renaming of VS projects and other minor structural fixes

31 files changed, 3455 insertions, 0 deletions

diff --git a/src/csharp/Grpc.Core/.gitignore b/src/csharp/Grpc.Core/.gitignore
new file mode 100644
index 0000000000..8d4a6c08a8
--- /dev/null
+++ b/src/csharp/Grpc.Core/.gitignore
@@ -0,0 +1,2 @@
+bin
+obj
\ No newline at end of file
diff --git a/src/csharp/Grpc.Core/Call.cs b/src/csharp/Grpc.Core/Call.cs
new file mode 100644
index 0000000000..72dca68895
--- /dev/null
+++ b/src/csharp/Grpc.Core/Call.cs
@@ -0,0 +1,98 @@
+#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.Internal;
+
+namespace Grpc.Core
+{
+    public class Call<TRequest, TResponse>
+    {
+        readonly string methodName;
+        readonly Func<TRequest, byte[]> requestSerializer;
+        readonly Func<byte[], TResponse> responseDeserializer;
+        readonly Channel channel;
+
+        public Call(string methodName,
+                    Func<TRequest, byte[]> requestSerializer,
+                    Func<byte[], TResponse> responseDeserializer,
+                    TimeSpan timeout,
+                    Channel channel) {
+            this.methodName = methodName;
+            this.requestSerializer = requestSerializer;
+            this.responseDeserializer = responseDeserializer;
+            this.channel = channel;
+        }
+
+        public Call(Method<TRequest, TResponse> method, Channel channel)
+        {
+            this.methodName = method.Name;
+            this.requestSerializer = method.RequestMarshaller.Serializer;
+            this.responseDeserializer = method.ResponseMarshaller.Deserializer;
+            this.channel = channel;
+        }
+
+        public Channel Channel
+        {
+            get
+            {
+                return this.channel;
+            }
+        }
+
+        public string MethodName
+        {
+            get
+            {
+                return this.methodName;
+            }
+        }
+
+        public Func<TRequest, byte[]> RequestSerializer
+        {
+            get
+            {
+                return this.requestSerializer;
+            }
+        }
+
+        public Func<byte[], TResponse> ResponseDeserializer
+        {
+            get
+            {
+                return this.responseDeserializer;
+            }
+        }
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/Calls.cs b/src/csharp/Grpc.Core/Calls.cs
new file mode 100644
index 0000000000..b67332676a
--- /dev/null
+++ b/src/csharp/Grpc.Core/Calls.cs
@@ -0,0 +1,108 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Grpc.Core.Internal;
+
+namespace Grpc.Core
+{
+    // NOTE: this class is work-in-progress
+
+    /// <summary>
+    /// Helper methods for generated stubs to make RPC calls.
+    /// </summary>
+    public static class Calls
+    {
+        public static TResponse BlockingUnaryCall<TRequest, TResponse>(Call<TRequest, TResponse> call, TRequest req, CancellationToken token)
+        {
+            //TODO: implement this in real synchronous style.
+            try {
+                return AsyncUnaryCall(call, req, token).Result;
+            } catch(AggregateException ae) {
+                foreach (var e in ae.InnerExceptions)
+                {
+                    if (e is RpcException)
+                    {
+                        throw e;
+                    }
+                }
+                throw;
+            }
+        }
+
+        public static async Task<TResponse> AsyncUnaryCall<TRequest, TResponse>(Call<TRequest, TResponse> call, TRequest req, CancellationToken token)
+        {
+            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestSerializer, call.ResponseDeserializer);
+            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.MethodName);
+            return await asyncCall.UnaryCallAsync(req);
+        }
+
+        public static void AsyncServerStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, TRequest req, IObserver<TResponse> outputs, CancellationToken token)
+        {
+            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestSerializer, call.ResponseDeserializer);
+
+            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.MethodName);
+            asyncCall.StartServerStreamingCall(req, outputs);
+        }
+
+        public static ClientStreamingAsyncResult<TRequest, TResponse> AsyncClientStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, CancellationToken token)
+        {
+            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestSerializer, call.ResponseDeserializer);
+            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.MethodName);
+            var task = asyncCall.ClientStreamingCallAsync();
+            var inputs = new ClientStreamingInputObserver<TRequest, TResponse>(asyncCall);
+            return new ClientStreamingAsyncResult<TRequest, TResponse>(task, inputs);
+        }
+
+        public static TResponse BlockingClientStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, IObservable<TRequest> inputs, CancellationToken token)
+        {
+            throw new NotImplementedException();
+        }
+
+        public static IObserver<TRequest> DuplexStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, IObserver<TResponse> outputs, CancellationToken token)
+        {
+            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestSerializer, call.ResponseDeserializer);
+            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.MethodName);
+
+            asyncCall.StartDuplexStreamingCall(outputs);
+            return new ClientStreamingInputObserver<TRequest, TResponse>(asyncCall);
+        }
+
+        private static CompletionQueueSafeHandle GetCompletionQueue() {
+            return GrpcEnvironment.ThreadPool.CompletionQueue;
+        }
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/Channel.cs b/src/csharp/Grpc.Core/Channel.cs
new file mode 100644
index 0000000000..942651cf39
--- /dev/null
+++ b/src/csharp/Grpc.Core/Channel.cs
@@ -0,0 +1,85 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Runtime.InteropServices;
+using System.Threading;
+using System.Threading.Tasks;
+using Grpc.Core.Internal;
+
+namespace Grpc.Core
+{
+	public class Channel : IDisposable
+	{
+        readonly ChannelSafeHandle handle;
+        readonly String target;
+
+        // TODO: add way how to create grpc_secure_channel....
+		// TODO: add support for channel args...
+		public Channel(string target)
+		{
+            this.handle = ChannelSafeHandle.Create(target, IntPtr.Zero);
+			this.target = target;
+		}
+
+        internal ChannelSafeHandle Handle
+        {
+            get
+            {
+                return this.handle;
+            }
+        }
+
+        public string Target
+        {
+            get
+            {
+                return this.target;
+            }
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (handle != null && !handle.IsInvalid)
+            {
+                handle.Dispose();
+            }
+        }
+	}
+}
diff --git a/src/csharp/Grpc.Core/ClientStreamingAsyncResult.cs b/src/csharp/Grpc.Core/ClientStreamingAsyncResult.cs
new file mode 100644
index 0000000000..44580a1154
--- /dev/null
+++ b/src/csharp/Grpc.Core/ClientStreamingAsyncResult.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 System.Threading.Tasks;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// Return type for client streaming async method.
+    /// </summary>
+    public struct ClientStreamingAsyncResult<TRequest, TResponse>
+    {
+        readonly Task<TResponse> task;
+        readonly IObserver<TRequest> inputs;
+
+        public ClientStreamingAsyncResult(Task<TResponse> task, IObserver<TRequest> inputs)
+        {
+            this.task = task;
+            this.inputs = inputs;
+        }
+
+        public Task<TResponse> Task
+        {
+            get
+            {
+                return this.task;
+            }
+        }
+
+        public IObserver<TRequest> Inputs
+        {
+            get
+            {
+                return this.inputs;
+            }
+        }
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/Grpc.Core.csproj b/src/csharp/Grpc.Core/Grpc.Core.csproj
new file mode 100644
index 0000000000..4ad32e10e4
--- /dev/null
+++ b/src/csharp/Grpc.Core/Grpc.Core.csproj
@@ -0,0 +1,71 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProductVersion>10.0.0</ProductVersion>
+    <SchemaVersion>2.0</SchemaVersion>
+    <ProjectGuid>{CCC4440E-49F7-4790-B0AF-FEABB0837AE7}</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <RootNamespace>Grpc.Core</RootNamespace>
+    <AssemblyName>Grpc.Core</AssemblyName>
+    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug</OutputPath>
+    <DefineConstants>DEBUG;</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <ConsolePause>false</ConsolePause>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <DebugType>full</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release</OutputPath>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <ConsolePause>false</ConsolePause>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="RpcException.cs" />
+    <Compile Include="Calls.cs" />
+    <Compile Include="Call.cs" />
+    <Compile Include="ClientStreamingAsyncResult.cs" />
+    <Compile Include="GrpcEnvironment.cs" />
+    <Compile Include="Status.cs" />
+    <Compile Include="StatusCode.cs" />
+    <Compile Include="Server.cs" />
+    <Compile Include="Channel.cs" />
+    <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" />
+    <Compile Include="Internal\AsyncCall.cs" />
+    <Compile Include="Internal\ServerSafeHandle.cs" />
+    <Compile Include="Method.cs" />
+    <Compile Include="ServerCalls.cs" />
+    <Compile Include="ServerCallHandler.cs" />
+    <Compile Include="Marshaller.cs" />
+    <Compile Include="ServerServiceDefinition.cs" />
+    <Compile Include="Utils\RecordingObserver.cs" />
+    <Compile Include="Utils\RecordingQueue.cs" />
+    <Compile Include="Internal\ClientStreamingInputObserver.cs" />
+    <Compile Include="Internal\ServerStreamingOutputObserver.cs" />
+    <Compile Include="Internal\BatchContextSafeHandleNotOwned.cs" />
+  </ItemGroup>
+  <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
+  <ItemGroup>
+    <Folder Include="Internal\" />
+    <Folder Include="Utils\" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/csharp/Grpc.Core/GrpcEnvironment.cs b/src/csharp/Grpc.Core/GrpcEnvironment.cs
new file mode 100644
index 0000000000..0e3a0a581c
--- /dev/null
+++ b/src/csharp/Grpc.Core/GrpcEnvironment.cs
@@ -0,0 +1,135 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Runtime.InteropServices;
+using Grpc.Core.Internal;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// Encapsulates initialization and shutdown of gRPC library.
+    /// </summary>
+    public class GrpcEnvironment
+    {
+        const int THREAD_POOL_SIZE = 4;
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern void grpcsharp_init();
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern void grpcsharp_shutdown();
+
+        static object staticLock = new object();
+        static volatile GrpcEnvironment instance;
+
+        readonly GrpcThreadPool threadPool;
+        bool isClosed;
+
+        /// <summary>
+        /// Makes sure GRPC environment is initialized. Subsequent invocations don't have any
+        /// effect unless you call Shutdown first.
+        /// Although normal use cases assume you will call this just once in your application's
+        /// lifetime (and call Shutdown once you're done), for the sake of easier testing it's
+        /// allowed to initialize the environment again after it has been successfully shutdown.
+        /// </summary>
+        public static void Initialize() {
+            lock(staticLock)
+            {
+                if (instance == null)
+                {
+                    instance = new GrpcEnvironment();
+                }
+            }
+        }
+
+        /// <summary>
+        /// Shuts down the GRPC environment if it was initialized before.
+        /// Repeated invocations have no effect.
+        /// </summary>
+        public static void Shutdown()
+        {
+            lock(staticLock)
+            {
+                if (instance != null)
+                {
+                    instance.Close();
+                    instance = null;
+                }
+            }
+        }
+
+        internal static GrpcThreadPool ThreadPool
+        {
+            get
+            {
+                var inst = instance;
+                if (inst == null)
+                {
+                    throw new InvalidOperationException("GRPC environment not initialized");
+                }
+                return inst.threadPool;
+            }
+        }
+
+        /// <summary>
+        /// Creates gRPC environment.
+        /// </summary>
+        private GrpcEnvironment()
+        {
+            grpcsharp_init();
+            threadPool = new GrpcThreadPool(THREAD_POOL_SIZE);
+            threadPool.Start();
+            // TODO: use proper logging here
+            Console.WriteLine("GRPC initialized.");
+        }
+
+        /// <summary>
+        /// Shuts down this environment.
+        /// </summary>
+        private void Close()
+        {
+            if (isClosed)
+            {
+                throw new InvalidOperationException("Close has already been called");
+            }
+            threadPool.Stop();
+            grpcsharp_shutdown();
+            isClosed = true;
+
+            // TODO: use proper logging here
+            Console.WriteLine("GRPC shutdown.");
+        }
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCall.cs b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
new file mode 100644
index 0000000000..5e96092e27
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
@@ -0,0 +1,616 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+// 
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Diagnostics;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using System.Threading;
+using System.Threading.Tasks;
+using Grpc.Core.Internal;
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// Handles native call lifecycle and provides convenience methods.
+    /// </summary>
+    internal class AsyncCall<TWrite, TRead>
+    {
+        readonly Func<TWrite, byte[]> serializer;
+        readonly Func<byte[], TRead> deserializer;
+
+        readonly CompletionCallbackDelegate unaryResponseHandler;
+        readonly CompletionCallbackDelegate finishedHandler;
+        readonly CompletionCallbackDelegate writeFinishedHandler;
+        readonly CompletionCallbackDelegate readFinishedHandler;
+        readonly CompletionCallbackDelegate halfclosedHandler;
+        readonly CompletionCallbackDelegate finishedServersideHandler;
+
+        object myLock = new object();
+        GCHandle gchandle;
+        CallSafeHandle call;
+        bool disposed;
+
+        bool server;
+
+        bool started;
+        bool errorOccured;
+        bool cancelRequested;
+        bool readingDone;
+        bool halfcloseRequested;
+        bool halfclosed;
+        bool finished;
+
+        // Completion of a pending write if not null.
+        TaskCompletionSource<object> writeTcs;
+
+        // Completion of a pending read if not null.
+        TaskCompletionSource<TRead> readTcs;
+
+        // Completion of a pending halfclose if not null.
+        TaskCompletionSource<object> halfcloseTcs;
+
+        // Completion of a pending unary response if not null.
+        TaskCompletionSource<TRead> unaryResponseTcs;
+
+        // Set after status is received on client. Only used for server streaming and duplex streaming calls.
+        Nullable<Status> finishedStatus;
+        TaskCompletionSource<object> finishedServersideTcs = new TaskCompletionSource<object>();
+
+        // For streaming, the reads will be delivered to this observer.
+        IObserver<TRead> readObserver;
+
+        public AsyncCall(Func<TWrite, byte[]> serializer, Func<byte[], TRead> deserializer)
+        {
+            this.serializer = serializer;
+            this.deserializer = deserializer;
+            this.unaryResponseHandler = HandleUnaryResponse;
+            this.finishedHandler = HandleFinished;
+            this.writeFinishedHandler = HandleWriteFinished;
+            this.readFinishedHandler = HandleReadFinished;
+            this.halfclosedHandler = HandleHalfclosed;
+            this.finishedServersideHandler = HandleFinishedServerside;
+        }
+
+        public void Initialize(Channel channel, CompletionQueueSafeHandle cq, String methodName)
+        {
+            InitializeInternal(CallSafeHandle.Create(channel.Handle, cq, methodName, channel.Target, Timespec.InfFuture), false);
+        }
+
+        public void InitializeServer(CallSafeHandle call)
+        {
+            InitializeInternal(call, true);
+        }
+
+        public Task<TRead> UnaryCallAsync(TWrite msg)
+        {
+            lock (myLock)
+            {
+                started = true;
+                halfcloseRequested = true;
+                readingDone = true;
+
+                // TODO: handle serialization error...
+                byte[] payload = serializer(msg);
+
+                unaryResponseTcs = new TaskCompletionSource<TRead>();
+                call.StartUnary(payload, unaryResponseHandler);
+
+                return unaryResponseTcs.Task;
+            }
+        }
+
+        public Task<TRead> ClientStreamingCallAsync()
+        {
+            lock (myLock)
+            {
+                started = true;
+                readingDone = true;
+
+                unaryResponseTcs = new TaskCompletionSource<TRead>();
+                call.StartClientStreaming(unaryResponseHandler);
+
+                return unaryResponseTcs.Task;
+            }
+        }
+
+        public void StartServerStreamingCall(TWrite msg, IObserver<TRead> readObserver)
+        {
+            lock (myLock)
+            {
+                started = true;
+                halfcloseRequested = true;
+        
+                this.readObserver = readObserver;
+
+                // TODO: handle serialization error...
+                byte[] payload = serializer(msg);
+        
+                call.StartServerStreaming(payload, finishedHandler);
+
+                ReceiveMessageAsync();
+            }
+        }
+
+        public void StartDuplexStreamingCall(IObserver<TRead> readObserver)
+        {
+            lock (myLock)
+            {
+                started = true;
+
+                this.readObserver = readObserver;
+
+                call.StartDuplexStreaming(finishedHandler);
+
+                ReceiveMessageAsync();
+            }
+        }
+
+        public Task ServerSideUnaryRequestCallAsync()
+        {
+            lock (myLock)
+            {
+                started = true;
+                call.StartServerSide(finishedServersideHandler);
+                return finishedServersideTcs.Task;
+            }
+        }
+
+        public Task ServerSideStreamingRequestCallAsync(IObserver<TRead> readObserver)
+        {
+            lock (myLock)
+            {
+                started = true;
+                call.StartServerSide(finishedServersideHandler);
+               
+                if (this.readObserver != null)
+                {
+                    throw new InvalidOperationException("Already registered an observer.");
+                }
+                this.readObserver = readObserver;
+                ReceiveMessageAsync();
+
+                return finishedServersideTcs.Task;
+            }
+        }
+
+        public Task SendMessageAsync(TWrite msg)
+        {
+            lock (myLock)
+            {
+                CheckNotDisposed();
+                CheckStarted();
+                CheckNoError();
+
+                if (halfcloseRequested)
+                {
+                    throw new InvalidOperationException("Already halfclosed.");
+                }
+
+                if (writeTcs != null)
+                {
+                    throw new InvalidOperationException("Only one write can be pending at a time");
+                }
+
+                // TODO: wrap serialization...
+                byte[] payload = serializer(msg);
+
+                call.StartSendMessage(payload, writeFinishedHandler);
+                writeTcs = new TaskCompletionSource<object>();
+                return writeTcs.Task;
+            }
+        }
+
+        public Task SendCloseFromClientAsync()
+        {
+            lock (myLock)
+            {
+                CheckNotDisposed();
+                CheckStarted();
+                CheckNoError();
+
+                if (halfcloseRequested)
+                {
+                    throw new InvalidOperationException("Already halfclosed.");
+                }
+
+                call.StartSendCloseFromClient(halfclosedHandler);
+
+                halfcloseRequested = true;
+                halfcloseTcs = new TaskCompletionSource<object>();
+                return halfcloseTcs.Task;
+            }
+        }
+
+        public Task SendStatusFromServerAsync(Status status)
+        {
+            lock (myLock)
+            {
+                CheckNotDisposed();
+                CheckStarted();
+                CheckNoError();
+
+                if (halfcloseRequested)
+                {
+                    throw new InvalidOperationException("Already halfclosed.");
+                }
+
+                call.StartSendStatusFromServer(status, halfclosedHandler);
+                halfcloseRequested = true;
+                halfcloseTcs = new TaskCompletionSource<object>();
+                return halfcloseTcs.Task;
+            }
+        }
+
+        public Task<TRead> ReceiveMessageAsync()
+        {
+            lock (myLock)
+            {
+                CheckNotDisposed();
+                CheckStarted();
+                CheckNoError();
+
+                if (readingDone)
+                {
+                    throw new InvalidOperationException("Already read the last message.");
+                }
+
+                if (readTcs != null)
+                {
+                    throw new InvalidOperationException("Only one read can be pending at a time");
+                }
+
+                call.StartReceiveMessage(readFinishedHandler);
+
+                readTcs = new TaskCompletionSource<TRead>();
+                return readTcs.Task;
+            }
+        }
+
+        public void Cancel()
+        {
+            lock (myLock)
+            {
+                CheckNotDisposed();
+                CheckStarted();
+                cancelRequested = true;
+            }
+            // grpc_call_cancel is threadsafe
+            call.Cancel();
+        }
+
+        public void CancelWithStatus(Status status)
+        {
+            lock (myLock)
+            {
+                CheckNotDisposed();
+                CheckStarted();
+                cancelRequested = true;
+            }
+            // grpc_call_cancel_with_status is threadsafe
+            call.CancelWithStatus(status);
+        }
+
+        private void InitializeInternal(CallSafeHandle call, bool server)
+        {
+            lock (myLock)
+            {
+                // Make sure this object and the delegated held by it will not be garbage collected
+                // before we release this handle.
+                gchandle = GCHandle.Alloc(this);
+                this.call = call;
+                this.server = server;
+            }
+        }
+
+        private void CheckStarted()
+        {
+            if (!started)
+            {
+                throw new InvalidOperationException("Call not started");
+            }
+        }
+
+        private void CheckNotDisposed()
+        {
+            if (disposed)
+            {
+                throw new InvalidOperationException("Call has already been disposed.");
+            }
+        }
+
+        private void CheckNoError()
+        {
+            if (errorOccured)
+            {
+                throw new InvalidOperationException("Error occured when processing call.");
+            }
+        }
+
+        private bool ReleaseResourcesIfPossible()
+        {
+            if (!disposed && call != null)
+            {
+                if (halfclosed && readingDone && finished)
+                {
+                    ReleaseResources();
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        private void ReleaseResources()
+        {
+            if (call != null) {
+                call.Dispose();
+            }
+            gchandle.Free();
+            disposed = true;
+        }
+
+        private void CompleteStreamObserver(Status status)
+        {
+            if (status.StatusCode != StatusCode.OK)
+            {
+                // TODO: wrap to handle exceptions;
+                readObserver.OnError(new RpcException(status));
+            } else {
+                // TODO: wrap to handle exceptions;
+                readObserver.OnCompleted();
+            }
+        }
+
+        /// <summary>
+        /// Handler for unary response completion.
+        /// </summary>
+        private void HandleUnaryResponse(GRPCOpError error, IntPtr batchContextPtr)
+        {
+            try
+            {
+                TaskCompletionSource<TRead> tcs;
+                lock(myLock)
+                {
+                    finished = true;
+                    halfclosed = true;
+                    tcs = unaryResponseTcs;
+
+                    ReleaseResourcesIfPossible();
+                }
+
+                var ctx = new BatchContextSafeHandleNotOwned(batchContextPtr);
+
+                if (error != GRPCOpError.GRPC_OP_OK)
+                {
+                    tcs.SetException(new RpcException(
+                        new Status(StatusCode.Internal, "Internal error occured.")
+                    ));
+                    return;
+                }
+
+                var status = ctx.GetReceivedStatus();
+                if (status.StatusCode != StatusCode.OK)
+                {
+                    tcs.SetException(new RpcException(status));
+                    return;
+                }
+
+                // TODO: handle deserialize error...
+                var msg = deserializer(ctx.GetReceivedMessage());
+                tcs.SetResult(msg);
+            } 
+            catch(Exception e)
+            {
+                Console.WriteLine("Caught exception in a native handler: " + e);
+            }
+        }
+
+        private void HandleWriteFinished(GRPCOpError error, IntPtr batchContextPtr)
+        {
+            try
+            {
+                TaskCompletionSource<object> oldTcs = null;
+                lock (myLock)
+                {
+                    oldTcs = writeTcs;
+                    writeTcs = null;
+                }
+
+                if (errorOccured)
+                {
+                    // TODO: use the right type of exception...
+                    oldTcs.SetException(new Exception("Write failed"));
+                }
+                else
+                {
+                    // TODO: where does the continuation run?
+                    oldTcs.SetResult(null);
+                }
+
+            }
+            catch(Exception e)
+            {
+                Console.WriteLine("Caught exception in a native handler: " + e);
+            }
+        }
+
+        private void HandleHalfclosed(GRPCOpError error, IntPtr batchContextPtr)
+        {
+            try
+            {
+                lock (myLock)
+                {
+                    halfclosed = true;
+
+                    ReleaseResourcesIfPossible();
+                }
+
+                if (error != GRPCOpError.GRPC_OP_OK)
+                {
+                    halfcloseTcs.SetException(new Exception("Halfclose failed"));
+
+                }
+                else
+                {
+                    halfcloseTcs.SetResult(null);
+                }
+            }
+            catch(Exception e)
+            {
+                Console.WriteLine("Caught exception in a native handler: " + e);
+            }
+        }
+
+        private void HandleReadFinished(GRPCOpError error, IntPtr batchContextPtr)
+        {
+            try
+            {
+                var ctx = new BatchContextSafeHandleNotOwned(batchContextPtr);
+                var payload = ctx.GetReceivedMessage();
+
+                TaskCompletionSource<TRead> oldTcs = null;
+                IObserver<TRead> observer = null;
+
+                Nullable<Status> status = null;
+
+                lock (myLock)
+                {
+                    oldTcs = readTcs;
+                    readTcs = null;
+                    if (payload == null)
+                    {
+                        readingDone = true;
+                    }
+                    observer = readObserver;
+                    status = finishedStatus;
+                }
+
+                // TODO: wrap deserialization...
+                TRead msg = payload != null ? deserializer(payload) : default(TRead);
+
+                oldTcs.SetResult(msg);
+
+                // TODO: make sure we deliver reads in the right order.
+
+                if (observer != null)
+                {
+                    if (payload != null)
+                    {
+                        // TODO: wrap to handle exceptions
+                        observer.OnNext(msg);
+
+                        // start a new read
+                        ReceiveMessageAsync();
+                    }
+                    else
+                    {
+                        if (!server)
+                        {
+                            if (status.HasValue)
+                            {
+                                CompleteStreamObserver(status.Value);
+                            }
+                        } 
+                        else 
+                        {
+                            // TODO: wrap to handle exceptions..
+                            observer.OnCompleted();
+                        }
+                        // TODO: completeStreamObserver serverside...
+                    }
+               }
+            }
+            catch(Exception e)
+            {
+                Console.WriteLine("Caught exception in a native handler: " + e);
+            }
+        }
+
+        private void HandleFinished(GRPCOpError error, IntPtr batchContextPtr)
+        {
+            try
+            {
+                var ctx = new BatchContextSafeHandleNotOwned(batchContextPtr);
+                var status = ctx.GetReceivedStatus();
+
+                bool wasReadingDone;
+
+                lock (myLock)
+                {
+                    finished = true;
+                    finishedStatus = status;
+
+                    wasReadingDone = readingDone;
+
+                    ReleaseResourcesIfPossible();
+                }
+
+                if (wasReadingDone) {
+                    CompleteStreamObserver(status);
+                }
+
+            }
+            catch(Exception e)
+            {
+                Console.WriteLine("Caught exception in a native handler: " + e);
+            }
+        }
+
+        private void HandleFinishedServerside(GRPCOpError error, IntPtr batchContextPtr)
+        {
+            try
+            {
+                var ctx = new BatchContextSafeHandleNotOwned(batchContextPtr);
+
+                lock(myLock)
+                {
+                    finished = true;
+
+                    // TODO: because of the way server calls are implemented, we need to set
+                    // reading done to true here. Should be fixed in the future.
+                    readingDone = true;
+
+                    ReleaseResourcesIfPossible();
+                }
+                // TODO: handle error ...
+
+                finishedServersideTcs.SetResult(null);
+
+            }
+            catch(Exception e)
+            {
+                Console.WriteLine("Caught exception in a native handler: " + e);
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/csharp/Grpc.Core/Internal/BatchContextSafeHandleNotOwned.cs b/src/csharp/Grpc.Core/Internal/BatchContextSafeHandleNotOwned.cs
new file mode 100644
index 0000000000..75cd30e1a2
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/BatchContextSafeHandleNotOwned.cs
@@ -0,0 +1,96 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+// 
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Runtime.InteropServices;
+using Grpc.Core;
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// Not owned version of 
+    /// grpcsharp_batch_context
+    /// </summary>
+    internal class BatchContextSafeHandleNotOwned : SafeHandleZeroIsInvalid
+    {
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern IntPtr grpcsharp_batch_context_recv_message_length(BatchContextSafeHandleNotOwned ctx);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern void grpcsharp_batch_context_recv_message_to_buffer(BatchContextSafeHandleNotOwned ctx, byte[] buffer, UIntPtr bufferLen);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern StatusCode grpcsharp_batch_context_recv_status_on_client_status(BatchContextSafeHandleNotOwned ctx);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern IntPtr grpcsharp_batch_context_recv_status_on_client_details(BatchContextSafeHandleNotOwned ctx);  // returns const char*
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern CallSafeHandle grpcsharp_batch_context_server_rpc_new_call(BatchContextSafeHandleNotOwned ctx);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern IntPtr grpcsharp_batch_context_server_rpc_new_method(BatchContextSafeHandleNotOwned ctx);  // returns const char*
+
+        public BatchContextSafeHandleNotOwned(IntPtr handle) : base(false)
+        {
+            SetHandle(handle);
+        }
+
+        public Status GetReceivedStatus()
+        {
+            // 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);
+        }
+
+        public byte[] GetReceivedMessage()
+        {
+            IntPtr len = grpcsharp_batch_context_recv_message_length(this);
+            if (len == new IntPtr(-1))
+            {
+                return null;
+            }
+            byte[] data = new byte[(int) len];
+            grpcsharp_batch_context_recv_message_to_buffer(this, data, new UIntPtr((ulong)data.Length));
+            return data;
+        }
+
+        public CallSafeHandle GetServerRpcNewCall() {
+            return grpcsharp_batch_context_server_rpc_new_call(this);
+        }
+
+        public string GetServerRpcNewMethod() {
+            return Marshal.PtrToStringAnsi(grpcsharp_batch_context_server_rpc_new_method(this));
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
new file mode 100644
index 0000000000..659a383b4b
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
@@ -0,0 +1,181 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+// 
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+using Grpc.Core;
+
+namespace Grpc.Core.Internal
+{
+    //TODO: rename the delegate
+    internal delegate void CompletionCallbackDelegate(GRPCOpError error, IntPtr batchContextPtr);
+
+    /// <summary>
+    /// grpc_call from <grpc/grpc.h>
+    /// </summary>
+	internal class CallSafeHandle : SafeHandleZeroIsInvalid
+	{
+        const UInt32 GRPC_WRITE_BUFFER_HINT = 1;
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern CallSafeHandle grpcsharp_channel_create_call(ChannelSafeHandle channel, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_cancel(CallSafeHandle call);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_cancel_with_status(CallSafeHandle call, StatusCode status, string description);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_start_unary(CallSafeHandle call,
+                                                                        [MarshalAs(UnmanagedType.FunctionPtr)] CompletionCallbackDelegate callback,
+                                                                        byte[] send_buffer, UIntPtr send_buffer_len);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_start_client_streaming(CallSafeHandle call,
+                                                                      [MarshalAs(UnmanagedType.FunctionPtr)] CompletionCallbackDelegate callback);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_start_server_streaming(CallSafeHandle call,
+                                                                      [MarshalAs(UnmanagedType.FunctionPtr)] CompletionCallbackDelegate callback,
+                                                                      byte[] send_buffer, UIntPtr send_buffer_len);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_start_duplex_streaming(CallSafeHandle call,
+                                                                          [MarshalAs(UnmanagedType.FunctionPtr)] CompletionCallbackDelegate callback);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_send_message(CallSafeHandle call,
+                                                                      [MarshalAs(UnmanagedType.FunctionPtr)] CompletionCallbackDelegate callback,
+                                                                      byte[] send_buffer, UIntPtr send_buffer_len);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_send_close_from_client(CallSafeHandle call,
+                                                                             [MarshalAs(UnmanagedType.FunctionPtr)] CompletionCallbackDelegate callback);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_send_status_from_server(CallSafeHandle call, [MarshalAs(UnmanagedType.FunctionPtr)] CompletionCallbackDelegate callback, StatusCode statusCode, string statusMessage);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_recv_message(CallSafeHandle call,
+                                                               [MarshalAs(UnmanagedType.FunctionPtr)] CompletionCallbackDelegate callback);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_call_start_serverside(CallSafeHandle call,
+                                                                [MarshalAs(UnmanagedType.FunctionPtr)] CompletionCallbackDelegate callback);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern void grpcsharp_call_destroy(IntPtr call);
+
+
+        private CallSafeHandle()
+        {
+        }
+
+        public static CallSafeHandle Create(ChannelSafeHandle channel, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline)
+        {
+            return grpcsharp_channel_create_call(channel, cq, method, host, deadline);
+        }
+
+        public void StartUnary(byte[] payload, CompletionCallbackDelegate callback)
+        {
+            AssertCallOk(grpcsharp_call_start_unary(this, callback, payload, new UIntPtr((ulong) payload.Length)));
+        }
+
+        public void StartClientStreaming(CompletionCallbackDelegate callback)
+        {
+            AssertCallOk(grpcsharp_call_start_client_streaming(this, callback));
+        }
+
+        public void StartServerStreaming(byte[] payload, CompletionCallbackDelegate callback)
+        {
+            AssertCallOk(grpcsharp_call_start_server_streaming(this, callback, payload, new UIntPtr((ulong) payload.Length)));
+        }
+
+        public void StartDuplexStreaming(CompletionCallbackDelegate callback)
+        {
+            AssertCallOk(grpcsharp_call_start_duplex_streaming(this, callback));
+        }
+
+        public void StartSendMessage(byte[] payload, CompletionCallbackDelegate callback)
+        {
+            AssertCallOk(grpcsharp_call_send_message(this, callback, payload, new UIntPtr((ulong) payload.Length)));
+        }
+
+        public void StartSendCloseFromClient(CompletionCallbackDelegate callback)
+        {
+            AssertCallOk(grpcsharp_call_send_close_from_client(this, callback));
+        }
+
+        public void StartSendStatusFromServer(Status status, CompletionCallbackDelegate callback)
+        {
+            AssertCallOk(grpcsharp_call_send_status_from_server(this, callback, status.StatusCode, status.Detail));
+        }
+
+        public void StartReceiveMessage(CompletionCallbackDelegate callback)
+        {
+            AssertCallOk(grpcsharp_call_recv_message(this, callback));
+        }
+
+        public void StartServerSide(CompletionCallbackDelegate callback)
+        {
+            AssertCallOk(grpcsharp_call_start_serverside(this, callback));
+        }
+
+        public void Cancel()
+        {
+            AssertCallOk(grpcsharp_call_cancel(this));
+        }
+
+        public void CancelWithStatus(Status status)
+        {
+            AssertCallOk(grpcsharp_call_cancel_with_status(this, status.StatusCode, status.Detail));
+        }
+
+		protected override bool ReleaseHandle()
+		{
+            grpcsharp_call_destroy(handle);
+			return true;
+		}
+
+        private static void AssertCallOk(GRPCCallError callError)
+        {
+            Trace.Assert(callError == GRPCCallError.GRPC_CALL_OK, "Status not GRPC_CALL_OK");
+        }
+
+        private static UInt32 GetFlags(bool buffered) {
+            return buffered ? 0 : GRPC_WRITE_BUFFER_HINT;
+        }
+	}
+}
\ No newline at end of file
diff --git a/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs b/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
new file mode 100644
index 0000000000..f15ead3572
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/ChannelSafeHandle.cs
@@ -0,0 +1,67 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Runtime.InteropServices;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// grpc_channel from <grpc/grpc.h>
+    /// </summary>
+	internal class ChannelSafeHandle : SafeHandleZeroIsInvalid
+	{
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern ChannelSafeHandle grpcsharp_channel_create(string target, IntPtr channelArgs);
+
+		[DllImport("grpc_csharp_ext.dll")]
+		static extern void grpcsharp_channel_destroy(IntPtr channel);
+
+        private ChannelSafeHandle()
+        {
+        }
+
+        public static ChannelSafeHandle Create(string target, IntPtr channelArgs)
+        {
+            return grpcsharp_channel_create(target, channelArgs);
+        }
+
+		protected override bool ReleaseHandle()
+		{
+			grpcsharp_channel_destroy(handle);
+			return true;
+		}
+	}
+}
diff --git a/src/csharp/Grpc.Core/Internal/ClientStreamingInputObserver.cs b/src/csharp/Grpc.Core/Internal/ClientStreamingInputObserver.cs
new file mode 100644
index 0000000000..fb59e86e2d
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/ClientStreamingInputObserver.cs
@@ -0,0 +1,67 @@
+#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.Internal;
+
+namespace Grpc.Core.Internal
+{
+    internal class ClientStreamingInputObserver<TWrite, TRead> : IObserver<TWrite>
+	{
+        readonly AsyncCall<TWrite, TRead> call;
+
+        public ClientStreamingInputObserver(AsyncCall<TWrite, TRead> call)
+		{
+            this.call = call;
+		}
+
+		public void OnCompleted()
+		{
+
+            // TODO: how bad is the Wait here?
+            call.SendCloseFromClientAsync().Wait();
+		}
+
+		public void OnError(Exception error)
+		{
+			throw new InvalidOperationException("This should never be called.");
+		}
+
+		public void OnNext(TWrite value)
+		{
+            // TODO: how bad is the Wait here?
+            call.SendMessageAsync(value).Wait();
+		}
+	}
+}
+
diff --git a/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
new file mode 100644
index 0000000000..3f01fdbfd0
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
@@ -0,0 +1,83 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Runtime.InteropServices;
+using System.Threading.Tasks;
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// grpc_completion_queue from <grpc/grpc.h>
+    /// </summary>
+	internal class CompletionQueueSafeHandle : SafeHandleZeroIsInvalid
+	{
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern CompletionQueueSafeHandle grpcsharp_completion_queue_create();
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern void grpcsharp_completion_queue_shutdown(CompletionQueueSafeHandle cq);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCompletionType grpcsharp_completion_queue_next_with_callback(CompletionQueueSafeHandle cq);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern void grpcsharp_completion_queue_destroy(IntPtr cq);
+
+        private CompletionQueueSafeHandle()
+        {
+        }
+
+        public static CompletionQueueSafeHandle Create()
+        {
+            return grpcsharp_completion_queue_create();
+        }
+
+        public GRPCCompletionType NextWithCallback()
+        {
+            return grpcsharp_completion_queue_next_with_callback(this);
+        }
+
+        public void Shutdown()
+        {
+            grpcsharp_completion_queue_shutdown(this);
+        }
+
+		protected override bool ReleaseHandle()
+        {
+            grpcsharp_completion_queue_destroy(handle);
+			return true;
+		}
+	}
+}
+
diff --git a/src/csharp/Grpc.Core/Internal/Enums.cs b/src/csharp/Grpc.Core/Internal/Enums.cs
new file mode 100644
index 0000000000..f363050b07
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/Enums.cs
@@ -0,0 +1,115 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Runtime.InteropServices;
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// from grpc/grpc.h
+    /// </summary>
+    internal enum GRPCCallError
+    {
+        /* everything went ok */
+        GRPC_CALL_OK = 0,
+        /* something failed, we don't know what */
+        GRPC_CALL_ERROR,
+        /* this method is not available on the server */
+        GRPC_CALL_ERROR_NOT_ON_SERVER,
+        /* this method is not available on the client */
+        GRPC_CALL_ERROR_NOT_ON_CLIENT,
+        /* this method must be called before server_accept */
+        GRPC_CALL_ERROR_ALREADY_ACCEPTED,
+        /* this method must be called before invoke */
+        GRPC_CALL_ERROR_ALREADY_INVOKED,
+        /* this method must be called after invoke */
+        GRPC_CALL_ERROR_NOT_INVOKED,
+        /* this call is already finished
+     (writes_done or write_status has already been called) */
+        GRPC_CALL_ERROR_ALREADY_FINISHED,
+        /* there is already an outstanding read/write operation on the call */
+        GRPC_CALL_ERROR_TOO_MANY_OPERATIONS,
+        /* the flags value was illegal for this call */
+        GRPC_CALL_ERROR_INVALID_FLAGS
+    }
+
+    /// <summary>
+    /// grpc_completion_type from grpc/grpc.h
+    /// </summary>
+    internal enum GRPCCompletionType
+    {
+        /* Shutting down */
+        GRPC_QUEUE_SHUTDOWN,
+
+        /* operation completion */
+        GRPC_OP_COMPLETE,
+
+        /* A read has completed */
+        GRPC_READ,
+
+        /* A write has been accepted by flow control */
+        GRPC_WRITE_ACCEPTED,
+
+        /* writes_done or write_status has been accepted */
+        GRPC_FINISH_ACCEPTED,
+
+        /* The metadata array sent by server received at client */
+        GRPC_CLIENT_METADATA_READ,
+
+        /* An RPC has finished. The event contains status.
+         * On the server this will be OK or Cancelled. */
+        GRPC_FINISHED,
+
+        /* A new RPC has arrived at the server */
+        GRPC_SERVER_RPC_NEW,
+
+        /* The server has finished shutting down */
+        GRPC_SERVER_SHUTDOWN,
+
+        /* must be last, forces users to include a default: case */
+        GRPC_COMPLETION_DO_NOT_USE
+    }
+
+    /// <summary>
+    /// grpc_op_error from grpc/grpc.h
+    /// </summary>
+    internal enum GRPCOpError
+    {
+        /* everything went ok */
+        GRPC_OP_OK = 0,
+        /* something failed, we don't know what */
+        GRPC_OP_ERROR
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs b/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
new file mode 100644
index 0000000000..9e69fe2f43
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
@@ -0,0 +1,125 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Threading;
+using System.Threading.Tasks;
+using Grpc.Core.Internal;
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// Pool of threads polling on the same completion queue.
+    /// </summary>
+    internal class GrpcThreadPool
+    {
+        readonly object myLock = new object();
+        readonly List<Thread> threads = new List<Thread>();
+        readonly int poolSize;
+
+        CompletionQueueSafeHandle cq;
+
+        public GrpcThreadPool(int poolSize) {
+            this.poolSize = poolSize;
+        }
+
+        public void Start() {
+
+            lock (myLock)
+            {
+                if (cq != null)
+                {
+                    throw new InvalidOperationException("Already started.");
+                }
+
+                cq = CompletionQueueSafeHandle.Create();
+
+                for (int i = 0; i < poolSize; i++)
+                {
+                    threads.Add(CreateAndStartThread(i));
+                }
+            }
+        }
+
+        public void Stop() {
+
+            lock (myLock)
+            {
+                cq.Shutdown();
+
+                Console.WriteLine("Waiting for GPRC threads to finish.");
+                foreach (var thread in threads)
+                {
+                    thread.Join();
+                }
+
+                cq.Dispose();
+
+            }
+        }
+
+        internal CompletionQueueSafeHandle CompletionQueue
+        {
+            get
+            {
+                return cq;
+            }
+        }
+
+        private Thread CreateAndStartThread(int i)
+        {
+            var thread = new Thread(new ThreadStart(RunHandlerLoop));
+            thread.IsBackground = false;
+            thread.Start();
+            thread.Name = "grpc " + i;
+            return thread;
+        }
+
+        /// <summary>
+        /// Body of the polling thread.
+        /// </summary>
+        private void RunHandlerLoop()
+        {
+            GRPCCompletionType completionType;
+            do
+            {
+                completionType = cq.NextWithCallback();
+            } while(completionType != GRPCCompletionType.GRPC_QUEUE_SHUTDOWN);
+            Console.WriteLine("Completion queue has shutdown successfully, thread " + Thread.CurrentThread.Name + " exiting.");
+        }
+    }
+
+}
+
diff --git a/src/csharp/Grpc.Core/Internal/SafeHandleZeroIsInvalid.cs b/src/csharp/Grpc.Core/Internal/SafeHandleZeroIsInvalid.cs
new file mode 100644
index 0000000000..aa6fce2e96
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/SafeHandleZeroIsInvalid.cs
@@ -0,0 +1,67 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Runtime.InteropServices;
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// Safe handle to wrap native objects.
+    /// </summary>
+    internal abstract class SafeHandleZeroIsInvalid : SafeHandle
+    {
+        public SafeHandleZeroIsInvalid() : base(IntPtr.Zero, true)
+        {
+        }
+
+        public SafeHandleZeroIsInvalid(bool ownsHandle) : base(IntPtr.Zero, ownsHandle)
+        {
+        }
+
+        public override bool IsInvalid
+        {
+            get
+            {
+                return handle == IntPtr.Zero;
+            }
+        }
+
+        protected override bool ReleaseHandle()
+        {
+            // handle is not owned.
+            return true;
+        }
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs b/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs
new file mode 100644
index 0000000000..de9bbaf7c1
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs
@@ -0,0 +1,112 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Collections.Concurrent;
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+
+namespace Grpc.Core.Internal
+{
+    // TODO: we need to make sure that the delegates are not collected before invoked.
+    internal delegate void ServerShutdownCallbackDelegate(IntPtr eventPtr);
+
+    /// <summary>
+    /// grpc_server from grpc/grpc.h
+    /// </summary>
+    internal sealed class ServerSafeHandle : SafeHandleZeroIsInvalid
+    {
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern GRPCCallError grpcsharp_server_request_call(ServerSafeHandle server, CompletionQueueSafeHandle cq, [MarshalAs(UnmanagedType.FunctionPtr)] CompletionCallbackDelegate callback);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern ServerSafeHandle grpcsharp_server_create(CompletionQueueSafeHandle cq, IntPtr args);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern Int32 grpcsharp_server_add_http2_port(ServerSafeHandle server, string addr);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern void grpcsharp_server_start(ServerSafeHandle server);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern void grpcsharp_server_shutdown(ServerSafeHandle server);
+
+        // TODO: get rid of the old callback style
+        [DllImport("grpc_csharp_ext.dll", EntryPoint = "grpcsharp_server_shutdown_and_notify")]
+        static extern void grpcsharp_server_shutdown_and_notify_CALLBACK(ServerSafeHandle server, [MarshalAs(UnmanagedType.FunctionPtr)] ServerShutdownCallbackDelegate callback);
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern void grpcsharp_server_destroy(IntPtr server);
+
+        private ServerSafeHandle()
+        {
+        }
+
+        public static ServerSafeHandle NewServer(CompletionQueueSafeHandle cq, IntPtr args)
+        {
+            // TODO: also grpc_secure_server_create...
+            return grpcsharp_server_create(cq, args);
+        }
+
+        public int AddPort(string addr)
+        {
+            return grpcsharp_server_add_http2_port(this, addr);
+        }
+
+        public void Start()
+        {
+            grpcsharp_server_start(this);
+        }
+
+        public void Shutdown()
+        {
+            grpcsharp_server_shutdown(this);
+        }
+
+        public void ShutdownAndNotify(ServerShutdownCallbackDelegate callback)
+        {
+            grpcsharp_server_shutdown_and_notify_CALLBACK(this, callback);
+        }
+
+        public GRPCCallError RequestCall(CompletionQueueSafeHandle cq, CompletionCallbackDelegate callback)
+        {
+            return grpcsharp_server_request_call(this, cq, callback);
+        }
+
+        protected override bool ReleaseHandle()
+        {
+            grpcsharp_server_destroy(handle);
+            return true;
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core/Internal/ServerStreamingOutputObserver.cs b/src/csharp/Grpc.Core/Internal/ServerStreamingOutputObserver.cs
new file mode 100644
index 0000000000..08d9921475
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/ServerStreamingOutputObserver.cs
@@ -0,0 +1,71 @@
+#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.Internal;
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// Observer that writes all arriving messages to a call abstraction (in blocking fashion)
+    /// and then halfcloses the call. Used for server-side call handling.
+    /// </summary>
+    internal class ServerStreamingOutputObserver<TWrite, TRead> : IObserver<TWrite>
+	{
+        readonly AsyncCall<TWrite, TRead> call;
+
+        public ServerStreamingOutputObserver(AsyncCall<TWrite, TRead> call)
+		{
+            this.call = call;
+		}
+
+		public void OnCompleted()
+		{
+            // TODO: how bad is the Wait here?
+            call.SendStatusFromServerAsync(new Status(StatusCode.OK, "")).Wait();
+		}
+
+		public void OnError(Exception error)
+		{
+            // TODO: implement this...
+			throw new InvalidOperationException("This should never be called.");
+		}
+
+		public void OnNext(TWrite value)
+		{
+            // TODO: how bad is the Wait here?
+            call.SendMessageAsync(value).Wait();
+		}
+	}
+}
+
diff --git a/src/csharp/Grpc.Core/Internal/Timespec.cs b/src/csharp/Grpc.Core/Internal/Timespec.cs
new file mode 100644
index 0000000000..b191ecde94
--- /dev/null
+++ b/src/csharp/Grpc.Core/Internal/Timespec.cs
@@ -0,0 +1,114 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Runtime.InteropServices;
+using System.Threading;
+
+namespace Grpc.Core.Internal
+{
+	/// <summary>
+	/// gpr_timespec from grpc/support/time.h
+	/// </summary>
+	[StructLayout(LayoutKind.Sequential)]
+	internal struct Timespec
+	{
+        const int nanosPerSecond = 1000 * 1000 * 1000;
+        const int nanosPerTick = 100;
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern Timespec gprsharp_now();
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern Timespec gprsharp_inf_future();
+
+        [DllImport("grpc_csharp_ext.dll")]
+        static extern int gprsharp_sizeof_timespec();
+
+        // TODO: revisit this.
+		// 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;
+		public System.IntPtr tv_nsec;
+
+		/// <summary>
+		/// Timespec a long time in the future.
+		/// </summary>
+		public static Timespec InfFuture
+		{
+			get
+			{
+                return gprsharp_inf_future();
+			}
+		}
+
+        public static Timespec Now
+        {
+            get
+            {
+                return gprsharp_now();
+            }
+        }
+
+        internal static int NativeSize
+        {
+            get
+            {
+                return gprsharp_sizeof_timespec();
+            }
+        }
+
+        /// <summary>
+        /// Creates a GPR deadline from current instant and given timeout.
+        /// </summary>
+        /// <returns>The from timeout.</returns>
+        public static Timespec DeadlineFromTimeout(TimeSpan timeout) {
+            if (timeout == Timeout.InfiniteTimeSpan)
+            {
+                return Timespec.InfFuture;
+            }
+            return Timespec.Now.Add(timeout);
+        }
+
+        public Timespec Add(TimeSpan timeSpan) {
+            long nanos = tv_nsec.ToInt64() + (timeSpan.Ticks % TimeSpan.TicksPerSecond) * nanosPerTick;
+            long overflow_sec = (nanos > nanosPerSecond) ? 1 : 0;
+
+            Timespec result;
+            result.tv_nsec = new IntPtr(nanos % nanosPerSecond);
+            result.tv_sec = new IntPtr(tv_sec.ToInt64() + (timeSpan.Ticks / TimeSpan.TicksPerSecond) + overflow_sec);
+            return result;
+        }
+	}
+}
+
diff --git a/src/csharp/Grpc.Core/Marshaller.cs b/src/csharp/Grpc.Core/Marshaller.cs
new file mode 100644
index 0000000000..602e0eb824
--- /dev/null
+++ b/src/csharp/Grpc.Core/Marshaller.cs
@@ -0,0 +1,87 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// For serializing and deserializing messages.
+    /// </summary>
+    public struct Marshaller<T>
+    {
+        readonly Func<T,byte[]> serializer;
+        readonly Func<byte[],T> deserializer;
+
+        public Marshaller(Func<T, byte[]> serializer, Func<byte[], T> deserializer)
+        {
+            this.serializer = serializer;
+            this.deserializer = deserializer;
+        }
+
+        public Func<T, byte[]> Serializer
+        {
+            get
+            {
+                return this.serializer;
+            }
+        }
+
+        public Func<byte[], T> Deserializer
+        {
+            get
+            {
+                return this.deserializer;
+            }
+        }
+    }
+
+    public static class Marshallers {
+
+        public static Marshaller<T> Create<T>(Func<T,byte[]> serializer, Func<byte[],T> deserializer)
+        {
+            return new Marshaller<T>(serializer, deserializer);
+        }
+
+        public static Marshaller<string> StringMarshaller
+        {
+            get
+            {
+                return new Marshaller<string>(System.Text.Encoding.UTF8.GetBytes,
+                                              System.Text.Encoding.UTF8.GetString);
+            }
+        }
+
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/Method.cs b/src/csharp/Grpc.Core/Method.cs
new file mode 100644
index 0000000000..c94aa8161f
--- /dev/null
+++ b/src/csharp/Grpc.Core/Method.cs
@@ -0,0 +1,97 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+
+namespace Grpc.Core
+{
+    public enum MethodType
+    {
+        Unary,
+        ClientStreaming,
+        ServerStreaming,
+        DuplexStreaming
+    }
+
+    /// <summary>
+    /// A description of a service method.
+    /// </summary>
+    public class Method<TRequest, TResponse>
+    {
+        readonly MethodType type;
+        readonly string name;
+        readonly Marshaller<TRequest> requestMarshaller;
+        readonly Marshaller<TResponse> responseMarshaller;
+
+        public Method(MethodType type, string name, Marshaller<TRequest> requestMarshaller, Marshaller<TResponse> responseMarshaller)
+        {
+            this.type = type;
+            this.name = name;
+            this.requestMarshaller = requestMarshaller;
+            this.responseMarshaller = responseMarshaller;
+        }
+
+        public MethodType Type
+        {
+            get
+            {
+                return this.type;
+            }
+        }
+
+        public string Name
+        {
+            get
+            {
+                return this.name;
+            }
+        }
+
+        public Marshaller<TRequest> RequestMarshaller
+        {
+            get
+            {
+                return this.requestMarshaller;
+            }
+        }
+
+        public Marshaller<TResponse> ResponseMarshaller
+        {
+            get
+            {
+                return this.responseMarshaller;
+            }
+        }
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs b/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs
new file mode 100644
index 0000000000..37ba1e2263
--- /dev/null
+++ b/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs
@@ -0,0 +1,24 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+
+// Information about this assembly is defined by the following attributes.
+// Change them to the values specific to your project.
+[assembly: AssemblyTitle ("Grpc.Core")]
+[assembly: AssemblyDescription ("")]
+[assembly: AssemblyConfiguration ("")]
+[assembly: AssemblyCompany ("")]
+[assembly: AssemblyProduct ("")]
+[assembly: AssemblyCopyright ("Google Inc.  All rights reserved.")]
+[assembly: AssemblyTrademark ("")]
+[assembly: AssemblyCulture ("")]
+// The assembly version has the format "{Major}.{Minor}.{Build}.{Revision}".
+// The form "{Major}.{Minor}.*" will automatically update the build and revision,
+// and "{Major}.{Minor}.{Build}.*" will update just the revision.
+[assembly: AssemblyVersion ("0.1.*")]
+// The following attributes are used to specify the signing key for the assembly,
+// if desired. See the Mono documentation for more information about signing.
+//[assembly: AssemblyDelaySign(false)]
+//[assembly: AssemblyKeyFile("")]
+
+[assembly: InternalsVisibleTo("Grpc.Core.Tests")]
+
diff --git a/src/csharp/Grpc.Core/RpcException.cs b/src/csharp/Grpc.Core/RpcException.cs
new file mode 100644
index 0000000000..5a9d0039bc
--- /dev/null
+++ b/src/csharp/Grpc.Core/RpcException.cs
@@ -0,0 +1,60 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+
+namespace Grpc.Core
+{
+    public class RpcException : Exception
+    {
+        private readonly Status status;
+
+        public RpcException(Status status)
+        {
+            this.status = status;
+        }
+
+        public RpcException(Status status, string message) : base(message)
+        {
+            this.status = status;
+        }
+
+        public Status Status {
+            get
+            {
+                return status;
+            }
+        }
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/Server.cs b/src/csharp/Grpc.Core/Server.cs
new file mode 100644
index 0000000000..002592a3d8
--- /dev/null
+++ b/src/csharp/Grpc.Core/Server.cs
@@ -0,0 +1,213 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+using System.Threading.Tasks;
+using Grpc.Core.Internal;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// Server is implemented only to be able to do
+    /// in-process testing.
+    /// </summary>
+    public class Server
+    {
+        // TODO: make sure the delegate doesn't get garbage collected while
+        // native callbacks are in the completion queue.
+        readonly ServerShutdownCallbackDelegate serverShutdownHandler;
+        readonly CompletionCallbackDelegate newServerRpcHandler;
+
+        readonly BlockingCollection<NewRpcInfo> newRpcQueue = new BlockingCollection<NewRpcInfo>();
+        readonly ServerSafeHandle handle;
+
+        readonly Dictionary<string, IServerCallHandler> callHandlers = new Dictionary<string, IServerCallHandler>();
+
+        readonly TaskCompletionSource<object> shutdownTcs = new TaskCompletionSource<object>();
+
+        public Server()
+        {
+            this.handle = ServerSafeHandle.NewServer(GetCompletionQueue(), IntPtr.Zero);
+            this.newServerRpcHandler = HandleNewServerRpc;
+            this.serverShutdownHandler = HandleServerShutdown;
+        }
+
+        // only call this before Start()
+        public void AddServiceDefinition(ServerServiceDefinition serviceDefinition) {
+            foreach(var entry in serviceDefinition.CallHandlers)
+            {
+                callHandlers.Add(entry.Key, entry.Value);
+            }
+        }
+
+        // only call before Start()
+        public int AddPort(string addr) {
+            return handle.AddPort(addr);
+        }
+
+        public void Start()
+        {
+            handle.Start();
+
+            // TODO: this basically means the server is single threaded....
+            StartHandlingRpcs();
+        }
+
+        /// <summary>
+        /// Requests and handles single RPC call.
+        /// </summary>
+        internal void RunRpc()
+        {
+            AllowOneRpc();
+
+            try
+            {
+                var rpcInfo = newRpcQueue.Take();
+
+                //Console.WriteLine("Server received RPC " + rpcInfo.Method);
+
+                IServerCallHandler callHandler;
+                if (!callHandlers.TryGetValue(rpcInfo.Method, out callHandler))
+                {
+                    callHandler = new NoSuchMethodCallHandler();
+                }
+                callHandler.StartCall(rpcInfo.Method, rpcInfo.Call, GetCompletionQueue());
+            }
+            catch(Exception e)
+            {
+                Console.WriteLine("Exception while handling RPC: " + e);
+            }
+        }
+
+        /// <summary>
+        /// Requests server shutdown and when there are no more calls being serviced,
+        /// cleans up used resources.
+        /// </summary>
+        /// <returns>The async.</returns>
+        public async Task ShutdownAsync() {
+            handle.ShutdownAndNotify(serverShutdownHandler);
+            await shutdownTcs.Task;
+            handle.Dispose();
+        }
+
+        public void Kill() {
+            handle.Dispose();
+        }
+
+        private async Task StartHandlingRpcs() {
+            while (true)
+            {
+                await Task.Factory.StartNew(RunRpc);
+            }
+        }
+
+        private void AllowOneRpc()
+        {
+            AssertCallOk(handle.RequestCall(GetCompletionQueue(), newServerRpcHandler));
+        }
+
+        private void HandleNewServerRpc(GRPCOpError error, IntPtr batchContextPtr) {
+            try {
+                var ctx = new BatchContextSafeHandleNotOwned(batchContextPtr);
+
+                if (error != GRPCOpError.GRPC_OP_OK) {
+                    // TODO: handle error
+                }
+
+                var rpcInfo = new NewRpcInfo(ctx.GetServerRpcNewCall(), ctx.GetServerRpcNewMethod());
+
+                // after server shutdown, the callback returns with null call
+                if (!rpcInfo.Call.IsInvalid) {
+                    newRpcQueue.Add(rpcInfo);
+                }
+
+            } catch(Exception e) {
+                Console.WriteLine("Caught exception in a native handler: " + e);
+            }
+        }
+
+        private void HandleServerShutdown(IntPtr eventPtr)
+        {
+            try
+            {
+                shutdownTcs.SetResult(null);
+            }
+            catch (Exception e)
+            {
+                Console.WriteLine("Caught exception in a native handler: " + e);
+            }
+        }
+
+        private static void AssertCallOk(GRPCCallError callError)
+        {
+            Trace.Assert(callError == GRPCCallError.GRPC_CALL_OK, "Status not GRPC_CALL_OK");
+        }
+
+        private static CompletionQueueSafeHandle GetCompletionQueue()
+        {
+            return GrpcEnvironment.ThreadPool.CompletionQueue;
+        }
+
+        private struct NewRpcInfo
+        {
+            private CallSafeHandle call;
+            private string method;
+
+            public NewRpcInfo(CallSafeHandle call, string method)
+            {
+                this.call = call;
+                this.method = method;
+            }
+
+            public CallSafeHandle Call
+            {
+                get
+                {
+                    return this.call;
+                }
+            }
+
+            public string Method
+            {
+                get
+                {
+                    return this.method;
+                }
+            }
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core/ServerCallHandler.cs b/src/csharp/Grpc.Core/ServerCallHandler.cs
new file mode 100644
index 0000000000..1296947f34
--- /dev/null
+++ b/src/csharp/Grpc.Core/ServerCallHandler.cs
@@ -0,0 +1,136 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using Grpc.Core.Internal;
+
+namespace Grpc.Core
+{
+    internal interface IServerCallHandler
+    {
+        void StartCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq);
+    }
+
+    internal class UnaryRequestServerCallHandler<TRequest, TResponse> : IServerCallHandler
+    {
+        readonly Method<TRequest, TResponse> method;
+        readonly UnaryRequestServerMethod<TRequest, TResponse> handler;
+
+        public UnaryRequestServerCallHandler(Method<TRequest, TResponse> method, UnaryRequestServerMethod<TRequest, TResponse> handler)
+        {
+            this.method = method;
+            this.handler = handler;
+        }
+
+        public void StartCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        {
+            var asyncCall = new AsyncCall<TResponse, TRequest>(
+                method.ResponseMarshaller.Serializer,
+                method.RequestMarshaller.Deserializer);
+
+            asyncCall.InitializeServer(call);
+           
+            var finishedTask = asyncCall.ServerSideUnaryRequestCallAsync();
+
+            var request = asyncCall.ReceiveMessageAsync().Result;
+
+            var responseObserver = new ServerStreamingOutputObserver<TResponse, TRequest>(asyncCall);
+            handler(request, responseObserver);
+
+            finishedTask.Wait();
+
+        }
+    }
+
+    internal class StreamingRequestServerCallHandler<TRequest, TResponse> : IServerCallHandler
+    {
+        readonly Method<TRequest, TResponse> method;
+        readonly StreamingRequestServerMethod<TRequest, TResponse> handler;
+
+        public StreamingRequestServerCallHandler(Method<TRequest, TResponse> method, StreamingRequestServerMethod<TRequest, TResponse> handler)
+        {
+            this.method = method;
+            this.handler = handler;
+        }
+
+        public void StartCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        {
+            var asyncCall = new AsyncCall<TResponse, TRequest>(
+                method.ResponseMarshaller.Serializer,
+                method.RequestMarshaller.Deserializer);
+
+            asyncCall.InitializeServer(call);
+
+            var responseObserver = new ServerStreamingOutputObserver<TResponse, TRequest>(asyncCall);
+            var requestObserver = handler(responseObserver);
+            var finishedTask = asyncCall.ServerSideStreamingRequestCallAsync(requestObserver);
+            finishedTask.Wait();
+        }
+    }
+
+    internal class NoSuchMethodCallHandler : IServerCallHandler
+    {
+        public void StartCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        {
+            // We don't care about the payload type here.
+            AsyncCall<byte[], byte[]> asyncCall = new AsyncCall<byte[], byte[]>(
+                (payload) => payload, (payload) => payload);
+
+
+            asyncCall.InitializeServer(call);
+
+            var finishedTask = asyncCall.ServerSideStreamingRequestCallAsync(new NullObserver<byte[]>());
+
+            asyncCall.SendStatusFromServerAsync(new Status(StatusCode.Unimplemented, "No such method.")).Wait();
+
+            finishedTask.Wait();
+        }
+    }
+
+    internal class NullObserver<T> : IObserver<T>
+    {
+        public void OnCompleted()
+        {
+        }
+
+        public void OnError(Exception error)
+        {
+        }
+
+        public void OnNext(T value)
+        {
+        }
+
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/ServerCalls.cs b/src/csharp/Grpc.Core/ServerCalls.cs
new file mode 100644
index 0000000000..bed77796de
--- /dev/null
+++ b/src/csharp/Grpc.Core/ServerCalls.cs
@@ -0,0 +1,58 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+
+namespace Grpc.Core
+{
+    // TODO: perhaps add also serverSideStreaming and clientSideStreaming
+
+    public delegate void UnaryRequestServerMethod<TRequest, TResponse> (TRequest request, IObserver<TResponse> responseObserver);
+
+    public delegate IObserver<TRequest> StreamingRequestServerMethod<TRequest, TResponse> (IObserver<TResponse> responseObserver);
+
+    internal static class ServerCalls {
+
+        public static IServerCallHandler UnaryRequestCall<TRequest, TResponse>(Method<TRequest, TResponse> method, UnaryRequestServerMethod<TRequest, TResponse> handler)
+        {
+            return new UnaryRequestServerCallHandler<TRequest, TResponse>(method, handler);
+        }
+
+        public static IServerCallHandler StreamingRequestCall<TRequest, TResponse>(Method<TRequest, TResponse> method, StreamingRequestServerMethod<TRequest, TResponse> handler)
+        {
+            return new StreamingRequestServerCallHandler<TRequest, TResponse>(method, handler);
+        }
+
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/ServerServiceDefinition.cs b/src/csharp/Grpc.Core/ServerServiceDefinition.cs
new file mode 100644
index 0000000000..231c376062
--- /dev/null
+++ b/src/csharp/Grpc.Core/ServerServiceDefinition.cs
@@ -0,0 +1,98 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Collections.Generic;
+
+namespace Grpc.Core
+{
+    public class ServerServiceDefinition
+    {
+        readonly string serviceName;
+        // TODO: we would need an immutable dictionary here...
+        readonly Dictionary<string, IServerCallHandler> callHandlers;
+
+        private ServerServiceDefinition(string serviceName, Dictionary<string, IServerCallHandler> callHandlers)
+        {
+            this.serviceName = serviceName;
+            this.callHandlers = new Dictionary<string, IServerCallHandler>(callHandlers);
+        }
+
+        internal Dictionary<string, IServerCallHandler> CallHandlers
+        {
+            get
+            {
+                return this.callHandlers;
+            }
+        }
+
+
+        public static Builder CreateBuilder(String serviceName)
+        {
+            return new Builder(serviceName);
+        }
+
+        public class Builder
+        {
+            readonly string serviceName;
+            readonly Dictionary<string, IServerCallHandler> callHandlers = new Dictionary<String, IServerCallHandler>();
+
+            public Builder(string serviceName)
+            {
+                this.serviceName = serviceName;
+            }
+
+            public Builder AddMethod<TRequest, TResponse>(
+                Method<TRequest, TResponse> method,
+                UnaryRequestServerMethod<TRequest, TResponse> handler)
+            {
+                callHandlers.Add(method.Name, ServerCalls.UnaryRequestCall(method, handler));
+                return this;
+            }
+
+            public Builder AddMethod<TRequest, TResponse>(
+                Method<TRequest, TResponse> method,
+                StreamingRequestServerMethod<TRequest, TResponse> handler)
+            {
+                callHandlers.Add(method.Name, ServerCalls.StreamingRequestCall(method, handler));
+                return this;
+            }
+
+            public ServerServiceDefinition Build()
+            {
+                return new ServerServiceDefinition(serviceName, callHandlers);
+            }
+        }
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/Status.cs b/src/csharp/Grpc.Core/Status.cs
new file mode 100644
index 0000000000..5ea1df7b48
--- /dev/null
+++ b/src/csharp/Grpc.Core/Status.cs
@@ -0,0 +1,69 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Runtime.InteropServices;
+
+namespace Grpc.Core
+{
+	/// <summary>
+	/// Represents RPC result.
+	/// </summary>
+	public struct Status
+	{
+		readonly StatusCode statusCode;
+		readonly string detail;
+
+		public Status(StatusCode statusCode, string detail)
+		{
+			this.statusCode = statusCode;
+			this.detail = detail;
+		}
+
+		public StatusCode StatusCode
+		{
+			get
+			{
+				return statusCode;
+			}
+		}
+
+		public string Detail
+		{
+			get
+			{
+				return detail;
+			}
+		}
+	}
+}
diff --git a/src/csharp/Grpc.Core/StatusCode.cs b/src/csharp/Grpc.Core/StatusCode.cs
new file mode 100644
index 0000000000..1fbf9c1b68
--- /dev/null
+++ b/src/csharp/Grpc.Core/StatusCode.cs
@@ -0,0 +1,181 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+
+namespace Grpc.Core
+{
+    // TODO: element names should changed to comply with C# naming conventions.
+    /// <summary>
+    /// based on grpc_status_code from grpc/status.h
+    /// </summary>
+    public enum StatusCode
+    {
+        /* Not an error; returned on success
+
+     HTTP Mapping: 200 OK */
+        OK = 0,
+        /* The operation was cancelled (typically by the caller).
+
+     HTTP Mapping: 499 Client Closed Request */
+        Cancelled = 1,
+        /* Unknown error.  An example of where this error may be returned is
+     if a Status value received from another address space belongs to
+     an error-space that is not known in this address space.  Also
+     errors raised by APIs that do not return enough error information
+     may be converted to this error.
+
+     HTTP Mapping: 500 Internal Server Error */
+        Unknown = 2,
+        /* Client specified an invalid argument.  Note that this differs
+     from FAILED_PRECONDITION.  INVALID_ARGUMENT indicates arguments
+     that are problematic regardless of the state of the system
+     (e.g., a malformed file name).
+
+     HTTP Mapping: 400 Bad Request */
+        InvalidArgument = 3,
+        /* Deadline expired before operation could complete.  For operations
+     that change the state of the system, this error may be returned
+     even if the operation has completed successfully.  For example, a
+     successful response from a server could have been delayed long
+     enough for the deadline to expire.
+
+     HTTP Mapping: 504 Gateway Timeout */
+        DeadlineExceeded = 4,
+        /* Some requested entity (e.g., file or directory) was not found.
+
+     HTTP Mapping: 404 Not Found */
+        NotFound = 5,
+        /* Some entity that we attempted to create (e.g., file or directory)
+     already exists.
+
+     HTTP Mapping: 409 Conflict */
+        AlreadyExists = 6,
+        /* The caller does not have permission to execute the specified
+     operation.  PERMISSION_DENIED must not be used for rejections
+     caused by exhausting some resource (use RESOURCE_EXHAUSTED
+     instead for those errors).  PERMISSION_DENIED must not be
+     used if the caller can not be identified (use UNAUTHENTICATED
+     instead for those errors).
+
+     HTTP Mapping: 403 Forbidden */
+        PermissionDenied = 7,
+        /* The request does not have valid authentication credentials for the
+     operation.
+
+     HTTP Mapping: 401 Unauthorized */
+        Unauthenticated = 16,
+        /* Some resource has been exhausted, perhaps a per-user quota, or
+     perhaps the entire file system is out of space.
+
+     HTTP Mapping: 429 Too Many Requests */
+        ResourceExhausted = 8,
+        /* Operation was rejected because the system is not in a state
+     required for the operation's execution.  For example, directory
+     to be deleted may be non-empty, an rmdir operation is applied to
+     a non-directory, etc.
+
+     A litmus test that may help a service implementor in deciding
+     between FAILED_PRECONDITION, ABORTED, and UNAVAILABLE:
+      (a) Use UNAVAILABLE if the client can retry just the failing call.
+      (b) Use ABORTED if the client should retry at a higher-level
+          (e.g., restarting a read-modify-write sequence).
+      (c) Use FAILED_PRECONDITION if the client should not retry until
+          the system state has been explicitly fixed.  E.g., if an "rmdir"
+          fails because the directory is non-empty, FAILED_PRECONDITION
+          should be returned since the client should not retry unless
+          they have first fixed up the directory by deleting files from it.
+      (d) Use FAILED_PRECONDITION if the client performs conditional
+          REST Get/Update/Delete on a resource and the resource on the
+          server does not match the condition. E.g., conflicting
+          read-modify-write on the same resource.
+
+     HTTP Mapping: 400 Bad Request
+
+     NOTE: HTTP spec says 412 Precondition Failed should only be used if
+     the request contains Etag related headers. So if the server does see
+     Etag related headers in the request, it may choose to return 412
+     instead of 400 for this error code. */
+        FailedPrecondition = 9,
+        /* The operation was aborted, typically due to a concurrency issue
+     like sequencer check failures, transaction aborts, etc.
+
+     See litmus test above for deciding between FAILED_PRECONDITION,
+     ABORTED, and UNAVAILABLE.
+
+     HTTP Mapping: 409 Conflict */
+        Aborted = 10,
+        /* Operation was attempted past the valid range.  E.g., seeking or
+     reading past end of file.
+
+     Unlike INVALID_ARGUMENT, this error indicates a problem that may
+     be fixed if the system state changes. For example, a 32-bit file
+     system will generate INVALID_ARGUMENT if asked to read at an
+     offset that is not in the range [0,2^32-1], but it will generate
+     OUT_OF_RANGE if asked to read from an offset past the current
+     file size.
+
+     There is a fair bit of overlap between FAILED_PRECONDITION and
+     OUT_OF_RANGE.  We recommend using OUT_OF_RANGE (the more specific
+     error) when it applies so that callers who are iterating through
+     a space can easily look for an OUT_OF_RANGE error to detect when
+     they are done.
+
+     HTTP Mapping: 400 Bad Request */
+        OutOfRange = 11,
+        /* Operation is not implemented or not supported/enabled in this service.
+
+     HTTP Mapping: 501 Not Implemented */
+        Unimplemented = 12,
+        /* Internal errors.  Means some invariants expected by underlying
+     system has been broken.  If you see one of these errors,
+     something is very broken.
+
+     HTTP Mapping: 500 Internal Server Error */
+        Internal = 13,
+        /* The service is currently unavailable.  This is a most likely a
+     transient condition and may be corrected by retrying with
+     a backoff.
+
+     See litmus test above for deciding between FAILED_PRECONDITION,
+     ABORTED, and UNAVAILABLE.
+
+     HTTP Mapping: 503 Service Unavailable */
+        Unavailable = 14,
+        /* Unrecoverable data loss or corruption.
+
+     HTTP Mapping: 500 Internal Server Error */
+        DataLoss = 15
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/Utils/RecordingObserver.cs b/src/csharp/Grpc.Core/Utils/RecordingObserver.cs
new file mode 100644
index 0000000000..99d2725b70
--- /dev/null
+++ b/src/csharp/Grpc.Core/Utils/RecordingObserver.cs
@@ -0,0 +1,65 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace Grpc.Core.Utils
+{
+    public class RecordingObserver<T> : IObserver<T>
+    {
+        TaskCompletionSource<List<T>> tcs = new TaskCompletionSource<List<T>>();
+        List<T> data = new List<T>();
+
+        public void OnCompleted()
+        {
+            tcs.SetResult(data);
+        }
+
+        public void OnError(Exception error)
+        {
+            tcs.SetException(error);
+        }
+
+        public void OnNext(T value)
+        {
+            data.Add(value);
+        }
+
+        public Task<List<T>> ToList() {
+            return tcs.Task;
+        }
+    }
+}
+
diff --git a/src/csharp/Grpc.Core/Utils/RecordingQueue.cs b/src/csharp/Grpc.Core/Utils/RecordingQueue.cs
new file mode 100644
index 0000000000..63992da6a9
--- /dev/null
+++ b/src/csharp/Grpc.Core/Utils/RecordingQueue.cs
@@ -0,0 +1,84 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Threading.Tasks;
+using System.Collections.Generic;
+using System.Collections.Concurrent;
+
+namespace Grpc.Core.Utils
+{
+    // TODO: replace this by something that implements IAsyncEnumerator.
+    /// <summary>
+    /// Observer that allows us to await incoming messages one-by-one.
+    /// The implementation is not ideal and class will be probably replaced
+    /// by something more versatile in the future.
+    /// </summary>
+    public class RecordingQueue<T> : IObserver<T>
+    {
+        readonly BlockingCollection<T> queue = new BlockingCollection<T>();
+        TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
+
+        public void OnCompleted()
+        {
+            tcs.SetResult(null);
+        }
+
+        public void OnError(Exception error)
+        {
+            tcs.SetException(error);
+        }
+
+        public void OnNext(T value)
+        {
+            queue.Add(value);
+        }
+
+        public BlockingCollection<T> Queue
+        {
+            get
+            {
+                return queue;
+            }
+        }
+
+        public Task Finished
+        {
+            get
+            {
+                return tcs.Task;
+            }
+        }
+    }
+}
+