Resolve warnings and use features from .NET 6.

Program.cs

@@ -1,96 +1,88 @@
-using System;
-using System.Net.WebSockets;
+using System.Net.WebSockets;
 using System.Text;
-using System.Threading;
-using System.Threading.Tasks;
-using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting.Server;
-using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Server.Kestrel.Core;
 using Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets;
 using Microsoft.AspNetCore.WebSockets;
-using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.Extensions.Options;
 using Microsoft.Extensions.Primitives;
 
-namespace Kestrel
+namespace Kestrel;
+
+class Context
 {
-    class Context
-    {
-        public IFeatureCollection features;
+    public IFeatureCollection features;
 
-        public Context(IFeatureCollection features)
-        {
-            this.features = features;
-        }
+    public Context(IFeatureCollection features)
+    {
+        this.features = features;
+    }
+}
+
+class Application : IHttpApplication<Context>
+{
+    private readonly WebSocketMiddleware wsMiddleware;
+
+    public Application(ILoggerFactory loggerFactory)
+    {
+        var wsOptions = new WebSocketOptions();
+        wsMiddleware = new WebSocketMiddleware(ContinueRequest, new OptionsWrapper<WebSocketOptions>(wsOptions),
+            loggerFactory);
     }
 
-    class Application : IHttpApplication<Context>
+    public Context CreateContext(IFeatureCollection contextFeatures)
     {
-        private WebSocketMiddleware wsMiddleware;
-
-        public Application(ILoggerFactory loggerFactory)
-        {
-            var wsOptions = new WebSocketOptions();
-            wsMiddleware = new WebSocketMiddleware(continueRequest, new OptionsWrapper<WebSocketOptions>(wsOptions),
-                loggerFactory);
-        }
-
-        public Context CreateContext(IFeatureCollection contextFeatures)
-        {
-            return new Context(contextFeatures);
-        }
-
-        public void DisposeContext(Context context, Exception exception)
-        {
-        }
-
-        public async Task ProcessRequestAsync(Context context)
-        {
-            HttpContext httpContext = new DefaultHttpContext(context.features);
-            await wsMiddleware.Invoke(httpContext);
-        }
-
-        private async Task continueRequest(HttpContext httpContext)
-        {
-            if (httpContext.WebSockets.IsWebSocketRequest)
-            {
-                var socket = await httpContext.WebSockets.AcceptWebSocketAsync();
-                var message = Encoding.ASCII.GetBytes("hello world");
-                await socket.SendAsync(new ArraySegment<byte>(message), WebSocketMessageType.Text, true,
-                    CancellationToken.None);
-
-                await socket.ReceiveAsync(new byte[4096], CancellationToken.None);
-            }
-            else
-            {
-                httpContext.Response.Headers.Add("Content-Type", new StringValues("text/plain"));
-                await httpContext.Response.Body.WriteAsync(Encoding.ASCII.GetBytes("hello world"));
-            }
-        }
+        return new Context(contextFeatures);
     }
 
-    class Program
+    public void DisposeContext(Context context, Exception? exception)
     {
-        static async Task Main(string[] args)
+    }
+
+    public async Task ProcessRequestAsync(Context context)
+    {
+        HttpContext httpContext = new DefaultHttpContext(context.features);
+        await wsMiddleware.Invoke(httpContext);
+    }
+
+    private async Task ContinueRequest(HttpContext httpContext)
+    {
+        if (httpContext.WebSockets.IsWebSocketRequest)
         {
-            var serverOptions = new KestrelServerOptions();
-            serverOptions.ListenAnyIP(8080);
+            var socket = await httpContext.WebSockets.AcceptWebSocketAsync();
+            var message = Encoding.ASCII.GetBytes("hello world");
+            await socket.SendAsync(new ArraySegment<byte>(message), WebSocketMessageType.Text, true,
+                CancellationToken.None);
 
-            var transportOptions = new SocketTransportOptions();
-            var loggerFactory = new NullLoggerFactory();
-
-            var transportFactory = new SocketTransportFactory(
-                new OptionsWrapper<SocketTransportOptions>(transportOptions), loggerFactory);
-
-            using (var server = new KestrelServer(new OptionsWrapper<KestrelServerOptions>(serverOptions),
-                transportFactory, loggerFactory))
-            {
-                await server.StartAsync(new Application(loggerFactory), CancellationToken.None);
-                Console.ReadLine();
-            }
+            await socket.ReceiveAsync(new byte[4096], CancellationToken.None);
+        }
+        else
+        {
+            httpContext.Response.Headers.Add("Content-Type", new StringValues("text/plain"));
+            await httpContext.Response.Body.WriteAsync(Encoding.ASCII.GetBytes("hello world\n"));
         }
     }
 }
+
+class Program
+{
+    static async Task Main()
+    {
+        var serverOptions = new KestrelServerOptions();
+        serverOptions.ListenAnyIP(8080);
+
+        var transportOptions = new SocketTransportOptions();
+        var loggerFactory = new NullLoggerFactory();
+
+        var transportFactory = new SocketTransportFactory(
+            new OptionsWrapper<SocketTransportOptions>(transportOptions), loggerFactory);
+
+        using var server = new KestrelServer(
+            new OptionsWrapper<KestrelServerOptions>(serverOptions), transportFactory, loggerFactory);
+
+        await server.StartAsync(new Application(loggerFactory), CancellationToken.None);
+        Console.ReadLine();
+    }
+}

kestrel.csproj

@@ -2,6 +2,8 @@
 
   <PropertyGroup>
     <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
 </Project>