WebSockets

Introduction

WebSockets enable real-time bidirectional communication between client and server.

Python WebSocket Server

import asyncio
import websockets

async def echo(websocket, path):
    async for message in websocket:
        await websocket.send(f"Echo: {message}")

asyncio.get_event_loop().run_until_complete(
    websockets.serve(echo, "localhost", 8765)
)
asyncio.get_event_loop().run_forever()

Client Connection

// JavaScript client
const ws = new WebSocket("ws://localhost:8765");

ws.onopen = () => {
    ws.send("Hello!");
};

ws.onmessage = (event) => {
    console.log("Received:", event.data);
};

ws.close();

FastAPI WebSocket

from fastapi import WebSocket

@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    while True:
        data = await websocket.receive_text()
        await websocket.send_text(f"Echo: {data}")

Practice Problems

1. Create WebSocket server
2. Implement chat functionality
3. Handle multiple connections
4. Add authentication
5. Broadcast to all clients