Subject: [Simple] xcap/geopriv alignment issue 6: subscription confirmation

From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 24 Nov 2003 01:42:11 -0500

Folks,

In the current xcap-auth model, there is an important assumption that 
if there are no statements that apply to a watcher, the implication is 
that their subscription is pending, and that the presentity should get 
a winfo notification about the fact that its pending, so that they can 
make a policy decision. This assumption is based on another assumption 
I made, which is that the ONLY reason that a watcher would go into the 
pending state, is if you have not specified a policy for them yet.

However, geopriv doesnt make this assumption. They have an element 
called "confirm-subscription". If present, it means that the 
presentity should be alerted about the subscription, and asked for 
confirmation. As a result, there is a way to EXPLICITLY say "let me 
know if this person subscribes".

I think there are legitimate use cases for this, which came up during 
the geopriv meeting in Minneapolis. In particular, I may grant my boss 
permission to subscribe during the day, but during the evening, I want 
to be prompted each time, to see if I will grant it or not.

To do this, we could follow their lead and add a 
"confirm-subscription" boolean, which would explicitly place the 
watcher into the pending state.

I think this makes sense, and I would suggest adding this capability 
to xcap-auth.

-Jonathan R.
-- 
Jonathan D. Rosenberg, Ph.D.                600 Lanidex Plaza
Chief Technology Officer                    Parsippany, NJ 07054-2711
dynamicsoft
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

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---

From: Ben Campbell <[email-masked]>
Date: Mon, 24 Nov 2003 14:47:43 -0600

Jonathan Rosenberg wrote:

> Folks,
> 
> In the current xcap-auth model, there is an important assumption that if 
> there are no statements that apply to a watcher, the implication is that 
> their subscription is pending, and that the presentity should get a 
> winfo notification about the fact that its pending, so that they can 
> make a policy decision. This assumption is based on another assumption I 
> made, which is that the ONLY reason that a watcher would go into the 
> called "confirm-subscription". If present, it means that the presentity 
> should be alerted about the subscription, and asked for confirmation. As 
> a result, there is a way to EXPLICITLY say "let me know if this person 
> subscribes".
> 
> To do this, we could follow their lead and add a "confirm-subscription" 
> boolean, which would explicitly place the watcher into the pending state.
> 
> I think this makes sense, and I would suggest adding this capability to 
> xcap-auth.

I think I like this. So if we were to do this, would that mean the 
default for when no rules apply would become "deny"?

This does, however, bring up a concern that I tried to express in 
Minneapolis, but am not sure I ever managed to make my point. Most 
existing presence systems have a concept of blocking an identity. The 
additive permissions approach seems to make this difficult to implement. 
If I, for example, want to block [email-masked], I must make sure 
that no other rule can possibly include alice. This is further 
complicated if some of my rules apply to external lists. Even if Alice 
is not on such a list today, someone might put her on one tomorrow, and 
invalidate my block. The easiest way to make sure this never happens 
would be to add an except clause for Alice to _every_ rule I have. That 
seems pretty cumbersome and error prone.

And yes, I understand the arguments in geopriv about black-lists being 
useless. I just don't think I could sell those arguments to a customer.

---

From: Ben Campbell <[email-masked]>
Date: Mon, 24 Nov 2003 14:47:43 -0600