app.js

server = require('http').Server();
var socketIO = require('socket.io');
var io = socketIO.listen(server);
io.sockets.on('connection', function(socket){
    console.log("connect");
    socket.on('hello', function(data){
        console.log("hello : " + data.value);
        io.sockets.emit('hello', {value: data.value});
    });
    io.sockets.emit('hello', {value: "welcome"});
});

server.listen(3000);