Cowboy 开源 WebSocket 网络库

Cowboy.WebSockets 是一个托管在 GitHub 上的基于 .NET/C# 实现的开源 WebSocket 网络库，其完整的实现了 RFC 6455 (The WebSocket Protocol) 协议标准，并部分实现了 RFC 7692 (Compression Extensions for WebSocket) 协议标准。

WebSocket 可理解为建立在 TCP 连接通道上的更进一步的握手，并确定了消息封装格式。

通过定义控制帧 (Control Frame) 和数据帧 (Data Frame) 来控制通道内的通信和数据传输，下图用使用 ABNF 格式描述了帧头部的格式。

Cowboy.WebSockets 中对于 WebSocket 的 Client/Server 分别做了实现，分别对应代码中的：

• AsyncWebSocketClient
• AsyncWebSocketServer

Cowboy.WebSockets 的内部实现是基于 Cowboy.Sockets 中的 TAP 模式的 AsyncTcpSocketServer 和 AsyncTcpSocketClient 。关于 Cowboy.Sockets 可以参考文章《C#高性能TCP服务的多种实现方式》。

可通过 NuGet 查找 Cowboy 来获取 nuget 包。

WebSocket 服务端应用

实现 AsyncWebSocketServerModule 抽象类，其中 ModulePath 对应着 "ws://host:port/path" 中的 path 部分。可以实现多个 Module，将多个 Module 注入到 AsyncWebSocketServerModuleCatalog 中，或者采用反射机制等自动发现 Module。

  public class TestWebSocketModule : AsyncWebSocketServerModule
  {
      public TestWebSocketModule()
          : base(@"/test")
      {
      }
  
      public override async Task OnSessionStarted(AsyncWebSocketSession session)
      {
          Console.WriteLine(string.Format("WebSocket session [{0}] has connected.", session.RemoteEndPoint));
          await Task.CompletedTask;
      }
  
      public override async Task OnSessionTextReceived(AsyncWebSocketSession session, string text)
      {
          Console.Write(string.Format("WebSocket session [{0}] received Text --> ", session.RemoteEndPoint));
          Console.WriteLine(string.Format("{0}", text));
  
          await session.SendTextAsync(text);
      }
  
      public override async Task OnSessionBinaryReceived(AsyncWebSocketSession session, byte[] data, int offset, int count)
      {
          var text = Encoding.UTF8.GetString(data, offset, count);
          Console.Write(string.Format("WebSocket session [{0}] received Binary --> ", session.RemoteEndPoint));
          Console.WriteLine(string.Format("{0}", text));
  
          await session.SendBinaryAsync(Encoding.UTF8.GetBytes(text));
      }
  
      public override async Task OnSessionClosed(AsyncWebSocketSession session)
      {
          Console.WriteLine(string.Format("WebSocket session [{0}] has disconnected.", session.RemoteEndPoint));
          await Task.CompletedTask;
      }
  }

实例化 AsyncWebSocketServer，并将 AsyncWebSocketServerModuleCatalog 实例注入，即可启动 WebSocket 的服务端监听。

  class Program
  {
      static AsyncWebSocketServer _server;
  
      static void Main(string[] args)
      {
          NLogLogger.Use();
  
          try
          {
              var catalog = new AsyncWebSocketServerModuleCatalog();
              catalog.RegisterModule(new TestWebSocketModule());
  
              var config = new AsyncWebSocketServerConfiguration();
              //config.SslEnabled = true;
              //config.SslServerCertificate = new System.Security.Cryptography.X509Certificates.X509Certificate2(@"D:\Cowboy.pfx", "Cowboy");
              //config.SslPolicyErrorsBypassed = true;
  
              _server = new AsyncWebSocketServer(22222, catalog, config);
              _server.Listen();
  
              Console.WriteLine("WebSocket server has been started on [{0}].", _server.ListenedEndPoint);
              Console.WriteLine("Type something to send to clients...");
              while (true)
              {
                  try
                  {
                      string text = Console.ReadLine();
                      if (text == "quit")
                          break;
                      Task.Run(async () =>
                      {
                          //await _server.BroadcastText(text);
                          //Console.WriteLine("WebSocket server [{0}] broadcasts text -> [{1}].", _server.ListenedEndPoint, text);
                          await _server.BroadcastBinaryAsync(Encoding.UTF8.GetBytes(text));
                          Console.WriteLine("WebSocket server [{0}] broadcasts binary -> [{1}].", _server.ListenedEndPoint, text);
                      });
                  }
                  catch (Exception ex)
                  {
                      Console.WriteLine(ex.Message);
                  }
              }
  
              _server.Shutdown();
              Console.WriteLine("WebSocket server has been stopped on [{0}].", _server.ListenedEndPoint);
          }
          catch (Exception ex)
          {
              Logger.Get<Program>().Error(ex.Message, ex);
          }
  
          Console.ReadKey();
      }
  }

WebSocket 客户端应用

客户端侧在实例化 AsyncWebSocketClient 时有两种方式：

1. 实现 IAsyncWebSocketClientMessageDispatcher 接口；
2. 直接构造函数注入接受各种事件的 Func<> 实现；

  public interface IAsyncWebSocketClientMessageDispatcher
  {
      Task OnServerConnected(AsyncWebSocketClient client);
      Task OnServerTextReceived(AsyncWebSocketClient client, string text);
      Task OnServerBinaryReceived(AsyncWebSocketClient client, byte[] data, int offset, int count);
      Task OnServerDisconnected(AsyncWebSocketClient client);
  
      Task OnServerFragmentationStreamOpened(AsyncWebSocketClient client, byte[] data, int offset, int count);
      Task OnServerFragmentationStreamContinued(AsyncWebSocketClient client, byte[] data, int offset, int count);
      Task OnServerFragmentationStreamClosed(AsyncWebSocketClient client, byte[] data, int offset, int count);
  }

下面的 DEMO 采用了方式二。

  class Program
  {
      static AsyncWebSocketClient _client;
  
      static void Main(string[] args)
      {
          NLogLogger.Use();
  
          Task.Run(async () =>
          {
              try
              {
                  var config = new AsyncWebSocketClientConfiguration();
                  //config.SslTargetHost = "Cowboy";
                  //config.SslClientCertificates.Add(new System.Security.Cryptography.X509Certificates.X509Certificate2(@"D:\Cowboy.cer"));
                  //config.SslPolicyErrorsBypassed = true;
  
                  //var uri = new Uri("ws://echo.websocket.org/");
                  //var uri = new Uri("wss://127.0.0.1:22222/test");
                  var uri = new Uri("ws://127.0.0.1:22222/test");
                  _client = new AsyncWebSocketClient(uri,
                      OnServerTextReceived,
                      OnServerBinaryReceived,
                      OnServerConnected,
                      OnServerDisconnected,
                      config);
                  await _client.Connect();
  
                  Console.WriteLine("WebSocket client has connected to server [{0}].", uri);
                  Console.WriteLine("Type something to send to server...");
                  while (_client.State == WebSocketState.Open)
                  {
                      try
                      {
                          string text = Console.ReadLine();
                          if (text == "quit")
                              break;
                          Task.Run(async () =>
                          {
                              //await _client.SendText(text);
                              //Console.WriteLine("Client [{0}] send text -> [{1}].", _client.LocalEndPoint, text);
                              await _client.SendBinaryAsync(Encoding.UTF8.GetBytes(text));
                              Console.WriteLine("Client [{0}] send binary -> [{1}].", _client.LocalEndPoint, text);
                          }).Forget();
                      }
                      catch (Exception ex)
                      {
                          Console.WriteLine(ex.Message);
                      }
                  }
  
                  await _client.Close(WebSocketCloseCode.NormalClosure);
                  Console.WriteLine("WebSocket client has disconnected from server [{0}].", uri);
              }
              catch (Exception ex)
              {
                  Logger.Get<Program>().Error(ex.Message, ex);
              }
          }).Wait();
  
          Console.ReadKey();
      }
  
      private static async Task OnServerConnected(AsyncWebSocketClient client)
      {
          Console.WriteLine(string.Format("WebSocket server [{0}] has connected.", client.RemoteEndPoint));
          await Task.CompletedTask;
      }
  
      private static async Task OnServerTextReceived(AsyncWebSocketClient client, string text)
      {
          Console.Write(string.Format("WebSocket server [{0}] received Text --> ", client.RemoteEndPoint));
          Console.WriteLine(string.Format("{0}", text));
  
          await Task.CompletedTask;
      }
  
      private static async Task OnServerBinaryReceived(AsyncWebSocketClient client, byte[] data, int offset, int count)
      {
          var text = Encoding.UTF8.GetString(data, offset, count);
          Console.Write(string.Format("WebSocket server [{0}] received Binary --> ", client.RemoteEndPoint));
          Console.WriteLine(string.Format("{0}", text));
  
          await Task.CompletedTask;
      }
  
      private static async Task OnServerDisconnected(AsyncWebSocketClient client)
      {
          Console.WriteLine(string.Format("WebSocket server [{0}] has disconnected.", client.RemoteEndPoint));
          await Task.CompletedTask;
      }
  }

相关资料

• RFC6455: The WebSocket Protocol
• RFC7692: Compression Extensions for WebSocket
• IANA: WebSocket Opcode Registry
• LZ77 and LZ78
• LZ77 Compression Algorithm
• DeflateStream Class
• zlib 1.2.8 Manual
• WebSocket Extensions in Tyrus

本篇文章《Cowboy 开源 WebSocket 网络库》由 Dennis Gao 发表自博客园个人博客，未经作者本人同意禁止以任何的形式转载，任何自动的或人为的爬虫转载行为均为耍流氓。