Subject: Re: [Simple] [Geopriv] question on presrules

From: "Erik Shani" <[email-masked]>
Date: Sun, 17 Feb 2008 22:28:07 +0200

I still feel that the question raised by Enrique exists.

Is it the job of the UI to prevent such scenarios?

In my opinion this is impossible. Let us take a scenario when two
different clients work with the same server. 

It is impossible to predict what will be the behavior of the other
client, hence it is required (in my opinion) that the client
"understands" the current document and performs its operations
accordingly.

Otherwise I see no real chance for full interoperability between
clients.

Enrique Izaguirre wrote:

> Hi,

> according to RFC5025 there could be scenarios where the 

> transformations within a matching ruled whose action=block may filter 

> the presence document showed to the requestor.

> E.g. this can happen when there are two matching rules, one that is 

> blocking and the other is allowing, and they have different 

> transformation elements. If RFC4745 is applied, the combined action is

> "allow" and the combined transformation is a superset of both 

> "transformations".

Right. That is a possibility.

> So, is the assumption that clients are smart enough so they will never

> fall into the above case? or should a presence server prevent clients 

> from not doing such combination of rules?

Its a job of the UI on the client to prevent this. Normally its not a
problem. The spec has this to say:

A consequence of this design is that the results of combining several

    authorization documents can be non-obvious to end users.  For

    example, if one authorization document grants permission for all

    users from the example.com domain to see their presence, and another

    document blocks [email-masked], the combination of these will still

    provide presence to [email-masked].  Designers of user interfaces

    are encouraged to carefully pay attention to the results of
combining

    multiple rules.

-Jonathan R.

-- 

Erik Shani:  NeuStar - Next Generation Messaging 

Presence Platform System engineer

[ M ] +972(0)54 252 2034 [ T ] +972(0)4 814 2234    [ F ] +972(0)4 855
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---

From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 29 Feb 2008 16:49:08 -0500

Erik Shani wrote:
> “understands” the current document and performs its operations accordingly.

Right, this is what I was saying. The client has to retrieve the current 
documents and present the user with a correct representation of what 
will happen, and then translate the desired user experience into the 
right set of documents.

-Jonathan R>

-- 
Jonathan D. Rosenberg, Ph.D.                   499 Thornall St.
Cisco Fellow                                   Edison, NJ 08837
Cisco, Voice Technology Group
[email-masked]
http://www.jdrosen.net                         PHONE: (408) 902-3084
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