//客户端请求
GET / HTTP/1.1
Upgrade: websocket
Connection: Upgrade
Host: example.com
Origin: http://example.com
Sec-WebSocket-Key: sN9cRrP/n9NdMgdcy2VJFQ==
Sec-WebSocket-Version: 13

//服务端响应
HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: fFBooB7FAkLlXgRSz0BT3v4hq5s=
Sec-WebSocket-Location: ws://example.com/

 public async Task Invoke(HttpContext context)
 {
  if (context.Request.Path == "/ws")
  {
  if (context.WebSockets.IsWebSocketRequest)
  {
   WebSocket webSocket = await context.WebSockets.AcceptWebSocketAsync();
   string clientId = Guid.NewGuid().ToString(); ;
   var wsClient = new WebsocketClient
   {
   Id = clientId,
   WebSocket = webSocket
   };
   try
   {
   await Handle(wsClient);
   }
   catch (Exception ex)
   {
   _logger.LogError(ex, "Echo websocket client {0} err .", clientId);
   await context.Response.WriteAsync("closed");
   }
  }
  else
  {
   context.Response.StatusCode = 404;
  }
  }
  else
  {
  await _next(context);
  }
 }

 private async Task Handle(WebsocketClient webSocket)
 {
  WebsocketClientCollection.Add(webSocket);
  _logger.LogInformation($"Websocket client added.");
  
  WebSocketReceiveResult result = null;
  do
  {
  var buffer = new byte[1024 * 1];
  result = await webSocket.WebSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);
  if (result.MessageType == WebSocketMessageType.Text && !result.CloseStatus.HasValue)
  {
   var msgString = Encoding.UTF8.GetString(buffer);
   _logger.LogInformation($"Websocket client ReceiveAsync message {msgString}.");
   var message = JsonConvert.DeserializeObject<Message>(msgString);
   message.SendClientId = webSocket.Id;
   MessageRoute(message);
  }
  }
  while (!result.CloseStatus.HasValue);
  WebsocketClientCollection.Remove(webSocket);
  _logger.LogInformation($"Websocket client closed.");
 }

private void MessageRoute(Message message)
 {
  var client = WebsocketClientCollection.Get(message.SendClientId);
  switch (message.action)
  {
  case "join":
   client.RoomNo = message.msg;
   client.SendMessageAsync($"{message.nick} join room {client.RoomNo} success .");
   _logger.LogInformation($"Websocket client {message.SendClientId} join room {client.RoomNo}.");
   break;
  case "send_to_room":
   if (string.IsNullOrEmpty(client.RoomNo))
   {
   break;
   }
   var clients = WebsocketClientCollection.GetRoomClients(client.RoomNo);
   clients.ForEach(c =>
   {
   c.SendMessageAsync(message.nick + " : " + message.msg);
   });
   _logger.LogInformation($"Websocket client {message.SendClientId} send message {message.msg} to room {client.RoomNo}");

   break;
  case "leave":
   var roomNo = client.RoomNo;
   client.RoomNo = "";
   client.SendMessageAsync($"{message.nick} leave room {roomNo} success .");
   _logger.LogInformation($"Websocket client {message.SendClientId} leave room {roomNo}");
   break;
  default:
   break;
  }
 }

 public class WebsocketClientCollection
 {
 private static List<WebsocketClient> _clients = new List<WebsocketClient>();

 public static void Add(WebsocketClient client)
 {
  _clients.Add(client);
 }

 public static void Remove(WebsocketClient client)
 {
  _clients.Remove(client);
 }

 public static WebsocketClient Get(string clientId)
 {
  var client = _clients.FirstOrDefault(c=>c.Id == clientId);

  return client;
 }

 public static List<WebsocketClient> GetRoomClients(string roomNo)
 {
  var client = _clients.Where(c => c.RoomNo == roomNo);
  return client.ToList();
 }
 }

 app.UseWebSockets(new WebSocketOptions
  {
  KeepAliveInterval = TimeSpan.FromSeconds(60),
  ReceiveBufferSize = 1* 1024
  });
 app.UseMiddleware<WebsocketHandlerMiddleware>();

<div>
 room no: <input type="text" id="txtRoomNo" value="8888"/> <button id="btnJoin">join room</button> <button id="btnLeave">leave room</button>
</div>
<div>
 nick name: <input type="text" id="txtNickName" value="batman" /> 
</div>
<div>
 <textareaid="msgList"></textarea>
 <div>
 <input type="text" id="txtMsg" value="" /> <button id="btnSend">send</button>
 </div>
</div>

var server = ''ws://localhost:5000''; //如果开启了https则这里是wss

var WEB_SOCKET = new WebSocket(server + ''/ws'');

WEB_SOCKET.onopen = function (evt) {
 console.log(''Connection open ...'');
 $(''#msgList'').val(''websocket connection opened .'');
};

WEB_SOCKET.onmessage = function (evt) {
 console.log(''Received Message: '' + evt.data);
 if (evt.data) {
 var content = $(''#msgList'').val();
 content = content + ''\r\n'' + evt.data;

 $(''#msgList'').val(content);
 }
};

WEB_SOCKET.onclose = function (evt) {
 console.log(''Connection closed.'');
};

$(''#btnJoin'').on(''click'', function () {
 var roomNo = $(''#txtRoomNo'').val();
 var nick = $(''#txtNickName'').val();
 if (roomNo) {
 var msg = {
  action: ''join'',
  msg: roomNo,
  nick: nick
 };
 WEB_SOCKET.send(JSON.stringify(msg));
 }
});

$(''#btnSend'').on(''click'', function () {
 var message = $(''#txtMsg'').val();
 var nick = $(''#txtNickName'').val();
 if (message) {
 WEB_SOCKET.send(JSON.stringify({
  action: ''send_to_room'',
  msg: message,
  nick: nick
 }));
 }
});

$(''#btnLeave'').on(''click'', function () {
 var nick = $(''#txtNickName'').val();
 var msg = {
 action: ''leave'',
 msg: '''',
 nick: nick
 };
 WEB_SOCKET.send(JSON.stringify(msg));
});

• Asp.net Core中如何使用中间件来管理websocket
• Asp.Net Core中WebSocket绑定的方法详解
• NetCore WebSocket即时通讯示例
• 在Asp.net core中实现websocket通信

using System;
using System.Collections;
using System.Text;
using System.Security.Cryptography;
 
namespace SocketDemo
{
    // Server助手 负责：1 握手 2 请求转换 3 响应转换
    class ServerHelper
    {
        /// <summary>
        /// 输出连接头信息
        /// </summary>
        public static string ResponseHeader(string requestHeader)
        {
            Hashtable table = new Hashtable();
 
            // 拆分成键值对，保存到哈希表
            string[] rows = requestHeader.Split(new string[] { "\r\n" }, StringSplitOptions.RemoveEmptyEntries);
            foreach (string row in rows)
            {
                int splitIndex = row.IndexOf('':'');
                if (splitIndex > 0)
                {
                    table.Add(row.Substring(0, splitIndex).Trim(), row.Substring(splitIndex + 1).Trim());
                }
            }
 
            StringBuilder header = new StringBuilder();
            header.Append("HTTP/1.1 101 Web Socket Protocol Handshake\r\n");
            header.AppendFormat("Upgrade: {0}\r\n", table.ContainsKey("Upgrade") ? table["Upgrade"].ToString() : string.Empty);
            header.AppendFormat("Connection: {0}\r\n", table.ContainsKey("Connection") ? table["Connection"].ToString() : string.Empty);
            header.AppendFormat("WebSocket-Origin: {0}\r\n", table.ContainsKey("Sec-WebSocket-Origin") ? table["Sec-WebSocket-Origin"].ToString() : string.Empty);
            header.AppendFormat("WebSocket-Location: {0}\r\n", table.ContainsKey("Host") ? table["Host"].ToString() : string.Empty);
 
            string key = table.ContainsKey("Sec-WebSocket-Key") ? table["Sec-WebSocket-Key"].ToString() : string.Empty;
            string magic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
            header.AppendFormat("Sec-WebSocket-Accept: {0}\r\n", Convert.ToBase64String(SHA1.Create().ComputeHash(Encoding.ASCII.GetBytes(key + magic))));
 
            header.Append("\r\n");
 
            return header.ToString();
        }
 
        /// <summary>
        /// 解码请求内容
        /// </summary>
        public static string DecodeMsg(Byte[] buffer, int len)
        {
            if (buffer[0] != 0x81
                || (buffer[0] & 0x80) != 0x80
                || (buffer[1] & 0x80) != 0x80)
            {
                return null;
            }
            Byte[] mask = new Byte[4];
            int beginIndex = 0;
            int payload_len = buffer[1] & 0x7F;
            if (payload_len == 0x7E)
            {
                Array.Copy(buffer, 4, mask, 0, 4);
                payload_len = payload_len & 0x00000000;
                payload_len = payload_len | buffer[2];
                payload_len = (payload_len << 8) | buffer[3];
                beginIndex = 8;
            }
            else if (payload_len != 0x7F)
            {
                Array.Copy(buffer, 2, mask, 0, 4);
                beginIndex = 6;
            }
 
            for (int i = 0; i < payload_len; i++)
            {
                buffer[i + beginIndex] = (byte)(buffer[i + beginIndex] ^ mask[i % 4]);
            }
            return Encoding.UTF8.GetString(buffer, beginIndex, payload_len);
        }
 
        /// <summary>
        /// 编码响应内容
        /// </summary>
        public static byte[] EncodeMsg(string content)
        {
            byte[] bts = null;
            byte[] temp = Encoding.UTF8.GetBytes(content);
            if (temp.Length < 126)
            {
                bts = new byte[temp.Length + 2];
                bts[0] = 0x81;
                bts[1] = (byte)temp.Length;
                Array.Copy(temp, 0, bts, 2, temp.Length);
            }
            else if (temp.Length < 0xFFFF)
            {
                bts = new byte[temp.Length + 4];
                bts[0] = 0x81;
                bts[1] = 126;
                bts[2] = (byte)(temp.Length & 0xFF);
                bts[3] = (byte)(temp.Length >> 8 & 0xFF);
                Array.Copy(temp, 0, bts, 4, temp.Length);
            }
            else
            {
                byte[] st = System.Text.Encoding.UTF8.GetBytes(string.Format("暂不处理超长内容").ToCharArray());
            }
            return bts;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.Net.Sockets;
 
namespace SocketDemo
{
    class ClientInfo
    {
        public Socket Socket { get; set; }
        public bool IsOpen { get; set; }
        public string Address { get; set; }
    }
 
    // 管理Client
    class ClientManager
    {
        static List<ClientInfo> clientList = new List<ClientInfo>();
        public static void Add(ClientInfo info)
        {
            if (!IsExist(info.Address))
            {
                clientList.Add(info);
            }
        }
        public static bool IsExist(string address)
        {
            return clientList.Exists(item => string.Compare(address, item.Address, true) == 0);
        }
        public static bool IsExist(string address, bool isOpen)
        {
            return clientList.Exists(item => string.Compare(address, item.Address, true) == 0 && item.IsOpen == isOpen);
        }
        public static void Open(string address)
        {
            clientList.ForEach(item =>
            {
                if (string.Compare(address, item.Address, true) == 0)
                {
                    item.IsOpen = true;
                }
            });
        }
        public static void Close(string address = null)
        {
            clientList.ForEach(item =>
            {
                if (address == null || string.Compare(address, item.Address, true) == 0)
                {
                    item.IsOpen = false;
                    item.Socket.Shutdown(SocketShutdown.Both);
                }
            });
        }
        // 发送消息到ClientList
        public static void SendMsgToClientList(string msg, string address = null)
        {
            clientList.ForEach(item =>
            {
                if (item.IsOpen && (address == null || item.Address != address))
                {
                    SendMsgToClient(item.Socket, msg);
                }
            });
        }
        public static void SendMsgToClient(Socket client, string msg)
        {
            byte[] bt = ServerHelper.EncodeMsg(msg);
            client.BeginSend(bt, 0, bt.Length, SocketFlags.None, new AsyncCallback(SendTarget), client);
        }
        private static void SendTarget(IAsyncResult res)
        {
            //Socket client = (Socket)res.AsyncState;
            //int size = client.EndSend(res);
        }
    }
 
    // 接收消息
    class ReceiveHelper
    {
        public byte[] Bytes { get; set; }
        public void ReceiveTarget(IAsyncResult res)
        {
            Socket client = (Socket)res.AsyncState;
            int size = client.EndReceive(res);
            if (size > 0)
            {
                string address = client.RemoteEndPoint.ToString(); // 获取Client的IP和端口
                string stringdata = null;
                if (ClientManager.IsExist(address, false)) // 握手
                {
                    stringdata = Encoding.UTF8.GetString(Bytes, 0, size);
                    ClientManager.SendMsgToClient(client, ServerHelper.ResponseHeader(stringdata));
                    ClientManager.Open(address);
                }
                else
                {
                    stringdata = ServerHelper.DecodeMsg(Bytes, size);
                }
                if (stringdata.IndexOf("exit") > -1)
                {
                    ClientManager.SendMsgToClientList(address + "已从服务器断开", address);
                    ClientManager.Close(address);
                    Console.WriteLine(address + "已从服务器断开");
                    Console.WriteLine(address + " " + DateTimeOffset.Now.ToString("G"));
                    return;
                }
                else
                {
                    Console.WriteLine(stringdata);
                    Console.WriteLine(address + " " + DateTimeOffset.Now.ToString("G"));
                    ClientManager.SendMsgToClientList(stringdata, address);
                }
            }
            // 继续等待
            client.BeginReceive(Bytes, 0, Bytes.Length, SocketFlags.None, new AsyncCallback(ReceiveTarget), client);
        }
    }
 
    // 监听请求
    class AcceptHelper
    {
        public byte[] Bytes { get; set; }
 
        public void AcceptTarget(IAsyncResult res)
        {
            Socket server = (Socket)res.AsyncState;
            Socket client = server.EndAccept(res);
            string address = client.RemoteEndPoint.ToString();
 
            ClientManager.Add(new ClientInfo() { Socket = client, Address = address, IsOpen = false });
            ReceiveHelper rs = new ReceiveHelper() { Bytes = this.Bytes };
            IAsyncResult recres = client.BeginReceive(rs.Bytes, 0, rs.Bytes.Length, SocketFlags.None, new AsyncCallback(rs.ReceiveTarget), client);
            // 继续监听
            server.BeginAccept(new AsyncCallback(AcceptTarget), server);
        }
    }
 
    class Program
    {
        static void Main(string[] args)
        {
            Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            server.Bind(new IPEndPoint(IPAddress.Parse("127.0.0.1"), 200)); // 绑定IP+端口
            server.Listen(10); // 开始监听
 
            Console.WriteLine("等待连接...");
 
            AcceptHelper ca = new AcceptHelper() { Bytes = new byte[2048] };
            IAsyncResult res = server.BeginAccept(new AsyncCallback(ca.AcceptTarget), server);
 
            string str = string.Empty;
            while (str != "exit")
            {
                str = Console.ReadLine();
                Console.WriteLine("ME: " + DateTimeOffset.Now.ToString("G"));
                ClientManager.SendMsgToClientList(str);
            }
            ClientManager.Close();
            server.Close();
        }
    }
}

<!DOCTYPE html>
<script>
    var mySocket;
    function Star() {
        mySocket = new WebSocket("ws://127.0.0.1:200", "my-custom-protocol");
        mySocket.onopen = function Open() {
            Show("连接打开");
        };
        mySocket.onmessage = function (evt) {
            Show(evt.data);
        };
        mySocket.onclose = function Close() {
            Show("连接关闭");
            mySocket.close();
        };
    }
    function Send() {
        var content = document.getElementById("content").value;
        Show(content);
        mySocket.send(content);
    }
    function Show(msg) {
        var roomContent = document.getElementById("roomContent");
        roomContent.innerHTML = msg + "<br/>" + roomContent.innerHTML;
    }
</script>
<html>
<head>
    <title></title>
</head>
<body>
    <div id="roomContent">
    </div>
    <div>
        <textarea id="content" cols="50" rows="3"></textarea>
    </div>
    <input type="button" value="Connection" οnclick="Star()" />
    <input type="button" value="Send" οnclick="Send()" />
</body>
</html>

• C#用websocket实现简易聊天功能(客户端)
• C#用websocket实现简易聊天功能(服务端)
• C#使用WebSocket实现聊天室功能
• C# 实现WebSocket服务端教程
• C# websocket及时通信协议的实现方法示例
• C#实现WebSocket协议客户端和服务器websocket sharp组件实例解析
• C# Websocket连接实现wss协议

var express=require(''express'');
var app=express();


//加载express web server
var http=require(''http'').Server(app);
//加载websocket server-->http://localhost:3000/socket.io/socket.io.js
var io=require(''socket.io'')(http);
//监听端口3000
http.listen(3000);

app.get app.post
app.set("view engine","ejs");
app.use(express.static(''./public''));

<script src="/socket.io/socket.io.js"></script>
<script src="/jquery-1.12.4.js"></script>

<script src="http://code.jquery.com/jquery-latest.js"></script>

<script src="/socket.io/socket.io.js"></script>
<script src="/jquery-1.12.4.js"></script>

<script>
   var socket=io();

   socke.emit(''事件名''，''数据'')； 数据可以是对象（登陆者和内容）
</script>

 io.on(''connection'',function(socket){
  socket.on(''事件名'',function(data){

    io.emit(''新的事件名'',data);
  });
});

socket.on(''新的事件名'',function(msg){
     dom操作  把msg数据渲染给我们的dom结构
})

var express=require(''express'');
var app=express();
var http=require(''http'').Server(app);
var io=require(''socket.io'')(http);

var session=require(''express-session'');
app.use(session({
 secret: ''keyboard cat'',
 resave: false,
 saveUninitialized: true,
 //cookie: { secure: true }
}));

//模板引擎
app.set("view engine","ejs");
//静态服务
app.use(express.static(''./public''));

var alluser=[];
//中间件
//显示首页
app.get(''/'',function(req,res,next){
  res.render(''index'');
});

//确认登录，检查此人是否有用户名 昵称不能重复
app.get(''/check'',function(req,res,next){
  var yonghuming=req.query.yonghuming;

  if(!yonghuming){
    res.send(''必须填写用户名'');
    return;
  }

  if(alluser.indexOf(yonghuming) != -1){
    res.send(''用户名重名'');
    return;
  }

  alluser.push(yonghuming);

  console.log(alluser);

  req.session.yonghuming=yonghuming;
  res.redirect("/chat");
});

//聊天室
app.get(''/chat'',function(req,res,next){
  //console.log(req.session.yonghuming);
  //console.log(123);
  if(!req.session.yonghuming){
    res.redirect("/");
    return;
  }
  res.render(''chat'',{
    ''yonghuming'':req.session.yonghuming
  });
});

io.on(''connection'',function(socket){
  socket.on(''liaotian'',function(msg){
    console.log(msg);
    //io.emit(''liaotian'',msg);
    //console.log(io);
    io.emit(''liaotian'',msg);
  });
})

//监听端口
http.listen(3000);
console.log(''server start port 3000'');

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <style>
    div{
      width:700px;
      height:30px;
      padding:40px;
      border:1px solid #000;
      margin:0 auto;
    }
    #yonghuming{
      font-size:30px;
    }
  </style>
</head>
<body>
  <div>
    <form action="/check" method="get">
    输入昵称:
    <input type="text" id="yonghuming" name="yonghuming">
    <input type="submit" value="进入聊天室">
    </form>
  </div>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8"/>
  <title>Document</title>
  <style>
    .caozuo{
      position:fixed;
      bottom:0;
      left:0;
      height:100px;
      background-color:#eee;
      width:100%;
    }
    .caozuo input{
      font-size:30px;
    }
    .caozuo input[type=text]{
      width:100%;
    }
  </style>
</head>
<body>
  <h1>Edison聊天室<span id="yonghu"> 欢迎：<%=yonghuming %></span></h1>
  <div>
    <ul></ul>
  </div>
  <div>
  <input type="text" id="neirong"/>
  <input type="button" id="fayan" value="发言"/>
  </div>

  <script src="/socket.io/socket.io.js"></script>
  <script src="/jquery-1.12.4.min.js"></script>
  <script>
    var socket=io();
    $(''#neirong'').keydown(function(e){
      if(e.keyCode==13){
            //回车发送消息
        socket.emit(''liaotian'',{
          ''neirong'':$(''#neirong'').val(),
          ''ren'':$(''#yonghu'').html(),
        });
        $(this).val('''');
      }


    });

    /*
    $("#fayan").click(function(){
       //点击发言按钮发送消息
      socket.emit(''liaotian'',{
        ''neirong'':$(''#neirong'').val(),
        ''ren'':$(''#yonghu'').html(),
      });
    });*/

    socket.on(''liaotian'',function(msg){
      $(".liebiao").prepend("<li><b>"+msg.ren+": </b>"+msg.neirong+"</li>");
    });
  </script>
</body>
</html>

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