KbWebSocketServer

KbWebSocketServer is a lightweight .net websocket server library.

• Simple Api interface
• No 3rd-party package dependency required
• Fast and GC friendly
• Target framework: net5.0 (compatible with higher .net version)

Usage Tutorials

Install package

Install-Package KbWebSocketServer

Or, if you don't want to add another package to your project, you can just copy all source files into your codebase. KbWebSocketServer is a clean and lightweight project, it doesn't require any additional package but only .net coreclr library itself.

Start up a websocket server and accept client requests

// specify server listening IP and port. var wss = new WebSocketServer(8000); // start up server, pass in a client request handler. wss.Start(async ctx => { // accept this client request. var ws = await ctx.AcceptWebSocketAsync(); Write(ws); }); async ValueTask Write(WebSocket ws) { await foreach (var message in ws.ReceiveMessagesAsync()) { if (message.MessageType == WebSocketMessageType.Text) { Console.WriteLine(message.Text.ToString()); } } }

Reject client requests

var wss = new WebSocketServer(8000); wss.Start(async ctx => { if (ctx.Request.Ip.ToString() == "127.0.0.1") { // put some error information in response headers, // to allow client getting error details from server response. // // it's optional, but useful. ctx.Response.Set("x-custom-error", "You should not connect from local."); // reject client request with status code 401. await ctx.RejectWebSocketAsync(HttpStatusCode.Unauthorized); } else { var ws = await ctx.AcceptWebSocketAsync(); } });

Receive/send messages from/to a client

var wss = new WebSocketServer(8000); wss.Start(async ctx => { var ws = await ctx.AcceptWebSocketAsync(); Echo(ws); }); async ValueTask Echo(WebSocket ws) { // ReceiveMessagesAsync() returns an IAsyncEnumerable, // which can be consumed by `await foreach`. await foreach (var message in ws.ReceiveMessagesAsync()) { // message type can be `Text` or `Binary`. if (message.MessageType == WebSocketMessageType.Text) { // send back a text message. await ws.SendTextAsync($"Reply: {message.Text}"); } } }

Broadcast to all clients

var wss = new WebSocketServer(8000); var clients = ImmutableArray<WebSocket>.Empty; wss.Start(async ctx => { var ws = await ctx.AcceptWebSocketAsync(); // put new client into a collection. ImmutableInterlocked.Update( ref clients, arr => arr.Add(ws)); Pub(ws); }); async ValueTask Pub(WebSocket ws) { var textMessages = ws .ReceiveMessagesAsync() .Where(msg => msg.MessageType == WebSocketMessageType.Text); await foreach (var message in textMessages) { // broadcast message to all opened clients. foreach (var client in clients) { if (client.State == WebSocketState.Open) { await client.SendTextAsync($"Pub: {message.Text}"); } } } }

Determine client disconnects

var wss = new WebSocketServer(8000); wss.Start(async ctx => { var ws = await ctx.AcceptWebSocketAsync(); Echo(ws); }); async ValueTask Echo(WebSocket ws) { var textMessages = ws .ReceiveMessagesAsync() .Where(msg => msg.MessageType == WebSocketMessageType.Text); // when this client is disconnected, // it'll break the `await foreach` loop. await foreach (var message in textMessages) { // ... } if (ws.State != WebSocketState.Open) { Console.WriteLine($"a client is disconnected. state={ws.State}"); } }

Close client connection from server

var wss = new WebSocketServer(8000); wss.Start(async ctx => { var ws = await ctx.AcceptWebSocketAsync(); Echo(ws); }); async ValueTask Echo(WebSocket ws) { var textMessages = ws .ReceiveMessagesAsync() .Where(msg => msg.MessageType == WebSocketMessageType.Text); await foreach (var message in textMessages) { if (message.Text.ToString().Equals("PleaseClose", StringComparison.OrdinalIgnoreCase)) { // close client connection. await ws.CloseAsync( WebSocketCloseStatus.NormalClosure, "Closed by server.", CancellationToken.None); break; } } if (ws.State != WebSocketState.Open) { Console.WriteLine($"a client is disconnected. state={ws.State}"); } }

Decorate client stream

var wss = new WebSocketServer(8000); // specify a custom decorator to decorate client network stream. wss.ClientStreamDecorator = stream => { return new SslStream(new GZipStream(stream, CompressionMode.Decompress)); }; wss.Start(async ctx => { var ws = await ctx.AcceptWebSocketAsync(); Echo(ws); });