WebSocket & Real-Time

WebSocket Server

import { WebSocketServer, WebSocket } from "ws";

const wss = new WebSocketServer({ port: 8080 });

const rooms = new Map<string, Set<WebSocket>>();

wss.on("connection", (ws, req) => {
  const userId = authenticateFromUrl(req.url);
  if (!userId) {
    ws.close(4001, "Unauthorized");
    return;
  }

  ws.on("message", (data) => {
    const message = JSON.parse(data.toString());

    switch (message.type) {
      case "join":
        joinRoom(message.room, ws);
        break;
      case "leave":
        leaveRoom(message.room, ws);
        break;
      case "broadcast":
        broadcastToRoom(message.room, message.payload, ws);
        break;
    }
  });

  ws.on("close", () => {
    rooms.forEach((members) => members.delete(ws));
  });

  ws.send(JSON.stringify({ type: "connected", userId }));
});

function joinRoom(room: string, ws: WebSocket) {
  if (!rooms.has(room)) rooms.set(room, new Set());
  rooms.get(room)!.add(ws);
}

function broadcastToRoom(room: string, payload: unknown, sender: WebSocket) {
  const members = rooms.get(room);
  if (!members) return;
  const message = JSON.stringify({ type: "message", room, payload });
  members.forEach((client) => {
    if (client !== sender && client.readyState === WebSocket.OPEN) {
      client.send(message);
    }
  });
}

Socket.io with Rooms

import { Server } from "socket.io";
import { createAdapter } from "@socket.io/redis-adapter";
import { createClient } from "redis";

const io = new Server(httpServer, {
  cors: { origin: "https://app.example.com" },
  pingTimeout: 20000,
  pingInterval: 25000,
});

const pubClient = createClient({ url: "redis://localhost:6379" });
const subClient = pubClient.duplicate();
await Promise.all([pubClient.connect(), subClient.connect()]);
io.adapter(createAdapter(pubClient, subClient));