Yeah, we can define a new header and just ignore the use of a basic SIP 
building block that the WG spent 2.5 years  (note this doesn't include the 2+ 
years spent on the doc as an individual and as a SIPPING WG document ;)  And, 
while we're at it, let's just go ahead and obsolete 4244 altogether and 
standardize diversion (something the WG rejected almost a decade ago). That 
will make one vendor and a handful of SPs very happy and those of us that have 
implemented the specs can ripout some code after while when we have some spare 
change to pay folks to do so (and of course, this is after the folks that have 
not implemented diversion actually implement it - there are actually some of 
those out there). 

As an aside, this is another fine example as to why we don't seem to make great 
progress or produce specs that are deemed useful - we agree on a way forward 
and then change our minds later (sometimes for good reasons and sometimes 
because a shortcut seems easier or it's just arbitrary based on the phase of 
the moon it seems).  

Mary. 

-----Original Message-----
From: Hadriel Kaplan [mailto:[email protected]] 
Sent: Wednesday, March 11, 2009 1:55 AM
To: Shida Schubert; [email protected] List
Cc: Barnes, Mary (RICH2:AR00)
Subject: RE: [Sip] Fwd: I-D 
ACTION:draft-rosenberg-sip-target-uri-delivery-01.txt


At the risk of opening up a topic we have already agreed on, but in the spirit 
of open communication... [how's that for an opener!?]

Are we absolutely sure we want to put this target-URI in the History-Info 
header?

I am not asking this because I think it's hard.  I am asking because I am not 
sure it will be used.  Several of us from this same WG are involved in the 
SIP-Forum's SIP-Connect profile, and when faced with either using this new 
History-Info mechanism for a target-uri delivery issue, vs. not, we chose not 
to.  And we were mostly the same people who liked the idea of putting it in 
History-Info in the IETF! (myself included)  But I am concerned that when given 
a reasonable opportunity to use a mechanism we ourselves promote when wearing a 
different hat, we chose not to use it in practice.  It doesn't bode well. :(

-hadriel
p.s. sorry Mary for raising this, but there isn't much email traffic anyway. :)

________________________________________
From: [email protected] [mailto:[email protected]] On Behalf Of Shida 
Schubert
Sent: Wednesday, March 11, 2009 2:13 AM
To: [email protected] List

We have submitted the updated target-uri draft based on the comments submitted 
to the list and comments received at IETF73. 

I have taken over as editor as Jonathan didn't have the cycles to update the 
draft, with Francois, Christer and Hans Erick as additional co-authors and 
great deal of help from Mary.  
 
The following summarizes the changes made to the target-uri document 1. Added 
use-case for toll-free number back 2. Added definition of "retarget" operation. 
3. Removed a reference to URN 4. Added a text discussing the difference to 
P-Called-Party-Id 5. Changed parameter name from "target" to "istarget"
 
Note, that the target-uri document still contains the normative text for the 
History-Info header.
 
In addition, Mary (with Francois as co-author) has submitted a rfc4244bis, with 
the following changes:
1. Incorporated the normative aspects of the target-uri document into the 
existing normative text in RFC 4244 - the functionality is virtually identical 
(as is some of the text) as the HI based solution described in the target-uri 
document.  It's important that the solution be integrated into RFC 4244 as it 
MUST work and be based on the normative aspects of RFC 4244.
2.  Added the use cases from target-uri the the summary in the overview of 
rfc4244bis.
3. Added an additional requirement to capture the "target-uri" information.
4. Fixed an error in the RFC 4244 ABNF and added "retarget" parameter.
5. Added a more simplified example.
 
 
We had some very long offline exchanges as to the best way forward and
remaining work for both documents.
 
Some of the issues identified are:

::Issues::
   1. Should we remove the normative text from target-uri and progress
       4244bis along with the target-uri document to meet the chartered
      SIP WG milestone? 
 
 
   2. Name of the parameter. 
      At the last meeting, parameter "target" was said inappropriate 
      because voicemail-uri spec already defines a parameter called 
      "target" which also can be found in hi-entry, thus potentially 
      causing confusion.
     
      Currently the target-uri draft uses "istarget" and 4244bis uses
      "retarget"  but we could never come to 
      a consensus on what name is appropriate.  Other suggestions have
      included the following:
      "target-identity" (someone didn't like that "identity" is also a SIP 
header)
      "reg-uri"  (can be paired with "mapped-uri" for item 3 below)
      "aor"
      "jibberish" 
      etc.
 
      One reason this is so difficult relates to the problem statement in 
target-uri in that
      RFC 3261 doesn't differentiate the mechanism by which the new
      (target) Request-URI is selected.  Another issue is that some of the 
terminology in
      RFC 3261 is overloaded - e.g., "forwarding" refers both to a Proxy
      which does not have responsibility for the domain of the request-URI
      in the incoming request, thus the proxy just "forwards" the request to
      the next hop AND "forwarding" is used to describe the process whereby
      the outgoing request is built and "forwarded" to the next hop at which
      point the proxy does not know how the new request-uri was selected.
      RFC 4244 has attempted to clarify the terms and attempts to use "forward" 
      in the context of the former situation and "retarget" for the case whereby
      a proxy is responsible for the domain and thus can use a number of 
      mechanism to select the new target for the request - e.g., a REGISTRAR, 
      configured data, etc.  

 3.  Related to the last point in item 2 above, it has been proposed that
      we differentiate the hi-entries even more by defining separate parameters
     for registered and configured/mapped contacts. 
     Currently when the R-URI is translated to a URI which is either derived 
     from location service lookup(registered by UA) or from mapping 
     table, there is no differentiation as to how the URI was derived once it is
     added to the list of potential targets.
     
     The general consensus of the authors of the two documents was that it may 
     be useful for some services to have the hi-entries tagged with the
     more specific information. 
 
     And, of course, this gets us into another naming contest. In the end, the 
naming
     is not so important as long as the term isn't too overloaded and it is 
defined
     precisely in the document(s).
 
We would appreciate WG feedback on these issues and any other comments on
the two documents prior to IETF-74.
 
Regards,
Shida and Mary.



Begin forwarded message:
From: [email protected]
Date: March 10, 2009 2:30:01 AM JST
To: [email protected]
Subject: I-D ACTION:draft-rosenberg-sip-target-uri-delivery-01.txt 
Reply-To: [email protected]

A New Internet-Draft is available from the on-line Internet-Drafts 
directories.


        Title           : Delivery of Request-URI Targets to User Agents
        Author(s)       : J. Rosenberg, H. van Elburg, C. Holmberg, F. Audet, 
S. Schubert
        Filename        : draft-rosenberg-sip-target-uri-delivery-01.txt
        Pages           : 16
        Date            : 2009-3-9
        
When a Session Initiation Protocol (SIP) proxy receives a request
  targeted at a URI identifying a user or resource it is responsible
  for, the proxy translates the URI to a registered or configured
  contact URI of an agent representing that user or resource.  In the
  process, the original URI is removed from the request.  Numerous use
  cases have arisen which require this information to be delivered to
  the user agent.  This document describes these use cases and defines
  an extension to the History-Info header field which allows it to be
  used to support those cases.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-rosenberg-sip-target-uri-delivery-01.txt

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