WebSocket

// Node.js 서버 (ws 라이브러리)
import { WebSocketServer, WebSocket } from 'ws';
import http from 'http';

// HTTP 서버와 함께 WebSocket 서버 생성
const server = http.createServer();
const wss = new WebSocketServer({ server });

// 연결된 클라이언트 관리
const clients = new Map();

wss.on('connection', (ws, req) => {
    const clientId = req.headers['sec-websocket-key'];
    clients.set(clientId, ws);
    console.log(`클라이언트 연결: ${clientId}`);

    // ping/pong으로 연결 상태 확인
    ws.isAlive = true;
    ws.on('pong', () => { ws.isAlive = true; });

    // 메시지 수신
    ws.on('message', (data) => {
        const message = JSON.parse(data);
        console.log('수신:', message);

        // 모든 클라이언트에게 브로드캐스트
        wss.clients.forEach((client) => {
            if (client.readyState === WebSocket.OPEN) {
                client.send(JSON.stringify({
                    ...message,
                    timestamp: Date.now()
                }));
            }
        });
    });

    ws.on('close', () => {
        clients.delete(clientId);
        console.log(`클라이언트 종료: ${clientId}`);
    });
});

// Heartbeat - 30초마다 연결 상태 확인
const heartbeat = setInterval(() => {
    wss.clients.forEach((ws) => {
        if (!ws.isAlive) return ws.terminate();
        ws.isAlive = false;
        ws.ping();
    });
}, 30000);

wss.on('close', () => clearInterval(heartbeat));

server.listen(8080, () => console.log('WebSocket 서버: ws://localhost:8080'));

// Socket.IO (룸, 네임스페이스, 자동 재연결)
import { Server } from 'socket.io';
const io = new Server(server, { cors: { origin: '*' } });

io.on('connection', (socket) => {
    socket.join('room-1');  // 룸 참가
    socket.to('room-1').emit('user-joined', socket.id);  // 룸에 브로드캐스트
});

# Python 클라이언트 (websockets 라이브러리)
import asyncio
import websockets
import json

# 기본 WebSocket 클라이언트
async def websocket_client():
    uri = "wss://example.com/chat"

    async with websockets.connect(uri) as ws:
        # 메시지 전송
        await ws.send(json.dumps({
            "type": "join",
            "room": "general"
        }))

        # 메시지 수신 (무한 루프)
        async for message in ws:
            data = json.loads(message)
            print(f"수신: {data}")

asyncio.run(websocket_client())

# Python 서버 (websockets 라이브러리)
import asyncio
import websockets
import json

connected_clients = set()

async def handler(websocket, path):
    connected_clients.add(websocket)
    try:
        async for message in websocket:
            data = json.loads(message)
            print(f"수신: {data}")

            # 모든 클라이언트에게 브로드캐스트
            broadcast = json.dumps({**data, "timestamp": asyncio.get_event_loop().time()})
            await asyncio.gather(
                *[client.send(broadcast) for client in connected_clients]
            )
    finally:
        connected_clients.remove(websocket)

async def main():
    async with websockets.serve(handler, "localhost", 8080):
        print("WebSocket 서버: ws://localhost:8080")
        await asyncio.Future()  # 무한 대기

asyncio.run(main())

# FastAPI + WebSocket (프로덕션 권장)
from fastapi import FastAPI, WebSocket, WebSocketDisconnect
from typing import List

app = FastAPI()
connections: List[WebSocket] = []

@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    connections.append(websocket)
    try:
        while True:
            data = await websocket.receive_json()
            for conn in connections:
                await conn.send_json(data)
    except WebSocketDisconnect:
        connections.remove(websocket)