Hi! 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 indicated).
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 in case... Greetings, Robin Redeker -- Robin Redeker | Deliantra, the free code+content MORPG el...@ta-sa.org / r.rede...@gmail.com | http://www.deliantra.net http://www.ta-sa.org/ |
