Re: [Simple] Presence data model: devices

[Paul Kyzivat <pkyzivat at cisco.com>]

Jonathan,

There is one point in here that I want to comment on...

	Paul

Jonathan Rosenberg wrote:
> You have two phones, this CDMA and GSM one. Lets say they both work 
> (i.e., you are in the U.S). Your presence document indicates a voice 
> service and a SIP messaging service on the GSM phone, and an sms service 
> on the CDMA phone. Lets say I'm talking to you on your GSM phone, which 
> is low on power. While talking, you say, "hey, can you send me a 
> message, but send it to me other phone since I am about to run out of 
> ...." and at that moment, the call ends since power is out. I want to 
> send you a message now, but not to the gsm phone. I have no way to know 
> which of the two messaging services is accessible on that phone, or 
> another phone, without device information.
>
> Indeed, a convenient user interface would show user "henning" with two 
> device icons, each a cell phone. Perhaps one has "gsm" inside, and the 
> other "cdma" (again, these are DEVICE characteristics). So, if you say 
> to someone, "call my gsm", it becomes very easy for me, or anyone else, 
> to call it, or PTT it, or sms it, or access any of the other services 
> avaialble on it. Without a device concept, I can't do that.

As long as the data model has a many:many relationship between services 
and devices there is going to be a problem deciding what is the best, 
most convenient, user model. Most of the user models of this sort of 
thing are tree oriented one way or another. A many:many model has to be 
unwound using repetition to be displayed as a tree. So either the top 
level view can be devices, with services within and possibly replicated, 
or else the top level can be services, with devices within, possibly 
replicated.

The case you describe, while real, is a fairly obscure one. I think it 
would be sufficient to have the service view, and for each service to 
list the associated device(s).

This need to replicate would be simpler if the device is simply an 
attribute rather than a separate item that has state that also needs to 
be replicated.

(Of course another UI might show services and devices at the same level, 
with cross references between them, but that doesn't sound like a very 
appealing UI.)

	Paul


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