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Komunikasi masa nyata adalah penting dalam aplikasi moden seperti apl sembang, permainan dalam talian dan alatan kerjasama langsung. WebSockets menyediakan saluran komunikasi dupleks penuh melalui sambungan TCP tunggal, membolehkan pertukaran data antara klien dan pelayan dalam masa nyata. Artikel ini akan menerangkan WebSockets, kes penggunaannya dan cara melaksanakannya dalam Node.js. Selain itu, kami akan menyelami Socket.IO, perpustakaan popular yang memudahkan komunikasi WebSocket, bersama-sama dengan contoh praktikal.
Dalam artikel ini, kami akan membincangkan:
WebSockets menyediakan protokol komunikasi dua arah yang membolehkan pelayan dan klien menghantar data pada bila-bila masa. Tidak seperti HTTP, di mana pelanggan memulakan semua komunikasi dan meminta data daripada pelayan, WebSockets mendayakan sambungan berterusan, membolehkan kedua-dua pihak bertukar data secara berterusan tanpa mewujudkan semula sambungan.
Walaupun kedua-dua protokol dijalankan melalui TCP, ia mempunyai perbezaan yang ketara:
Feature | WebSockets | HTTP |
---|---|---|
Connection | Persistent, full-duplex | Stateless, new connection for each request |
Directionality | Bi-directional (server and client communicate) | Client to server only (server responds) |
Overhead | Low after connection establishment | Higher due to headers with every request |
Use Case | Real-time applications (chats, games) | Traditional websites, API requests |
To create a WebSocket server, Node.js provides a built-in ws library that allows you to create a WebSocket server and establish communication with clients.
npm install ws
const WebSocket = require('ws'); // Create a WebSocket server on port 8080 const wss = new WebSocket.Server({ port: 8080 }); // Listen for incoming connections wss.on('connection', (ws) => { console.log('Client connected'); // Send a message to the client ws.send('Welcome to the WebSocket server!'); // Listen for messages from the client ws.on('message', (message) => { console.log(`Received: ${message}`); ws.send(`Echo: ${message}`); }); // Handle connection closure ws.on('close', () => { console.log('Client disconnected'); }); }); console.log('WebSocket server running on ws://localhost:8080');
In this example:
On the client side, you can connect to the WebSocket server using JavaScript:
const socket = new WebSocket('ws://localhost:8080'); // Event listener for when the connection is established socket.addEventListener('open', (event) => { socket.send('Hello Server!'); }); // Listen for messages from the server socket.addEventListener('message', (event) => { console.log(`Message from server: ${event.data}`); });
Socket.IO is a library that makes WebSocket communication easier by providing:
npm install socket.io
const express = require('express'); const http = require('http'); const socketIo = require('socket.io'); const app = express(); const server = http.createServer(app); const io = socketIo(server); // Listen for incoming connections io.on('connection', (socket) => { console.log('New client connected'); // Listen for messages from the client socket.on('message', (msg) => { console.log(`Message from client: ${msg}`); socket.emit('response', `Server received: ${msg}`); }); // Handle disconnection socket.on('disconnect', () => { console.log('Client disconnected'); }); }); // Start the server server.listen(3000, () => { console.log('Server running on http://localhost:3000'); });
In this code:
Let's build a simple real-time chat application using Socket.IO to demonstrate its power.
const express = require('express'); const http = require('http'); const socketIo = require('socket.io'); const app = express(); const server = http.createServer(app); const io = socketIo(server); app.get('/', (req, res) => { res.sendFile(__dirname + '/index.html'); }); io.on('connection', (socket) => { console.log('A user connected'); // Broadcast when a user sends a message socket.on('chat message', (msg) => { io.emit('chat message', msg); }); socket.on('disconnect', () => { console.log('User disconnected'); }); }); server.listen(3000, () => { console.log('Listening on *:3000'); });
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Socket.IO Chat</title> <script src="/socket.io/socket.io.js"></script> </head> <body> <h1>Real-time Chat</h1> <ul id="messages"></ul> <form id="chatForm"> <input id="message" autocomplete="off" /><button>Send</button> </form> <script> const socket = io(); // Listen for incoming chat messages socket.on('chat message', (msg) => { const li = document.createElement('li'); li.textContent = msg; document.getElementById('messages').appendChild(li); }); // Send chat message const form = document.getElementById('chatForm'); form.addEventListener('submit', (e) => { e.preventDefault(); const message = document.getElementById('message').value; socket.emit('chat message', message); document.getElementById('message').value = ''; }); </script> </body> </html>
This simple chat application allows multiple users to connect and exchange messages in real-time. Messages sent by one user are broadcast to all other users connected to the server.
WebSockets and Socket.IO are perfect for scenarios requiring real-time communication, including:
Like HTTP, WebSocket connections should be secured to protect sensitive data. This can be done by using wss:// (WebSocket Secure), which is essentially WebSockets over TLS (Transport Layer Security).
Example NGINX configuration:
server { listen 443 ssl; server_name yourdomain.com; ssl_certificate /etc/ssl/certs/yourdomain.crt; ssl_certificate_key /etc/ssl/private/yourdomain.key; location / { proxy_pass http://localhost:8080; proxy_set_header Upgrade $http_upgrade; proxy_set_header Connection "upgrade"; } }
This ensures that all WebSocket traffic is encrypted, protecting it from eavesdropping and tampering.
WebSockets and Socket.IO enable real-time communication between clients and servers, which is essential for modern applications requiring instant updates. By implementing WebSocket or Socket.IO-based solutions, you can build responsive and efficient applications such as chat systems, collaborative tools, and live dashboards.
In this article, we've covered the basics of WebSockets, the advantages of using Socket.IO, and how to create real-time applications in Node.js. Additionally, we've explored how to secure WebSocket connections to ensure data safety during transmission.
Mastering these technologies will open up numerous possibilities for building powerful, interactive, and scalable web applications.
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