soket.io in cunjunction with express

var express = require("express");
var http = require("http");
var socket = require("socket.io");

// express app
app = express();
// http server based on express app
server = http.createServer(app);
io = socket(server);

// sockets
io.on("connect", function(socket){
    
    
    });
    
var host = "localhost";
var port = 3000;
    
server.listen(port, host, function(){
    console.log("Listening on %s:%d", host, port);
    });