liwo_socket/index.js

const express = require("express");
const app = express();
const server = require('http').createServer(app);
const io = require('socket.io')(server, {
    cors: {
        origin: "http://127.0.0.1:8000",
        methods: ["GET", "POST"],
      }
});
const redisAdapter = require('socket.io-redis');
const redis = require("redis");
const subscriber = redis.createClient({host: '127.0.0.1', port: 6379, password: 'root'});

//setup redis
io.adapter(redisAdapter({host: '127.0.0.1', port: 6379, password: 'root'}));

// parse application/x-www-form-urlencoded
app.use(express.urlencoded({ extended: false }));

// parse application/json
app.use(express.json());

// server main route
app.get('/', (req, res) => {
    res.sendFile(__dirname + '/static/index.html');
});

io.on('connection', async (socket) => {
    socket.join('room');
    // this is just for testing.
    setTimeout(() => {
            io.to('room').emit('room-event', {index: 'users', id: undefined});
    }, 10*1000);
});


app.post('/emit/:room', function (req, res) {
    console.log('room is :','room-' + req.params.room);
    console.log('message',req.body.data.title);
    io.to('room-' + req.params.room).emit('room-event', req.body.data.title);
    res.send('done');
});
subscriber.on("message", function (channel, message) {
    io.to('room').emit('server-msg', message);
   });

server.listen(3030, () => {
    console.log('listening on *:3030');
});

subscriber.subscribe("test-channel");