[Standards] presences and server restarts
elmex at x-paste.de
Mon Feb 9 00:26:24 UTC 2009
I've recently tripped over another really annoying ghost presence while I was
chatting with someone. He always showed up as online, while he actually wasn't,
just that I never got a 'unavailable' presence stanza and wondered whether my
client was actually broken (which it wasn't as a glance on the stanza log
It was a private server on the other end, so something that easily restarts/crashes
from time to time. So it might be one of those ghost presences.
The issue of ghost presences is of course known, and I don't know currently
I was reminded of the concept of rpc.statd by a friend: It's there to inform
other NFS server about unclean restarts.
So, in XMPP that would be: A server telling the other server that he would love
to receive a message when the other server restarts/crashed. Then the servers
that receive that notice could send presence probes again for the contacts
on the server that restarts.
That would probably be at least less overhead than re-probing again and again,
like it's suggested in rfc3921bis:
In addition, a server MAY periodically send a presence probe to a contact if it
has not received presence information or other traffic from the contact in some
configurable amount of time; this can help to prevent "ghost" contacts who
appear to be online but in fact are not.
I don't know if this "problem" has already been solved, I couldn't find much
on a quick look over the XEPs. Just wanted to throw in another idea, just
Robin Redeker | Deliantra, the free code+content MORPG
elmex at ta-sa.org / r.redeker at gmail.com | http://www.deliantra.net
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