespace Grpc.Core.Internal
             where TRequest : class
             where TResponse : class
         {
-            DateTime realtimeDeadline = newRpc.Deadline.ToClockType(GPRClockType.Realtime).ToDateTime();
+            DateTime realtimeDeadline = newRpc.Deadline.ToClockType(ClockType.Realtime).ToDateTime();
 
             return new ServerCallContext(newRpc.Call, newRpc.Method, newRpc.Host, peer, realtimeDeadline,
                 newRpc.RequestMetadata, cancellationToken, serverResponseStream.WriteResponseHeadersAsync, serverResponseStream);
diff --git a/src/csharp/Grpc.Core/Internal/ServerResponseStream.cs b/src/csharp/Grpc.Core/Internal/ServerResponseStream.cs
index ecfee0bfdd..25b79b4398 100644
--- a/src/csharp/Grpc.Core/Internal/ServerResponseStream.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerResponseStream.cs
@@ -52,16 +52,12 @@ namespace Grpc.Core.Internal
 
         public Task WriteAsync(TResponse message)
         {
-            var taskSource = new AsyncCompletionTaskSource<object>();
-            call.StartSendMessage(message, GetWriteFlags(), taskSource.CompletionDelegate);
-            return taskSource.Task;
+            return call.SendMessageAsync(message, GetWriteFlags());
         }
 
         public Task WriteResponseHeadersAsync(Metadata responseHeaders)
         {
-            var taskSource = new AsyncCompletionTaskSource<object>();
-            call.StartSendInitialMetadata(responseHeaders, taskSource.CompletionDelegate);
-            return taskSource.Task;
+            return call.SendInitialMetadataAsync(responseHeaders);
         }
 
         public WriteOptions WriteOptions
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCompletion.cs b/src/csharp/Grpc.Core/Internal/ServerRpcNew.cs
index 7e86fddb4d..e4f1880bdb 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCompletion.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerRpcNew.cs
@@ -32,63 +32,78 @@
 #endregion
 
 using System;
-using System.Diagnostics;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-using System.Threading;
-using System.Threading.Tasks;
-using Grpc.Core.Internal;
-using Grpc.Core.Utils;
+using Grpc.Core;
 
 namespace Grpc.Core.Internal
 {
     /// <summary>
-    /// If error != null, there's been an error or operation has been cancelled.
+    /// Details of a newly received RPC.
     /// </summary>
-    internal delegate void AsyncCompletionDelegate<T>(T result, Exception error);
-
-    /// <summary>
-    /// Helper for transforming AsyncCompletionDelegate into full-fledged Task.
-    /// </summary>
-    internal class AsyncCompletionTaskSource<T>
+    internal struct ServerRpcNew
     {
-        readonly TaskCompletionSource<T> tcs = new TaskCompletionSource<T>();
-        readonly AsyncCompletionDelegate<T> completionDelegate;
+        readonly Server server;
+        readonly CallSafeHandle call;
+        readonly string method;
+        readonly string host;
+        readonly Timespec deadline;
+        readonly Metadata requestMetadata;
+
+        public ServerRpcNew(Server server, CallSafeHandle call, string method, string host, Timespec deadline, Metadata requestMetadata)
+        {
+            this.server = server;
+            this.call = call;
+            this.method = method;
+            this.host = host;
+            this.deadline = deadline;
+            this.requestMetadata = requestMetadata;
+        }
+
+        public Server Server
+        {
+            get
+            {
+                return this.server;
+            }
+        }
 
-        public AsyncCompletionTaskSource()
+        public CallSafeHandle Call
         {
-            completionDelegate = new AsyncCompletionDelegate<T>(HandleCompletion);
+            get
+            {
+                return this.call;
+            }
         }
 
-        public Task<T> Task
+        public string Method
         {
             get
             {
-                return tcs.Task;
+                return this.method;
             }
         }
 
-        public AsyncCompletionDelegate<T> CompletionDelegate
+        public string Host
         {
             get
             {
-                return completionDelegate;
+                return this.host;
             }
         }
 
-        private void HandleCompletion(T value, Exception error)
+        public Timespec Deadline
         {
-            if (error == null)
+            get
             {
-                tcs.SetResult(value);
-                return;
+                return this.deadline;
             }
-            if (error is OperationCanceledException)
+        }
+
+        public Metadata RequestMetadata
+        {
+            get
             {
-                tcs.SetCanceled();
-                return;
+                return this.requestMetadata;
             }
-            tcs.SetException(error);
         }
     }
 }
diff --git a/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs b/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs
index 6b5f70e220..8581302706 100644
--- a/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs
@@ -31,12 +31,6 @@
 
 #endregion
 
-using System;
-using System.Collections.Concurrent;
-using System.Diagnostics;
-using System.Runtime.InteropServices;
-using Grpc.Core.Utils;
-
 namespace Grpc.Core.Internal
 {
     /// <summary>
@@ -50,12 +44,17 @@ namespace Grpc.Core.Internal
         {
         }
 
-        public static ServerSafeHandle NewServer(CompletionQueueSafeHandle cq, ChannelArgsSafeHandle args)
+        public static ServerSafeHandle NewServer(ChannelArgsSafeHandle args)
         {
             // Increment reference count for the native gRPC environment to make sure we don't do grpc_shutdown() before destroying the server handle.
             // Doing so would make object finalizer crash if we end up abandoning the handle.
             GrpcEnvironment.GrpcNativeInit();
-            return Native.grpcsharp_server_create(cq, args);
+            return Native.grpcsharp_server_create(args);
+        }
+
+        public void RegisterCompletionQueue(CompletionQueueSafeHandle cq)
+        {
+            Native.grpcsharp_server_register_completion_queue(this, cq);
         }
 
         public int AddInsecurePort(string addr)
@@ -73,18 +72,18 @@ namespace Grpc.Core.Internal
             Native.grpcsharp_server_start(this);
         }
     
-        public void ShutdownAndNotify(BatchCompletionDelegate callback, GrpcEnvironment environment)
+        public void ShutdownAndNotify(BatchCompletionDelegate callback, CompletionQueueSafeHandle completionQueue)
         {
             var ctx = BatchContextSafeHandle.Create();
-            environment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
-            Native.grpcsharp_server_shutdown_and_notify_callback(this, environment.CompletionQueue, ctx);
+            completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            Native.grpcsharp_server_shutdown_and_notify_callback(this, completionQueue, ctx);
         }
 
-        public void RequestCall(BatchCompletionDelegate callback, GrpcEnvironment environment)
+        public void RequestCall(BatchCompletionDelegate callback, CompletionQueueSafeHandle completionQueue)
         {
             var ctx = BatchContextSafeHandle.Create();
-            environment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
-            Native.grpcsharp_server_request_call(this, environment.CompletionQueue, ctx).CheckOk();
+            completionQueue.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            Native.grpcsharp_server_request_call(this, completionQueue, ctx).CheckOk();
         }
 
         protected override bool ReleaseHandle()
diff --git a/src/csharp/Grpc.Core/Internal/Timespec.cs b/src/csharp/Grpc.Core/Internal/Timespec.cs
index 56172a5dda..c9fd710e1e 100644
--- a/src/csharp/Grpc.Core/Internal/Timespec.cs
+++ b/src/csharp/Grpc.Core/Internal/Timespec.cs
@@ -49,11 +49,11 @@ namespace Grpc.Core.Internal
         static readonly NativeMethods Native = NativeMethods.Get();
         static readonly DateTime UnixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
 
-        public Timespec(long tv_sec, int tv_nsec) : this(tv_sec, tv_nsec, GPRClockType.Realtime)
+        public Timespec(long tv_sec, int tv_nsec) : this(tv_sec, tv_nsec, ClockType.Realtime)
         {
         }
 
-        public Timespec(long tv_sec, int tv_nsec, GPRClockType clock_type)
+        public Timespec(long tv_sec, int tv_nsec, ClockType clock_type)
         {
             this.tv_sec = tv_sec;
             this.tv_nsec = tv_nsec;
@@ -62,7 +62,7 @@ namespace Grpc.Core.Internal
 
         private long tv_sec;
         private int tv_nsec;
-        private GPRClockType clock_type;
+        private ClockType clock_type;
 
         /// <summary>
         /// Timespec a long time in the future.
@@ -71,7 +71,7 @@ namespace Grpc.Core.Internal
         {
             get
             {
-                return Native.gprsharp_inf_future(GPRClockType.Realtime);
+                return new Timespec(long.MaxValue, 0, ClockType.Realtime);
             }
         }
 
@@ -82,7 +82,7 @@ namespace Grpc.Core.Internal
         {
             get
             {
-                return Native.gprsharp_inf_past(GPRClockType.Realtime);
+                return new Timespec(long.MinValue, 0, ClockType.Realtime);
             }
         }
 
@@ -93,7 +93,7 @@ namespace Grpc.Core.Internal
         {
             get
             {
-                return Native.gprsharp_now(GPRClockType.Realtime);
+                return Native.gprsharp_now(ClockType.Realtime);
             }
         }
 
@@ -122,7 +122,7 @@ namespace Grpc.Core.Internal
         /// <summary>
         /// Converts the timespec to desired clock type.
         /// </summary>
-        public Timespec ToClockType(GPRClockType targetClock)
+        public Timespec ToClockType(ClockType targetClock)
         {
             return Native.gprsharp_convert_clock_type(this, targetClock);
         }
@@ -142,7 +142,7 @@ namespace Grpc.Core.Internal
         public DateTime ToDateTime()
         {
             GrpcPreconditions.CheckState(tv_nsec >= 0 && tv_nsec < NanosPerSecond);
-            GrpcPreconditions.CheckState(clock_type == GPRClockType.Realtime);
+            GrpcPreconditions.CheckState(clock_type == ClockType.Realtime);
 
             // fast path for InfFuture
             if (this.Equals(InfFuture))
@@ -227,10 +227,11 @@ namespace Grpc.Core.Internal
         {
             get
             {
-                return Native.gprsharp_now(GPRClockType.Precise);
+                return Native.gprsharp_now(ClockType.Precise);
             }
         }
 
+        // for tests only
         internal static int NativeSize
         {
             get
@@ -238,5 +239,23 @@ namespace Grpc.Core.Internal
                 return Native.gprsharp_sizeof_timespec();
             }
         }
+
+        // for tests only
+        internal static Timespec NativeInfFuture
+        {
+            get
+            {
+                return Native.gprsharp_inf_future(ClockType.Realtime);
+            }
+        }
+
+        // for tests only
+        public static Timespec NativeInfPast
+        {
+            get
+            {
+                return Native.gprsharp_inf_past(ClockType.Realtime);
+            }
+        }
     }
 }
diff --git a/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs b/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs
index bde74945fb..370fa98687 100644
--- a/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs
+++ b/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs
@@ -16,6 +16,12 @@ using System.Runtime.CompilerServices;
     "0442bb8e12768722de0b0cb1b15e955b32a11352740ee59f2c94c48edc8e177d1052536b8ac651bce11ce5da3a" +
     "27fc95aff3dc604a6971417453f9483c7b5e836756d5b271bf8f2403fe186e31956148c03d804487cf642f8cc0" +
     "71394ee9672dfe5b55ea0f95dfd5a7f77d22c962ccf51320d3")]
+[assembly: InternalsVisibleTo("Grpc.IntegrationTesting,PublicKey=" +
+    "00240000048000009400000006020000002400005253413100040000010001002f5797a92c6fcde81bd4098f43" +
+    "0442bb8e12768722de0b0cb1b15e955b32a11352740ee59f2c94c48edc8e177d1052536b8ac651bce11ce5da3a" +
+    "27fc95aff3dc604a6971417453f9483c7b5e836756d5b271bf8f2403fe186e31956148c03d804487cf642f8cc0" +
+    "71394ee9672dfe5b55ea0f95dfd5a7f77d22c962ccf51320d3")]
 #else
 [assembly: InternalsVisibleTo("Grpc.Core.Tests")]
+[assembly: InternalsVisibleTo("Grpc.IntegrationTesting")]
 #endif
diff --git a/src/csharp/Grpc.Core/Server.cs b/src/csharp/Grpc.Core/Server.cs
index d538a4671f..069185e13a 100644
--- a/src/csharp/Grpc.Core/Server.cs
+++ b/src/csharp/Grpc.Core/Server.cs
@@ -34,8 +34,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.Diagnostics;
-using System.Runtime.InteropServices;
+using System.Linq;
 using System.Threading.Tasks;
 using Grpc.Core.Internal;
 using Grpc.Core.Logging;
@@ -48,7 +47,7 @@ namespace Grpc.Core
     /// </summary>
     public class Server
     {
-        const int InitialAllowRpcTokenCount = 10;
+        const int InitialAllowRpcTokenCountPerCq = 10;
         static readonly ILogger Logger = GrpcEnvironment.Logger.ForType<Server>();
 
         readonly AtomicCounter activeCallCounter = new AtomicCounter();
@@ -80,7 +79,12 @@ namespace Grpc.Core
             this.options = options != null ? new List<ChannelOption>(options) : new List<ChannelOption>();
             using (var channelArgs = ChannelOptions.CreateChannelArgs(this.options))
             {
-                this.handle = ServerSafeHandle.NewServer(environment.CompletionQueue, channelArgs);
+                this.handle = ServerSafeHandle.NewServer(channelArgs);
+            }
+
+            foreach (var cq in environment.CompletionQueues)
+            {
+                this.handle.RegisterCompletionQueue(cq);
             }
         }
 
@@ -133,9 +137,12 @@ namespace Grpc.Core
 
                 // Starting with more than one AllowOneRpc tokens can significantly increase
                 // unary RPC throughput.
-                for (int i = 0; i < InitialAllowRpcTokenCount; i++)
+                for (int i = 0; i < InitialAllowRpcTokenCountPerCq; i++)
                 {
-                    AllowOneRpc();
+                    foreach (var cq in environment.CompletionQueues)
+                    {
+                        AllowOneRpc(cq);
+                    }
                 }
             }
         }
@@ -154,7 +161,8 @@ namespace Grpc.Core
                 shutdownRequested = true;
             }
 
-            handle.ShutdownAndNotify(HandleServerShutdown, environment);
+            var cq = environment.CompletionQueues.First();  // any cq will do
+            handle.ShutdownAndNotify(HandleServerShutdown, cq);
             await shutdownTcs.Task.ConfigureAwait(false);
             DisposeHandle();
 
@@ -174,7 +182,8 @@ namespace Grpc.Core
                 shutdownRequested = true;
             }
 
-            handle.ShutdownAndNotify(HandleServerShutdown, environment);
+            var cq = environment.CompletionQueues.First();  // any cq will do
+            handle.ShutdownAndNotify(HandleServerShutdown, cq);
             handle.CancelAllCalls();
             await shutdownTcs.Task.ConfigureAwait(false);
             DisposeHandle();
@@ -244,11 +253,11 @@ namespace Grpc.Core
         /// <summary>
         /// Allows one new RPC call to be received by server.
         /// </summary>
-        private void AllowOneRpc()
+        private void AllowOneRpc(CompletionQueueSafeHandle cq)
         {
             if (!shutdownRequested)
             {
-                handle.RequestCall(HandleNewServerRpc, environment);
+                handle.RequestCall((success, ctx) => HandleNewServerRpc(success, ctx, cq), cq);
             }
         }
 
@@ -265,7 +274,7 @@ namespace Grpc.Core
         /// <summary>
         /// Selects corresponding handler for given call and handles the call.
         /// </summary>
-        private async Task HandleCallAsync(ServerRpcNew newRpc)
+        private async Task HandleCallAsync(ServerRpcNew newRpc, CompletionQueueSafeHandle cq)
         {
             try
             {
@@ -274,7 +283,7 @@ namespace Grpc.Core
                 {
                     callHandler = NoSuchMethodCallHandler.Instance;
                 }
-                await callHandler.HandleCall(newRpc, environment).ConfigureAwait(false);
+                await callHandler.HandleCall(newRpc, cq).ConfigureAwait(false);
             }
             catch (Exception e)
             {
@@ -285,9 +294,9 @@ namespace Grpc.Core
         /// <summary>
         /// Handles the native callback.
         /// </summary>
-        private void HandleNewServerRpc(bool success, BatchContextSafeHandle ctx)
+        private void HandleNewServerRpc(bool success, BatchContextSafeHandle ctx, CompletionQueueSafeHandle cq)
         {
-			Task.Run(() => AllowOneRpc());
+			Task.Run(() => AllowOneRpc(cq));
 
             if (success)
             {
@@ -296,7 +305,7 @@ namespace Grpc.Core
                 // after server shutdown, the callback returns with null call
                 if (!newRpc.Call.IsInvalid)
                 {
-                    HandleCallAsync(newRpc);  // we don't need to await.
+                    HandleCallAsync(newRpc, cq);  // we don't need to await.
                 }
             }
         }
diff --git a/src/csharp/Grpc.Core/WriteOptions.cs b/src/csharp/Grpc.Core/WriteOptions.cs
index 7523ada84a..4c9706d966 100644
--- a/src/csharp/Grpc.Core/WriteOptions.cs
+++ b/src/csharp/Grpc.Core/WriteOptions.cs
@@ -1,6 +1,6 @@
 #region Copyright notice and license
 
-// Copyright 2015, Google Inc.
+// Copyright 2015-2016, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
@@ -64,7 +64,7 @@ namespace Grpc.Core
         /// </summary>
         public static readonly WriteOptions Default = new WriteOptions();
             
-        private WriteFlags flags;
+        private readonly WriteFlags flags;
 
         /// <summary>
         /// Initializes a new instance of <c>WriteOptions</c> class.
diff --git a/src/csharp/Grpc.Examples.Tests/Grpc.Examples.Tests.csproj b/src/csharp/Grpc.Examples.Tests/Grpc.Examples.Tests.csproj
index cfe668b6be..3fd28c6528 100644
--- a/src/csharp/Grpc.Examples.Tests/Grpc.Examples.Tests.csproj
+++ b/src/csharp/Grpc.Examples.Tests/Grpc.Examples.Tests.csproj
@@ -37,7 +37,7 @@
   <ItemGroup>
     <Reference Include="System" />
     <Reference Include="Google.Protobuf">
-      <HintPath>..\packages\Google.Protobuf.3.0.0-beta2\lib\portable-net45+netcore45+wpa81+wp8\Google.Protobuf.dll</HintPath>
+      <HintPath>..\packages\Google.Protobuf.3.0.0-beta3\lib\portable-net45+netcore45+wpa81+wp8\Google.Protobuf.dll</HintPath>
     </Reference>
     <Reference Include="nunit.framework">
       <HintPath>..\packages\NUnit.3.2.0\lib\net45\nunit.framework.dll</HintPath>
diff --git a/src/csharp/Grpc.Examples.Tests/packages.config b/src/csharp/Grpc.Examples.Tests/packages.config
index ce030f9d77..668601af8e 100644
--- a/src/csharp/Grpc.Examples.Tests/packages.config
+++ b/src/csharp/Grpc.Examples.Tests/packages.config
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="Google.Protobuf" version="3.0.0-beta2" targetFramework="net45" />
+  <package id="Google.Protobuf" version="3.0.0-beta3" targetFramework="net45" />
   <package id="Ix-Async" version="1.2.5" targetFramework="net45" />
   <package id="NUnit" version="3.2.0" targetFramework="net45" />
   <package id="NUnitLite" version="3.2.0" targetFramework="net45" />
diff --git a/src/csharp/Grpc.Examples/Grpc.Examples.csproj b/src/csharp/Grpc.Examples/Grpc.Examples.csproj
index f0a0aa3a26..30170ab03c 100644
--- a/src/csharp/Grpc.Examples/Grpc.Examples.csproj
+++ b/src/csharp/Grpc.Examples/Grpc.Examples.csproj
@@ -39,7 +39,7 @@
   <ItemGroup>
     <Reference Include="Google.Protobuf, Version=3.0.0.0, Culture=neutral, PublicKeyToken=a7d26565bac4d604, processorArchitecture=MSIL">
       <SpecificVersion>False</SpecificVersion>
-      <HintPath>..\packages\Google.Protobuf.3.0.0-beta2\lib\portable-net45+netcore45+wpa81+wp8\Google.Protobuf.dll</HintPath>
+      <HintPath>..\packages\Google.Protobuf.3.0.0-beta3\lib\portable-net45+netcore45+wpa81+wp8\Google.Protobuf.dll</HintPath>
     </Reference>
     <Reference Include="nunit.framework">
       <HintPath>..\packages\NUnit.3.2.0\lib\net45\nunit.framework.dll</HintPath>
diff --git a/src/csharp/Grpc.Examples/Math.cs b/src/csharp/Grpc.Examples/Math.cs
index 33c4f8d9c0..a17228c8c5 100644
--- a/src/csharp/Grpc.Examples/Math.cs
+++ b/src/csharp/Grpc.Examples/Math.cs
@@ -34,12 +34,12 @@ namespace Math {
             "Mw=="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
-          new pbr::GeneratedCodeInfo(null, new pbr::GeneratedCodeInfo[] {
-            new pbr::GeneratedCodeInfo(typeof(global::Math.DivArgs), global::Math.DivArgs.Parser, new[]{ "Dividend", "Divisor" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Math.DivReply), global::Math.DivReply.Parser, new[]{ "Quotient", "Remainder" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Math.FibArgs), global::Math.FibArgs.Parser, new[]{ "Limit" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Math.Num), global::Math.Num.Parser, new[]{ "Num_" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Math.FibReply), global::Math.FibReply.Parser, new[]{ "Count" }, null, null, null)
+          new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Math.DivArgs), global::Math.DivArgs.Parser, new[]{ "Dividend", "Divisor" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Math.DivReply), global::Math.DivReply.Parser, new[]{ "Quotient", "Remainder" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Math.FibArgs), global::Math.FibArgs.Parser, new[]{ "Limit" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Math.Num), global::Math.Num.Parser, new[]{ "Num_" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Math.FibReply), global::Math.FibReply.Parser, new[]{ "Count" }, null, null, null)
           }));
     }
     #endregion
diff --git a/src/csharp/Grpc.Examples/packages.config b/src/csharp/Grpc.Examples/packages.config
index a424cd2ea0..a70dcbd4c6 100644
--- a/src/csharp/Grpc.Examples/packages.config
+++ b/src/csharp/Grpc.Examples/packages.config
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="Google.Protobuf" version="3.0.0-beta2" targetFramework="net45" />
+  <package id="Google.Protobuf" version="3.0.0-beta3" targetFramework="net45" />
   <package id="Ix-Async" version="1.2.5" targetFramework="net45" />
   <package id="NUnit" version="3.2.0" targetFramework="net45" />
 </packages>
\ No newline at end of file
diff --git a/src/csharp/Grpc.HealthCheck.Tests/Grpc.HealthCheck.Tests.csproj b/src/csharp/Grpc.HealthCheck.Tests/Grpc.HealthCheck.Tests.csproj
index 0bea9c03e7..a5ee4fdb46 100644
--- a/src/csharp/Grpc.HealthCheck.Tests/Grpc.HealthCheck.Tests.csproj
+++ b/src/csharp/Grpc.HealthCheck.Tests/Grpc.HealthCheck.Tests.csproj
@@ -45,7 +45,7 @@
     <Reference Include="System.Data" />
     <Reference Include="System.Xml" />
     <Reference Include="Google.Protobuf">
-      <HintPath>..\packages\Google.Protobuf.3.0.0-beta2\lib\portable-net45+netcore45+wpa81+wp8\Google.Protobuf.dll</HintPath>
+      <HintPath>..\packages\Google.Protobuf.3.0.0-beta3\lib\portable-net45+netcore45+wpa81+wp8\Google.Protobuf.dll</HintPath>
     </Reference>
     <Reference Include="nunit.framework">
       <HintPath>..\packages\NUnit.3.2.0\lib\net45\nunit.framework.dll</HintPath>
diff --git a/src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs b/src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs
index fb292945a6..070674bae9 100644
--- a/src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs
+++ b/src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs
@@ -79,16 +79,17 @@ namespace Grpc.HealthCheck.Tests
         [Test]
         public void ServiceIsRunning()
         {
-            serviceImpl.SetStatus("", HealthCheckResponse.Types.ServingStatus.SERVING);
+            serviceImpl.SetStatus("", HealthCheckResponse.Types.ServingStatus.Serving);
 
             var response = client.Check(new HealthCheckRequest { Service = "" });
-            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.SERVING, response.Status);
+            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.Serving, response.Status);
         }
 
         [Test]
         public void ServiceDoesntExist()
         {
-            Assert.Throws(Is.TypeOf(typeof(RpcException)).And.Property("Status").Property("StatusCode").EqualTo(StatusCode.NotFound), () => client.Check(new HealthCheckRequest { Service = "nonexistent.service" }));
+            var ex = Assert.Throws<RpcException>(() => client.Check(new HealthCheckRequest { Service = "nonexistent.service" }));
+            Assert.AreEqual(StatusCode.NotFound, ex.Status.StatusCode);
         }
 
         // TODO(jtattermusch): add test with timeout once timeouts are supported
diff --git a/src/csharp/Grpc.HealthCheck.Tests/HealthServiceImplTest.cs b/src/csharp/Grpc.HealthCheck.Tests/HealthServiceImplTest.cs
index a4b79e3a7d..15703604ba 100644
--- a/src/csharp/Grpc.HealthCheck.Tests/HealthServiceImplTest.cs
+++ b/src/csharp/Grpc.HealthCheck.Tests/HealthServiceImplTest.cs
@@ -50,38 +50,39 @@ namespace Grpc.HealthCheck.Tests
         public void SetStatus()
         {
             var impl = new HealthServiceImpl();
-            impl.SetStatus("", HealthCheckResponse.Types.ServingStatus.SERVING);
-            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.SERVING, GetStatusHelper(impl, ""));
+            impl.SetStatus("", HealthCheckResponse.Types.ServingStatus.Serving);
+            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.Serving, GetStatusHelper(impl, ""));
 
-            impl.SetStatus("", HealthCheckResponse.Types.ServingStatus.NOT_SERVING);
-            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.NOT_SERVING, GetStatusHelper(impl, ""));
+            impl.SetStatus("", HealthCheckResponse.Types.ServingStatus.NotServing);
+            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.NotServing, GetStatusHelper(impl, ""));
 
-            impl.SetStatus("", HealthCheckResponse.Types.ServingStatus.UNKNOWN);
-            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.UNKNOWN, GetStatusHelper(impl, ""));
+            impl.SetStatus("", HealthCheckResponse.Types.ServingStatus.Unknown);
+            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.Unknown, GetStatusHelper(impl, ""));
 
-            impl.SetStatus("grpc.test.TestService", HealthCheckResponse.Types.ServingStatus.SERVING);
-            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.SERVING, GetStatusHelper(impl, "grpc.test.TestService"));
+            impl.SetStatus("grpc.test.TestService", HealthCheckResponse.Types.ServingStatus.Serving);
+            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.Serving, GetStatusHelper(impl, "grpc.test.TestService"));
         }
 
         [Test]
         public void ClearStatus()
         {
             var impl = new HealthServiceImpl();
-            impl.SetStatus("", HealthCheckResponse.Types.ServingStatus.SERVING);
-            impl.SetStatus("grpc.test.TestService", HealthCheckResponse.Types.ServingStatus.UNKNOWN);
+            impl.SetStatus("", HealthCheckResponse.Types.ServingStatus.Serving);
+            impl.SetStatus("grpc.test.TestService", HealthCheckResponse.Types.ServingStatus.Unknown);
 
             impl.ClearStatus("");
 
-            Assert.Throws(Is.TypeOf(typeof(RpcException)).And.Property("Status").Property("StatusCode").EqualTo(StatusCode.NotFound), () => GetStatusHelper(impl, ""));
-            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.UNKNOWN, GetStatusHelper(impl, "grpc.test.TestService"));
+            var ex = Assert.Throws<RpcException>(() => GetStatusHelper(impl, ""));
+            Assert.AreEqual(StatusCode.NotFound, ex.Status.StatusCode);
+            Assert.AreEqual(HealthCheckResponse.Types.ServingStatus.Unknown, GetStatusHelper(impl, "grpc.test.TestService"));
         }
 
         [Test]
         public void ClearAll()
         {
             var impl = new HealthServiceImpl();
-            impl.SetStatus("", HealthCheckResponse.Types.ServingStatus.SERVING);
-            impl.SetStatus("grpc.test.TestService", HealthCheckResponse.Types.ServingStatus.UNKNOWN);
+            impl.SetStatus("", HealthCheckResponse.Types.ServingStatus.Serving);
+            impl.SetStatus("grpc.test.TestService", HealthCheckResponse.Types.ServingStatus.Unknown);
 
             impl.ClearAll();
             Assert.Throws(typeof(RpcException), () => GetStatusHelper(impl, ""));
@@ -92,7 +93,7 @@ namespace Grpc.HealthCheck.Tests
         public void NullsRejected()
         {
             var impl = new HealthServiceImpl();
-            Assert.Throws(typeof(ArgumentNullException), () => impl.SetStatus(null, HealthCheckResponse.Types.ServingStatus.SERVING));
+            Assert.Throws(typeof(ArgumentNullException), () => impl.SetStatus(null, HealthCheckResponse.Types.ServingStatus.Serving));
 
             Assert.Throws(typeof(ArgumentNullException), () => impl.ClearStatus(null));
         }
diff --git a/src/csharp/Grpc.HealthCheck.Tests/packages.config b/src/csharp/Grpc.HealthCheck.Tests/packages.config
index 8066d8fceb..2bcfec8829 100644
--- a/src/csharp/Grpc.HealthCheck.Tests/packages.config
+++ b/src/csharp/Grpc.HealthCheck.Tests/packages.config
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="Google.Protobuf" version="3.0.0-beta2" targetFramework="net45" />
+  <package id="Google.Protobuf" version="3.0.0-beta3" targetFramework="net45" />
   <package id="NUnit" version="3.2.0" targetFramework="net45" />
   <package id="NUnitLite" version="3.2.0" targetFramework="net45" />
 </packages>
\ No newline at end of file
diff --git a/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.csproj b/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.csproj
index 498528aa18..2697b74f59 100644
--- a/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.csproj
+++ b/src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.csproj
@@ -40,7 +40,7 @@
   <ItemGroup>
     <Reference Include="Google.Protobuf, Version=3.0.0.0, Culture=neutral, PublicKeyToken=a7d26565bac4d604, processorArchitecture=MSIL">
       <SpecificVersion>False</SpecificVersion>
-      <HintPath>..\packages\Google.Protobuf.3.0.0-beta2\lib\portable-net45+netcore45+wpa81+wp8\Google.Protobuf.dll</HintPath>
+      <HintPath>..\packages\Google.Protobuf.3.0.0-beta3\lib\portable-net45+netcore45+wpa81+wp8\Google.Protobuf.dll</HintPath>
     </Reference>
     <Reference Include="System" />
     <Reference Include="System.Core" />
diff --git a/src/csharp/Grpc.HealthCheck/Health.cs b/src/csharp/Grpc.HealthCheck/Health.cs
index d0d0c0b519..100ad187d7 100644
--- a/src/csharp/Grpc.HealthCheck/Health.cs
+++ b/src/csharp/Grpc.HealthCheck/Health.cs
@@ -33,9 +33,9 @@ namespace Grpc.Health.V1 {
             "Ag5HcnBjLkhlYWx0aC5WMWIGcHJvdG8z"));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
-          new pbr::GeneratedCodeInfo(null, new pbr::GeneratedCodeInfo[] {
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Health.V1.HealthCheckRequest), global::Grpc.Health.V1.HealthCheckRequest.Parser, new[]{ "Service" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Health.V1.HealthCheckResponse), global::Grpc.Health.V1.HealthCheckResponse.Parser, new[]{ "Status" }, null, new[]{ typeof(global::Grpc.Health.V1.HealthCheckResponse.Types.ServingStatus) }, null)
+          new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Health.V1.HealthCheckRequest), global::Grpc.Health.V1.HealthCheckRequest.Parser, new[]{ "Service" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Health.V1.HealthCheckResponse), global::Grpc.Health.V1.HealthCheckResponse.Parser, new[]{ "Status" }, null, new[]{ typeof(global::Grpc.Health.V1.HealthCheckResponse.Types.ServingStatus) }, null)
           }));
     }
     #endregion
@@ -75,7 +75,7 @@ namespace Grpc.Health.V1 {
     public string Service {
       get { return service_; }
       set {
-        service_ = pb::Preconditions.CheckNotNull(value, "value");
+        service_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
       }
     }
 
@@ -174,7 +174,7 @@ namespace Grpc.Health.V1 {
 
     /// <summary>Field number for the "status" field.</summary>
     public const int StatusFieldNumber = 1;
-    private global::Grpc.Health.V1.HealthCheckResponse.Types.ServingStatus status_ = global::Grpc.Health.V1.HealthCheckResponse.Types.ServingStatus.UNKNOWN;
+    private global::Grpc.Health.V1.HealthCheckResponse.Types.ServingStatus status_ = 0;
     public global::Grpc.Health.V1.HealthCheckResponse.Types.ServingStatus Status {
       get { return status_; }
       set {
@@ -199,7 +199,7 @@ namespace Grpc.Health.V1 {
 
     public override int GetHashCode() {
       int hash = 1;
-      if (Status != global::Grpc.Health.V1.HealthCheckResponse.Types.ServingStatus.UNKNOWN) hash ^= Status.GetHashCode();
+      if (Status != 0) hash ^= Status.GetHashCode();
       return hash;
     }
 
@@ -208,7 +208,7 @@ namespace Grpc.Health.V1 {
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
-      if (Status != global::Grpc.Health.V1.HealthCheckResponse.Types.ServingStatus.UNKNOWN) {
+      if (Status != 0) {
         output.WriteRawTag(8);
         output.WriteEnum((int) Status);
       }
@@ -216,7 +216,7 @@ namespace Grpc.Health.V1 {
 
     public int CalculateSize() {
       int size = 0;
-      if (Status != global::Grpc.Health.V1.HealthCheckResponse.Types.ServingStatus.UNKNOWN) {
+      if (Status != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Status);
       }
       return size;
@@ -226,7 +226,7 @@ namespace Grpc.Health.V1 {
       if (other == null) {
         return;
       }
-      if (other.Status != global::Grpc.Health.V1.HealthCheckResponse.Types.ServingStatus.UNKNOWN) {
+      if (other.Status != 0) {
         Status = other.Status;
       }
     }
@@ -251,9 +251,9 @@ namespace Grpc.Health.V1 {
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
     public static partial class Types {
       public enum ServingStatus {
-        UNKNOWN = 0,
-        SERVING = 1,
-        NOT_SERVING = 2,
+        [pbr::OriginalName("UNKNOWN")] Unknown = 0,
+        [pbr::OriginalName("SERVING")] Serving = 1,
+        [pbr::OriginalName("NOT_SERVING")] NotServing = 2,
       }
 
     }
diff --git a/src/csharp/Grpc.HealthCheck/packages.config b/src/csharp/Grpc.HealthCheck/packages.config
index 358a978ba9..a52d9e508f 100644
--- a/src/csharp/Grpc.HealthCheck/packages.config
+++ b/src/csharp/Grpc.HealthCheck/packages.config
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="Google.Protobuf" version="3.0.0-beta2" targetFramework="net45" />
+  <package id="Google.Protobuf" version="3.0.0-beta3" targetFramework="net45" />
   <package id="Ix-Async" version="1.2.5" targetFramework="net45" />
 </packages>
\ No newline at end of file
diff --git a/src/csharp/Grpc.IntegrationTesting/ClientRunners.cs b/src/csharp/Grpc.IntegrationTesting/ClientRunners.cs
index 9eaf6bf7ce..39b9ae08e6 100644
--- a/src/csharp/Grpc.IntegrationTesting/ClientRunners.cs
+++ b/src/csharp/Grpc.IntegrationTesting/ClientRunners.cs
@@ -32,6 +32,7 @@
 #endregion
 
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
@@ -41,7 +42,9 @@ using System.Threading;
 using System.Threading.Tasks;
 using Google.Protobuf;
 using Grpc.Core;
+using Grpc.Core.Internal;
 using Grpc.Core.Logging;
+using Grpc.Core.Profiling;
 using Grpc.Core.Utils;
 using NUnit.Framework;
 using Grpc.Testing;
@@ -55,6 +58,15 @@ namespace Grpc.IntegrationTesting
     {
         static readonly ILogger Logger = GrpcEnvironment.Logger.ForType<ClientRunners>();
 
+        // Profilers to use for clients.
+        static readonly BlockingCollection<BasicProfiler> profilers = new BlockingCollection<BasicProfiler>();
+
+        internal static void AddProfiler(BasicProfiler profiler)
+        {
+            GrpcPreconditions.CheckNotNull(profiler);
+            profilers.Add(profiler);
+        }
+
         /// <summary>
         /// Creates a started client runner.
         /// </summary>
@@ -83,7 +95,8 @@ namespace Grpc.IntegrationTesting
                 config.OutstandingRpcsPerChannel,
                 config.LoadParams,
                 config.PayloadConfig,
-                config.HistogramParams);
+                config.HistogramParams,
+                () => GetNextProfiler());
         }
 
         private static List<Channel> CreateChannels(int clientChannels, IEnumerable<string> serverTargets, SecurityParams securityParams)
@@ -110,9 +123,16 @@ namespace Grpc.IntegrationTesting
             }
             return result;
         }
+
+        private static BasicProfiler GetNextProfiler()
+        {
+            BasicProfiler result = null;
+            profilers.TryTake(out result);
+            return result;
+        }
     }
 
-    public class ClientRunnerImpl : IClientRunner
+    internal class ClientRunnerImpl : IClientRunner
     {
         const double SecondsToNanos = 1e9;
 
@@ -125,8 +145,9 @@ namespace Grpc.IntegrationTesting
         readonly List<Task> runnerTasks;
         readonly CancellationTokenSource stoppedCts = new CancellationTokenSource();
         readonly WallClockStopwatch wallClockStopwatch = new WallClockStopwatch();
+        readonly AtomicCounter statsResetCount = new AtomicCounter();
         
-        public ClientRunnerImpl(List<Channel> channels, ClientType clientType, RpcType rpcType, int outstandingRpcsPerChannel, LoadParams loadParams, PayloadConfig payloadConfig, HistogramParams histogramParams)
+        public ClientRunnerImpl(List<Channel> channels, ClientType clientType, RpcType rpcType, int outstandingRpcsPerChannel, LoadParams loadParams, PayloadConfig payloadConfig, HistogramParams histogramParams, Func<BasicProfiler> profilerFactory)
         {
             GrpcPreconditions.CheckArgument(outstandingRpcsPerChannel > 0, "outstandingRpcsPerChannel");
             GrpcPreconditions.CheckNotNull(histogramParams, "histogramParams");
@@ -142,7 +163,8 @@ namespace Grpc.IntegrationTesting
                 for (int i = 0; i < outstandingRpcsPerChannel; i++)
                 {
                     var timer = CreateTimer(loadParams, 1.0 / this.channels.Count / outstandingRpcsPerChannel);
-                    this.runnerTasks.Add(RunClientAsync(channel, timer));
+                    var optionalProfiler = profilerFactory();
+                    this.runnerTasks.Add(RunClientAsync(channel, timer, optionalProfiler));
                 }
             }
         }
@@ -152,6 +174,11 @@ namespace Grpc.IntegrationTesting
             var histogramData = histogram.GetSnapshot(reset);
             var secondsElapsed = wallClockStopwatch.GetElapsedSnapshot(reset).TotalSeconds;
 
+            if (reset)
+            {
+                statsResetCount.Increment();
+            }
+
             // TODO: populate user time and system time
             return new ClientStats
             {
@@ -175,14 +202,28 @@ namespace Grpc.IntegrationTesting
             }
         }
 
-        private void RunUnary(Channel channel, IInterarrivalTimer timer)
+        private void RunUnary(Channel channel, IInterarrivalTimer timer, BasicProfiler optionalProfiler)
         {
+            if (optionalProfiler != null)
+            {
+                Profilers.SetForCurrentThread(optionalProfiler);
+            }
+
+            bool profilerReset = false;
+
             var client = BenchmarkService.NewClient(channel);
             var request = CreateSimpleRequest();
             var stopwatch = new Stopwatch();
 
             while (!stoppedCts.Token.IsCancellationRequested)
             {
+                // after the first stats reset, also reset the profiler.
+                if (optionalProfiler != null && !profilerReset && statsResetCount.Count > 0)
+                {
+                    optionalProfiler.Reset();
+                    profilerReset = true;
+                }
+
                 stopwatch.Restart();
                 client.UnaryCall(request);
                 stopwatch.Stop();
@@ -268,29 +309,29 @@ namespace Grpc.IntegrationTesting
             }
         }
 
-        private Task RunClientAsync(Channel channel, IInterarrivalTimer timer)
+        private Task RunClientAsync(Channel channel, IInterarrivalTimer timer, BasicProfiler optionalProfiler)
         {
             if (payloadConfig.PayloadCase == PayloadConfig.PayloadOneofCase.BytebufParams)
             {
-                GrpcPreconditions.CheckArgument(clientType == ClientType.ASYNC_CLIENT, "Generic client only supports async API");
-                GrpcPreconditions.CheckArgument(rpcType == RpcType.STREAMING, "Generic client only supports streaming calls");
+                GrpcPreconditions.CheckArgument(clientType == ClientType.AsyncClient, "Generic client only supports async API");
+                GrpcPreconditions.CheckArgument(rpcType == RpcType.Streaming, "Generic client only supports streaming calls");
                 return RunGenericStreamingAsync(channel, timer);
             }
 
             GrpcPreconditions.CheckNotNull(payloadConfig.SimpleParams);
-            if (clientType == ClientType.SYNC_CLIENT)
+            if (clientType == ClientType.SyncClient)
             {
-                GrpcPreconditions.CheckArgument(rpcType == RpcType.UNARY, "Sync client can only be used for Unary calls in C#");
+                GrpcPreconditions.CheckArgument(rpcType == RpcType.Unary, "Sync client can only be used for Unary calls in C#");
                 // create a dedicated thread for the synchronous client
-                return Task.Factory.StartNew(() => RunUnary(channel, timer), TaskCreationOptions.LongRunning);
+                return Task.Factory.StartNew(() => RunUnary(channel, timer, optionalProfiler), TaskCreationOptions.LongRunning);
             }
-            else if (clientType == ClientType.ASYNC_CLIENT)
+            else if (clientType == ClientType.AsyncClient)
             {
                 switch (rpcType)
                 {
-                    case RpcType.UNARY:
+                    case RpcType.Unary:
                         return RunUnaryAsync(channel, timer);
-                    case RpcType.STREAMING:
+                    case RpcType.Streaming:
                         return RunStreamingPingPongAsync(channel, timer);
                 }
             }
diff --git a/src/csharp/Grpc.IntegrationTesting/Control.cs b/src/csharp/Grpc.IntegrationTesting/Control.cs
index 3fa8d43f38..412f800ff9 100644
--- a/src/csharp/Grpc.IntegrationTesting/Control.cs
+++ b/src/csharp/Grpc.IntegrationTesting/Control.cs
@@ -85,25 +85,25 @@ namespace Grpc.Testing {
             "RUFNSU5HEAFiBnByb3RvMw=="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { global::Grpc.Testing.PayloadsReflection.Descriptor, global::Grpc.Testing.StatsReflection.Descriptor, },
-          new pbr::GeneratedCodeInfo(new[] {typeof(global::Grpc.Testing.ClientType), typeof(global::Grpc.Testing.ServerType), typeof(global::Grpc.Testing.RpcType), }, new pbr::GeneratedCodeInfo[] {
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.PoissonParams), global::Grpc.Testing.PoissonParams.Parser, new[]{ "OfferedLoad" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ClosedLoopParams), global::Grpc.Testing.ClosedLoopParams.Parser, null, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.LoadParams), global::Grpc.Testing.LoadParams.Parser, new[]{ "ClosedLoop", "Poisson" }, new[]{ "Load" }, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.SecurityParams), global::Grpc.Testing.SecurityParams.Parser, new[]{ "UseTestCa", "ServerHostOverride" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ClientConfig), global::Grpc.Testing.ClientConfig.Parser, new[]{ "ServerTargets", "ClientType", "SecurityParams", "OutstandingRpcsPerChannel", "ClientChannels", "AsyncClientThreads", "RpcType", "LoadParams", "PayloadConfig", "HistogramParams", "CoreList", "CoreLimit", "OtherClientApi" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ClientStatus), global::Grpc.Testing.ClientStatus.Parser, new[]{ "Stats" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.Mark), global::Grpc.Testing.Mark.Parser, new[]{ "Reset" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ClientArgs), global::Grpc.Testing.ClientArgs.Parser, new[]{ "Setup", "Mark" }, new[]{ "Argtype" }, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ServerConfig), global::Grpc.Testing.ServerConfig.Parser, new[]{ "ServerType", "SecurityParams", "Port", "AsyncServerThreads", "CoreLimit", "PayloadConfig", "CoreList", "OtherServerApi" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ServerArgs), global::Grpc.Testing.ServerArgs.Parser, new[]{ "Setup", "Mark" }, new[]{ "Argtype" }, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ServerStatus), global::Grpc.Testing.ServerStatus.Parser, new[]{ "Stats", "Port", "Cores" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.CoreRequest), global::Grpc.Testing.CoreRequest.Parser, null, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.CoreResponse), global::Grpc.Testing.CoreResponse.Parser, new[]{ "Cores" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.Void), global::Grpc.Testing.Void.Parser, null, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.Scenario), global::Grpc.Testing.Scenario.Parser, new[]{ "Name", "ClientConfig", "NumClients", "ServerConfig", "NumServers", "WarmupSeconds", "BenchmarkSeconds", "SpawnLocalWorkerCount" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.Scenarios), global::Grpc.Testing.Scenarios.Parser, new[]{ "Scenarios_" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ScenarioResultSummary), global::Grpc.Testing.ScenarioResultSummary.Parser, new[]{ "Qps", "QpsPerServerCore", "ServerSystemTime", "ServerUserTime", "ClientSystemTime", "ClientUserTime", "Latency50", "Latency90", "Latency95", "Latency99", "Latency999" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ScenarioResult), global::Grpc.Testing.ScenarioResult.Parser, new[]{ "Scenario", "Latencies", "ClientStats", "ServerStats", "ServerCores", "Summary" }, null, null, null)
+          new pbr::GeneratedClrTypeInfo(new[] {typeof(global::Grpc.Testing.ClientType), typeof(global::Grpc.Testing.ServerType), typeof(global::Grpc.Testing.RpcType), }, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.PoissonParams), global::Grpc.Testing.PoissonParams.Parser, new[]{ "OfferedLoad" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ClosedLoopParams), global::Grpc.Testing.ClosedLoopParams.Parser, null, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.LoadParams), global::Grpc.Testing.LoadParams.Parser, new[]{ "ClosedLoop", "Poisson" }, new[]{ "Load" }, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.SecurityParams), global::Grpc.Testing.SecurityParams.Parser, new[]{ "UseTestCa", "ServerHostOverride" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ClientConfig), global::Grpc.Testing.ClientConfig.Parser, new[]{ "ServerTargets", "ClientType", "SecurityParams", "OutstandingRpcsPerChannel", "ClientChannels", "AsyncClientThreads", "RpcType", "LoadParams", "PayloadConfig", "HistogramParams", "CoreList", "CoreLimit", "OtherClientApi" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ClientStatus), global::Grpc.Testing.ClientStatus.Parser, new[]{ "Stats" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.Mark), global::Grpc.Testing.Mark.Parser, new[]{ "Reset" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ClientArgs), global::Grpc.Testing.ClientArgs.Parser, new[]{ "Setup", "Mark" }, new[]{ "Argtype" }, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ServerConfig), global::Grpc.Testing.ServerConfig.Parser, new[]{ "ServerType", "SecurityParams", "Port", "AsyncServerThreads", "CoreLimit", "PayloadConfig", "CoreList", "OtherServerApi" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ServerArgs), global::Grpc.Testing.ServerArgs.Parser, new[]{ "Setup", "Mark" }, new[]{ "Argtype" }, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ServerStatus), global::Grpc.Testing.ServerStatus.Parser, new[]{ "Stats", "Port", "Cores" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.CoreRequest), global::Grpc.Testing.CoreRequest.Parser, null, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.CoreResponse), global::Grpc.Testing.CoreResponse.Parser, new[]{ "Cores" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.Void), global::Grpc.Testing.Void.Parser, null, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.Scenario), global::Grpc.Testing.Scenario.Parser, new[]{ "Name", "ClientConfig", "NumClients", "ServerConfig", "NumServers", "WarmupSeconds", "BenchmarkSeconds", "SpawnLocalWorkerCount" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.Scenarios), global::Grpc.Testing.Scenarios.Parser, new[]{ "Scenarios_" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ScenarioResultSummary), global::Grpc.Testing.ScenarioResultSummary.Parser, new[]{ "Qps", "QpsPerServerCore", "ServerSystemTime", "ServerUserTime", "ClientSystemTime", "ClientUserTime", "Latency50", "Latency90", "Latency95", "Latency99", "Latency999" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ScenarioResult), global::Grpc.Testing.ScenarioResult.Parser, new[]{ "Scenario", "Latencies", "ClientStats", "ServerStats", "ServerCores", "Summary" }, null, null, null)
           }));
     }
     #endregion
@@ -115,27 +115,27 @@ namespace Grpc.Testing {
     ///  Many languages support a basic distinction between using
     ///  sync or async client, and this allows the specification
     /// </summary>
-    SYNC_CLIENT = 0,
-    ASYNC_CLIENT = 1,
+    [pbr::OriginalName("SYNC_CLIENT")] SyncClient = 0,
+    [pbr::OriginalName("ASYNC_CLIENT")] AsyncClient = 1,
     /// <summary>
     ///  used for some language-specific variants
     /// </summary>
-    OTHER_CLIENT = 2,
+    [pbr::OriginalName("OTHER_CLIENT")] OtherClient = 2,
   }
 
   public enum ServerType {
-    SYNC_SERVER = 0,
-    ASYNC_SERVER = 1,
-    ASYNC_GENERIC_SERVER = 2,
+    [pbr::OriginalName("SYNC_SERVER")] SyncServer = 0,
+    [pbr::OriginalName("ASYNC_SERVER")] AsyncServer = 1,
+    [pbr::OriginalName("ASYNC_GENERIC_SERVER")] AsyncGenericServer = 2,
     /// <summary>
     ///  used for some language-specific variants
     /// </summary>
-    OTHER_SERVER = 3,
+    [pbr::OriginalName("OTHER_SERVER")] OtherServer = 3,
   }
 
   public enum RpcType {
-    UNARY = 0,
-    STREAMING = 1,
+    [pbr::OriginalName("UNARY")] Unary = 0,
+    [pbr::OriginalName("STREAMING")] Streaming = 1,
   }
 
   #endregion
@@ -547,7 +547,7 @@ namespace Grpc.Testing {
     public string ServerHostOverride {
       get { return serverHostOverride_; }
       set {
-        serverHostOverride_ = pb::Preconditions.CheckNotNull(value, "value");
+        serverHostOverride_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
       }
     }
 
@@ -686,7 +686,7 @@ namespace Grpc.Testing {
 
     /// <summary>Field number for the "client_type" field.</summary>
     public const int ClientTypeFieldNumber = 2;
-    private global::Grpc.Testing.ClientType clientType_ = global::Grpc.Testing.ClientType.SYNC_CLIENT;
+    private global::Grpc.Testing.ClientType clientType_ = 0;
     public global::Grpc.Testing.ClientType ClientType {
       get { return clientType_; }
       set {
@@ -747,7 +747,7 @@ namespace Grpc.Testing {
 
     /// <summary>Field number for the "rpc_type" field.</summary>
     public const int RpcTypeFieldNumber = 8;
-    private global::Grpc.Testing.RpcType rpcType_ = global::Grpc.Testing.RpcType.UNARY;
+    private global::Grpc.Testing.RpcType rpcType_ = 0;
     public global::Grpc.Testing.RpcType RpcType {
       get { return rpcType_; }
       set {
@@ -819,7 +819,7 @@ namespace Grpc.Testing {
     public string OtherClientApi {
       get { return otherClientApi_; }
       set {
-        otherClientApi_ = pb::Preconditions.CheckNotNull(value, "value");
+        otherClientApi_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
       }
     }
 
@@ -853,12 +853,12 @@ namespace Grpc.Testing {
     public override int GetHashCode() {
       int hash = 1;
       hash ^= serverTargets_.GetHashCode();
-      if (ClientType != global::Grpc.Testing.ClientType.SYNC_CLIENT) hash ^= ClientType.GetHashCode();
+      if (ClientType != 0) hash ^= ClientType.GetHashCode();
       if (securityParams_ != null) hash ^= SecurityParams.GetHashCode();
       if (OutstandingRpcsPerChannel != 0) hash ^= OutstandingRpcsPerChannel.GetHashCode();
       if (ClientChannels != 0) hash ^= ClientChannels.GetHashCode();
       if (AsyncClientThreads != 0) hash ^= AsyncClientThreads.GetHashCode();
-      if (RpcType != global::Grpc.Testing.RpcType.UNARY) hash ^= RpcType.GetHashCode();
+      if (RpcType != 0) hash ^= RpcType.GetHashCode();
       if (loadParams_ != null) hash ^= LoadParams.GetHashCode();
       if (payloadConfig_ != null) hash ^= PayloadConfig.GetHashCode();
       if (histogramParams_ != null) hash ^= HistogramParams.GetHashCode();
@@ -874,7 +874,7 @@ namespace Grpc.Testing {
 
     public void WriteTo(pb::CodedOutputStream output) {
       serverTargets_.WriteTo(output, _repeated_serverTargets_codec);
-      if (ClientType != global::Grpc.Testing.ClientType.SYNC_CLIENT) {
+      if (ClientType != 0) {
         output.WriteRawTag(16);
         output.WriteEnum((int) ClientType);
       }
@@ -894,7 +894,7 @@ namespace Grpc.Testing {
         output.WriteRawTag(56);
         output.WriteInt32(AsyncClientThreads);
       }
-      if (RpcType != global::Grpc.Testing.RpcType.UNARY) {
+      if (RpcType != 0) {
         output.WriteRawTag(64);
         output.WriteEnum((int) RpcType);
       }
@@ -924,7 +924,7 @@ namespace Grpc.Testing {
     public int CalculateSize() {
       int size = 0;
       size += serverTargets_.CalculateSize(_repeated_serverTargets_codec);
-      if (ClientType != global::Grpc.Testing.ClientType.SYNC_CLIENT) {
+      if (ClientType != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) ClientType);
       }
       if (securityParams_ != null) {
@@ -939,7 +939,7 @@ namespace Grpc.Testing {
       if (AsyncClientThreads != 0) {
         size += 1 + pb::CodedOutputStream.ComputeInt32Size(AsyncClientThreads);
       }
-      if (RpcType != global::Grpc.Testing.RpcType.UNARY) {
+      if (RpcType != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) RpcType);
       }
       if (loadParams_ != null) {
@@ -966,7 +966,7 @@ namespace Grpc.Testing {
         return;
       }
       serverTargets_.Add(other.serverTargets_);
-      if (other.ClientType != global::Grpc.Testing.ClientType.SYNC_CLIENT) {
+      if (other.ClientType != 0) {
         ClientType = other.ClientType;
       }
       if (other.securityParams_ != null) {
@@ -984,7 +984,7 @@ namespace Grpc.Testing {
       if (other.AsyncClientThreads != 0) {
         AsyncClientThreads = other.AsyncClientThreads;
       }
-      if (other.RpcType != global::Grpc.Testing.RpcType.UNARY) {
+      if (other.RpcType != 0) {
         RpcType = other.RpcType;
       }
       if (other.loadParams_ != null) {
@@ -1515,7 +1515,7 @@ namespace Grpc.Testing {
 
     /// <summary>Field number for the "server_type" field.</summary>
     public const int ServerTypeFieldNumber = 1;
-    private global::Grpc.Testing.ServerType serverType_ = global::Grpc.Testing.ServerType.SYNC_SERVER;
+    private global::Grpc.Testing.ServerType serverType_ = 0;
     public global::Grpc.Testing.ServerType ServerType {
       get { return serverType_; }
       set {
@@ -1606,7 +1606,7 @@ namespace Grpc.Testing {
     public string OtherServerApi {
       get { return otherServerApi_; }
       set {
-        otherServerApi_ = pb::Preconditions.CheckNotNull(value, "value");
+        otherServerApi_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
       }
     }
 
@@ -1634,7 +1634,7 @@ namespace Grpc.Testing {
 
     public override int GetHashCode() {
       int hash = 1;
-      if (ServerType != global::Grpc.Testing.ServerType.SYNC_SERVER) hash ^= ServerType.GetHashCode();
+      if (ServerType != 0) hash ^= ServerType.GetHashCode();
       if (securityParams_ != null) hash ^= SecurityParams.GetHashCode();
       if (Port != 0) hash ^= Port.GetHashCode();
       if (AsyncServerThreads != 0) hash ^= AsyncServerThreads.GetHashCode();
@@ -1650,7 +1650,7 @@ namespace Grpc.Testing {
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
-      if (ServerType != global::Grpc.Testing.ServerType.SYNC_SERVER) {
+      if (ServerType != 0) {
         output.WriteRawTag(8);
         output.WriteEnum((int) ServerType);
       }
@@ -1683,7 +1683,7 @@ namespace Grpc.Testing {
 
     public int CalculateSize() {
       int size = 0;
-      if (ServerType != global::Grpc.Testing.ServerType.SYNC_SERVER) {
+      if (ServerType != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) ServerType);
       }
       if (securityParams_ != null) {
@@ -1712,7 +1712,7 @@ namespace Grpc.Testing {
       if (other == null) {
         return;
       }
-      if (other.ServerType != global::Grpc.Testing.ServerType.SYNC_SERVER) {
+      if (other.ServerType != 0) {
         ServerType = other.ServerType;
       }
       if (other.securityParams_ != null) {
@@ -2436,7 +2436,7 @@ namespace Grpc.Testing {
     public string Name {
       get { return name_; }
       set {
-        name_ = pb::Preconditions.CheckNotNull(value, "value");
+        name_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
       }
     }
 
diff --git a/src/csharp/Grpc.IntegrationTesting/Empty.cs b/src/csharp/Grpc.IntegrationTesting/Empty.cs
index 4323c5a09f..cf1c23fb0f 100644
--- a/src/csharp/Grpc.IntegrationTesting/Empty.cs
+++ b/src/csharp/Grpc.IntegrationTesting/Empty.cs
@@ -27,8 +27,8 @@ namespace Grpc.Testing {
             "c3RpbmciBwoFRW1wdHliBnByb3RvMw=="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
-          new pbr::GeneratedCodeInfo(null, new pbr::GeneratedCodeInfo[] {
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.Empty), global::Grpc.Testing.Empty.Parser, null, null, null, null)
+          new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.Empty), global::Grpc.Testing.Empty.Parser, null, null, null, null)
           }));
     }
     #endregion
diff --git a/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj b/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
index 9685cf1837..0089049408 100644
--- a/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
+++ b/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
@@ -61,7 +61,7 @@
       <HintPath>..\packages\Google.Apis.Core.1.11.1\lib\net45\Google.Apis.Core.dll</HintPath>
     </Reference>
     <Reference Include="Google.Protobuf">
-      <HintPath>..\packages\Google.Protobuf.3.0.0-beta2\lib\portable-net45+netcore45+wpa81+wp8\Google.Protobuf.dll</HintPath>
+      <HintPath>..\packages\Google.Protobuf.3.0.0-beta3\lib\portable-net45+netcore45+wpa81+wp8\Google.Protobuf.dll</HintPath>
     </Reference>
     <Reference Include="Newtonsoft.Json">
       <HintPath>..\packages\Newtonsoft.Json.7.0.1\lib\net45\Newtonsoft.Json.dll</HintPath>
diff --git a/src/csharp/Grpc.IntegrationTesting/InteropClient.cs b/src/csharp/Grpc.IntegrationTesting/InteropClient.cs
index cff8508631..aea40afee2 100644
--- a/src/csharp/Grpc.IntegrationTesting/InteropClient.cs
+++ b/src/csharp/Grpc.IntegrationTesting/InteropClient.cs
@@ -230,13 +230,13 @@ namespace Grpc.IntegrationTesting
             Console.WriteLine("running large_unary");
             var request = new SimpleRequest
             {
-                ResponseType = PayloadType.COMPRESSABLE,
+                ResponseType = PayloadType.Compressable,
                 ResponseSize = 314159,
                 Payload = CreateZerosPayload(271828)
             };
             var response = client.UnaryCall(request);
 
-            Assert.AreEqual(PayloadType.COMPRESSABLE, response.Payload.Type);
+            Assert.AreEqual(PayloadType.Compressable, response.Payload.Type);
             Assert.AreEqual(314159, response.Payload.Body.Length);
             Console.WriteLine("Passed!");
         }
@@ -265,7 +265,7 @@ namespace Grpc.IntegrationTesting
 
             var request = new StreamingOutputCallRequest
             {
-                ResponseType = PayloadType.COMPRESSABLE,
+                ResponseType = PayloadType.Compressable,
                 ResponseParameters = { bodySizes.ConvertAll((size) => new ResponseParameters { Size = size }) }
             };
 
@@ -274,7 +274,7 @@ namespace Grpc.IntegrationTesting
                 var responseList = await call.ResponseStream.ToListAsync();
                 foreach (var res in responseList)
                 {
-                    Assert.AreEqual(PayloadType.COMPRESSABLE, res.Payload.Type);
+                    Assert.AreEqual(PayloadType.Compressable, res.Payload.Type);
                 }
                 CollectionAssert.AreEqual(bodySizes, responseList.ConvertAll((item) => item.Payload.Body.Length));
             }
@@ -289,46 +289,46 @@ namespace Grpc.IntegrationTesting
             {
                 await call.RequestStream.WriteAsync(new StreamingOutputCallRequest
                 {
-                    ResponseType = PayloadType.COMPRESSABLE,
+                    ResponseType = PayloadType.Compressable,
                     ResponseParameters = { new ResponseParameters { Size = 31415 } },
                     Payload = CreateZerosPayload(27182)
                 });
 
                 Assert.IsTrue(await call.ResponseStream.MoveNext());
-                Assert.AreEqual(PayloadType.COMPRESSABLE, call.ResponseStream.Current.Payload.Type);
+                Assert.AreEqual(PayloadType.Compressable, call.ResponseStream.Current.Payload.Type);
                 Assert.AreEqual(31415, call.ResponseStream.Current.Payload.Body.Length);
 
                 await call.RequestStream.WriteAsync(new StreamingOutputCallRequest
                 {
-                    ResponseType = PayloadType.COMPRESSABLE,
+                    ResponseType = PayloadType.Compressable,
                     ResponseParameters = { new ResponseParameters { Size = 9 } },
                     Payload = CreateZerosPayload(8)
                 });
 
                 Assert.IsTrue(await call.ResponseStream.MoveNext());
-                Assert.AreEqual(PayloadType.COMPRESSABLE, call.ResponseStream.Current.Payload.Type);
+                Assert.AreEqual(PayloadType.Compressable, call.ResponseStream.Current.Payload.Type);
                 Assert.AreEqual(9, call.ResponseStream.Current.Payload.Body.Length);
 
                 await call.RequestStream.WriteAsync(new StreamingOutputCallRequest
                 {
-                    ResponseType = PayloadType.COMPRESSABLE,
+                    ResponseType = PayloadType.Compressable,
                     ResponseParameters = { new ResponseParameters { Size = 2653 } },
                     Payload = CreateZerosPayload(1828)
                 });
 
                 Assert.IsTrue(await call.ResponseStream.MoveNext());
-                Assert.AreEqual(PayloadType.COMPRESSABLE, call.ResponseStream.Current.Payload.Type);
+                Assert.AreEqual(PayloadType.Compressable, call.ResponseStream.Current.Payload.Type);
                 Assert.AreEqual(2653, call.ResponseStream.Current.Payload.Body.Length);
 
                 await call.RequestStream.WriteAsync(new StreamingOutputCallRequest
                 {
-                    ResponseType = PayloadType.COMPRESSABLE,
+                    ResponseType = PayloadType.Compressable,
                     ResponseParameters = { new ResponseParameters { Size = 58979 } },
                     Payload = CreateZerosPayload(45904)
                 });
 
                 Assert.IsTrue(await call.ResponseStream.MoveNext());
-                Assert.AreEqual(PayloadType.COMPRESSABLE, call.ResponseStream.Current.Payload.Type);
+                Assert.AreEqual(PayloadType.Compressable, call.ResponseStream.Current.Payload.Type);
                 Assert.AreEqual(58979, call.ResponseStream.Current.Payload.Body.Length);
 
                 await call.RequestStream.CompleteAsync();
@@ -357,7 +357,7 @@ namespace Grpc.IntegrationTesting
 
             var request = new SimpleRequest
             {
-                ResponseType = PayloadType.COMPRESSABLE,
+                ResponseType = PayloadType.Compressable,
                 ResponseSize = 314159,
                 Payload = CreateZerosPayload(271828),
                 FillUsername = true,
@@ -367,7 +367,7 @@ namespace Grpc.IntegrationTesting
             // not setting credentials here because they were set on channel already
             var response = client.UnaryCall(request);
 
-            Assert.AreEqual(PayloadType.COMPRESSABLE, response.Payload.Type);
+            Assert.AreEqual(PayloadType.Compressable, response.Payload.Type);
             Assert.AreEqual(314159, response.Payload.Body.Length);
             Assert.False(string.IsNullOrEmpty(response.OauthScope));
             Assert.True(oauthScope.Contains(response.OauthScope));
@@ -381,7 +381,7 @@ namespace Grpc.IntegrationTesting
            
             var request = new SimpleRequest
             {
-                ResponseType = PayloadType.COMPRESSABLE,
+                ResponseType = PayloadType.Compressable,
                 ResponseSize = 314159,
                 Payload = CreateZerosPayload(271828),
                 FillUsername = true,
@@ -390,7 +390,7 @@ namespace Grpc.IntegrationTesting
             // not setting credentials here because they were set on channel already
             var response = client.UnaryCall(request);
 
-            Assert.AreEqual(PayloadType.COMPRESSABLE, response.Payload.Type);
+            Assert.AreEqual(PayloadType.Compressable, response.Payload.Type);
             Assert.AreEqual(314159, response.Payload.Body.Length);
             Assert.AreEqual(GetEmailFromServiceAccountFile(), response.Username);
             Console.WriteLine("Passed!");
@@ -460,19 +460,27 @@ namespace Grpc.IntegrationTesting
             {
                 await call.RequestStream.WriteAsync(new StreamingOutputCallRequest
                 {
-                    ResponseType = PayloadType.COMPRESSABLE,
+                    ResponseType = PayloadType.Compressable,
                     ResponseParameters = { new ResponseParameters { Size = 31415 } },
                     Payload = CreateZerosPayload(27182)
                 });
 
                 Assert.IsTrue(await call.ResponseStream.MoveNext());
-                Assert.AreEqual(PayloadType.COMPRESSABLE, call.ResponseStream.Current.Payload.Type);
+                Assert.AreEqual(PayloadType.Compressable, call.ResponseStream.Current.Payload.Type);
                 Assert.AreEqual(31415, call.ResponseStream.Current.Payload.Body.Length);
 
                 cts.Cancel();
 
-                var ex = Assert.ThrowsAsync<RpcException>(async () => await call.ResponseStream.MoveNext());
-                Assert.AreEqual(StatusCode.Cancelled, ex.Status.StatusCode);
+                try
+                {
+                    // cannot use Assert.ThrowsAsync because it uses Task.Wait and would deadlock.
+                    await call.ResponseStream.MoveNext();
+                    Assert.Fail();
+                }
+                catch (RpcException ex)
+                {
+                    Assert.AreEqual(StatusCode.Cancelled, ex.Status.StatusCode);
+                }
             }
             Console.WriteLine("Passed!");
         }
@@ -497,9 +505,16 @@ namespace Grpc.IntegrationTesting
                     // Deadline was reached before write has started. Eat the exception and continue.
                 }
 
-                var ex = Assert.ThrowsAsync<RpcException>(async () => await call.ResponseStream.MoveNext());
-                // We can't guarantee the status code always DeadlineExceeded. See issue #2685.
-                Assert.Contains(ex.Status.StatusCode, new[] { StatusCode.DeadlineExceeded, StatusCode.Internal });
+                try
+                {
+                    await call.ResponseStream.MoveNext();
+                    Assert.Fail();
+                }
+                catch (RpcException ex)
+                {
+                    // We can't guarantee the status code always DeadlineExceeded. See issue #2685.
+                    Assert.Contains(ex.Status.StatusCode, new[] { StatusCode.DeadlineExceeded, StatusCode.Internal });
+                }
             }
             Console.WriteLine("Passed!");
         }
@@ -511,7 +526,7 @@ namespace Grpc.IntegrationTesting
                 // step 1: test unary call
                 var request = new SimpleRequest
                 {
-                    ResponseType = PayloadType.COMPRESSABLE,
+                    ResponseType = PayloadType.Compressable,
                     ResponseSize = 314159,
                     Payload = CreateZerosPayload(271828)
                 };
@@ -530,7 +545,7 @@ namespace Grpc.IntegrationTesting
                 // step 2: test full duplex call
                 var request = new StreamingOutputCallRequest
                 {
-                    ResponseType = PayloadType.COMPRESSABLE,
+                    ResponseType = PayloadType.Compressable,
                     ResponseParameters = { new ResponseParameters { Size = 31415 } },
                     Payload = CreateZerosPayload(27182)
                 };
@@ -577,9 +592,17 @@ namespace Grpc.IntegrationTesting
                 await call.RequestStream.WriteAsync(request);
                 await call.RequestStream.CompleteAsync();
 
-                var e = Assert.ThrowsAsync<RpcException>(async () => await call.ResponseStream.ToListAsync());
-                Assert.AreEqual(StatusCode.Unknown, e.Status.StatusCode);
-                Assert.AreEqual(echoStatus.Message, e.Status.Detail);
+                try
+                {
+                    // cannot use Assert.ThrowsAsync because it uses Task.Wait and would deadlock.
+                    await call.ResponseStream.ToListAsync();
+                    Assert.Fail();
+                }
+                catch (RpcException e)
+                {
+                    Assert.AreEqual(StatusCode.Unknown, e.Status.StatusCode);
+                    Assert.AreEqual(echoStatus.Message, e.Status.Detail);
+                }
             }
 
             Console.WriteLine("Passed!");
diff --git a/src/csharp/Grpc.IntegrationTesting/Messages.cs b/src/csharp/Grpc.IntegrationTesting/Messages.cs
index fcff475941..d42501aa5b 100644
--- a/src/csharp/Grpc.IntegrationTesting/Messages.cs
+++ b/src/csharp/Grpc.IntegrationTesting/Messages.cs
@@ -55,18 +55,18 @@ namespace Grpc.Testing {
             "TkUQABIICgRHWklQEAESCwoHREVGTEFURRACYgZwcm90bzM="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
-          new pbr::GeneratedCodeInfo(new[] {typeof(global::Grpc.Testing.PayloadType), typeof(global::Grpc.Testing.CompressionType), }, new pbr::GeneratedCodeInfo[] {
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.Payload), global::Grpc.Testing.Payload.Parser, new[]{ "Type", "Body" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.EchoStatus), global::Grpc.Testing.EchoStatus.Parser, new[]{ "Code", "Message" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.SimpleRequest), global::Grpc.Testing.SimpleRequest.Parser, new[]{ "ResponseType", "ResponseSize", "Payload", "FillUsername", "FillOauthScope", "ResponseCompression", "ResponseStatus" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.SimpleResponse), global::Grpc.Testing.SimpleResponse.Parser, new[]{ "Payload", "Username", "OauthScope" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.StreamingInputCallRequest), global::Grpc.Testing.StreamingInputCallRequest.Parser, new[]{ "Payload" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.StreamingInputCallResponse), global::Grpc.Testing.StreamingInputCallResponse.Parser, new[]{ "AggregatedPayloadSize" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ResponseParameters), global::Grpc.Testing.ResponseParameters.Parser, new[]{ "Size", "IntervalUs" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.StreamingOutputCallRequest), global::Grpc.Testing.StreamingOutputCallRequest.Parser, new[]{ "ResponseType", "ResponseParameters", "Payload", "ResponseCompression", "ResponseStatus" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.StreamingOutputCallResponse), global::Grpc.Testing.StreamingOutputCallResponse.Parser, new[]{ "Payload" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ReconnectParams), global::Grpc.Testing.ReconnectParams.Parser, new[]{ "MaxReconnectBackoffMs" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ReconnectInfo), global::Grpc.Testing.ReconnectInfo.Parser, new[]{ "Passed", "BackoffMs" }, null, null, null)
+          new pbr::GeneratedClrTypeInfo(new[] {typeof(global::Grpc.Testing.PayloadType), typeof(global::Grpc.Testing.CompressionType), }, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.Payload), global::Grpc.Testing.Payload.Parser, new[]{ "Type", "Body" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.EchoStatus), global::Grpc.Testing.EchoStatus.Parser, new[]{ "Code", "Message" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.SimpleRequest), global::Grpc.Testing.SimpleRequest.Parser, new[]{ "ResponseType", "ResponseSize", "Payload", "FillUsername", "FillOauthScope", "ResponseCompression", "ResponseStatus" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.SimpleResponse), global::Grpc.Testing.SimpleResponse.Parser, new[]{ "Payload", "Username", "OauthScope" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.StreamingInputCallRequest), global::Grpc.Testing.StreamingInputCallRequest.Parser, new[]{ "Payload" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.StreamingInputCallResponse), global::Grpc.Testing.StreamingInputCallResponse.Parser, new[]{ "AggregatedPayloadSize" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ResponseParameters), global::Grpc.Testing.ResponseParameters.Parser, new[]{ "Size", "IntervalUs" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.StreamingOutputCallRequest), global::Grpc.Testing.StreamingOutputCallRequest.Parser, new[]{ "ResponseType", "ResponseParameters", "Payload", "ResponseCompression", "ResponseStatus" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.StreamingOutputCallResponse), global::Grpc.Testing.StreamingOutputCallResponse.Parser, new[]{ "Payload" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ReconnectParams), global::Grpc.Testing.ReconnectParams.Parser, new[]{ "MaxReconnectBackoffMs" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ReconnectInfo), global::Grpc.Testing.ReconnectInfo.Parser, new[]{ "Passed", "BackoffMs" }, null, null, null)
           }));
     }
     #endregion
@@ -80,15 +80,15 @@ namespace Grpc.Testing {
     /// <summary>
     ///  Compressable text format.
     /// </summary>
-    COMPRESSABLE = 0,
+    [pbr::OriginalName("COMPRESSABLE")] Compressable = 0,
     /// <summary>
     ///  Uncompressable binary format.
     /// </summary>
-    UNCOMPRESSABLE = 1,
+    [pbr::OriginalName("UNCOMPRESSABLE")] Uncompressable = 1,
     /// <summary>
     ///  Randomly chosen from all other formats defined in this enum.
     /// </summary>
-    RANDOM = 2,
+    [pbr::OriginalName("RANDOM")] Random = 2,
   }
 
   /// <summary>
@@ -98,9 +98,9 @@ namespace Grpc.Testing {
     /// <summary>
     ///  No compression
     /// </summary>
-    NONE = 0,
-    GZIP = 1,
-    DEFLATE = 2,
+    [pbr::OriginalName("NONE")] None = 0,
+    [pbr::OriginalName("GZIP")] Gzip = 1,
+    [pbr::OriginalName("DEFLATE")] Deflate = 2,
   }
 
   #endregion
@@ -139,7 +139,7 @@ namespace Grpc.Testing {
 
     /// <summary>Field number for the "type" field.</summary>
     public const int TypeFieldNumber = 1;
-    private global::Grpc.Testing.PayloadType type_ = global::Grpc.Testing.PayloadType.COMPRESSABLE;
+    private global::Grpc.Testing.PayloadType type_ = 0;
     /// <summary>
     ///  The type of data in body.
     /// </summary>
@@ -159,7 +159,7 @@ namespace Grpc.Testing {
     public pb::ByteString Body {
       get { return body_; }
       set {
-        body_ = pb::Preconditions.CheckNotNull(value, "value");
+        body_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
       }
     }
 
@@ -181,7 +181,7 @@ namespace Grpc.Testing {
 
     public override int GetHashCode() {
       int hash = 1;
-      if (Type != global::Grpc.Testing.PayloadType.COMPRESSABLE) hash ^= Type.GetHashCode();
+      if (Type != 0) hash ^= Type.GetHashCode();
       if (Body.Length != 0) hash ^= Body.GetHashCode();
       return hash;
     }
@@ -191,7 +191,7 @@ namespace Grpc.Testing {
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
-      if (Type != global::Grpc.Testing.PayloadType.COMPRESSABLE) {
+      if (Type != 0) {
         output.WriteRawTag(8);
         output.WriteEnum((int) Type);
       }
@@ -203,7 +203,7 @@ namespace Grpc.Testing {
 
     public int CalculateSize() {
       int size = 0;
-      if (Type != global::Grpc.Testing.PayloadType.COMPRESSABLE) {
+      if (Type != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Type);
       }
       if (Body.Length != 0) {
@@ -216,7 +216,7 @@ namespace Grpc.Testing {
       if (other == null) {
         return;
       }
-      if (other.Type != global::Grpc.Testing.PayloadType.COMPRESSABLE) {
+      if (other.Type != 0) {
         Type = other.Type;
       }
       if (other.Body.Length != 0) {
@@ -293,7 +293,7 @@ namespace Grpc.Testing {
     public string Message {
       get { return message_; }
       set {
-        message_ = pb::Preconditions.CheckNotNull(value, "value");
+        message_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
       }
     }
 
@@ -417,7 +417,7 @@ namespace Grpc.Testing {
 
     /// <summary>Field number for the "response_type" field.</summary>
     public const int ResponseTypeFieldNumber = 1;
-    private global::Grpc.Testing.PayloadType responseType_ = global::Grpc.Testing.PayloadType.COMPRESSABLE;
+    private global::Grpc.Testing.PayloadType responseType_ = 0;
     /// <summary>
     ///  Desired payload type in the response from the server.
     ///  If response_type is RANDOM, server randomly chooses one from other formats.
@@ -484,7 +484,7 @@ namespace Grpc.Testing {
 
     /// <summary>Field number for the "response_compression" field.</summary>
     public const int ResponseCompressionFieldNumber = 6;
-    private global::Grpc.Testing.CompressionType responseCompression_ = global::Grpc.Testing.CompressionType.NONE;
+    private global::Grpc.Testing.CompressionType responseCompression_ = 0;
     /// <summary>
     ///  Compression algorithm to be used by the server for the response (stream)
     /// </summary>
@@ -531,12 +531,12 @@ namespace Grpc.Testing {
 
     public override int GetHashCode() {
       int hash = 1;
-      if (ResponseType != global::Grpc.Testing.PayloadType.COMPRESSABLE) hash ^= ResponseType.GetHashCode();
+      if (ResponseType != 0) hash ^= ResponseType.GetHashCode();
       if (ResponseSize != 0) hash ^= ResponseSize.GetHashCode();
       if (payload_ != null) hash ^= Payload.GetHashCode();
       if (FillUsername != false) hash ^= FillUsername.GetHashCode();
       if (FillOauthScope != false) hash ^= FillOauthScope.GetHashCode();
-      if (ResponseCompression != global::Grpc.Testing.CompressionType.NONE) hash ^= ResponseCompression.GetHashCode();
+      if (ResponseCompression != 0) hash ^= ResponseCompression.GetHashCode();
       if (responseStatus_ != null) hash ^= ResponseStatus.GetHashCode();
       return hash;
     }
@@ -546,7 +546,7 @@ namespace Grpc.Testing {
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
-      if (ResponseType != global::Grpc.Testing.PayloadType.COMPRESSABLE) {
+      if (ResponseType != 0) {
         output.WriteRawTag(8);
         output.WriteEnum((int) ResponseType);
       }
@@ -566,7 +566,7 @@ namespace Grpc.Testing {
         output.WriteRawTag(40);
         output.WriteBool(FillOauthScope);
       }
-      if (ResponseCompression != global::Grpc.Testing.CompressionType.NONE) {
+      if (ResponseCompression != 0) {
         output.WriteRawTag(48);
         output.WriteEnum((int) ResponseCompression);
       }
@@ -578,7 +578,7 @@ namespace Grpc.Testing {
 
     public int CalculateSize() {
       int size = 0;
-      if (ResponseType != global::Grpc.Testing.PayloadType.COMPRESSABLE) {
+      if (ResponseType != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) ResponseType);
       }
       if (ResponseSize != 0) {
@@ -593,7 +593,7 @@ namespace Grpc.Testing {
       if (FillOauthScope != false) {
         size += 1 + 1;
       }
-      if (ResponseCompression != global::Grpc.Testing.CompressionType.NONE) {
+      if (ResponseCompression != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) ResponseCompression);
       }
       if (responseStatus_ != null) {
@@ -606,7 +606,7 @@ namespace Grpc.Testing {
       if (other == null) {
         return;
       }
-      if (other.ResponseType != global::Grpc.Testing.PayloadType.COMPRESSABLE) {
+      if (other.ResponseType != 0) {
         ResponseType = other.ResponseType;
       }
       if (other.ResponseSize != 0) {
@@ -624,7 +624,7 @@ namespace Grpc.Testing {
       if (other.FillOauthScope != false) {
         FillOauthScope = other.FillOauthScope;
       }
-      if (other.ResponseCompression != global::Grpc.Testing.CompressionType.NONE) {
+      if (other.ResponseCompression != 0) {
         ResponseCompression = other.ResponseCompression;
       }
       if (other.responseStatus_ != null) {
@@ -737,7 +737,7 @@ namespace Grpc.Testing {
     public string Username {
       get { return username_; }
       set {
-        username_ = pb::Preconditions.CheckNotNull(value, "value");
+        username_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
       }
     }
 
@@ -750,7 +750,7 @@ namespace Grpc.Testing {
     public string OauthScope {
       get { return oauthScope_; }
       set {
-        oauthScope_ = pb::Preconditions.CheckNotNull(value, "value");
+        oauthScope_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
       }
     }
 
@@ -1259,7 +1259,7 @@ namespace Grpc.Testing {
 
     /// <summary>Field number for the "response_type" field.</summary>
     public const int ResponseTypeFieldNumber = 1;
-    private global::Grpc.Testing.PayloadType responseType_ = global::Grpc.Testing.PayloadType.COMPRESSABLE;
+    private global::Grpc.Testing.PayloadType responseType_ = 0;
     /// <summary>
     ///  Desired payload type in the response from the server.
     ///  If response_type is RANDOM, the payload from each response in the stream
@@ -1300,7 +1300,7 @@ namespace Grpc.Testing {
 
     /// <summary>Field number for the "response_compression" field.</summary>
     public const int ResponseCompressionFieldNumber = 6;
-    private global::Grpc.Testing.CompressionType responseCompression_ = global::Grpc.Testing.CompressionType.NONE;
+    private global::Grpc.Testing.CompressionType responseCompression_ = 0;
     /// <summary>
     ///  Compression algorithm to be used by the server for the response (stream)
     /// </summary>
@@ -1345,10 +1345,10 @@ namespace Grpc.Testing {
 
     public override int GetHashCode() {
       int hash = 1;
-      if (ResponseType != global::Grpc.Testing.PayloadType.COMPRESSABLE) hash ^= ResponseType.GetHashCode();
+      if (ResponseType != 0) hash ^= ResponseType.GetHashCode();
       hash ^= responseParameters_.GetHashCode();
       if (payload_ != null) hash ^= Payload.GetHashCode();
-      if (ResponseCompression != global::Grpc.Testing.CompressionType.NONE) hash ^= ResponseCompression.GetHashCode();
+      if (ResponseCompression != 0) hash ^= ResponseCompression.GetHashCode();
       if (responseStatus_ != null) hash ^= ResponseStatus.GetHashCode();
       return hash;
     }
@@ -1358,7 +1358,7 @@ namespace Grpc.Testing {
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
-      if (ResponseType != global::Grpc.Testing.PayloadType.COMPRESSABLE) {
+      if (ResponseType != 0) {
         output.WriteRawTag(8);
         output.WriteEnum((int) ResponseType);
       }
@@ -1367,7 +1367,7 @@ namespace Grpc.Testing {
         output.WriteRawTag(26);
         output.WriteMessage(Payload);
       }
-      if (ResponseCompression != global::Grpc.Testing.CompressionType.NONE) {
+      if (ResponseCompression != 0) {
         output.WriteRawTag(48);
         output.WriteEnum((int) ResponseCompression);
       }
@@ -1379,14 +1379,14 @@ namespace Grpc.Testing {
 
     public int CalculateSize() {
       int size = 0;
-      if (ResponseType != global::Grpc.Testing.PayloadType.COMPRESSABLE) {
+      if (ResponseType != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) ResponseType);
       }
       size += responseParameters_.CalculateSize(_repeated_responseParameters_codec);
       if (payload_ != null) {
         size += 1 + pb::CodedOutputStream.ComputeMessageSize(Payload);
       }
-      if (ResponseCompression != global::Grpc.Testing.CompressionType.NONE) {
+      if (ResponseCompression != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) ResponseCompression);
       }
       if (responseStatus_ != null) {
@@ -1399,7 +1399,7 @@ namespace Grpc.Testing {
       if (other == null) {
         return;
       }
-      if (other.ResponseType != global::Grpc.Testing.PayloadType.COMPRESSABLE) {
+      if (other.ResponseType != 0) {
         ResponseType = other.ResponseType;
       }
       responseParameters_.Add(other.responseParameters_);
@@ -1409,7 +1409,7 @@ namespace Grpc.Testing {
         }
         Payload.MergeFrom(other.Payload);
       }
-      if (other.ResponseCompression != global::Grpc.Testing.CompressionType.NONE) {
+      if (other.ResponseCompression != 0) {
         ResponseCompression = other.ResponseCompression;
       }
       if (other.responseStatus_ != null) {
diff --git a/src/csharp/Grpc.IntegrationTesting/Metrics.cs b/src/csharp/Grpc.IntegrationTesting/Metrics.cs
index 3163949d32..8f31fbc2a9 100644
--- a/src/csharp/Grpc.IntegrationTesting/Metrics.cs
+++ b/src/csharp/Grpc.IntegrationTesting/Metrics.cs
@@ -34,10 +34,10 @@ namespace Grpc.Testing {
             "dWdlUmVzcG9uc2ViBnByb3RvMw=="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
-          new pbr::GeneratedCodeInfo(null, new pbr::GeneratedCodeInfo[] {
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.GaugeResponse), global::Grpc.Testing.GaugeResponse.Parser, new[]{ "Name", "LongValue", "DoubleValue", "StringValue" }, new[]{ "Value" }, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.GaugeRequest), global::Grpc.Testing.GaugeRequest.Parser, new[]{ "Name" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.EmptyMessage), global::Grpc.Testing.EmptyMessage.Parser, null, null, null, null)
+          new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.GaugeResponse), global::Grpc.Testing.GaugeResponse.Parser, new[]{ "Name", "LongValue", "DoubleValue", "StringValue" }, new[]{ "Value" }, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.GaugeRequest), global::Grpc.Testing.GaugeRequest.Parser, new[]{ "Name" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.EmptyMessage), global::Grpc.Testing.EmptyMessage.Parser, null, null, null, null)
           }));
     }
     #endregion
@@ -92,7 +92,7 @@ namespace Grpc.Testing {
     public string Name {
       get { return name_; }
       set {
-        name_ = pb::Preconditions.CheckNotNull(value, "value");
+        name_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
       }
     }
 
@@ -121,7 +121,7 @@ namespace Grpc.Testing {
     public string StringValue {
       get { return valueCase_ == ValueOneofCase.StringValue ? (string) value_ : ""; }
       set {
-        value_ = pb::Preconditions.CheckNotNull(value, "value");
+        value_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
         valueCase_ = ValueOneofCase.StringValue;
       }
     }
@@ -299,7 +299,7 @@ namespace Grpc.Testing {
     public string Name {
       get { return name_; }
       set {
-        name_ = pb::Preconditions.CheckNotNull(value, "value");
+        name_ = pb::ProtoPreconditions.CheckNotNull(value, "value");
       }
     }
 
diff --git a/src/csharp/Grpc.IntegrationTesting/Payloads.cs b/src/csharp/Grpc.IntegrationTesting/Payloads.cs
index 663f625aa7..3ad7a44f4b 100644
--- a/src/csharp/Grpc.IntegrationTesting/Payloads.cs
+++ b/src/csharp/Grpc.IntegrationTesting/Payloads.cs
@@ -34,11 +34,11 @@ namespace Grpc.Testing {
             "aW5nLkNvbXBsZXhQcm90b1BhcmFtc0gAQgkKB3BheWxvYWRiBnByb3RvMw=="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
-          new pbr::GeneratedCodeInfo(null, new pbr::GeneratedCodeInfo[] {
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ByteBufferParams), global::Grpc.Testing.ByteBufferParams.Parser, new[]{ "ReqSize", "RespSize" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.SimpleProtoParams), global::Grpc.Testing.SimpleProtoParams.Parser, new[]{ "ReqSize", "RespSize" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ComplexProtoParams), global::Grpc.Testing.ComplexProtoParams.Parser, null, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.PayloadConfig), global::Grpc.Testing.PayloadConfig.Parser, new[]{ "BytebufParams", "SimpleParams", "ComplexParams" }, new[]{ "Payload" }, null, null)
+          new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ByteBufferParams), global::Grpc.Testing.ByteBufferParams.Parser, new[]{ "ReqSize", "RespSize" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.SimpleProtoParams), global::Grpc.Testing.SimpleProtoParams.Parser, new[]{ "ReqSize", "RespSize" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ComplexProtoParams), global::Grpc.Testing.ComplexProtoParams.Parser, null, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.PayloadConfig), global::Grpc.Testing.PayloadConfig.Parser, new[]{ "BytebufParams", "SimpleParams", "ComplexParams" }, new[]{ "Payload" }, null, null)
           }));
     }
     #endregion
diff --git a/src/csharp/Grpc.IntegrationTesting/RunnerClientServerTest.cs b/src/csharp/Grpc.IntegrationTesting/RunnerClientServerTest.cs
index 13ab5a25ab..b2f2e4d691 100644
--- a/src/csharp/Grpc.IntegrationTesting/RunnerClientServerTest.cs
+++ b/src/csharp/Grpc.IntegrationTesting/RunnerClientServerTest.cs
@@ -55,7 +55,7 @@ namespace Grpc.IntegrationTesting
         {
             var serverConfig = new ServerConfig
             {
-                ServerType = ServerType.ASYNC_SERVER
+                ServerType = ServerType.AsyncServer
             };
             serverRunner = ServerRunners.CreateStarted(serverConfig);
         }
@@ -75,7 +75,7 @@ namespace Grpc.IntegrationTesting
             var config = new ClientConfig
             {
                 ServerTargets = { string.Format("{0}:{1}", "localhost", serverRunner.BoundPort) },
-                RpcType = RpcType.UNARY,
+                RpcType = RpcType.Unary,
                 LoadParams = new LoadParams { ClosedLoop = new ClosedLoopParams() },
                 PayloadConfig = new PayloadConfig
                 {
diff --git a/src/csharp/Grpc.IntegrationTesting/ServerRunners.cs b/src/csharp/Grpc.IntegrationTesting/ServerRunners.cs
index d7859443e0..8689d188ae 100644
--- a/src/csharp/Grpc.IntegrationTesting/ServerRunners.cs
+++ b/src/csharp/Grpc.IntegrationTesting/ServerRunners.cs
@@ -77,13 +77,13 @@ namespace Grpc.IntegrationTesting
             }
 
             ServerServiceDefinition service = null;
-            if (config.ServerType == ServerType.ASYNC_SERVER)
+            if (config.ServerType == ServerType.AsyncServer)
             {
                 GrpcPreconditions.CheckArgument(config.PayloadConfig == null,
                     "ServerConfig.PayloadConfig shouldn't be set for BenchmarkService based server.");    
                 service = BenchmarkService.BindService(new BenchmarkServiceImpl());
             }
-            else if (config.ServerType == ServerType.ASYNC_GENERIC_SERVER)
+            else if (config.ServerType == ServerType.AsyncGenericServer)
             {
                 var genericService = new GenericServiceImpl(config.PayloadConfig.BytebufParams.RespSize);
                 service = GenericService.BindHandler(genericService.StreamingCall);
diff --git a/src/csharp/Grpc.IntegrationTesting/Services.cs b/src/csharp/Grpc.IntegrationTesting/Services.cs
index a8475c1817..e10b45c9a2 100644
--- a/src/csharp/Grpc.IntegrationTesting/Services.cs
+++ b/src/csharp/Grpc.IntegrationTesting/Services.cs
@@ -39,7 +39,7 @@ namespace Grpc.Testing {
             "YgZwcm90bzM="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { global::Grpc.Testing.MessagesReflection.Descriptor, global::Grpc.Testing.ControlReflection.Descriptor, },
-          new pbr::GeneratedCodeInfo(null, null));
+          new pbr::GeneratedClrTypeInfo(null, null));
     }
     #endregion
 
diff --git a/src/csharp/Grpc.IntegrationTesting/Stats.cs b/src/csharp/Grpc.IntegrationTesting/Stats.cs
index 39c00ea88c..304d676113 100644
--- a/src/csharp/Grpc.IntegrationTesting/Stats.cs
+++ b/src/csharp/Grpc.IntegrationTesting/Stats.cs
@@ -35,11 +35,11 @@ namespace Grpc.Testing {
             "ZXIYAyABKAESEwoLdGltZV9zeXN0ZW0YBCABKAFiBnByb3RvMw=="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
-          new pbr::GeneratedCodeInfo(null, new pbr::GeneratedCodeInfo[] {
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ServerStats), global::Grpc.Testing.ServerStats.Parser, new[]{ "TimeElapsed", "TimeUser", "TimeSystem" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.HistogramParams), global::Grpc.Testing.HistogramParams.Parser, new[]{ "Resolution", "MaxPossible" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.HistogramData), global::Grpc.Testing.HistogramData.Parser, new[]{ "Bucket", "MinSeen", "MaxSeen", "Sum", "SumOfSquares", "Count" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.ClientStats), global::Grpc.Testing.ClientStats.Parser, new[]{ "Latencies", "TimeElapsed", "TimeUser", "TimeSystem" }, null, null, null)
+          new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ServerStats), global::Grpc.Testing.ServerStats.Parser, new[]{ "TimeElapsed", "TimeUser", "TimeSystem" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.HistogramParams), global::Grpc.Testing.HistogramParams.Parser, new[]{ "Resolution", "MaxPossible" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.HistogramData), global::Grpc.Testing.HistogramData.Parser, new[]{ "Bucket", "MinSeen", "MaxSeen", "Sum", "SumOfSquares", "Count" }, null, null, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Grpc.Testing.ClientStats), global::Grpc.Testing.ClientStats.Parser, new[]{ "Latencies", "TimeElapsed", "TimeUser", "TimeSystem" }, null, null, null)
           }));
     }
     #endregion
diff --git a/src/csharp/Grpc.IntegrationTesting/Test.cs b/src/csharp/Grpc.IntegrationTesting/Test.cs
index 363f6444ec..9258dc185d 100644
--- a/src/csharp/Grpc.IntegrationTesting/Test.cs
+++ b/src/csharp/Grpc.IntegrationTesting/Test.cs
@@ -46,7 +46,7 @@ namespace Grpc.Testing {
             "cnBjLnRlc3RpbmcuUmVjb25uZWN0SW5mb2IGcHJvdG8z"));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { global::Grpc.Testing.EmptyReflection.Descriptor, global::Grpc.Testing.MessagesReflection.Descriptor, },
-          new pbr::GeneratedCodeInfo(null, null));
+          new pbr::GeneratedClrTypeInfo(null, null));
     }
     #endregion
 
diff --git a/src/csharp/Grpc.IntegrationTesting/WorkerServiceImpl.cs b/src/csharp/Grpc.IntegrationTesting/WorkerServiceImpl.cs
index 80dad9fdd9..c9eca73452 100644
--- a/src/csharp/Grpc.IntegrationTesting/WorkerServiceImpl.cs
+++ b/src/csharp/Grpc.IntegrationTesting/WorkerServiceImpl.cs
@@ -64,7 +64,7 @@ namespace Grpc.Testing
             {
                 Stats = runner.GetStats(false),
                 Port = runner.BoundPort,
-                Cores = 0,  // TODO: set number of cores
+                Cores = Environment.ProcessorCount,
             });
                 
             while (await requestStream.MoveNext())
diff --git a/src/csharp/Grpc.IntegrationTesting/packages.config b/src/csharp/Grpc.IntegrationTesting/packages.config
index 3fef67dca4..3161c5b755 100644
--- a/src/csharp/Grpc.IntegrationTesting/packages.config
+++ b/src/csharp/Grpc.IntegrationTesting/packages.config
@@ -4,7 +4,7 @@
   <package id="CommandLineParser" version="1.9.71" targetFramework="net45" />
   <package id="Google.Apis.Auth" version="1.11.1" targetFramework="net45" />
   <package id="Google.Apis.Core" version="1.11.1" targetFramework="net45" />
-  <package id="Google.Protobuf" version="3.0.0-beta2" targetFramework="net45" />
+  <package id="Google.Protobuf" version="3.0.0-beta3" targetFramework="net45" />
   <package id="Ix-Async" version="1.2.5" targetFramework="net45" />
   <package id="Moq" version="4.2.1510.2205" targetFramework="net45" />
   <package id="Newtonsoft.Json" version="7.0.1" targetFramework="net45" />
diff --git a/src/csharp/build_packages.bat b/src/csharp/build_packages.bat
index 28e4262121..1cc63da970 100644
--- a/src/csharp/build_packages.bat
+++ b/src/csharp/build_packages.bat
@@ -31,7 +31,7 @@
 
 @rem Current package versions
 set VERSION=0.15.0-dev
-set PROTOBUF_VERSION=3.0.0-beta2
+set PROTOBUF_VERSION=3.0.0-beta3
 
 @rem Packages that depend on prerelease packages (like Google.Protobuf) need to have prerelease suffix as well.
 set VERSION_WITH_BETA=%VERSION%-beta
diff --git a/src/csharp/ext/grpc_csharp_ext.c b/src/csharp/ext/grpc_csharp_ext.c
index 49198cb708..4782654250 100644
--- a/src/csharp/ext/grpc_csharp_ext.c
+++ b/src/csharp/ext/grpc_csharp_ext.c
@@ -45,7 +45,7 @@
 
 #include <string.h>
 
-#ifdef GPR_WIN32
+#ifdef GPR_WINDOWS
 #define GPR_EXPORT __declspec(dllexport)
 #define GPR_CALLTYPE __stdcall
 #endif
@@ -809,11 +809,14 @@ GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_set_credentials(
 /* Server */
 
 GPR_EXPORT grpc_server *GPR_CALLTYPE
-grpcsharp_server_create(grpc_completion_queue *cq,
-                        const grpc_channel_args *args) {
-  grpc_server *server = grpc_server_create(args, NULL);
+grpcsharp_server_create(const grpc_channel_args *args) {
+  return grpc_server_create(args, NULL);
+}
+
+GPR_EXPORT void GPR_CALLTYPE
+grpcsharp_server_register_completion_queue(grpc_server *server,
+                                           grpc_completion_queue *cq) {
   grpc_server_register_completion_queue(server, cq, NULL);
-  return server;
 }
 
 GPR_EXPORT int32_t GPR_CALLTYPE