cleaned up ChatClient / ChatServer sample (#6824)

* removed mutable state on messages
* migrated to using record types for all messages
* `await` on `ActorSystem` termination
* cleaned up styles and formatting

Author: Aaronontheweb

src/examples/Chat/ChatClient/Program.cs

@@ -7,6 +7,7 @@
 
 using System;
 using System.Linq;
+using System.Threading.Tasks;
 using Akka.Actor;
 using Akka.Configuration;
 using ChatMessages;
@@ -15,7 +16,7 @@ namespace ChatClient
 {
     class Program
     {
-        static void Main(string[] args)
+        public static async Task Main(string[] args)
         {
             var config = ConfigurationFactory.ParseString(@"
 akka {  
@@ -31,54 +32,50 @@ static void Main(string[] args)
 }
 ");
 
-            using (var system = ActorSystem.Create("MyClient", config))
+            var system = ActorSystem.Create("MyClient", config);
+            var chatClient = system.ActorOf(Props.Create<ChatClientActor>());
+            chatClient.Tell(new ConnectRequest("Roggan"));
+
+            while (true)
             {
-                var chatClient = system.ActorOf(Props.Create<ChatClientActor>());
-                chatClient.Tell(new ConnectRequest()
+                var input = Console.ReadLine();
+                if (input.StartsWith('/'))
                 {
-                    Username = "Roggan",
-                });
+                    var parts = input.Split(' ');
+                    var cmd = parts[0].ToLowerInvariant();
+                    var rest = string.Join(" ", parts.Skip(1));
 
-                while (true)
-                {
-                    var input = Console.ReadLine();
-                    if (input.StartsWith('/'))
+                    if (cmd == "/nick")
                     {
-                        var parts = input.Split(' ');
-                        var cmd = parts[0].ToLowerInvariant();
-                        var rest = string.Join(" ", parts.Skip(1));
-
-                        if (cmd == "/nick")
-                        {
-                            chatClient.Tell(new NickRequest
-                            {
-                                NewUsername = rest
-                            });
-                        }
-                        if (cmd == "/exit")
-                        {
-                            Console.WriteLine("exiting");
-                            break;
-                        }
+                        chatClient.Tell(new ChatClientActor.RequestNewNick(rest));
                     }
-                    else
+
+                    if (cmd == "/exit")
                     {
-                        chatClient.Tell(new SayRequest()
-                        {
-                            Text = input,
-                        });
+                        Console.WriteLine("exiting");
+                        break;
                     }
                 }
-
-                system.Terminate().Wait();
+                else
+                {
+                    chatClient.Tell(new ChatClientActor.PushNewChatMessage(input));
+                }
             }
+
+            await system.Terminate();
         }
     }
 
-    class ChatClientActor : ReceiveActor, ILogReceive
+    internal class ChatClientActor : ReceiveActor, ILogReceive
     {
         private string _nick = "Roggan";
-        private readonly ActorSelection _server = Context.ActorSelection("akka.tcp://MyServer@localhost:8081/user/ChatServer");
+
+        private readonly ActorSelection _server =
+            Context.ActorSelection("akka.tcp://MyServer@localhost:8081/user/ChatServer");
+
+        public record RequestNewNick(string NewNick);
+
+        public record PushNewChatMessage(string Message);
 
         public ChatClientActor()
         {
@@ -94,30 +91,25 @@ public ChatClientActor()
                 Console.WriteLine(rsp.Message);
             });
 
-            Receive<NickRequest>(nr =>
+            Receive<RequestNewNick>(nr =>
             {
-                nr.OldUsername = _nick;
-                Console.WriteLine("Changing nick to {0}", nr.NewUsername);
-                _nick = nr.NewUsername;
-                _server.Tell(nr);
+                Console.WriteLine("Changing nick to {0}", nr.NewNick);
+                var request = new NickRequest(_nick, nr.NewNick);
+                _nick = nr.NewNick;
+                _server.Tell(request);
             });
 
             Receive<NickResponse>(nrsp =>
             {
                 Console.WriteLine("{0} is now known as {1}", nrsp.OldUsername, nrsp.NewUsername);
             });
 
-            Receive<SayRequest>(sr =>
+            Receive<PushNewChatMessage>(sr =>
             {
-                sr.Username = _nick;
-                _server.Tell(sr);
+                _server.Tell(new SayRequest(_nick, sr.Message));
             });
 
-            Receive<SayResponse>(srsp =>
-            {
-                Console.WriteLine("{0}: {1}", srsp.Username, srsp.Text);
-            });
+            Receive<SayResponse>(srsp => { Console.WriteLine("{0}: {1}", srsp.Username, srsp.Text); });
         }
     }
-}
-
+}

src/examples/Chat/ChatMessages/ChatMessages.csproj

@@ -1,12 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>$(NetStandardLibVersion)</TargetFramework>
+    <TargetFramework>$(NetTestVersion)</TargetFramework>
   </PropertyGroup>
 
-  <ItemGroup>
-    <Folder Include="Properties\" />
-  </ItemGroup>
-
   <ItemGroup>
     <ProjectReference Include="..\..\..\core\Akka\Akka.csproj" />
   </ItemGroup>

src/examples/Chat/ChatMessages/Messages.cs

@@ -5,41 +5,24 @@
 // </copyright>
 //-----------------------------------------------------------------------
 
-using Akka.Actor;
-
 namespace ChatMessages
 {
-    public class ConnectRequest
-    {
-        public string Username { get; set; }
-    }
-
-    public class ConnectResponse
-    {
-        public string Message { get; set; }
-    }
-
-    public class NickRequest
-    {
-        public string OldUsername { get; set; }
-        public string NewUsername { get; set; }
-    }
+    /// <summary>
+    /// Marker interface for all chat messages exchanged between client and server
+    /// </summary>
+    /// <remarks>
+    /// Currently not used for anything - can be used in the future for serialization
+    /// or routing purposes.
+    /// </remarks>
+    public interface IChatProtocol { }
+    
+    public record ConnectRequest(string Username) : IChatProtocol;
 
-    public class NickResponse
-    {
-        public string OldUsername { get; set; }
-        public string NewUsername { get; set; }
-    }
+    public record ConnectResponse(string Message) : IChatProtocol;
 
-    public class SayRequest
-    {
-        public string Username { get; set; }
-        public string Text { get; set; }
-    }
+    public record NickRequest(string OldUsername, string NewUsername) : IChatProtocol;
+    public record NickResponse(string OldUsername, string NewUsername) : IChatProtocol;
+    public record SayRequest(string Username, string Text) : IChatProtocol;
 
-    public class SayResponse
-    {
-        public string Username { get; set; }
-        public string Text { get; set; }
-    }
+    public record SayResponse(string Username, string Text) : IChatProtocol;
 }

src/examples/Chat/ChatServer/App.config

@@ -10,8 +10,4 @@
     <ProjectReference Include="..\ChatMessages\ChatMessages.csproj" />
   </ItemGroup>
 
-  <ItemGroup>
-    <Folder Include="Properties\" />
-  </ItemGroup>
-
 </Project>

src/examples/Chat/ChatServer/ChatServer.csproj

@@ -7,6 +7,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Threading.Tasks;
 using Akka.Actor;
 using Akka.Configuration;
 using ChatMessages;
@@ -15,7 +16,7 @@ namespace ChatServer
 {
     class Program
     {
-        static void Main(string[] args)
+        public static async Task Main(string[] args)
         {
             var config = ConfigurationFactory.ParseString(@"
 akka {  
@@ -32,51 +33,39 @@ static void Main(string[] args)
 }
 ");
 
-            using (var system = ActorSystem.Create("MyServer", config))
-            {
-                system.ActorOf(Props.Create(() => new ChatServerActor()), "ChatServer");
+            var system = ActorSystem.Create("MyServer", config);
+
+            system.ActorOf(Props.Create(() => new ChatServerActor()), "ChatServer");
 
-                Console.ReadLine();
-            }
+            Console.ReadLine();
+            await system.Terminate();
         }
     }
 
-    class ChatServerActor : ReceiveActor, ILogReceive
+    internal class ChatServerActor : ReceiveActor, ILogReceive
     {
         private readonly HashSet<IActorRef> _clients = new();
 
         public ChatServerActor()
         {
             Receive<SayRequest>(message =>
             {
-                var response = new SayResponse
-                {
-                    Username = message.Username,
-                    Text = message.Text,
-                };
+                var response = new SayResponse(message.Username, message.Text);
                 foreach (var client in _clients) client.Tell(response, Self);
             });
 
             Receive<ConnectRequest>(_ =>
             {
                 _clients.Add(Sender);
-                Sender.Tell(new ConnectResponse
-                {
-                    Message = "Hello and welcome to Akka.NET chat example",
-                }, Self);
+                Sender.Tell(new ConnectResponse("Hello and welcome to Akka.NET chat example"), Self);
             });
 
             Receive<NickRequest>(message =>
             {
-                var response = new NickResponse
-                {
-                    OldUsername = message.OldUsername,
-                    NewUsername = message.NewUsername,
-                };
+                var response = new NickResponse(message.OldUsername, message.NewUsername);
 
                 foreach (var client in _clients) client.Tell(response, Self);
             });
         }
     }
-}
-
+}