add C# xds example

examples/csharp/Xds/Greeter.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 15
+VisualStudioVersion = 15.0.26228.4
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Greeter", "Greeter\Greeter.csproj", "{13B6DFC8-F5F6-4CC2-99DF-57A7CF042033}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "GreeterClient", "GreeterClient\GreeterClient.csproj", "{B754FB02-D501-4308-8B89-33AB7119C80D}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "GreeterServer", "GreeterServer\GreeterServer.csproj", "{DDBFF994-E076-43AD-B18D-049DFC1B670C}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{13B6DFC8-F5F6-4CC2-99DF-57A7CF042033}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{13B6DFC8-F5F6-4CC2-99DF-57A7CF042033}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{13B6DFC8-F5F6-4CC2-99DF-57A7CF042033}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{13B6DFC8-F5F6-4CC2-99DF-57A7CF042033}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B754FB02-D501-4308-8B89-33AB7119C80D}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B754FB02-D501-4308-8B89-33AB7119C80D}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B754FB02-D501-4308-8B89-33AB7119C80D}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B754FB02-D501-4308-8B89-33AB7119C80D}.Release|Any CPU.Build.0 = Release|Any CPU
+		{DDBFF994-E076-43AD-B18D-049DFC1B670C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{DDBFF994-E076-43AD-B18D-049DFC1B670C}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{DDBFF994-E076-43AD-B18D-049DFC1B670C}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{DDBFF994-E076-43AD-B18D-049DFC1B670C}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+EndGlobal

examples/csharp/Xds/Greeter/Greeter.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Google.Protobuf" Version="3.12.2" />
+    <PackageReference Include="Grpc.Core" Version="2.29.0" />
+    <PackageReference Include="Grpc.HealthCheck" Version="2.29.0" />
+    <PackageReference Include="Grpc.Reflection" Version="2.29.0"/>
+    <PackageReference Include="Grpc.Tools" Version="2.29.0" PrivateAssets="All" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Protobuf Include="../../../protos/helloworld.proto" Link="helloworld.proto" />
+  </ItemGroup>
+
+</Project>

examples/csharp/Xds/GreeterClient/GreeterClient.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <OutputType>Exe</OutputType>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Greeter\Greeter.csproj" />
+  </ItemGroup>
+
+</Project>

examples/csharp/Xds/GreeterClient/Program.cs

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+// Copyright 2015 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
+using Grpc.Core;
+using Helloworld;
+
+namespace GreeterClient
+{
+    class Program
+    {
+        public static void Main(string[] args)
+        {
+            // TODO: specify server address..
+
+            Channel channel = new Channel("127.0.0.1:50051", ChannelCredentials.Insecure);
+
+            var client = new Greeter.GreeterClient(channel);
+            String user = "you";
+
+            var reply = client.SayHello(new HelloRequest { Name = user });
+            Console.WriteLine("Greeter client received: " + reply.Message);
+
+            channel.ShutdownAsync().Wait();
+            Console.WriteLine("Press any key to exit...");
+            Console.ReadKey();
+        }
+    }
+}

examples/csharp/Xds/GreeterServer/GreeterServer.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <OutputType>Exe</OutputType>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Greeter\Greeter.csproj" />
+  </ItemGroup>
+
+</Project>

examples/csharp/Xds/GreeterServer/Program.cs

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+// Copyright 2020 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
+using System.Net;
+using System.Threading.Tasks;
+using Grpc.Core;
+using Grpc.HealthCheck;
+using Helloworld;
+using Grpc.Health;
+using Grpc.Health.V1;
+using Grpc.Reflection;
+using Grpc.Reflection.V1Alpha;
+
+namespace GreeterServer
+{
+    class GreeterImpl : Greeter.GreeterBase
+    {
+        // Server side handler of the SayHello RPC
+        public override Task<HelloReply> SayHello(HelloRequest request, ServerCallContext context)
+        {
+            String hostName = Dns.GetHostName();
+            return Task.FromResult(new HelloReply { Message = $"Hello {request.Name} from {hostName}!"});
+        }
+    }
+
+    class Program
+    {
+        const int Port = 50051;
+
+        public static void Main(string[] args)
+        {
+            var serviceDescriptors = new [] {Greeter.Descriptor, Health.Descriptor, ServerReflection.Descriptor};
+            var greeterImpl = new GreeterImpl();
+            var healthServiceImpl = new HealthServiceImpl();
+            var reflectionImpl = new ReflectionServiceImpl(serviceDescriptors);
+
+            Server server = new Server
+            {
+                Services = { Greeter.BindService(greeterImpl), Health.BindService(healthServiceImpl), ServerReflection.BindService(reflectionImpl) },
+                Ports = { new ServerPort("localhost", Port, ServerCredentials.Insecure) }
+            };
+            server.Start();
+
+            // Mark all services as healthy.
+            foreach (var serviceDescriptor in serviceDescriptors)
+            {
+                healthServiceImpl.SetStatus(serviceDescriptor.FullName, HealthCheckResponse.Types.ServingStatus.Serving);
+            }
+            // Mark overall server status as healthy.
+            healthServiceImpl.SetStatus("", HealthCheckResponse.Types.ServingStatus.Serving);
+
+            Console.WriteLine("Greeter server listening on port " + Port);
+            Console.WriteLine("Press any key to stop the server...");
+            Console.ReadKey();
+
+            server.ShutdownAsync().Wait();
+        }
+    }
+}

examples/csharp/Xds/README.md

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+gRPC Hostname example (C#)
+========================
+
+BACKGROUND
+-------------
+This is a version of the helloworld example with a server whose response includes its hostname. It also supports health and reflection services. This makes it a good server to test infrastructure, like load balancing.
+
+PREREQUISITES
+-------------
+
+- The [.NET Core SDK 2.1+](https://www.microsoft.com/net/core)
+
+You can also build the solution `Greeter.sln` using Visual Studio 2019,
+but it's not a requirement.
+
+BUILD AND RUN
+-------------
+
+- Build and run the server
+
+  ```
+  > dotnet run -p GreeterServer
+  ```
+
+- Build and run the client
+
+  ```
+  > dotnet run -p GreeterClient
+  ```