[Standards-JIG] RFC 3921 Better User PresenceExperience (Implementation Detail)

[JD Conley]

Thanks for all the good feedback! 

> > I was wondering what you guys thought about this and if anyone
> already
> > implements something similar in their servers.
> 
> Ask some ircd coders, they know what you're describing ;-)

I knew someone would bring this up. Ideally some ircd coders can help us
avoid the pitfalls while we explore this new territory.

> Does 'netsplit' mean anything to you?

Yes, quite a bit. And this is a real problem for us in the land of real
time federated messaging/presence.

> What happens if the remote domain is reachable again?
> Does the server re-request the presence state of each remote user
> again?

I think we should develop a protocol for requesting _all_ presences for
a domain with a single stanza. Then a server could disable its flow
control for the relevant connection(s) to accept the incoming flood.

Send: <presence type="probe" to="remotedomain.com"
from="localdomain.com"/>
Recv: <presence from="user at remotedomain.com/resource"
to="user at localdomain.com/resource" />
Recv: <presence from="user2 at remotedomain.com/resource"
to="user at localdomain.com/resource" /> 

Etc...

-JD