Re: [xmpp] 3921bis: probe + unavailable

[Jonathan Schleifer <js-xmppwg at webkeks.org>]

Am 29.01.2010 um 15:58 schrieb Peter Saint-Andre:

> On 1/29/10 5:41 AM, Jonathan Schleifer wrote:
> > Am 28.01.2010 um 22:40 schrieb Dave Cridland:
> >
> > > So a note's needed at minimum to explain that this didn't used to  
> > > be a
> > > requirement, and clients (and servers) SHOULD cope with no  
> > > response as
> > > meaning unavailable.
>
> The default is always unavailable. If you receive positive <presence/>
> then you have some clue that the contact is online. If not, not. If  
> you
> receive a definitive answer that the contact is offline, that's even
> better, but you can never assume that the contact is online.
>
> > The problem with that is: How do you figure out if you don't get a
> > response or if you are just still waiting for it? We should define a
> > sane timeout here, I guess, to prevent incompatibilities. This also
> > means we need to figure out a sane value that even works with bad
> > connections.
>
> I don't see a good reason to go down that path, which introduces more
> complexity into clients.

So you suggest to assume all presences you already received as invalid  
when you send a presence probe and only take those into account that  
you got after the probe? Sounds like a solution, but a dirty one, IMO.

I think that sending back an unavailable a MUST is a good idea, as  
then you have a definite answer whether the user is online or not,  
whereas without, it could just be a laggy connection etc.

--
Jonathan