Subject: RE: [Simple] Extending <status> for presence

From: "Rosen, Brian" <[email-masked]>
Date: Tue, 21 Jan 2003 16:08:59 -0500

> Yes, we need more than CLOSED for "not Available".
> 
> That is why I have explicitly tried to find ways to encode 
> things like: 
> available for IM now, available for voice & IM eventually.
> 
> This is also why I have tried to provide for operational status like 
> active/inactive vs declarative status like available/unavailable/...
Okay, but I think we need to standardize tags so that both ends have
the same implications.  We need to agree that we have a state for
"On the phone" vs "Busy".  The latter may imply the former, but not
necessarily the other way around.

> 
> > 
> > To me, presence is guidance to the caller, and state for my
> > local devices to use when requests for calls arrive. 
> 
> Here we differ. I don't see presence as a guide for my 
> devices. Rather I 
> see my local devices as responsible for setting my presence status.
Well, I agree that if you have an activity detector, that your local
presentity client can set your status to Active.  What I meant was that
my incoming sip proxy can use my presence to guide forwarding decisions.
This lets calls from my wife come through if I'm in DND.

If my presence system and my phone system are one and the same,
that could be internally implemented.  If they are not, then my sip
proxy subscribes as a watcher to my presence system.  Either way,
presence becomes state to the incoming proxy server.
 
Brian 
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From: Paul Kyzivat <[email-masked]>
Date: Tue, 21 Jan 2003 18:36:08 -0500

> necessarily the other way around.

I don't know if we need a status that means "On the Phone". Maybe we do, 
or maybe a text string is sufficient for conveying the "what you are 
doing" part. I think that practically speaking the reason for reporting 
"On the Phone" is to indicate that you are currently unavailable to take 
voice calls, perhaps with the connotation that you will be available 
sooner than if you were "on Vacation". I have proposed separate notation 
both for indicating that you might be available for something, but not 
voice, and for indicating that eventually you will indeed be available 
for voice. Once you have those, "On the Phone" may be replaced by simple 
"Busy" or "Unavailable".

> presence becomes state to the incoming proxy server.

I think there are a couple of significantly different usage choices here:

- you can use your presence system to describe your presentity with a 
separate tuple/contact for each device you have, each with its own 
address. If you want a proxy to also choose among devices, you need an 
AOR different than the addresses of your devices. You could construct 
such a proxy that uses presence data to do the selection. Alternately, 
your buddies can simply pick contacts on their own based on the presence 
data.

- you can use your presence system to describe your presentity with a 
single tuple/contact, where this contact is an Address of Record known 
and managed by a registrar and proxy. There may be multiple devices, but 
they aren't visible to presence clients. The proxy could still use 
presence as input to device selection but its not clear how much value 
it can get out of it. Your buddies only have one choice of where to 
call, and so must use callerprefs to choose between devices.

Hybrids of the two are also possible. You seem to have the 1st in mind. 
I also have some applications in mind where I want to use something 
approaching that model. But the other model also has applicability.

	Paul