Socket.io calling http://undefined/.... in the URL

I'm starting with socket.io with a simple example:

Client Side:

    $(document).ready(function () {      
    var sock = new io.Socket();      
    sock.on('message', function (data) {        
        var obj = JSON.parse(data);        
        if(obj.message) {          
            $('#message').text(obj.message);        
        } else {          
            $('#timestamp').text(obj.timestamp);          
            $('#clients').text(obj.clients);        }      });      
            
    sock.connect('http://127.0.0.1:8333');      
    $("#poke").click(function() { 
        sock.send("Poke !"); 
    });     
});

Server Side:

var io = require('socket.io');var express = require('express');
var app = express.createServer();
app.configure(function(){  
    app.use(express.static(__dirname + '/public'));});
    app.get('/', function(req, res, next){  res.render('./public/index.html');});
app.listen(8333);

var socket = io.listen(app, {  
    flashPolicyServer: false,  
    transports: ['websocket', 'flashsocket', 'htmlfile', 'xhr-multipart', 'xhr-polling', 'jsonp-polling']});
var allClients = 0;
var clientId = 1;
socket.on('connection', function(client) {  var my_timer;  var my_client = { "id": clientId, "obj": client };
  clientId += 1;
  allClients += 1;
  my_timer = setInterval(function () {    
    my_client.obj.send(JSON.stringify({ "timestamp": (new Date()).getTime(), "clients": allClients }));  }, 1000);  
    client.on('message', function(data) {    my_client.obj.broadcast(JSON.stringify({ message: "poke send by client "+my_client.id }));    
    console.log(data);  
 });
    
client.on('disconnect', function() {    
    clearTimeout(my_timer);    
    allClients -= 1;    
    console.log('disconnect');  });});

My problem is that the client is trying to get:

http://undefined/socket.io/1/?t=1310142283769&jsonp=0

Which is undefined. When I curl my app with http://localhost/socket.io/1/?t=1310142283769&jsonp=1 I get something.

Why socket is calling undefined whereas everything seems to be set correctly.

Thank you if you can help me!

It looks like you are incorrectly creating the socket in your client. You should have something more like:

var sock = io.connect('http://127.0.0.1:8333');

and remove the sock.connect line entirely.

You should look over the examples on the SocketIO website. http://socket.io/#how-to-use