It wasn’t a change per se, those are names for two different things. Jabber is still the name of the federated network. XMPP is the name of the protocol (like for email it is SMTP).

https://joinjabber.org/tutorials/integration/

Not sure what you mean? It’s just XML, there’s no ‘XML in XML’ escaping or anything like that.

You might be interested in Quicksy or Snikket

Happy to answer any questions.