Re: [xmpp] 3921bis: probe + unavailable

[Justin Karneges <[e-mail]>]

On Monday 01 February 2010 12:46:52 Peter Saint-Andre wrote:
> I understand that the MUST here is an imposition on servers. IMHO the
> deterministic nature of the unavailable has many benefits, but I can see
> why large service providers would prefer to return a stanza to the
> probing user only if the contact is online. So I think it's good that we
> discuss the tradeoffs here.

A large benefit is to prevent a jabber:iq:last storm.  We don't want there to 
be any reason for a client to poll its entire roster.

I can see why a mobile client might not be interested in having that 
information pushed at it on login, to reduce resource usage.  Jonas' 
suggestion of making this a client-controlled option is probably best, but I 
don't know what the default behavior should be.

Also, there has been discussion in the past about sending presence only of 
certain contacts, groups, etc, when mobile, so the solution for filtering out 
unavailable presence might fit right in with that maybe.

Another thing: this issue is actually two-part: 1) should remote servers reply 
to probes if the contact is unavailable?  and 2) should the local server send 
unavailable presence to contacts that just logged in?  Both of these have 
resource usage implications, but only the second one impacts the client.

-Justin