Merge pull request #2597 from jtattermusch/csharp_metadata

Improving C# metadata API

src/compiler/csharp_generator.cc

@@ -149,7 +149,7 @@ std::string GetMethodRequestParamMaybe(const MethodDescriptor *method) {
 std::string GetMethodReturnTypeClient(const MethodDescriptor *method) {
   switch (GetMethodType(method)) {
     case METHODTYPE_NO_STREAMING:
-      return "Task<" + GetClassName(method->output_type()) + ">";
+      return "AsyncUnaryCall<" + GetClassName(method->output_type()) + ">";
     case METHODTYPE_CLIENT_STREAMING:
       return "AsyncClientStreamingCall<" + GetClassName(method->input_type())
           + ", " + GetClassName(method->output_type()) + ">";
@@ -298,7 +298,7 @@ void GenerateServerInterface(Printer* out, const ServiceDescriptor *service) {
   out->Indent();
   for (int i = 0; i < service->method_count(); i++) {
     const MethodDescriptor *method = service->method(i);
-    out->Print("$returntype$ $methodname$(ServerCallContext context, $request$$response_stream_maybe$);\n",
+    out->Print("$returntype$ $methodname$($request$$response_stream_maybe$, ServerCallContext context);\n",
                "methodname", method->name(), "returntype",
                GetMethodReturnTypeServer(method), "request",
                GetMethodRequestParamServer(method), "response_stream_maybe",

src/csharp/Grpc.Core.Tests/ClientServerTest.cs

@@ -99,17 +99,17 @@ namespace Grpc.Core.Tests
         [Test]
         public void UnaryCall()
         {
-            var call = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
+            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
-            Assert.AreEqual("ABC", Calls.BlockingUnaryCall(call, "ABC", CancellationToken.None));
+            Assert.AreEqual("ABC", Calls.BlockingUnaryCall(internalCall, "ABC", CancellationToken.None));
         }
 
         [Test]
         public void UnaryCall_ServerHandlerThrows()
         {
-            var call = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
+            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
             try
             {
-                Calls.BlockingUnaryCall(call, "THROW", CancellationToken.None);
+                Calls.BlockingUnaryCall(internalCall, "THROW", CancellationToken.None);
                 Assert.Fail();
             }
             catch (RpcException e)
@@ -118,11 +118,41 @@ namespace Grpc.Core.Tests
             }
         }
 
+        [Test]
+        public void UnaryCall_ServerHandlerThrowsRpcException()
+        {
+            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
+            try
+            {
+                Calls.BlockingUnaryCall(internalCall, "THROW_UNAUTHENTICATED", CancellationToken.None);
+                Assert.Fail();
+            }
+            catch (RpcException e)
+            {
+                Assert.AreEqual(StatusCode.Unauthenticated, e.Status.StatusCode);
+            }
+        }
+
+        [Test]
+        public void UnaryCall_ServerHandlerSetsStatus()
+        {
+            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
+            try
+            {
+                Calls.BlockingUnaryCall(internalCall, "SET_UNAUTHENTICATED", CancellationToken.None);
+                Assert.Fail();
+            }
+            catch (RpcException e)
+            {
+                Assert.AreEqual(StatusCode.Unauthenticated, e.Status.StatusCode); 
+            }
+        }
+
         [Test]
         public void AsyncUnaryCall()
         {
-            var call = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
+            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
-            var result = Calls.AsyncUnaryCall(call, "ABC", CancellationToken.None).Result;
+            var result = Calls.AsyncUnaryCall(internalCall, "ABC", CancellationToken.None).ResponseAsync.Result;
             Assert.AreEqual("ABC", result);
         }
 
@@ -131,10 +161,10 @@ namespace Grpc.Core.Tests
         {
             Task.Run(async () =>
             {
-                var call = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
+                var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
                 try
                 {
-                    await Calls.AsyncUnaryCall(call, "THROW", CancellationToken.None);
+                    await Calls.AsyncUnaryCall(internalCall, "THROW", CancellationToken.None);
                     Assert.Fail();
                 }
                 catch (RpcException e)
@@ -149,11 +179,11 @@ namespace Grpc.Core.Tests
         {
             Task.Run(async () => 
             {
-                var call = new Call<string, string>(ServiceName, ConcatAndEchoMethod, channel, Metadata.Empty);
+                var internalCall = new Call<string, string>(ServiceName, ConcatAndEchoMethod, channel, Metadata.Empty);
-                var callResult = Calls.AsyncClientStreamingCall(call, CancellationToken.None);
+                var call = Calls.AsyncClientStreamingCall(internalCall, CancellationToken.None);
 
-                await callResult.RequestStream.WriteAll(new string[] { "A", "B", "C" });
+                await call.RequestStream.WriteAll(new string[] { "A", "B", "C" });
-                Assert.AreEqual("ABC", await callResult.Result);
+                Assert.AreEqual("ABC", await call.ResponseAsync);
             }).Wait();
         }
 
@@ -162,10 +192,10 @@ namespace Grpc.Core.Tests
         {
             Task.Run(async () => 
             {
-                var call = new Call<string, string>(ServiceName, ConcatAndEchoMethod, channel, Metadata.Empty);
+                var internalCall = new Call<string, string>(ServiceName, ConcatAndEchoMethod, channel, Metadata.Empty);
 
                 var cts = new CancellationTokenSource();
-                var callResult = Calls.AsyncClientStreamingCall(call, cts.Token);
+                var call = Calls.AsyncClientStreamingCall(internalCall, cts.Token);
 
                 // TODO(jtattermusch): we need this to ensure call has been initiated once we cancel it.
                 await Task.Delay(1000);
@@ -173,7 +203,7 @@ namespace Grpc.Core.Tests
 
                 try
                 {
-                    await callResult.Result;
+                    await call.ResponseAsync;
                 }
                 catch (RpcException e)
                 {
@@ -182,30 +212,54 @@ namespace Grpc.Core.Tests
             }).Wait();
         }
 
+        [Test]
+        public void AsyncUnaryCall_EchoMetadata()
+        {
+            var headers = new Metadata
+            {
+                new Metadata.Entry("asciiHeader", "abcdefg"),
+                new Metadata.Entry("binaryHeader-bin", new byte[] { 1, 2, 3, 0, 0xff } ),
+            };
+            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, headers);
+            var call = Calls.AsyncUnaryCall(internalCall, "ABC", CancellationToken.None);
+
+            Assert.AreEqual("ABC", call.ResponseAsync.Result);
+
+            Assert.AreEqual(StatusCode.OK, call.GetStatus().StatusCode);
+
+            var trailers = call.GetTrailers();
+            Assert.AreEqual(2, trailers.Count);
+            Assert.AreEqual(headers[0].Key, trailers[0].Key);
+            Assert.AreEqual(headers[0].Value, trailers[0].Value);
+
+            Assert.AreEqual(headers[1].Key, trailers[1].Key);
+            CollectionAssert.AreEqual(headers[1].ValueBytes, trailers[1].ValueBytes);
+        }
+
         [Test]
         public void UnaryCall_DisposedChannel()
         {
             channel.Dispose();
 
-            var call = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
+            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
-            Assert.Throws(typeof(ObjectDisposedException), () => Calls.BlockingUnaryCall(call, "ABC", CancellationToken.None));
+            Assert.Throws(typeof(ObjectDisposedException), () => Calls.BlockingUnaryCall(internalCall, "ABC", CancellationToken.None));
         }
 
         [Test]
         public void UnaryCallPerformance()
         {
-            var call = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
+            var internalCall = new Call<string, string>(ServiceName, EchoMethod, channel, Metadata.Empty);
             BenchmarkUtil.RunBenchmark(100, 100,
-                                       () => { Calls.BlockingUnaryCall(call, "ABC", default(CancellationToken)); });
+                                       () => { Calls.BlockingUnaryCall(internalCall, "ABC", default(CancellationToken)); });
         }
             
         [Test]
         public void UnknownMethodHandler()
         {
-            var call = new Call<string, string>(ServiceName, NonexistentMethod, channel, Metadata.Empty);
+            var internalCall = new Call<string, string>(ServiceName, NonexistentMethod, channel, Metadata.Empty);
             try
             {
-                Calls.BlockingUnaryCall(call, "ABC", default(CancellationToken));
+                Calls.BlockingUnaryCall(internalCall, "ABC", default(CancellationToken));
                 Assert.Fail();
             }
             catch (RpcException e)
@@ -214,16 +268,33 @@ namespace Grpc.Core.Tests
             }
         }
 
-        private static async Task<string> EchoHandler(ServerCallContext context, string request)
+        private static async Task<string> EchoHandler(string request, ServerCallContext context)
         {
+            foreach (Metadata.Entry metadataEntry in context.RequestHeaders)
+            {
+                Console.WriteLine("Echoing header " + metadataEntry.Key + " as trailer");
+                context.ResponseTrailers.Add(metadataEntry);
+            }
+
             if (request == "THROW")
             {
                 throw new Exception("This was thrown on purpose by a test");
             }
+
+            if (request == "THROW_UNAUTHENTICATED")
+            {
+                throw new RpcException(new Status(StatusCode.Unauthenticated, ""));
+            }
+
+            if (request == "SET_UNAUTHENTICATED")
+            {
+                context.Status = new Status(StatusCode.Unauthenticated, "");
+            }
+
             return request;
         }
 
-        private static async Task<string> ConcatAndEchoHandler(ServerCallContext context, IAsyncStreamReader<string> requestStream)
+        private static async Task<string> ConcatAndEchoHandler(IAsyncStreamReader<string> requestStream, ServerCallContext context)
         {
             string result = "";
             await requestStream.ForEach(async (request) =>

src/csharp/Grpc.Core.Tests/Internal/MetadataArraySafeHandleTest.cs

@@ -59,5 +59,26 @@ namespace Grpc.Core.Internal.Tests
             var nativeMetadata = MetadataArraySafeHandle.Create(metadata);
             nativeMetadata.Dispose();
         }
+
+        [Test]
+        public void ReadMetadataFromPtrUnsafe()
+        {
+            var metadata = new Metadata
+            {
+                new Metadata.Entry("host", "somehost"),
+                new Metadata.Entry("header2", "header value"),
+            };
+            var nativeMetadata = MetadataArraySafeHandle.Create(metadata);
+
+            var copy = MetadataArraySafeHandle.ReadMetadataFromPtrUnsafe(nativeMetadata.Handle);
+            Assert.AreEqual(2, copy.Count);
+
+            Assert.AreEqual("host", copy[0].Key);
+            Assert.AreEqual("somehost", copy[0].Value);
+            Assert.AreEqual("header2", copy[1].Key);
+            Assert.AreEqual("header value", copy[1].Value);
+
+            nativeMetadata.Dispose();
+        }
     }
 }

src/csharp/Grpc.Core.Tests/TimespecTest.cs

@@ -58,6 +58,19 @@ namespace Grpc.Core.Internal.Tests
             Assert.AreEqual(Timespec.NativeSize, Marshal.SizeOf(typeof(Timespec)));
         }
 
+        [Test]
+        public void ToDateTime()
+        {
+            Assert.AreEqual(new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc),
+                new Timespec(IntPtr.Zero, 0).ToDateTime());
+
+            Assert.AreEqual(new DateTime(1970, 1, 1, 0, 0, 10, DateTimeKind.Utc).AddTicks(50),
+                new Timespec(new IntPtr(10), 5000).ToDateTime());
+
+            Assert.AreEqual(new DateTime(2015, 7, 21, 4, 21, 48, DateTimeKind.Utc),
+                new Timespec(new IntPtr(1437452508), 0).ToDateTime());
+        }
+
         [Test]
         public void Add()
         {

src/csharp/Grpc.Core/AsyncClientStreamingCall.cs

@@ -43,24 +43,28 @@ namespace Grpc.Core
     public sealed class AsyncClientStreamingCall<TRequest, TResponse> : IDisposable
     {
         readonly IClientStreamWriter<TRequest> requestStream;
-        readonly Task<TResponse> result;
+        readonly Task<TResponse> responseAsync;
+        readonly Func<Status> getStatusFunc;
+        readonly Func<Metadata> getTrailersFunc;
         readonly Action disposeAction;
 
-        public AsyncClientStreamingCall(IClientStreamWriter<TRequest> requestStream, Task<TResponse> result, Action disposeAction)
+        public AsyncClientStreamingCall(IClientStreamWriter<TRequest> requestStream, Task<TResponse> responseAsync, Func<Status> getStatusFunc, Func<Metadata> getTrailersFunc, Action disposeAction)
         {
             this.requestStream = requestStream;
-            this.result = result;
+            this.responseAsync = responseAsync;
+            this.getStatusFunc = getStatusFunc;
+            this.getTrailersFunc = getTrailersFunc;
             this.disposeAction = disposeAction;
         }
 
         /// <summary>
         /// Asynchronous call result.
         /// </summary>
-        public Task<TResponse> Result
+        public Task<TResponse> ResponseAsync
         {
             get
             {
-                return this.result;
+                return this.responseAsync;
             }
         }
 
@@ -81,11 +85,11 @@ namespace Grpc.Core
         /// <returns></returns>
         public TaskAwaiter<TResponse> GetAwaiter()
         {
-            return result.GetAwaiter();
+            return responseAsync.GetAwaiter();
         }
 
         /// <summary>
-        /// Provides means to provide after the call.
+        /// Provides means to cleanup after the call.
         /// If the call has already finished normally (request stream has been completed and call result has been received), doesn't do anything.
         /// Otherwise, requests cancellation of the call which should terminate all pending async operations associated with the call.
         /// As a result, all resources being used by the call should be released eventually.

src/csharp/Grpc.Core/AsyncDuplexStreamingCall.cs

@@ -44,15 +44,20 @@ namespace Grpc.Core
     {
         readonly IClientStreamWriter<TRequest> requestStream;
         readonly IAsyncStreamReader<TResponse> responseStream;
+        readonly Func<Status> getStatusFunc;
+        readonly Func<Metadata> getTrailersFunc;
         readonly Action disposeAction;
 
-        public AsyncDuplexStreamingCall(IClientStreamWriter<TRequest> requestStream, IAsyncStreamReader<TResponse> responseStream, Action disposeAction)
+        public AsyncDuplexStreamingCall(IClientStreamWriter<TRequest> requestStream, IAsyncStreamReader<TResponse> responseStream, Func<Status> getStatusFunc, Func<Metadata> getTrailersFunc, Action disposeAction)
         {
             this.requestStream = requestStream;
             this.responseStream = responseStream;
+            this.getStatusFunc = getStatusFunc;
+            this.getTrailersFunc = getTrailersFunc;
             this.disposeAction = disposeAction;
         }
         
+
         /// <summary>
         /// Async stream to read streaming responses.
         /// </summary>
@@ -75,6 +80,24 @@ namespace Grpc.Core
             }
         }
 
+        /// <summary>
+        /// Gets the call status if the call has already finished.
+        /// Throws InvalidOperationException otherwise.
+        /// </summary>
+        public Status GetStatus()
+        {
+            return getStatusFunc();
+        }
+
+        /// <summary>
+        /// Gets the call trailing metadata if the call has already finished.
+        /// Throws InvalidOperationException otherwise.
+        /// </summary>
+        public Metadata GetTrailers()
+        {
+            return getTrailersFunc();
+        }
+
         /// <summary>
         /// Provides means to cleanup after the call.
         /// If the call has already finished normally (request stream has been completed and response stream has been fully read), doesn't do anything.

src/csharp/Grpc.Core/AsyncServerStreamingCall.cs

@@ -43,11 +43,15 @@ namespace Grpc.Core
     public sealed class AsyncServerStreamingCall<TResponse> : IDisposable
     {
         readonly IAsyncStreamReader<TResponse> responseStream;
+        readonly Func<Status> getStatusFunc;
+        readonly Func<Metadata> getTrailersFunc;
         readonly Action disposeAction;
 
-        public AsyncServerStreamingCall(IAsyncStreamReader<TResponse> responseStream, Action disposeAction)
+        public AsyncServerStreamingCall(IAsyncStreamReader<TResponse> responseStream, Func<Status> getStatusFunc, Func<Metadata> getTrailersFunc, Action disposeAction)
         {
             this.responseStream = responseStream;
+            this.getStatusFunc = getStatusFunc;
+            this.getTrailersFunc = getTrailersFunc;
             this.disposeAction = disposeAction;
         }
 
@@ -62,6 +66,24 @@ namespace Grpc.Core
             }
         }
 
+        /// <summary>
+        /// Gets the call status if the call has already finished.
+        /// Throws InvalidOperationException otherwise.
+        /// </summary>
+        public Status GetStatus()
+        {
+            return getStatusFunc();
+        }
+
+        /// <summary>
+        /// Gets the call trailing metadata if the call has already finished.
+        /// Throws InvalidOperationException otherwise.
+        /// </summary>
+        public Metadata GetTrailers()
+        {
+            return getTrailersFunc();
+        }
+
         /// <summary>
         /// Provides means to cleanup after the call.
         /// If the call has already finished normally (response stream has been fully read), doesn't do anything.

src/csharp/Grpc.Core/AsyncUnaryCall.cs

@@ -0,0 +1,106 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Runtime.CompilerServices;
+using System.Threading.Tasks;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// Return type for single request - single response call.
+    /// </summary>
+    public sealed class AsyncUnaryCall<TResponse> : IDisposable
+    {
+        readonly Task<TResponse> responseAsync;
+        readonly Func<Status> getStatusFunc;
+        readonly Func<Metadata> getTrailersFunc;
+        readonly Action disposeAction;
+
+        public AsyncUnaryCall(Task<TResponse> responseAsync, Func<Status> getStatusFunc, Func<Metadata> getTrailersFunc, Action disposeAction)
+        {
+            this.responseAsync = responseAsync;
+            this.getStatusFunc = getStatusFunc;
+            this.getTrailersFunc = getTrailersFunc;
+            this.disposeAction = disposeAction;
+        }
+
+        /// <summary>
+        /// Asynchronous call result.
+        /// </summary>
+        public Task<TResponse> ResponseAsync
+        {
+            get
+            {
+                return this.responseAsync;
+            }
+        }
+
+        /// <summary>
+        /// Allows awaiting this object directly.
+        /// </summary>
+        public TaskAwaiter<TResponse> GetAwaiter()
+        {
+            return responseAsync.GetAwaiter();
+        }
+
+        /// <summary>
+        /// Gets the call status if the call has already finished.
+        /// Throws InvalidOperationException otherwise.
+        /// </summary>
+        public Status GetStatus()
+        {
+            return getStatusFunc();
+        }
+
+        /// <summary>
+        /// Gets the call trailing metadata if the call has already finished.
+        /// Throws InvalidOperationException otherwise.
+        /// </summary>
+        public Metadata GetTrailers()
+        {
+            return getTrailersFunc();
+        }
+
+        /// <summary>
+        /// Provides means to cleanup after the call.
+        /// If the call has already finished normally (request stream has been completed and call result has been received), doesn't do anything.
+        /// Otherwise, requests cancellation of the call which should terminate all pending async operations associated with the call.
+        /// As a result, all resources being used by the call should be released eventually.
+        /// </summary>
+        public void Dispose()
+        {
+            disposeAction.Invoke();
+        }
+    }
+}

src/csharp/Grpc.Core/Calls.cs

@@ -53,7 +53,7 @@ namespace Grpc.Core
             return asyncCall.UnaryCall(call.Channel, call.Name, req, call.Headers);
         }
 
-        public static async Task<TResponse> AsyncUnaryCall<TRequest, TResponse>(Call<TRequest, TResponse> call, TRequest req, CancellationToken token)
+        public static AsyncUnaryCall<TResponse> AsyncUnaryCall<TRequest, TResponse>(Call<TRequest, TResponse> call, TRequest req, CancellationToken token)
             where TRequest : class
             where TResponse : class
         {
@@ -61,7 +61,7 @@ namespace Grpc.Core
             asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name);
             var asyncResult = asyncCall.UnaryCallAsync(req, call.Headers);
             RegisterCancellationCallback(asyncCall, token);
-            return await asyncResult;
+            return new AsyncUnaryCall<TResponse>(asyncResult, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
         }
 
         public static AsyncServerStreamingCall<TResponse> AsyncServerStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, TRequest req, CancellationToken token)
@@ -73,7 +73,7 @@ namespace Grpc.Core
             asyncCall.StartServerStreamingCall(req, call.Headers);
             RegisterCancellationCallback(asyncCall, token);
             var responseStream = new ClientResponseStream<TRequest, TResponse>(asyncCall);
-            return new AsyncServerStreamingCall<TResponse>(responseStream, asyncCall.Cancel);
+            return new AsyncServerStreamingCall<TResponse>(responseStream, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
         }
 
         public static AsyncClientStreamingCall<TRequest, TResponse> AsyncClientStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, CancellationToken token)
@@ -85,7 +85,7 @@ namespace Grpc.Core
             var resultTask = asyncCall.ClientStreamingCallAsync(call.Headers);
             RegisterCancellationCallback(asyncCall, token);
             var requestStream = new ClientRequestStream<TRequest, TResponse>(asyncCall);
-            return new AsyncClientStreamingCall<TRequest, TResponse>(requestStream, resultTask, asyncCall.Cancel);
+            return new AsyncClientStreamingCall<TRequest, TResponse>(requestStream, resultTask, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
         }
 
         public static AsyncDuplexStreamingCall<TRequest, TResponse> AsyncDuplexStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, CancellationToken token)
@@ -98,7 +98,7 @@ namespace Grpc.Core
             RegisterCancellationCallback(asyncCall, token);
             var requestStream = new ClientRequestStream<TRequest, TResponse>(asyncCall);
             var responseStream = new ClientResponseStream<TRequest, TResponse>(asyncCall);
-            return new AsyncDuplexStreamingCall<TRequest, TResponse>(requestStream, responseStream, asyncCall.Cancel);
+            return new AsyncDuplexStreamingCall<TRequest, TResponse>(requestStream, responseStream, asyncCall.GetStatus, asyncCall.GetTrailers, asyncCall.Cancel);
         }
 
         private static void RegisterCancellationCallback<TRequest, TResponse>(AsyncCall<TRequest, TResponse> asyncCall, CancellationToken token)

src/csharp/Grpc.Core/Grpc.Core.csproj

@@ -33,13 +33,12 @@
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
-    <Reference Include="System.Collections.Immutable, Version=1.1.36.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-      <SpecificVersion>False</SpecificVersion>
-      <HintPath>..\packages\System.Collections.Immutable.1.1.36\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
-    </Reference>
     <Reference Include="System.Interactive.Async">
       <HintPath>..\packages\Ix-Async.1.2.3\lib\net45\System.Interactive.Async.dll</HintPath>
     </Reference>
+    <Reference Include="System.Collections.Immutable">
+      <HintPath>..\packages\System.Collections.Immutable.1.1.36\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+    </Reference>
   </ItemGroup>
   <ItemGroup>
     <Compile Include="AsyncDuplexStreamingCall.cs" />
@@ -102,6 +101,7 @@
     <Compile Include="Internal\CompletionRegistry.cs" />
     <Compile Include="Internal\BatchContextSafeHandle.cs" />
     <Compile Include="ChannelOptions.cs" />
+    <Compile Include="AsyncUnaryCall.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="Grpc.Core.nuspec" />

src/csharp/Grpc.Core/Internal/AsyncCall.cs

@@ -52,8 +52,8 @@ namespace Grpc.Core.Internal
         // Completion of a pending unary response if not null.
         TaskCompletionSource<TResponse> unaryResponseTcs;
 
-        // Set after status is received. Only used for streaming response calls.
+        // Set after status is received. Used for both unary and streaming response calls.
-        Status? finishedStatus;
+        ClientSideStatus? finishedStatus;
 
         bool readObserverCompleted;  // True if readObserver has already been completed.
 
@@ -248,6 +248,32 @@ namespace Grpc.Core.Internal
             }
         }
 
+        /// <summary>
+        /// Gets the resulting status if the call has already finished.
+        /// Throws InvalidOperationException otherwise.
+        /// </summary>
+        public Status GetStatus()
+        {
+            lock (myLock)
+            {
+                Preconditions.CheckState(finishedStatus.HasValue, "Status can only be accessed once the call has finished.");
+                return finishedStatus.Value.Status;
+            }
+        }
+
+        /// <summary>
+        /// Gets the trailing metadata if the call has already finished.
+        /// Throws InvalidOperationException otherwise.
+        /// </summary>
+        public Metadata GetTrailers()
+        {
+            lock (myLock)
+            {
+                Preconditions.CheckState(finishedStatus.HasValue, "Trailers can only be accessed once the call has finished.");
+                return finishedStatus.Value.Trailers;
+            }
+        }
+
         /// <summary>
         /// On client-side, we only fire readCompletionDelegate once all messages have been read 
         /// and status has been received.
@@ -265,7 +291,7 @@ namespace Grpc.Core.Internal
 
                 if (shouldComplete)
                 {
-                    var status = finishedStatus.Value;
+                    var status = finishedStatus.Value.Status;
                     if (status.StatusCode != StatusCode.OK)
                     {
                         FireCompletion(completionDelegate, default(TResponse), new RpcException(status));
@@ -288,9 +314,13 @@ namespace Grpc.Core.Internal
         /// </summary>
         private void HandleUnaryResponse(bool success, BatchContextSafeHandle ctx)
         {
+            var fullStatus = ctx.GetReceivedStatusOnClient();
+
             lock (myLock)
             {
                 finished = true;
+                finishedStatus = fullStatus;
+
                 halfclosed = true;
 
                 ReleaseResourcesIfPossible();
@@ -302,7 +332,8 @@ namespace Grpc.Core.Internal
                 return;
             }
 
-            var status = ctx.GetReceivedStatus();
+            var status = fullStatus.Status;
+
             if (status.StatusCode != StatusCode.OK)
             {
                 unaryResponseTcs.SetException(new RpcException(status));
@@ -321,13 +352,13 @@ namespace Grpc.Core.Internal
         /// </summary>
         private void HandleFinished(bool success, BatchContextSafeHandle ctx)
         {
-            var status = ctx.GetReceivedStatus();
+            var fullStatus = ctx.GetReceivedStatusOnClient();
 
             AsyncCompletionDelegate<TResponse> origReadCompletionDelegate = null;
             lock (myLock)
             {
                 finished = true;
-                finishedStatus = status;
+                finishedStatus = fullStatus;
 
                 origReadCompletionDelegate = readCompletionDelegate;
 

src/csharp/Grpc.Core/Internal/AsyncCallServer.cs

@@ -101,14 +101,17 @@ namespace Grpc.Core.Internal
         /// Only one pending send action is allowed at any given time.
         /// completionDelegate is called when the operation finishes.
         /// </summary>
-        public void StartSendStatusFromServer(Status status, AsyncCompletionDelegate<object> completionDelegate)
+        public void StartSendStatusFromServer(Status status, Metadata trailers, AsyncCompletionDelegate<object> completionDelegate)
         {
             lock (myLock)
             {
                 Preconditions.CheckNotNull(completionDelegate, "Completion delegate cannot be null");
                 CheckSendingAllowed();
 
-                call.StartSendStatusFromServer(status, HandleHalfclosed);
+                using (var metadataArray = MetadataArraySafeHandle.Create(trailers))
+                {
+                    call.StartSendStatusFromServer(status, HandleHalfclosed, metadataArray);
+                }
                 halfcloseRequested = true;
                 readingDone = true;
                 sendCompletionDelegate = completionDelegate;

src/csharp/Grpc.Core/Internal/BatchContextSafeHandle.cs

@@ -38,7 +38,6 @@ using Grpc.Core;
 namespace Grpc.Core.Internal
 {
     /// <summary>
-    /// Not owned version of 
     /// grpcsharp_batch_context
     /// </summary>
     internal class BatchContextSafeHandle : SafeHandleZeroIsInvalid
@@ -46,6 +45,9 @@ namespace Grpc.Core.Internal
         [DllImport("grpc_csharp_ext.dll")]
         static extern BatchContextSafeHandle grpcsharp_batch_context_create();
 
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern IntPtr grpcsharp_batch_context_recv_initial_metadata(BatchContextSafeHandle ctx);
+
         [DllImport("grpc_csharp_ext.dll")]
         static extern IntPtr grpcsharp_batch_context_recv_message_length(BatchContextSafeHandle ctx);
 
@@ -58,12 +60,24 @@ namespace Grpc.Core.Internal
         [DllImport("grpc_csharp_ext.dll")]
         static extern IntPtr grpcsharp_batch_context_recv_status_on_client_details(BatchContextSafeHandle ctx);  // returns const char*
 
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern IntPtr grpcsharp_batch_context_recv_status_on_client_trailing_metadata(BatchContextSafeHandle ctx);
+
         [DllImport("grpc_csharp_ext.dll")]
         static extern CallSafeHandle grpcsharp_batch_context_server_rpc_new_call(BatchContextSafeHandle ctx);
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern IntPtr grpcsharp_batch_context_server_rpc_new_method(BatchContextSafeHandle ctx);  // returns const char*
 
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern IntPtr grpcsharp_batch_context_server_rpc_new_host(BatchContextSafeHandle ctx);  // returns const char*
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern Timespec grpcsharp_batch_context_server_rpc_new_deadline(BatchContextSafeHandle ctx);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern IntPtr grpcsharp_batch_context_server_rpc_new_request_metadata(BatchContextSafeHandle ctx);
+
         [DllImport("grpc_csharp_ext.dll")]
         static extern int grpcsharp_batch_context_recv_close_on_server_cancelled(BatchContextSafeHandle ctx);
 
@@ -87,13 +101,26 @@ namespace Grpc.Core.Internal
             }
         }
 
-        public Status GetReceivedStatus()
+        // Gets data of recv_initial_metadata completion.
+        public Metadata GetReceivedInitialMetadata()
+        {
+            IntPtr metadataArrayPtr = grpcsharp_batch_context_recv_initial_metadata(this);
+            return MetadataArraySafeHandle.ReadMetadataFromPtrUnsafe(metadataArrayPtr);
+        }
+            
+        // Gets data of recv_status_on_client completion.
+        public ClientSideStatus GetReceivedStatusOnClient()
         {
-            // TODO: can the native method return string directly?
             string details = Marshal.PtrToStringAnsi(grpcsharp_batch_context_recv_status_on_client_details(this));
-            return new Status(grpcsharp_batch_context_recv_status_on_client_status(this), details);
+            var status = new Status(grpcsharp_batch_context_recv_status_on_client_status(this), details);
+
+            IntPtr metadataArrayPtr = grpcsharp_batch_context_recv_status_on_client_trailing_metadata(this);
+            var metadata = MetadataArraySafeHandle.ReadMetadataFromPtrUnsafe(metadataArrayPtr);
+
+            return new ClientSideStatus(status, metadata);
         }
 
+        // Gets data of recv_message completion.
         public byte[] GetReceivedMessage()
         {
             IntPtr len = grpcsharp_batch_context_recv_message_length(this);
@@ -106,16 +133,22 @@ namespace Grpc.Core.Internal
             return data;
         }
 
-        public CallSafeHandle GetServerRpcNewCall()
+        // Gets data of server_rpc_new completion.
+        public ServerRpcNew GetServerRpcNew()
         {
-            return grpcsharp_batch_context_server_rpc_new_call(this);
+            var call = grpcsharp_batch_context_server_rpc_new_call(this);
-        }
 
-        public string GetServerRpcNewMethod()
+            var method = Marshal.PtrToStringAnsi(grpcsharp_batch_context_server_rpc_new_method(this));
-        {
+            var host = Marshal.PtrToStringAnsi(grpcsharp_batch_context_server_rpc_new_host(this));
-            return Marshal.PtrToStringAnsi(grpcsharp_batch_context_server_rpc_new_method(this));
+            var deadline = grpcsharp_batch_context_server_rpc_new_deadline(this);
+
+            IntPtr metadataArrayPtr = grpcsharp_batch_context_server_rpc_new_request_metadata(this);
+            var metadata = MetadataArraySafeHandle.ReadMetadataFromPtrUnsafe(metadataArrayPtr);
+
+            return new ServerRpcNew(call, method, host, deadline, metadata);
         }
 
+        // Gets data of receive_close_on_server completion.
         public bool GetReceivedCloseOnServerCancelled()
         {
             return grpcsharp_batch_context_recv_close_on_server_cancelled(this) != 0;
@@ -127,4 +160,97 @@ 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 CallSafeHandle call;
+        readonly string method;
+        readonly string host;
+        readonly Timespec deadline;
+        readonly Metadata requestMetadata;
+
+        public ServerRpcNew(CallSafeHandle call, string method, string host, Timespec deadline, Metadata requestMetadata)
+        {
+            this.call = call;
+            this.method = method;
+            this.host = host;
+            this.deadline = deadline;
+            this.requestMetadata = requestMetadata;
+        }
+
+        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;
+            }
+        }
+    }
 }

src/csharp/Grpc.Core/Internal/CallSafeHandle.cs

@@ -81,7 +81,7 @@ namespace Grpc.Core.Internal
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern GRPCCallError grpcsharp_call_send_status_from_server(CallSafeHandle call, 
-            BatchContextSafeHandle ctx, StatusCode statusCode, string statusMessage);
+            BatchContextSafeHandle ctx, StatusCode statusCode, string statusMessage, MetadataArraySafeHandle metadataArray);
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern GRPCCallError grpcsharp_call_recv_message(CallSafeHandle call,
@@ -159,11 +159,11 @@ namespace Grpc.Core.Internal
             grpcsharp_call_send_close_from_client(this, ctx).CheckOk();
         }
 
-        public void StartSendStatusFromServer(Status status, BatchCompletionDelegate callback)
+        public void StartSendStatusFromServer(Status status, BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
         {
             var ctx = BatchContextSafeHandle.Create();
             completionRegistry.RegisterBatchCompletion(ctx, callback);
-            grpcsharp_call_send_status_from_server(this, ctx, status.StatusCode, status.Detail).CheckOk();
+            grpcsharp_call_send_status_from_server(this, ctx, status.StatusCode, status.Detail, metadataArray).CheckOk();
         }
 
         public void StartReceiveMessage(BatchCompletionDelegate callback)

src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs

@@ -45,6 +45,18 @@ namespace Grpc.Core.Internal
         [DllImport("grpc_csharp_ext.dll", CharSet = CharSet.Ansi)]
         static extern void grpcsharp_metadata_array_add(MetadataArraySafeHandle array, string key, byte[] value, UIntPtr valueLength);
 
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern UIntPtr grpcsharp_metadata_array_count(IntPtr metadataArray);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern IntPtr grpcsharp_metadata_array_get_key(IntPtr metadataArray, UIntPtr index);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern IntPtr grpcsharp_metadata_array_get_value(IntPtr metadataArray, UIntPtr index);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern UIntPtr grpcsharp_metadata_array_get_value_length(IntPtr metadataArray, UIntPtr index);
+
         [DllImport("grpc_csharp_ext.dll")]
         static extern void grpcsharp_metadata_array_destroy_full(IntPtr array);
 
@@ -63,6 +75,38 @@ namespace Grpc.Core.Internal
             return metadataArray;
         }
 
+        /// <summary>
+        /// Reads metadata from pointer to grpc_metadata_array
+        /// </summary>
+        public static Metadata ReadMetadataFromPtrUnsafe(IntPtr metadataArray)
+        {
+            if (metadataArray == IntPtr.Zero)
+            {
+                return null;
+            }
+
+            ulong count = grpcsharp_metadata_array_count(metadataArray).ToUInt64();
+
+            var metadata = new Metadata();
+            for (ulong i = 0; i < count; i ++)
+            {
+                var index = new UIntPtr(i);
+                string key = Marshal.PtrToStringAnsi(grpcsharp_metadata_array_get_key(metadataArray, index));
+                var bytes = new byte[grpcsharp_metadata_array_get_value_length(metadataArray, index).ToUInt64()];
+                Marshal.Copy(grpcsharp_metadata_array_get_value(metadataArray, index), bytes, 0, bytes.Length);
+                metadata.Add(new Metadata.Entry(key, bytes));
+            }
+            return metadata;
+        }
+
+        internal IntPtr Handle
+        {
+            get
+            {
+                return handle;
+            }
+        }
+
         protected override bool ReleaseHandle()
         {
             grpcsharp_metadata_array_destroy_full(handle);

src/csharp/Grpc.Core/Internal/ServerCallHandler.cs

@@ -34,6 +34,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading;
 using System.Threading.Tasks;
 using Grpc.Core.Internal;
 using Grpc.Core.Utils;
@@ -42,7 +43,7 @@ namespace Grpc.Core.Internal
 {
     internal interface IServerCallHandler
     {
-        Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment);
+        Task HandleCall(ServerRpcNew newRpc, GrpcEnvironment environment);
     }
 
     internal class UnaryServerCallHandler<TRequest, TResponse> : IServerCallHandler
@@ -58,27 +59,28 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
+        public async Task HandleCall(ServerRpcNew newRpc, GrpcEnvironment environment)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
                 method.RequestMarshaller.Deserializer,
                 environment);
 
-            asyncCall.Initialize(call);
+            asyncCall.Initialize(newRpc.Call);
             var finishedTask = asyncCall.ServerSideCallAsync();
             var requestStream = new ServerRequestStream<TRequest, TResponse>(asyncCall);
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
 
-            Status status = Status.DefaultSuccess;
+            Status status;
+            var context = HandlerUtils.NewContext(newRpc);
             try
             {
                 Preconditions.CheckArgument(await requestStream.MoveNext());
                 var request = requestStream.Current;
                 // TODO(jtattermusch): we need to read the full stream so that native callhandle gets deallocated.
                 Preconditions.CheckArgument(!await requestStream.MoveNext());
-                var context = new ServerCallContext();  // TODO(jtattermusch): initialize the context
+                var result = await handler(request, context);
-                var result = await handler(context, request);
+                status = context.Status;
                 await responseStream.WriteAsync(result);
             } 
             catch (Exception e)
@@ -88,7 +90,7 @@ namespace Grpc.Core.Internal
             }
             try
             {
-                await responseStream.WriteStatusAsync(status);
+                await responseStream.WriteStatusAsync(status, context.ResponseTrailers);
             }
             catch (OperationCanceledException)
             {
@@ -111,28 +113,28 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
+        public async Task HandleCall(ServerRpcNew newRpc, GrpcEnvironment environment)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
                 method.RequestMarshaller.Deserializer,
                 environment);
 
-            asyncCall.Initialize(call);
+            asyncCall.Initialize(newRpc.Call);
             var finishedTask = asyncCall.ServerSideCallAsync();
             var requestStream = new ServerRequestStream<TRequest, TResponse>(asyncCall);
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
 
-            Status status = Status.DefaultSuccess;
+            Status status;
+            var context = HandlerUtils.NewContext(newRpc);
             try
             {
                 Preconditions.CheckArgument(await requestStream.MoveNext());
                 var request = requestStream.Current;
                 // TODO(jtattermusch): we need to read the full stream so that native callhandle gets deallocated.
                 Preconditions.CheckArgument(!await requestStream.MoveNext());
-
+                await handler(request, responseStream, context);
-                var context = new ServerCallContext();  // TODO(jtattermusch): initialize the context
+                status = context.Status;
-                await handler(context, request, responseStream);
             }
             catch (Exception e)
             {
@@ -142,7 +144,7 @@ namespace Grpc.Core.Internal
 
             try
             {
-                await responseStream.WriteStatusAsync(status);
+                await responseStream.WriteStatusAsync(status, context.ResponseTrailers);
             }
             catch (OperationCanceledException)
             {
@@ -165,23 +167,25 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
+        public async Task HandleCall(ServerRpcNew newRpc, GrpcEnvironment environment)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
                 method.RequestMarshaller.Deserializer,
                 environment);
 
-            asyncCall.Initialize(call);
+            asyncCall.Initialize(newRpc.Call);
             var finishedTask = asyncCall.ServerSideCallAsync();
             var requestStream = new ServerRequestStream<TRequest, TResponse>(asyncCall);
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
-            var context = new ServerCallContext();  // TODO(jtattermusch): initialize the context
 
-            Status status = Status.DefaultSuccess;
+
+            Status status;
+            var context = HandlerUtils.NewContext(newRpc);
             try
             {
-                var result = await handler(context, requestStream);
+                var result = await handler(requestStream, context);
+                status = context.Status;
                 try
                 {
                     await responseStream.WriteAsync(result);
@@ -199,7 +203,7 @@ namespace Grpc.Core.Internal
 
             try
             {
-                await responseStream.WriteStatusAsync(status);
+                await responseStream.WriteStatusAsync(status, context.ResponseTrailers);
             }
             catch (OperationCanceledException)
             {
@@ -222,23 +226,24 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
+        public async Task HandleCall(ServerRpcNew newRpc, GrpcEnvironment environment)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
                 method.RequestMarshaller.Deserializer,
                 environment);
 
-            asyncCall.Initialize(call);
+            asyncCall.Initialize(newRpc.Call);
             var finishedTask = asyncCall.ServerSideCallAsync();
             var requestStream = new ServerRequestStream<TRequest, TResponse>(asyncCall);
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
-            var context = new ServerCallContext();  // TODO(jtattermusch): initialize the context
 
-            Status status = Status.DefaultSuccess;
+            Status status;
+            var context = HandlerUtils.NewContext(newRpc);
             try
             {
-                await handler(context, requestStream, responseStream);
+                await handler(requestStream, responseStream, context);
+                status = context.Status;
             }
             catch (Exception e)
             {
@@ -247,7 +252,7 @@ namespace Grpc.Core.Internal
             }
             try
             {
-                await responseStream.WriteStatusAsync(status);
+                await responseStream.WriteStatusAsync(status, context.ResponseTrailers);
             }
             catch (OperationCanceledException)
             {
@@ -259,18 +264,19 @@ namespace Grpc.Core.Internal
 
     internal class NoSuchMethodCallHandler : IServerCallHandler
     {
-        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
+        public static readonly NoSuchMethodCallHandler Instance = new NoSuchMethodCallHandler();
+
+        public async Task HandleCall(ServerRpcNew newRpc, GrpcEnvironment environment)
         {
             // We don't care about the payload type here.
             var asyncCall = new AsyncCallServer<byte[], byte[]>(
                 (payload) => payload, (payload) => payload, environment);
             
-            asyncCall.Initialize(call);
+            asyncCall.Initialize(newRpc.Call);
             var finishedTask = asyncCall.ServerSideCallAsync();
-            var requestStream = new ServerRequestStream<byte[], byte[]>(asyncCall);
             var responseStream = new ServerResponseStream<byte[], byte[]>(asyncCall);
 
-            await responseStream.WriteStatusAsync(new Status(StatusCode.Unimplemented, "No such method."));
+            await responseStream.WriteStatusAsync(new Status(StatusCode.Unimplemented, "No such method."), Metadata.Empty);
             await finishedTask;
         }
     }
@@ -279,8 +285,22 @@ namespace Grpc.Core.Internal
     {
         public static Status StatusFromException(Exception e)
         {
+            var rpcException = e as RpcException;
+            if (rpcException != null)
+            {
+                // use the status thrown by handler.
+                return rpcException.Status;
+            }
+
             // TODO(jtattermusch): what is the right status code here?
             return new Status(StatusCode.Unknown, "Exception was thrown by handler.");
         }
+
+        public static ServerCallContext NewContext(ServerRpcNew newRpc)
+        {
+            return new ServerCallContext(
+                newRpc.Method, newRpc.Host, newRpc.Deadline.ToDateTime(),
+                newRpc.RequestMetadata, CancellationToken.None);
+        }
     }
 }

src/csharp/Grpc.Core/Internal/ServerResponseStream.cs

@@ -56,10 +56,10 @@ namespace Grpc.Core.Internal
             return taskSource.Task;
         }
 
-        public Task WriteStatusAsync(Status status)
+        public Task WriteStatusAsync(Status status, Metadata trailers)
         {
             var taskSource = new AsyncCompletionTaskSource<object>();
-            call.StartSendStatusFromServer(status, taskSource.CompletionDelegate);
+            call.StartSendStatusFromServer(status, trailers, taskSource.CompletionDelegate);
             return taskSource.Task;
         }
     }

src/csharp/Grpc.Core/Internal/Timespec.cs

@@ -43,6 +43,8 @@ namespace Grpc.Core.Internal
         const int NanosPerSecond = 1000 * 1000 * 1000;
         const int NanosPerTick = 100;
 
+        static readonly DateTime UnixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
+
         [DllImport("grpc_csharp_ext.dll")]
         static extern Timespec gprsharp_now();
 
@@ -52,6 +54,13 @@ namespace Grpc.Core.Internal
         [DllImport("grpc_csharp_ext.dll")]
         static extern int gprsharp_sizeof_timespec();
 
+        public Timespec(IntPtr tv_sec, int tv_nsec)
+        {
+            this.tv_sec = tv_sec;
+            this.tv_nsec = tv_nsec;
+            this.clock_type = GPRClockType.Realtime;
+        }
+
         // NOTE: on linux 64bit  sizeof(gpr_timespec) = 16, on windows 32bit sizeof(gpr_timespec) = 8
         // so IntPtr seems to have the right size to work on both.
         public System.IntPtr tv_sec;
@@ -77,6 +86,11 @@ namespace Grpc.Core.Internal
             }
         }
             
+        public DateTime ToDateTime()
+        {
+            return UnixEpoch.AddTicks(tv_sec.ToInt64() * (NanosPerSecond / NanosPerTick) + tv_nsec / NanosPerTick);
+        }
+
         internal static int NativeSize
         {
             get

src/csharp/Grpc.Core/Metadata.cs

@@ -220,6 +220,12 @@ namespace Grpc.Core
                     return value;
                 }
             }
+                
+            public override string ToString()
+            {
+                return string.Format("[Entry: key={0}, value={1}]", Key, Value);
+            }
+            
         }
     }
 }

src/csharp/Grpc.Core/Server.cs

@@ -218,16 +218,16 @@ namespace Grpc.Core
         /// <summary>
         /// Selects corresponding handler for given call and handles the call.
         /// </summary>
-        private async Task InvokeCallHandler(CallSafeHandle call, string method)
+        private async Task HandleCallAsync(ServerRpcNew newRpc)
         {
             try
             {
                 IServerCallHandler callHandler;
-                if (!callHandlers.TryGetValue(method, out callHandler))
+                if (!callHandlers.TryGetValue(newRpc.Method, out callHandler))
                 {
-                    callHandler = new NoSuchMethodCallHandler();
+                    callHandler = NoSuchMethodCallHandler.Instance;
                 }
-                await callHandler.HandleCall(method, call, environment);
+                await callHandler.HandleCall(newRpc, environment);
             }
             catch (Exception e)
             {
@@ -240,15 +240,15 @@ namespace Grpc.Core
         /// </summary>
         private void HandleNewServerRpc(bool success, BatchContextSafeHandle ctx)
         {
-            // TODO: handle error
+            if (success)
-
-            CallSafeHandle call = ctx.GetServerRpcNewCall();
-            string method = ctx.GetServerRpcNewMethod();
-
-            // after server shutdown, the callback returns with null call
-            if (!call.IsInvalid)
             {
-                Task.Run(async () => await InvokeCallHandler(call, method));
+                ServerRpcNew newRpc = ctx.GetServerRpcNew();
+
+                // after server shutdown, the callback returns with null call
+                if (!newRpc.Call.IsInvalid)
+                {
+                    Task.Run(async () => await HandleCallAsync(newRpc));
+                }
             }
 
             AllowOneRpc();

src/csharp/Grpc.Core/ServerCallContext.cs

@@ -33,6 +33,7 @@
 
 using System;
 using System.Runtime.CompilerServices;
+using System.Threading;
 using System.Threading.Tasks;
 
 namespace Grpc.Core
@@ -42,14 +43,94 @@ namespace Grpc.Core
     /// </summary>
     public sealed class ServerCallContext
     {
-        // TODO(jtattermusch): add cancellationToken
+        // TODO(jtattermusch): expose method to send initial metadata back to client
 
-        // TODO(jtattermusch): add deadline info
+        // TODO(jtattermusch): allow setting status and trailing metadata to send after handler completes.
 
-        // TODO(jtattermusch): expose initial metadata sent by client for reading
+        private readonly string method;
+        private readonly string host;
+        private readonly DateTime deadline;
+        private readonly Metadata requestHeaders;
+        private readonly CancellationToken cancellationToken;
 
-        // TODO(jtattermusch): expose method to send initial metadata back to client
+        private Status status = Status.DefaultSuccess;
+        private readonly Metadata responseTrailers = new Metadata();
 
-        // TODO(jtattermusch): allow setting status and trailing metadata to send after handler completes.
+        public ServerCallContext(string method, string host, DateTime deadline, Metadata requestHeaders, CancellationToken cancellationToken)
+        {
+            this.method = method;
+            this.host = host;
+            this.deadline = deadline;
+            this.requestHeaders = requestHeaders;
+            this.cancellationToken = cancellationToken;
+        }
+            
+        /// <summary> Name of method called in this RPC. </summary>
+        public string Method
+        {
+            get
+            {
+                return this.method;
+            }
+        }
+
+        /// <summary> Name of host called in this RPC. </summary>
+        public string Host
+        {
+            get
+            {
+                return this.host;
+            }
+        }
+
+        /// <summary> Deadline for this RPC. </summary>
+        public DateTime Deadline
+        {
+            get
+            {
+                return this.deadline;
+            }
+        }
+
+        /// <summary> Initial metadata sent by client. </summary>
+        public Metadata RequestHeaders
+        {
+            get
+            {
+                return this.requestHeaders;
+            }
+        }
+
+        // TODO(jtattermusch): support signalling cancellation.
+        /// <summary> Cancellation token signals when call is cancelled. </summary>
+        public CancellationToken CancellationToken
+        {
+            get
+            {
+                return this.cancellationToken;
+            }
+        }
+
+        /// <summary> Trailers to send back to client after RPC finishes.</summary>
+        public Metadata ResponseTrailers
+        {
+            get
+            {
+                return this.responseTrailers;
+            }
+        }
+
+        /// <summary> Status to send back to client after RPC finishes.</summary>
+        public Status Status
+        {
+            get
+            {
+                return this.status;
+            }
+            set
+            {
+                status = value;
+            }
+        }
     }
 }

src/csharp/Grpc.Core/ServerMethods.cs

@@ -42,28 +42,28 @@ namespace Grpc.Core
     /// <summary>
     /// Server-side handler for unary call.
     /// </summary>
-    public delegate Task<TResponse> UnaryServerMethod<TRequest, TResponse>(ServerCallContext context, TRequest request)
+    public delegate Task<TResponse> UnaryServerMethod<TRequest, TResponse>(TRequest request, ServerCallContext context)
         where TRequest : class
         where TResponse : class;
 
     /// <summary>
     /// Server-side handler for client streaming call.
     /// </summary>
-    public delegate Task<TResponse> ClientStreamingServerMethod<TRequest, TResponse>(ServerCallContext context, IAsyncStreamReader<TRequest> requestStream)
+    public delegate Task<TResponse> ClientStreamingServerMethod<TRequest, TResponse>(IAsyncStreamReader<TRequest> requestStream, ServerCallContext context)
         where TRequest : class
         where TResponse : class;
 
     /// <summary>
     /// Server-side handler for server streaming call.
     /// </summary>
-    public delegate Task ServerStreamingServerMethod<TRequest, TResponse>(ServerCallContext context, TRequest request, IServerStreamWriter<TResponse> responseStream)
+    public delegate Task ServerStreamingServerMethod<TRequest, TResponse>(TRequest request, IServerStreamWriter<TResponse> responseStream, ServerCallContext context)
         where TRequest : class
         where TResponse : class;
 
     /// <summary>
     /// Server-side handler for bidi streaming call.
     /// </summary>
-    public delegate Task DuplexStreamingServerMethod<TRequest, TResponse>(ServerCallContext context, IAsyncStreamReader<TRequest> requestStream, IServerStreamWriter<TResponse> responseStream)
+    public delegate Task DuplexStreamingServerMethod<TRequest, TResponse>(IAsyncStreamReader<TRequest> requestStream, IServerStreamWriter<TResponse> responseStream, ServerCallContext context)
         where TRequest : class
         where TResponse : class;
 }

src/csharp/Grpc.Examples.Tests/MathClientServerTests.cs

@@ -144,7 +144,7 @@ namespace math.Tests
                              n => Num.CreateBuilder().SetNum_(n).Build());
 
                     await call.RequestStream.WriteAll(numbers);
-                    var result = await call.Result;
+                    var result = await call.ResponseAsync;
                     Assert.AreEqual(60, result.Num_);
                 }
             }).Wait();

src/csharp/Grpc.Examples/MathExamples.cs

@@ -46,8 +46,7 @@ namespace math
 
         public static async Task DivAsyncExample(Math.IMathClient client)
         {
-            Task<DivReply> resultTask = client.DivAsync(new DivArgs.Builder { Dividend = 4, Divisor = 5 }.Build());
+            DivReply result = await client.DivAsync(new DivArgs.Builder { Dividend = 4, Divisor = 5 }.Build());
-            DivReply result = await resultTask;
             Console.WriteLine("DivAsync Result: " + result);
         }
 
@@ -72,7 +71,7 @@ namespace math
             using (var call = client.Sum())
             {
                 await call.RequestStream.WriteAll(numbers);
-                Console.WriteLine("Sum Result: " + await call.Result);
+                Console.WriteLine("Sum Result: " + await call.ResponseAsync);
             }
         }
 
@@ -104,7 +103,7 @@ namespace math
             using (var sumCall = client.Sum())
             {
                 await sumCall.RequestStream.WriteAll(numbers);
-                sum = await sumCall.Result;
+                sum = await sumCall.ResponseAsync;
             }
 
             DivReply result = await client.DivAsync(new DivArgs.Builder { Dividend = sum.Num_, Divisor = numbers.Count }.Build());

src/csharp/Grpc.Examples/MathGrpc.cs

@@ -45,7 +45,7 @@ namespace math {
     public interface IMathClient
     {
       global::math.DivReply Div(global::math.DivArgs request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
-      Task<global::math.DivReply> DivAsync(global::math.DivArgs request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncUnaryCall<global::math.DivReply> DivAsync(global::math.DivArgs request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
       AsyncDuplexStreamingCall<global::math.DivArgs, global::math.DivReply> DivMany(Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
       AsyncServerStreamingCall<global::math.Num> Fib(global::math.FibArgs request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
       AsyncClientStreamingCall<global::math.Num, global::math.Num> Sum(Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
@@ -54,10 +54,10 @@ namespace math {
     // server-side interface
     public interface IMath
     {
-      Task<global::math.DivReply> Div(ServerCallContext context, global::math.DivArgs request);
+      Task<global::math.DivReply> Div(global::math.DivArgs request, ServerCallContext context);
-      Task DivMany(ServerCallContext context, IAsyncStreamReader<global::math.DivArgs> requestStream, IServerStreamWriter<global::math.DivReply> responseStream);
+      Task DivMany(IAsyncStreamReader<global::math.DivArgs> requestStream, IServerStreamWriter<global::math.DivReply> responseStream, ServerCallContext context);
-      Task Fib(ServerCallContext context, global::math.FibArgs request, IServerStreamWriter<global::math.Num> responseStream);
+      Task Fib(global::math.FibArgs request, IServerStreamWriter<global::math.Num> responseStream, ServerCallContext context);
-      Task<global::math.Num> Sum(ServerCallContext context, IAsyncStreamReader<global::math.Num> requestStream);
+      Task<global::math.Num> Sum(IAsyncStreamReader<global::math.Num> requestStream, ServerCallContext context);
     }
 
     // client stub
@@ -71,7 +71,7 @@ namespace math {
         var call = CreateCall(__ServiceName, __Method_Div, headers);
         return Calls.BlockingUnaryCall(call, request, cancellationToken);
       }
-      public Task<global::math.DivReply> DivAsync(global::math.DivArgs request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken))
+      public AsyncUnaryCall<global::math.DivReply> DivAsync(global::math.DivArgs request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken))
       {
         var call = CreateCall(__ServiceName, __Method_Div, headers);
         return Calls.AsyncUnaryCall(call, request, cancellationToken);

src/csharp/Grpc.Examples/MathServiceImpl.cs

@@ -45,12 +45,12 @@ namespace math
     /// </summary>
     public class MathServiceImpl : Math.IMath
     {
-        public Task<DivReply> Div(ServerCallContext context, DivArgs request)
+        public Task<DivReply> Div(DivArgs request, ServerCallContext context)
         {
             return Task.FromResult(DivInternal(request));
         }
 
-        public async Task Fib(ServerCallContext context, FibArgs request, IServerStreamWriter<Num> responseStream)
+        public async Task Fib(FibArgs request, IServerStreamWriter<Num> responseStream, ServerCallContext context)
         {
             if (request.Limit <= 0)
             {
@@ -67,7 +67,7 @@ namespace math
             }
         }
 
-        public async Task<Num> Sum(ServerCallContext context, IAsyncStreamReader<Num> requestStream)
+        public async Task<Num> Sum(IAsyncStreamReader<Num> requestStream, ServerCallContext context)
         {
             long sum = 0;
             await requestStream.ForEach(async num =>
@@ -77,7 +77,7 @@ namespace math
             return Num.CreateBuilder().SetNum_(sum).Build();
         }
 
-        public async Task DivMany(ServerCallContext context, IAsyncStreamReader<DivArgs> requestStream, IServerStreamWriter<DivReply> responseStream)
+        public async Task DivMany(IAsyncStreamReader<DivArgs> requestStream, IServerStreamWriter<DivReply> responseStream, ServerCallContext context)
         {
             await requestStream.ForEach(async divArgs =>
             {

src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs

@@ -87,9 +87,7 @@ namespace Grpc.HealthCheck.Tests
         [Test]
         public void ServiceDoesntExist()
         {
-            // TODO(jtattermusch): currently, this returns wrong status code, because we don't enable sending arbitrary status code from
+            Assert.Throws(Is.TypeOf(typeof(RpcException)).And.Property("Status").Property("StatusCode").EqualTo(StatusCode.NotFound), () => client.Check(HealthCheckRequest.CreateBuilder().SetHost("").SetService("nonexistent.service").Build()));
-            // server handlers yet.
-            Assert.Throws(typeof(RpcException), () => client.Check(HealthCheckRequest.CreateBuilder().SetHost("").SetService("nonexistent.service").Build()));
         }
 
         // TODO(jtattermusch): add test with timeout once timeouts are supported

src/csharp/Grpc.HealthCheck.Tests/HealthServiceImplTest.cs

@@ -101,7 +101,7 @@ namespace Grpc.HealthCheck.Tests
 
         private static HealthCheckResponse.Types.ServingStatus GetStatusHelper(HealthServiceImpl impl, string host, string service)
         {
-            return impl.Check(null, HealthCheckRequest.CreateBuilder().SetHost(host).SetService(service).Build()).Result.Status;
+            return impl.Check(HealthCheckRequest.CreateBuilder().SetHost(host).SetService(service).Build(), null).Result.Status;
         }
     }
 }

src/csharp/Grpc.HealthCheck/HealthGrpc.cs

@@ -25,13 +25,13 @@ namespace Grpc.Health.V1Alpha {
     public interface IHealthClient
     {
       global::Grpc.Health.V1Alpha.HealthCheckResponse Check(global::Grpc.Health.V1Alpha.HealthCheckRequest request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
-      Task<global::Grpc.Health.V1Alpha.HealthCheckResponse> CheckAsync(global::Grpc.Health.V1Alpha.HealthCheckRequest request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncUnaryCall<global::Grpc.Health.V1Alpha.HealthCheckResponse> CheckAsync(global::Grpc.Health.V1Alpha.HealthCheckRequest request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
     }
 
     // server-side interface
     public interface IHealth
     {
-      Task<global::Grpc.Health.V1Alpha.HealthCheckResponse> Check(ServerCallContext context, global::Grpc.Health.V1Alpha.HealthCheckRequest request);
+      Task<global::Grpc.Health.V1Alpha.HealthCheckResponse> Check(global::Grpc.Health.V1Alpha.HealthCheckRequest request, ServerCallContext context);
     }
 
     // client stub
@@ -45,7 +45,7 @@ namespace Grpc.Health.V1Alpha {
         var call = CreateCall(__ServiceName, __Method_Check, headers);
         return Calls.BlockingUnaryCall(call, request, cancellationToken);
       }
-      public Task<global::Grpc.Health.V1Alpha.HealthCheckResponse> CheckAsync(global::Grpc.Health.V1Alpha.HealthCheckRequest request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken))
+      public AsyncUnaryCall<global::Grpc.Health.V1Alpha.HealthCheckResponse> CheckAsync(global::Grpc.Health.V1Alpha.HealthCheckRequest request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken))
       {
         var call = CreateCall(__ServiceName, __Method_Check, headers);
         return Calls.AsyncUnaryCall(call, request, cancellationToken);

src/csharp/Grpc.HealthCheck/HealthServiceImpl.cs

@@ -95,7 +95,7 @@ namespace Grpc.HealthCheck
             }
         }
 
-        public Task<HealthCheckResponse> Check(ServerCallContext context, HealthCheckRequest request)
+        public Task<HealthCheckResponse> Check(HealthCheckRequest request, ServerCallContext context)
         {
             lock (myLock)
             {

src/csharp/Grpc.IntegrationTesting/InteropClient.cs

@@ -219,7 +219,7 @@ namespace Grpc.IntegrationTesting
                 {
                     await call.RequestStream.WriteAll(bodySizes);
 
-                    var response = await call.Result;
+                    var response = await call.ResponseAsync;
                     Assert.AreEqual(74922, response.AggregatedPayloadSize);
                 }
                 Console.WriteLine("Passed!");
@@ -421,7 +421,7 @@ namespace Grpc.IntegrationTesting
 
                     try
                     {
-                        var response = await call.Result;
+                        var response = await call.ResponseAsync;
                         Assert.Fail();
                     }
                     catch (RpcException e)

src/csharp/Grpc.IntegrationTesting/TestGrpc.cs

@@ -60,9 +60,9 @@ namespace grpc.testing {
     public interface ITestServiceClient
     {
       global::grpc.testing.Empty EmptyCall(global::grpc.testing.Empty request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
-      Task<global::grpc.testing.Empty> EmptyCallAsync(global::grpc.testing.Empty request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncUnaryCall<global::grpc.testing.Empty> EmptyCallAsync(global::grpc.testing.Empty request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
       global::grpc.testing.SimpleResponse UnaryCall(global::grpc.testing.SimpleRequest request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
-      Task<global::grpc.testing.SimpleResponse> UnaryCallAsync(global::grpc.testing.SimpleRequest request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
+      AsyncUnaryCall<global::grpc.testing.SimpleResponse> UnaryCallAsync(global::grpc.testing.SimpleRequest request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
       AsyncServerStreamingCall<global::grpc.testing.StreamingOutputCallResponse> StreamingOutputCall(global::grpc.testing.StreamingOutputCallRequest request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
       AsyncClientStreamingCall<global::grpc.testing.StreamingInputCallRequest, global::grpc.testing.StreamingInputCallResponse> StreamingInputCall(Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
       AsyncDuplexStreamingCall<global::grpc.testing.StreamingOutputCallRequest, global::grpc.testing.StreamingOutputCallResponse> FullDuplexCall(Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken));
@@ -72,12 +72,12 @@ namespace grpc.testing {
     // server-side interface
     public interface ITestService
     {
-      Task<global::grpc.testing.Empty> EmptyCall(ServerCallContext context, global::grpc.testing.Empty request);
+      Task<global::grpc.testing.Empty> EmptyCall(global::grpc.testing.Empty request, ServerCallContext context);
-      Task<global::grpc.testing.SimpleResponse> UnaryCall(ServerCallContext context, global::grpc.testing.SimpleRequest request);
+      Task<global::grpc.testing.SimpleResponse> UnaryCall(global::grpc.testing.SimpleRequest request, ServerCallContext context);
-      Task StreamingOutputCall(ServerCallContext context, global::grpc.testing.StreamingOutputCallRequest request, IServerStreamWriter<global::grpc.testing.StreamingOutputCallResponse> responseStream);
+      Task StreamingOutputCall(global::grpc.testing.StreamingOutputCallRequest request, IServerStreamWriter<global::grpc.testing.StreamingOutputCallResponse> responseStream, ServerCallContext context);
-      Task<global::grpc.testing.StreamingInputCallResponse> StreamingInputCall(ServerCallContext context, IAsyncStreamReader<global::grpc.testing.StreamingInputCallRequest> requestStream);
+      Task<global::grpc.testing.StreamingInputCallResponse> StreamingInputCall(IAsyncStreamReader<global::grpc.testing.StreamingInputCallRequest> requestStream, ServerCallContext context);
-      Task FullDuplexCall(ServerCallContext context, IAsyncStreamReader<global::grpc.testing.StreamingOutputCallRequest> requestStream, IServerStreamWriter<global::grpc.testing.StreamingOutputCallResponse> responseStream);
+      Task FullDuplexCall(IAsyncStreamReader<global::grpc.testing.StreamingOutputCallRequest> requestStream, IServerStreamWriter<global::grpc.testing.StreamingOutputCallResponse> responseStream, ServerCallContext context);
-      Task HalfDuplexCall(ServerCallContext context, IAsyncStreamReader<global::grpc.testing.StreamingOutputCallRequest> requestStream, IServerStreamWriter<global::grpc.testing.StreamingOutputCallResponse> responseStream);
+      Task HalfDuplexCall(IAsyncStreamReader<global::grpc.testing.StreamingOutputCallRequest> requestStream, IServerStreamWriter<global::grpc.testing.StreamingOutputCallResponse> responseStream, ServerCallContext context);
     }
 
     // client stub
@@ -91,7 +91,7 @@ namespace grpc.testing {
         var call = CreateCall(__ServiceName, __Method_EmptyCall, headers);
         return Calls.BlockingUnaryCall(call, request, cancellationToken);
       }
-      public Task<global::grpc.testing.Empty> EmptyCallAsync(global::grpc.testing.Empty request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken))
+      public AsyncUnaryCall<global::grpc.testing.Empty> EmptyCallAsync(global::grpc.testing.Empty request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken))
       {
         var call = CreateCall(__ServiceName, __Method_EmptyCall, headers);
         return Calls.AsyncUnaryCall(call, request, cancellationToken);
@@ -101,7 +101,7 @@ namespace grpc.testing {
         var call = CreateCall(__ServiceName, __Method_UnaryCall, headers);
         return Calls.BlockingUnaryCall(call, request, cancellationToken);
       }
-      public Task<global::grpc.testing.SimpleResponse> UnaryCallAsync(global::grpc.testing.SimpleRequest request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken))
+      public AsyncUnaryCall<global::grpc.testing.SimpleResponse> UnaryCallAsync(global::grpc.testing.SimpleRequest request, Metadata headers = null, CancellationToken cancellationToken = default(CancellationToken))
       {
         var call = CreateCall(__ServiceName, __Method_UnaryCall, headers);
         return Calls.AsyncUnaryCall(call, request, cancellationToken);

src/csharp/Grpc.IntegrationTesting/TestServiceImpl.cs

@@ -46,19 +46,19 @@ namespace grpc.testing
     /// </summary>
     public class TestServiceImpl : TestService.ITestService
     {
-        public Task<Empty> EmptyCall(ServerCallContext context, Empty request)
+        public Task<Empty> EmptyCall(Empty request, ServerCallContext context)
         {
             return Task.FromResult(Empty.DefaultInstance);
         }
 
-        public Task<SimpleResponse> UnaryCall(ServerCallContext context, SimpleRequest request)
+        public Task<SimpleResponse> UnaryCall(SimpleRequest request, ServerCallContext context)
         {
             var response = SimpleResponse.CreateBuilder()
                 .SetPayload(CreateZerosPayload(request.ResponseSize)).Build();
             return Task.FromResult(response);
         }
 
-        public async Task StreamingOutputCall(ServerCallContext context, StreamingOutputCallRequest request, IServerStreamWriter<StreamingOutputCallResponse> responseStream)
+        public async Task StreamingOutputCall(StreamingOutputCallRequest request, IServerStreamWriter<StreamingOutputCallResponse> responseStream, ServerCallContext context)
         {
             foreach (var responseParam in request.ResponseParametersList)
             {
@@ -68,7 +68,7 @@ namespace grpc.testing
             }
         }
 
-        public async Task<StreamingInputCallResponse> StreamingInputCall(ServerCallContext context, IAsyncStreamReader<StreamingInputCallRequest> requestStream)
+        public async Task<StreamingInputCallResponse> StreamingInputCall(IAsyncStreamReader<StreamingInputCallRequest> requestStream, ServerCallContext context)
         {
             int sum = 0;
             await requestStream.ForEach(async request =>
@@ -78,7 +78,7 @@ namespace grpc.testing
             return StreamingInputCallResponse.CreateBuilder().SetAggregatedPayloadSize(sum).Build();
         }
 
-        public async Task FullDuplexCall(ServerCallContext context, IAsyncStreamReader<StreamingOutputCallRequest> requestStream, IServerStreamWriter<StreamingOutputCallResponse> responseStream)
+        public async Task FullDuplexCall(IAsyncStreamReader<StreamingOutputCallRequest> requestStream, IServerStreamWriter<StreamingOutputCallResponse> responseStream, ServerCallContext context)
         {
             await requestStream.ForEach(async request =>
             {
@@ -91,7 +91,7 @@ namespace grpc.testing
             });
         }
 
-        public async Task HalfDuplexCall(ServerCallContext context, IAsyncStreamReader<StreamingOutputCallRequest> requestStream, IServerStreamWriter<StreamingOutputCallResponse> responseStream)
+        public async Task HalfDuplexCall(IAsyncStreamReader<StreamingOutputCallRequest> requestStream, IServerStreamWriter<StreamingOutputCallResponse> responseStream, ServerCallContext context)
         {
             throw new NotImplementedException();
         }

src/csharp/ext/grpc_csharp_ext.c

@@ -167,6 +167,29 @@ grpcsharp_metadata_array_add(grpc_metadata_array *array, const char *key,
   array->count++;
 }
 
+GPR_EXPORT gpr_intptr GPR_CALLTYPE
+grpcsharp_metadata_array_count(grpc_metadata_array *array) {
+  return (gpr_intptr) array->count;
+}
+
+GPR_EXPORT const char *GPR_CALLTYPE
+grpcsharp_metadata_array_get_key(grpc_metadata_array *array, size_t index) {
+  GPR_ASSERT(index < array->count);
+  return array->metadata[index].key;
+}
+
+GPR_EXPORT const char *GPR_CALLTYPE
+grpcsharp_metadata_array_get_value(grpc_metadata_array *array, size_t index) {
+  GPR_ASSERT(index < array->count);
+  return array->metadata[index].value;
+}
+
+GPR_EXPORT gpr_intptr GPR_CALLTYPE
+grpcsharp_metadata_array_get_value_length(grpc_metadata_array *array, size_t index) {
+  GPR_ASSERT(index < array->count);
+  return (gpr_intptr) array->metadata[index].value_length;
+}
+
 /* Move contents of metadata array */
 void grpcsharp_metadata_array_move(grpc_metadata_array *dest,
                                    grpc_metadata_array *src) {
@@ -218,6 +241,12 @@ GPR_EXPORT void GPR_CALLTYPE grpcsharp_batch_context_destroy(grpcsharp_batch_con
   gpr_free(ctx);
 }
 
+GPR_EXPORT const grpc_metadata_array *GPR_CALLTYPE
+grpcsharp_batch_context_recv_initial_metadata(
+    const grpcsharp_batch_context *ctx) {
+  return &(ctx->recv_initial_metadata);
+}
+
 GPR_EXPORT gpr_intptr GPR_CALLTYPE grpcsharp_batch_context_recv_message_length(
     const grpcsharp_batch_context *ctx) {
   if (!ctx->recv_message) {
@@ -260,6 +289,12 @@ grpcsharp_batch_context_recv_status_on_client_details(
   return ctx->recv_status_on_client.status_details;
 }
 
+GPR_EXPORT const grpc_metadata_array *GPR_CALLTYPE
+grpcsharp_batch_context_recv_status_on_client_trailing_metadata(
+    const grpcsharp_batch_context *ctx) {
+  return &(ctx->recv_status_on_client.trailing_metadata);
+}
+
 GPR_EXPORT grpc_call *GPR_CALLTYPE grpcsharp_batch_context_server_rpc_new_call(
     const grpcsharp_batch_context *ctx) {
   return ctx->server_rpc_new.call;
@@ -271,6 +306,24 @@ grpcsharp_batch_context_server_rpc_new_method(
   return ctx->server_rpc_new.call_details.method;
 }
 
+GPR_EXPORT const char *GPR_CALLTYPE
+grpcsharp_batch_context_server_rpc_new_host(
+    const grpcsharp_batch_context *ctx) {
+  return ctx->server_rpc_new.call_details.host;
+}
+
+GPR_EXPORT gpr_timespec GPR_CALLTYPE
+grpcsharp_batch_context_server_rpc_new_deadline(
+    const grpcsharp_batch_context *ctx) {
+  return ctx->server_rpc_new.call_details.deadline;
+}
+
+GPR_EXPORT const grpc_metadata_array *GPR_CALLTYPE
+grpcsharp_batch_context_server_rpc_new_request_metadata(
+    const grpcsharp_batch_context *ctx) {
+  return &(ctx->server_rpc_new.request_metadata);
+}
+
 GPR_EXPORT gpr_int32 GPR_CALLTYPE
 grpcsharp_batch_context_recv_close_on_server_cancelled(
     const grpcsharp_batch_context *ctx) {
@@ -589,15 +642,20 @@ GPR_EXPORT grpc_call_error GPR_CALLTYPE
 grpcsharp_call_send_status_from_server(grpc_call *call,
                                        grpcsharp_batch_context *ctx,
                                        grpc_status_code status_code,
-                                       const char *status_details) {
+                                       const char *status_details,
+                                       grpc_metadata_array *trailing_metadata) {
   /* TODO: don't use magic number */
   grpc_op ops[1];
   ops[0].op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   ops[0].data.send_status_from_server.status = status_code;
   ops[0].data.send_status_from_server.status_details =
       gpr_strdup(status_details);
-  ops[0].data.send_status_from_server.trailing_metadata = NULL;
+  grpcsharp_metadata_array_move(&(ctx->send_status_from_server.trailing_metadata),
-  ops[0].data.send_status_from_server.trailing_metadata_count = 0;
+                                  trailing_metadata);
+  ops[0].data.send_status_from_server.trailing_metadata_count =
+      ctx->send_status_from_server.trailing_metadata.count;
+  ops[0].data.send_status_from_server.trailing_metadata =
+      ctx->send_status_from_server.trailing_metadata.metadata;
   ops[0].flags = 0;
 
   return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx);