socket.io starts and stops again immediately

I'm playing around with node.js and socket.io. I have to files:

Server-side:

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

var app = express();
var server = http.createServer(app)
var io = socket.listen(server);

io.sockets.on('connect', function (client) {
    console.log('Client connected');
    client.emit('messages', {hello: "hello"});
});

Client-side:

<script src="/socket.io/socket.io.js"></script>

<script>
var server = io.connect('http://127.0.0.1:8000');
server.on('messages', function(data){
    alert(data.hello);
});
</script>

When i type node <name-of-my-file> this happens:

enter image description here

Any suggestion is appreciated!

You are using expressjs but you did not set it to listen to any port.

var app = express();
var server = http.createServer(app)
app.listen(8000);
var io = socket.listen(server);