Is google chat server based or p2p like skype?

For quite some time, I've been confused about whether 开发者_运维百科Google chat is server based or is peer to peer like skype or as someone told me is it mix of both server and p2p communication? Since Google chat history is stored on Google servers (unless you go off the record ), to me it indicates that it should be server based (but ofcourse if needed that's possible with p2p as well).

Now, the person who told me that Google chat is p2p (or that mix option if that makes sense) has quite a lot of experience in networking and I'd generally trust his words, but this time I'm just unable to convince myself that Google chat could be p2p and I'm looking for some citation or something which could help clarify the doubt. Is there someone who knows whether it's server based or p2p?

PS: Sorry if the question doesn't really belong to SO, please help me if another SE site is better place for this question. I just thought that since it's about networking and so it could possibly be fine here.

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Google ditched XMPP recently and is now shifting to it's own closed sourced proprietary protocols. Which are still Server Based since google will now record all chat activity and going off record is not an option.

"They phasing out 'chat; with 'hangouts', which reneges on the server-to-server aspects of XMPP. More information on the implications (not directly related to the question) here" - Barney

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Previos answer

They use XMPP ( jabber )

Extensible Messaging and Presence Protocol (XMPP)

As answered here

I guess reading Jabber would explain things a bit, it's an open protocol and much of the stuff would be available..

For instance Wikipedia explains a bit