Subject: [Simple] Query on Request URI of PUBLISH vs 'pres' URL of publishing entity

From: "Sean Leahy" <[email-masked]>
Date: Thu, 9 Mar 2006 13:01:21 +0000

Can anyone answer my previous questions as below ?:

- Is my understanding correct that the model allows for a separation of 
the subject entity (identified by the Request-URI) and the publishing 
entity (identified by the 'pres' URL)? 

- If there is no separation between the subject and the publisher 
intended, then can it be said that the Request URI of a PUBLISH request 
must always be the same as the  'pres' URL (in the PIDF in the PUBLISH 
request)  ?

Sean Leahy

----- Forwarded by Sean Leahy/MAIN/MC1 on 09/03/2006 12:58 -----

Sean Leahy
06/03/2006 11:06

        To:     [email-masked]
        cc: 
        Subject:        Request URI of PUBLISH vs 'pres' URL of publishing entity

There seems to be a contradiction within RFCs 3903, 3863 and 
draft-rosenburg-simple-presence-processing-model-01.

The Request-URI of a PUBLISH request contains the information necessary to 
route the request to the Presence Server and identifies the resource whose 
event state is to be published [RFC 3903]. Thus the PUBLISH request is 
sent to the Presence Server that composes the presence state bound to the 
address in the Request-URI.

The presence element of a Presence Information Data Format document (PIDF) 
[RFC 3863] must have an 'entity' attribute.  The value of the 'entity' 
attribute is the 'pres' URL of the presentity publishing this document. 
i.e. the 'pres' URL appears to identify the publisher rather than the 
subject of the presence document (these may or may not be the same).

Is my understanding correct that the model allows for a separation of the 
subject entity (identified by the Request-URI) and the publishing entity 
(identified by the 'pres' URL)? 

If so, I would have expected 'A Processing Model for Presence' (draft-rosenburg-simple-presence-processing-model-01) to show that the collection of event state centres around the 
Request-URI but in fact it identifies "the set of documents whose "entity" 
attribute in the <presence> element in the presence document is the same 
as that of the presentity." i.e. it appears to centre around the 'pres' 
URL (in the PIDF in the PUBLISH request) rather than the Request-URI.

This seems to contradict the position that the 'pres' URL identifies the 
publisher rather than the subject of the presence document or at least 
eliminates the idea that there is a separation of the subject entity 
(identified by the Request-URI) and the publishing entity (identified by 
the 'pres' URL).

Please can you clarify which position is correct ? 

If there is no separation between the subject and the publisher intended, 
then can it be said the the Request URI of a PUBLISH request must always 
be the same as the  'pres' URL (in the PIDF in the PUBLISH request)  ?
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---

From: Aki Niemi <[email-masked]>
Date: Thu, 09 Mar 2006 16:15:01 +0200

Hi Sean,

I can imagine a useful scenario where the Request-URI and the entity
attribute of the presence document weren't the same. For example, I
might have an alias address for myself at forever.example.com, where I
publish my presence documents using whatever identity my current ISP is
offering me, while at work:

PUBLISH sip:[email-masked] SIP/2.0
...
To: <[email-masked]>
From: <[email-masked]>;tag=skd8iehdl
...
<presence entity='pres:[email-masked]'>
...
</presence>

However, this sort of setup would require that the system duly
authorizes such "fourth-party" publications. It's maybe a bit far
fetched, but certainly allowed.

Cheers,
Aki

ext Sean Leahy wrote:
> 	*Sean Leahy*
> The Request-URI of a PUBLISH request contains the information necessary
> to route the request to the Presence Server and identifies the resource
> whose event state is to be published [RFC 3903]. Thus the PUBLISH
> request is sent to the Presence Server that composes the presence state
> bound to the address in the Request-URI.
> 
> The presence element of a Presence Information Data Format document
> (PIDF) [RFC 3863] must have an 'entity' attribute.  The value of the
> 'entity' attribute is the 'pres' URL of the presentity publishing this
> document. i.e. the 'pres' URL appears to identify the publisher rather
> than the subject of the presence document (these may or may not be the
> same).
> 
> Is my understanding correct that the model allows for a separation of
> If so, I would have expected 'A Processing Model for Presence'
> (/draft-rosenburg-simple-presence-processing-model-01/) to show that the
> collection of event state centres around the Request-URI but in fact it
> identifies "the set of documents whose "entity" attribute in the
> <presence> element in the presence document is the same as that of the
> presentity." i.e. it appears to centre around the 'pres' URL (in the
> PIDF in the PUBLISH request) rather than the Request-URI.
> 
> If there is no separation between the subject and the publisher
> intended, then can it be said the the Request URI of a PUBLISH request
> ------------------------------------------------------------------------
>

---

From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 09 Mar 2006 09:30:28 -0500

http://www.jdrosen.net/papers/draft-rosenberg-simple-presence-processing-model-01.txt

talks about motivations for why you might want them different. The idea 
there is that the presence server is going to collect presence documents 
for the presentity in the entity attribute, and compose them together. 
However, presence inputs for that presentity can be generated from 
presence documents from other presentities too, in cases where they have 
some kind of relationship.

Thus, I might want to send a PUBLISH request with URI A and entity with 
URI B if presence for presentity A requires state of presentity B. The 
PUBLISH URI is really used for routing; getting the presence document to 
the right place.

HTH,
Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
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