Facebook login button by AlterVista

Hello,
I see AlterVista uses the Facebook login button to make the login.
I need a free service like Janrain | user management platform for the social web but only for Facebook.

If you see here, is very simple the code to get the access token:
Authentication - Facebook-Entwickler

Can you (AlterVista) create this service for your users?

Follow these steps:

- the developer create the Facebook login button with:
redirect_uri=http://website.altervista.org/oauth_redirect.php
for example my page: http://zssingles.altervista.org/oauth_redirect.php

- an user click on the Facebook login button

- Facebook redirects here:
http://zssingles.altervista.org/oauth_redirect.php

- the PHP page sets the access token into the session
- others PHP pages are able to use the access token to call the Facebook API

Works?

No, unfortunately it does not work. The only way to use Facebook Connect on your website is to register your own application with Facebook, then you can create it with the php or javascript sdk provided by Facebook.

If we allow Facebook authentication on all our sites with our application anyone can access to the users data acting by Altervista.
I don't know how Janrain works, but i think that it does not share the Facebook session with your site, probably it allows to have a single sign on without having to develop it by yourself.