Websocket

簡介

WebSocket一種在單個 TCP 連線上進行全雙工通訊的協定

以前必須要用Ajax間隔時間去跟server要資料，websocket則可以在建立連線後持續傳送

簡單的比喻：

Ajax 喝水要拿起水杯，喝完要再放下
Websocket 用吸管喝水，要喝時或喝太多要退回去杯子都不必再次拿起水杯

webSocket相關框架

ws

https://github.com/websockets/ws

server.js

const WebSocket = require('ws');

const wss = new WebSocket.Server({ port: 3002 });

wss.on('connection', function connection(ws) {
  ws.on('message', function incoming(message) {
    console.log('received: %s', message);
  });

  ws.send('something');
});

client.js

const WebSocket = require('ws');
const readline = require('readline');

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

const ws = new WebSocket('ws://35.190.233.55:3002');

ws.on('open', function open() {
  ws.send('something');
});

rl.on('line', (input) => {
    console.log(`Received: ${input}`);
    ws.send(input);
  });

ws.on('message', function incoming(data) {
  console.log(data);
});

client with server

const WebSocket = require('ws');
const readline = require('readline');

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

const wss = new WebSocket.Server({ port: 3042 });
const ws = new WebSocket('ws://127.0.0.1:3032');

ws.on('open', function open() {
    ws.send('something');
});

rl.on('line', (input) => {
    console.log(`Received: ${input}`);
    ws.send(input);
});

ws.on('message', function incoming(data) {
    console.log(data);
});

廣播範例：

const WebSocket = require('ws');

const wss = new WebSocket.Server({ port: 8080 });
const connectionList = [];
wss.on('connection', function connection(ws) {
  connectionList.push({
    ws
  })
  ws.on('message', function incoming(message) {
    console.log('received: %s', message);
    connectionList.forEach(connection => {
      connection.ws.send(message);
    })
  });
});

讓同個房間接受廣播

const WebSocket = require('ws');
const express = require('express')
const app = express();

const wss = new WebSocket.Server({ port: 8080 });
const connectionList = [];
wss.on('connection', function connection(ws, req) {
  const roomId = req.url.replace('/ws/', '');
  connectionList.push({
    roomId,
    ws
  })
  ws.on('message', function incoming(message) {
    const sameRoomClient = connectionList.filter(connection => {
      return connection.roomId === roomId;
    })
    sameRoomClient.forEach(connection => {
      connection.ws.send(message)
    })
  });
});

app.use('/room/:id', (req, res, next) => {
  return express.static('../public/index.html')(req, res, next);
});

app.listen('8081');

其他相關框架

engine.io

這裡我們使用socket.io當教學範例

socket.io

npm install socket.io --save

之後新增server.js

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

app.get('/', function(req, res){
  res.sendFile(__dirname + '/index.html');
});

io.on('connection', function(socket){
  console.log('a user connected');
});

http.listen(3000, function(){
  console.log('listening on *:3000');
});

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Websocket Test</title>
    <script src="/socket.io/socket.io.js"></script>
    <script>
    var socket = io();
    </script>
</head>
<body>

</body>
</html>

之後啟動 node server.js

打開瀏覽器localhost:3000，並開啟開發人員工具的network觀察

以下取自維基百科https://zh.wikipedia.org/wiki/WebSocket

Connection必須設定Upgrade，表示用戶端希望連線升級。
Upgrade欄位必須設定Websocket，表示希望升級到Websocket協定。
Sec-WebSocket-Key是隨機的字串，伺服器端會用這些資料來構造出一個SHA-1的資訊摘要。把「Sec-WebSocket-Key」加上一個特殊字串「258EAFA5-E914-47DA-95CA-C5AB0DC85B11」，然後計算SHA-1摘要，之後進行BASE-64編碼，將結果做為「Sec-WebSocket-Accept」頭的值，返回給用戶端。如此操作，可以儘量避免普通HTTP請求被誤認為Websocket協定。
Sec-WebSocket-Version 表示支援的Websocket版本。RFC6455要求使用的版本是13，之前草案的版本均應當被棄用。
Origin欄位是可選的，通常用來表示在瀏覽器中發起此Websocket連線所在的頁面，類似於Referer。但是，於Referer不同的是，Origin只包含了協定和主機名稱。
其他一些定義在HTTP協定中的欄位，如Cookie等，也可以在Websocket中使用。

新增一個事件

server.js

io.on('connection', function(socket){
  console.log('a user connected');
  socket.on('chat', function(msg){
    console.log('message: ' + msg);
  });
});

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Websocket Test</title>
    <script src="/socket.io/socket.io.js"></script>
    <script>
      var socket = io();
      function clickBtn() {
        socket.emit('chat',document.getElementById('thisInput').value);
      }
    </script>
</head>
<body>
   <input id="thisInput"> </input>
   <button onclick="clickBtn()">點我</button> 
</body>
</html>

可看到我們在client端的方框輸入文字後按送出，可於terminal中看到訊息

接著

剛才是讓server接收client發出的事件，現在試著讓client接收server發送的事件

server.js

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

app.get('/', function(req, res){
  res.sendFile(__dirname + '/index.html');
});

io.on('connection', function(socket){
  console.log('a user connected');
  socket.on('chat', function(msg){
    console.log('message: ' + msg);
    socket.broadcast.emit('message',msg);//傳給所有人除了自己
    socket.emit('message',msg);//傳給自己
  });
});

http.listen(3000, function(){
  console.log('listening on *:3000');
});

記得更改完server.js後要記得把server重新啟動

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Websocket Test</title>
    <script src="/socket.io/socket.io.js"></script>
    <script>
      var socket = io();
      function clickBtn() {
        socket.emit('chat',document.getElementById('thisInput').value);
      }
      //接收事件
      socket.on('message',function(data) {
        document.getElementById('received').innerHTML = data;
      })
    </script>
</head>
<body>
   <input id="thisInput"> </input>
     <button onclick="clickBtn()">點我</button> 
   <div id="received"></div>
</body>
</html>

注意：socket.broadcast.emit會傳給所有connected user除了自己

這時開啟第二個瀏覽器，並在文字框輸入後按送出，即可看到另一個瀏覽器產生文字

再複習一次，首先必須先再連線範圍作用域才可做事

server.js

io.on('connection',(socket) => {
  利用socket來做事
}

client就是簡單使用on和emit

最基本兩種

分別是socket.on('事件名稱',cb)和socket.emit('事件名稱',cb)

server和client都一樣的用法

socket.broadcast.emit('user connected');給所有連線人廣播

再來是房間部分

socket.join('房間名稱')讓client加入房間

socket.leave('房間名稱')讓client離開房間

socket.broadcast.to('房間名稱').emit('chat',{data: res});給特定房間廣播訊息

簡單範例

server.js

export const socketio = (io, axios, config1) => {

io.on('connection', function(socket){
    console.log('a user connected');

    //房間
    socket.on('mainPage',() => {
        socket.join('mainPage',() => {
          console.log('join main okok')
            socket.leave('chatPage', () => {
                console.log('leave chat');
            })
        });
    })
    socket.on('chatPage',() => {
        socket.join('chatPage',() => {
          console.log('join chat')
            socket.leave('mainPage', () => {
                console.log('leave main')
            });
        });
    })


  //事件
  socket.on('chat',(res) => {
    console.log(res);
    socket.broadcast.to('chatPage').emit('chat',{data: res});
    socket.emit('chat',{data: res})
  })

    socket.on('postArticle', function(){
        axios.get(`${config1.origin}/getArticle`)
            .then(function(response){
                socket.broadcast.to('mainPage').emit('addArticle', response.data);//broadcast傳給所有人除了自己
                socket.emit('addArticle', response.data);//加上傳給自己的socket
         //socket.broadcast.to(id).emit('my message', msg);
            }).
            catch(err => {
                console.log(err);
            })
    });
    socket.on('chat', (data) => {
        console.log(data)
    })
});
}

Socket.io 模組之安全機制

client端

var socket = io.connect('http://localhost:8183/?token=localStorage.getItem('access_token'))

server端

io.on('connection', function(socket) {
    console.log("url"+socket.handshake.url);
    console.log(socket.handshake.query.token);

});

另外client端的cookie會在websocket連線時自動送到server

ws 模組之安全機制驗證

https://github.com/websockets/ws#client-authentication

const wss = new WebSocketServer({ server: httpsServer });
httpsServer.on("upgrade", function (request, socket, head) {
  // 用來驗證
  // if (err) {
  //   socket.write("HTTP/1.1 401 Unauthorized\r\n\r\n");
  //   socket.destroy();
  //   return;
  // }
});

注意事項

如果有時更新websocket的code卻發現emit還是只有舊的有反應，則可能是舊的socket連線沒斷開

ngrok

記得要用 https url

./ngrok http https://localhost:8443
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