app.js

var app = require('express')();
var server = require('http').Server(app);
var io = require('socket.io')(server);
server.listen(8080, function (err) {
    if (err) {
        console.error(err);
    } else {
        console.log("Server listening on port 8080");
    }
});

app.get('/operateLight', function (req, res) {

    var light = req.param('lightVal');
    console.log(light);
    res.json({light_value: light});
});

io.on('connection', function (socket) {
    socket.emit('light1', {status: light});
    socket.on('my other event', function (data) {
        console.log(data);
    });
});