Build websocket server in. Net5 webapi

background ： We need to develop a WebSocket Server side , Used to direct to h5 Client push message ; The previous practice was to directly make a windows service , Open a special port for WebSocket Connect , Now you can .net5 WebAPI Directly support WebSocket, And there is no need to open a single port

Use steps ：

1. stay Startup.cs Of Configure Enable WebSocket middleware

 app.UseWebSockets();

2. Add... To the controller Action, To receive WebSocket The connection and processing of the client receive 、 Send a message , Close the connection ;

      [HttpGet("/ws")]
        public async Task Get()
        {
            if (HttpContext.WebSockets.IsWebSocketRequest)
            {
                // Accept websocket Client connection 
                using var webSocket = await HttpContext.WebSockets.AcceptWebSocketAsync();
                await Echo(webSocket);
            }
            else
            {
                // No websocket Client request 
                HttpContext.Response.StatusCode = 400;//
            }
        }
        /// <summary>
        ///  Processing of clients , Receive a message , Send a message , Close the connection 
        /// </summary>
        /// <param name="webSocket"></param>
        /// <returns></returns>
        private async Task Echo(WebSocket webSocket)
        {
            var buffer = new byte[1024 * 4];
            var result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);

            while (!result.CloseStatus.HasValue)
            {
                var serverMsg = Encoding.UTF8.GetBytes($"Server: Hello. You said: {Encoding.UTF8.GetString(buffer)}");
                // Send a message to the client 
                await webSocket.SendAsync(new ArraySegment<byte>(serverMsg, 0, serverMsg.Length), result.MessageType, result.EndOfMessage, CancellationToken.None);
                // Continue to accept client messages 
                result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);
            }
            // Close and release the connection with the client 
            await webSocket.CloseAsync(result.CloseStatus.Value, result.CloseStatusDescription, CancellationToken.None);
        }

3. You can do it according to your own business , For example, store a client dictionary to maintain , Specify the client to send messages .

4.H5 That's how it works ：

let ws = new WebSocket('ws://api.zhandian.com/ws');// The connection is api Address of the website 
ws.onmessage = function (e) {
                // Listen to the message 
                console.log(e);
                console.log(e.data);
            };

Of course I am now websocket Not many clients , If you don't know how many clients there are , Will this affect api Interface , Waiting for verification