Developing a web chat using Rails 3


I'm trying to develop a web chat (like the facebook one, but much
simpler) that works inside Rails 3, and so I'm inquiring about the
methods used for this scope. I had some success applying this guide
, so now I am able to send messages form the server to the client.

Anyway, I read about some sort of XML-based protocol called XMPP, which
seems to be widley used in this cases. I really don't know anything
about either cramp or XMPP, and so I would ask:

* Do you have some info about cramp (guides, explanations, examples...)?
apart from the above post, I found this , and nothing else (maybe
because it is relatively young?) Above all..
* ... how does cramp work? Is a parallel server? A thread? What is it???
* Is XMPP the way? Do you know how to implement it?
* Do you know anything about the argument? Every contribute is