2010/10/21 Daniel-Constantin Mierla miconda@gmail.com:
I think it is just failure of one model over-complicated, the Presence Agent.
SIP has also end-to-end presence and it was/is working perfect in most of the cases.
Hi, I don't agree. SIP end-to-end presence fails when coming to privacy area as the watcher doens't receive the information from a server, but from the watched user itself (so the watcher knows if it's "online" or not). I've tryed end-to-end SIP presence and IMHO is just a toy.
Also, about XMPP and "ent-to-end" presence:
"distributing states" is done by sending <presence> stanzas. XMPP basic presence (online, offline and text note) works in this way. This is, a XMPP client gets online and sends <presence> stanza to all its non-blocked contacts to inform about its presence status. However, other presence features in XMPP as the avatar, advanced presence (like the music you are listening now), work with publish-subscribe mechanism. This mechanism is much more scalable.
Please read this short thread I open in XMPP-IETF about it: http://www.ietf.org/mail-archive/web/xmpp/current/msg01703.html
This is: publish-subscribe mechanism has also being adopted by XMPP. So IMHO this mechanism is the most suitable also for SIP, but it must be improved (the specs and features).
Regards.