Subject: Re: [Simple] Authorization Rules Discussion A: Sphere Interpretation

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 03 Nov 2004 02:36:07 -0500

inline.

[email-masked] wrote:

> I also assumed that composition is watcher specific, but something in
> this discussion has confused me.
> 
> If I publish 2 views of my presence, one for co-workers and another
> for friends.
> 
> In sphere "work-mode" : I am "in-a-meeting"
> 
> In sphere "play-mode": I am "busy"
> 
> I want my co-workers to see my person presence with sphere
> "work-mode" and my friends to see my person presence with sphere
> "play-mode".
> 
> Now, if the composition takes place before the authorisation policy,
> then I am no longer able to do that. The composition policy might
> merge these 2 to be sphere "play-mode".

Well, it wouldn't. Thats the point. Here is a classic case where you 
want to have watcher specific composition policies. So, in this case, 
you'd have a policy that is something like this:

for watchers that are my friends {
   keep the person tuple whose <sphere> is "play-mode"
} else for watchers that are co-workers {
   keep the person tuple whose <sphere> is "work-mode"
}

This would result in a different document, post composition, depending 
on who the watcher is.

> 
> If I have a rule for a co-worker, Aki, that says only show him
> presence info with sphere "work-mode", then Aki will not get any
> presence info of mine as a person. Is the right?

No. The composition would first make sure that the right <person> 
information is selected for the watcher. If you have privacy permissions 
which prevent <person> information from being sent if the <sphere> is 
not "work-mode", those would serve as an additional check. However, for 
the example composiiton algorithm, it would not remove any further 
information.

-Jonathan R.
-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Director, Service Provider VoIP Architecture   Parsippany, NJ 07054-2711
Cisco Systems
[email-masked]                              FAX:   (973) 952-5050
http://www.jdrosen.net                         PHONE: (973) 952-5000
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---

From: Henning Schulzrinne <[email-masked]>
Date: Wed, 03 Nov 2004 08:50:07 -0500

>   keep the person tuple whose <sphere> is "work-mode"

As I tried to point out in an earlier message, I think we have a 
somewhat different understanding of <sphere>. In my definition, <sphere> 
reflects the state of the presentity, just like mood, activity and 
location. Thus, normally a presentity can only be in one state. 
Naturally, different sensors may be confused as to the state, just like 
for the other descriptors, but you wouldn't have "work" tuples and 
"play" tuples.

The privacy rules reflect this, in that <sphere> is an input determining 
who gets my data.

Instead, the composition rule would be

if I'm in sphere = work
   send elements of class 'foo' to my work buddies
if I'm in sphere = play
   send elements of class 'bar', 'rab' and 'oof' to my play buddies

---

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 03 Nov 2004 09:20:17 -0500

inline.

Henning Schulzrinne wrote:

> location.

I understand that. The question that Aki was raising was a scenario in 
which there are two different person elements published for a user, one 
with <sphere> at home, and one at work. The objective was to select one 
of these two based on composition policies. This case would arise when a 
user wishes to appear in different spheres to different watchers.

> Thus, normally a presentity can only be in one state.

Right. Thats why the composition algorithm needs to pick one.

>   send elements of class 'bar', 'rab' and 'oof' to my play buddies

That wouldn't be a composition rule, it would be a privacy filtering rule.

-Jonathan R.

---

From: Henning Schulzrinne <[email-masked]>
Date: Mon, 08 Nov 2004 14:57:26 -0500

> Right. Thats why the composition algorithm needs to pick one.

That's the disagreement in a nutshell. The composition algorithm does 
not HAVE TO pick one and may not be able to. It may want to or be forced 
to expose this contradiction to the watcher.

> That wouldn't be a composition rule, it would be a privacy filtering rule.

The two are closely related.