Subject: [Sip] I-D ACTION:draft-ietf-sip-answermode-05.txt

From: [email-masked]
Date: Wed, 05 Sep 2007 16:15:02 -0400

A New Internet-Draft is available from the on-line Internet-Drafts 
directories.
This draft is a work item of the Session Initiation Protocol Working Group of the IETF.

	Title		: Requesting Answering Modes for the Session Initiation Protocol (SIP)
	Author(s)	: D. Willis, A. Allen
	Filename	: draft-ietf-sip-answermode-05.txt
	Pages		: 26
	Date		: 2007-9-5
	
This document defines extends SIP with two header fields and
   associated option tags that can be used in INVITE requests to convey
   the requester's preference for user-interface handling related to
   answering of that request.  The first header, "Answer-Mode",
   expresses a preference as to whether the target node's user interface
   waits for user input before accepting the request or instead accepts
   the request without waiting on user input.  The second header, "Priv-
   Answer-Mode" is similar to the first, except that it requests
   administrative-level access and has consequent additional
   authentication and authorization requirements.  These behaviors have
   applicability to applications such as Push-to-Talk and to diagnostics
   like loop-back.  Usage of each header field in a response to indicate
   how the request was handled is also defined.

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---

From: Dean Willis <[email-masked]>
Date: Wed, 5 Sep 2007 19:23:35 -0500

> 	Filename	: draft-ietf-sip-answermode-05.txt

Note that I had an accident with a xml editor that rewrapped all the  
SIP examples that I didn't notice until after sending -05, so I've  
fixed it up and sent -06.

--
Dean

---

From: "Steve Langstaff" <[email-masked]>
Date: Mon, 10 Sep 2007 07:19:31 -0700

At the last call of this document I raised the following issues:

SRL> Section 4.3.2 states:
SRL>
SRL>    The Answer-Mode and Priv-Answer-Mode header fields have
equivalent
SRL>    functions, except that Priv-Answer-Mode requests a higher level
of
SRL>    privilege in granting the answering mode specified by the
request.
SRL> 
SRL> Would it not make sense to have a single header that performs both 
SRL> of these equivalent functions, using a parameter (e.g. 'high' or
'level=high') to distinguish between the two?
SRL> 
SRL> This might have the following benefits:
SRL> 
SRL> 1) The document would be smaller.
SRL> 2) The implementation may be simpler.
SRL> 3) If the need for more than just two levels of privilege were
found in the future then this could be easily extended, rather than
following the current pattern of needing another header, e.g.
Really-High-Priv-Answer-Mode:

My questions were answered by Dean, but I now notice the following in
the current draft:

   "4.1.  Procedures at User Agent Clients (UAC)

    4.1.1.  All Requests

       A UA supporting the Answer-Mode and Priv-Answer-Mode header
fields
       SHOULD indicate its support by including an option tag of
       "answermode" in the Supported header field of all requests it
sends."

Other sections also mention this single option tag.
 
Would it not make more sense to use two separate option tags, e.g.
"answer-mode" and "priv-answer-mode"? That would seem to be more
orthogonal to me if this scheme were to be open to extension in the
future?