use local server in XamarinHelloworld

examples/csharp/HelloworldXamarin/Droid/MainActivity.cs

@@ -1,6 +1,7 @@
 using Android.App;
 using Android.Widget;
 using Android.OS;
+using System.Threading.Tasks;
 using Grpc.Core;
 using Helloworld;
 
@@ -9,7 +10,8 @@ namespace HelloworldXamarin.Droid
     [Activity(Label = "HelloworldXamarin", MainLauncher = true, Icon = "@mipmap/icon")]
     public class MainActivity : Activity
     {
-        //int count = 1;
+        const int Port = 50051;
+        int count = 1;
 
         protected override void OnCreate(Bundle savedInstanceState)
         {
@@ -27,21 +29,38 @@ namespace HelloworldXamarin.Droid
 
         private void SayHello(Button button)
         {
+            Server server = new Server
+            {
+              Services = { Greeter.BindService(new GreeterImpl()) },
+              Ports = { new ServerPort("localhost", Port, ServerCredentials.Insecure) }
+            };
+            server.Start();
 
             // use loopback on host machine: https://developer.android.com/studio/run/emulator-networking
-              Channel channel = new Channel("10.0.2.2:50051", ChannelCredentials.Insecure);
+            //10.0.2.2:50051
+            Channel channel = new Channel("localhost:50051", ChannelCredentials.Insecure);
 
             var client = new Greeter.GreeterClient(channel);
-              string user = "Xamarin";
+            string user = "Xamarin " + count;
 
             var reply = client.SayHello(new HelloRequest { Name = user });
 
             button.Text = "Greeting: " + reply.Message;
 
             channel.ShutdownAsync().Wait();
-            }
-    }
+            server.ShutdownAsync().Wait();
 
+            count++;
+        }
 
+        class GreeterImpl : Greeter.GreeterBase
+        {
+            // Server side handler of the SayHello RPC
+            public override Task<HelloReply> SayHello(HelloRequest request, ServerCallContext context)
+            {
+              return Task.FromResult(new HelloReply { Message = "Hello " + request.Name });
+            }
+        }
+    }
 }
 

examples/csharp/HelloworldXamarin/iOS/ViewController.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Threading.Tasks;
+
 using Grpc.Core;
 using Helloworld;
 
@@ -8,6 +10,7 @@ namespace HelloworldXamarin.iOS
 {
     public partial class ViewController : UIViewController
     {
+        const int Port = 50051;
         int count = 1;
 
         public ViewController(IntPtr handle) : base(handle)
@@ -35,18 +38,36 @@ namespace HelloworldXamarin.iOS
 
         private string SayHello()
         {
+            Server server = new Server
+            {
+                Services = { Greeter.BindService(new GreeterImpl()) },
+                Ports = { new ServerPort("localhost", Port, ServerCredentials.Insecure) }
+            };
+            server.Start();
 
-              // use loopback on host machine: https://developer.android.com/studio/run/emulator-networking
-              Channel channel = new Channel("10.0.2.2:50051", ChannelCredentials.Insecure);
+            Channel channel = new Channel("localhost:50051", ChannelCredentials.Insecure);
 
             var client = new Greeter.GreeterClient(channel);
-              string user = "Xamarin";
+            string user = "Xamarin " + count;
 
             var reply = client.SayHello(new HelloRequest { Name = user });
 
             channel.ShutdownAsync().Wait();
+            server.ShutdownAsync().Wait();
+
+            count++;
 
             return "Greeting: " + reply.Message;
         }
+
+
+        class GreeterImpl : Greeter.GreeterBase
+        {
+            // Server side handler of the SayHello RPC
+            public override Task<HelloReply> SayHello(HelloRequest request, ServerCallContext context)
+            {
+              return Task.FromResult(new HelloReply { Message = "Hello " + request.Name });
+            }
+        }
     }
 }