如何在asp.net core中使用websockets

Jos*_*osh 6 c# client websocket server asp.net-core

我正在尝试开发一个游戏,我将记分牌存储在存储在服务器上(当前在本地主机上)的文本文件中。我正在使用 http get 和 post 调用来与服务器通信并获取和发送我想要的数据。现在我想实现 websockets 以便从服务器向 c# 客户端发送通知。通知只会在控制台上为用户显示一条消息,例如在 mu 情况下,每次将用户添加到记分板时,每次调用 UpdateScoreBoard 方法时,我都想向用户显示一条消息。根据我在网上找到的教程,我已经设法构建了以下代码,谁能让我更清楚我将如何为服务器构建 websocket 以及如何在客户端上初始化 websocket?谢谢

Startup.cs(服务器)

        public void Configure(IApplicationBuilder app, IHostEnvironment env)
        {
          //deleted code

            var webSocketOptions = new WebSocketOptions()
            {
                KeepAliveInterval = TimeSpan.FromSeconds(120),
                ReceiveBufferSize = 4 * 1024
            };


            app.UseWebSockets(webSocketOptions);
        
            app.Use(async (context, next) =>
            {
                if (context.Request.Path == "/ws")
                {
                    if (context.WebSockets.IsWebSocketRequest)
                    {
                        WebSocket webSocket = await context.WebSockets.AcceptWebSocketAsync();
                        await Echo(context, webSocket);
                    }
                    else
                    {
                        context.Response.StatusCode = 400;
                    }
                }
                else
                {
                    await next();
                }

            });
        }

        private async Task Echo(HttpContext context, WebSocket webSocket)
        {
            var buffer = new byte[1024 * 4];
            WebSocketReceiveResult result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);
            while (!result.CloseStatus.HasValue)
            {
                await webSocket.SendAsync(new ArraySegment<byte>(buffer, 0, result.Count), result.MessageType, result.EndOfMessage, CancellationToken.None);

                result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);
            }
            await webSocket.CloseAsync(result.CloseStatus.Value, result.CloseStatusDescription, CancellationToken.None);
        }
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HttpClass.cs (Client) - 我调用 http post 请求的地方

public async override Task<List<Scoreboard>> UpdateScoreBoards(string username, int attempts, int seconds, DateTime date)
            {
                HttpResponseMessage response = null;
                //Creating a new instance of object Scoreboard
                //deleted code

                var url = "http://localhost:5000/api/Scoreboard";

                var socket_url = new Uri("ws://localhost:5000"); 
                var exitEvent = new ManualResetEvent(false);
                using (var client = new WebsocketClient(socket_url))
                {
                    client.ReconnectTimeout = TimeSpan.FromSeconds(30);
                    client.ReconnectionHappened.Subscribe(info =>
                        Log.Information($"Reconnection happened, type: {info.Type}"));

                    client.MessageReceived.Subscribe(msg => Log.Information($"Message received: {msg}"));
                    await client.Start();

                    await Task.Run(() => client.Send("test"));

                    exitEvent.WaitOne();
                }

// deleted code
            }
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Ber*_*ian 8

您唯一需要的Startup就是添加UseWebsockets中间件。然后,您可以定义自己的中间件和过滤器连接,如果它们的websocket类型如下:

启动

public void Configure(IApplicationBuilder app, IWebHostEnvironment env) {
            app.UseWebSockets();
            app.UseMiddleware<SocketWare>();
        }
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中间件

public class SocketWare {
        private RequestDelegate next;
        public SocketWare(RequestDelegate _next) {
            this.next = _next;
        }
        public async Task Invoke(HttpContext context) {
            if (!context.WebSockets.IsWebSocketRequest) {
                return;
            }
            var socket=await context.WebSockets.AcceptWebSocketAsync();
            await RunAsync(socket);
        }
        private async Task RunAsync(WebSocket socket) {
            try {
                var client = new ChatClient(socket);
                await client.RunAsync();
            } catch (Exception ex) {

                throw;
            }
            
        }
        

    }
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在我的中间件中,我更喜欢将业务逻辑保存在一个单独的类中,该类被注入Websocket到其中,如下所示:

客户

public class ChatClient
{
   private Task writeTask;
   private Task readTask;
   private WebSocket socket;
   private CancellationTokenSource cts=new CancellationTokenSource();
   ChatClient(WebSocket socket)
   {
       this.socket=socket;
   }
   public async Task RunAsync()
   {
      this.readTask=Task.Run(async ()=>await ReadLoopAsync(cts.Token),cts.Token);
      this.writeTask=Task.Run(async()=>await WriteLoopAsync(cts.Token),cts.Token);
      await Task.WhenAny(this.readTask,this.writeTask);
   }
   public async Task WriteLoopAsync()
   {
       Memory<byte> buffer=ArrayPool<byte>.Shared.Rent(1024);
       try {
           while (true) {
              var result= await this.socket.ReceiveAsync(buffer,....);
              var usefulBuffer=buffer.Slice(0,result.Count).ToArray();
              var raw=Encoding.Utf8.GetString(usefulBuffer);
              //deserialize it to whatever you need
              //handle message as you please (store it somwhere whatever)
            }
        } catch (Exception ex) {

               //socket error handling
               //break loop or continue with go to
        }
   }
   public async Task ReadLoopAsync()
   {
          try {
            while (true) {
              
                var data = await this.[someMessageProvider].GetMessageAsync() //read below !!!
                var bytes = Encoding.UTF8.GetBytes(data);
                //send the message on the websocket
                await this.socket.SendAsync(data, WebSocketMessageType.Text, true, CancellationToken.None);
            }
        } catch (Exception ex) {

            //do incorrect message/socket disconnect logic
        }
   }
}
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现在关于生成消息和使用它们。在您的情况下,您可以将生产者定义为Controller如下所示的一些路由。您将点击一个路由,生成一条消息并将其发布到某个消息代理。我会使用消息队列 (RabbitMQ) 甚至Redis Pub/Sub作为消息总线。您将发布来自您的消息route,然后在您的ReadLoopAsync方法中使用它们WebSocketClient(参见上文)。

生成消息

public UpdateController:Controller
{
   private IConnection
   [HttpPost]
   [someroute]
   public void UpdateScoreboard(string someMessage)
   {
       this.connection.Publish("someChannel",someMessage);
   }
   [HttpPost]
   [someotherroute]
   public void DeletePlayer(string someOtherMessage)
   {
       this.connection.Publish("someChannel",someMessage);
   }
}
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  • Redis pub/sub在这里
    查看 redis pub/sub还可以在 github 上查看我的存储库,其中我正在使用您所需要的内容(websockets、redis、pub sub)

  • RabbitMq
    作为消息总线的另一个选项是使用RabbitMQ,有关 C# 的更多信息请参见 API 此处

  • 在记忆中

    您还可以避免使用第三方并使用一些内存数据结构,例如 。BlockingCollection您可以将其作为服务注入 Singleton到您Controller(s)和您的套接字 中Middleware(s)


Fei*_*Han 5

任何人都可以让我更清楚我将如何为服务器构建 websocket 以及我将如何在客户端上初始化 websocket?

正如您引用的示例所示,利用 ASP.NET Core 中的 WebSocket,我们可以在方法中添加WebSockets 中间件Configure,然后添加/配置请求委托来检查和处理传入的 WebSocket 请求。

并且在使用AcceptWebSocketAsync()方法将请求转换为 WebSocket 连接后,我们可以使用返回的 WebSocket 对象来发送和接收消息。

Echo方法中,我们还可以执行自定义代码逻辑以根据收到的消息生成和发送回复消息/通知。

//received message
var mes = Encoding.UTF8.GetString(buffer, 0, result.Count);

//code logic here
//...

//create reply message
var reply_mes = $"You sent {mes}.";

byte[] reply_mes_buffer = Encoding.UTF8.GetBytes(reply_mes);

await webSocket.SendAsync(new ArraySegment<byte>(reply_mes_buffer, 0, reply_mes.Length), result.MessageType, result.EndOfMessage, CancellationToken.None);
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此外,ASP.NET Core SignalR 是一个开源库,可简化实时通信功能的实现。它确实支持 WebSockets 传输,我们可以轻松实现向所有连接的客户端或连接客户端的指定子集推送消息/通知。

有关 ASP.NET Core SignalR 的更多信息,您可以查看此文档:https ://docs.microsoft.com/en-us/aspnet/core/fundamentals/websockets?view=aspnetcore-3.1