2.1.23 SIP for Instant Messaging & Presence Leveraging Extensions BOF (simple)

Current Meeting Report

Minutes for SIMPLE BoF (IETF 49)

- Jonathan Rosenberg - Update on IMPP and SIP

Jonathan Rosenberg spoke generally of the applicability of SIP to presence (stressing that SIP has always provided presence since its inception) and messaging. He then introduced the existing work that had been done in the IMPP WG towards extending SIP for IM&P as defined in RFC2778/2779.

- Jonathan Rosenberg - Update on CPIM

Jonathan Rosenberg provided general historical information on the progress of the IMPP WG, the genesis of the 'Group of Nine' and the authoring of the CPIM draft. He focused a bit on outstanding issues associated with CPIM.

- Robert Sparks - Overview of SIP for Presence

Robert Sparks delved into some of the technical details of handling presence with SIP.

After the presentation, Jonathan Rosenberg requested a hum reflecting the interest in this approach to IM&P work - interest in the room was high.

- Robert Sparks - Relationship of SIP Events work to SIP for Presence work

Robert Sparks presented a brief gloss on parallel work being done within the SIP WG on unifying the use of SUBSCRIBE and NOTIFY within the SIP standard, namely in a draft by Adam Roach.

Jonathan Rosenberg requested a report on the recent SIP bake-off. Robert reported, as an implementor, that multiple interoperable IM&P clients (roughly a half-dozen) using SIP were present at the bake-off.

- Jon Peterson - Quick Charter Walkthrough

Jon Peterson presented the goals and deliverables associated with the proposed SIMPLE WG.

A long conversation ensued concerning the proposed SIP framework document deliverable - a proposed short document that would outline the minimum requirements for the implementation of SIP in response to IMPP WG concern that RFC2543 is too long and complicated. Jonathan Rosenberg and Henning Schulzrinne both opposed the creation of such a draft in the SIMPLE WG. Harald Alvestrand warned of the dangers of paraphrasing a pre-existing standard - Henning Schulzrinne corroborated this sentiment. Marshall Rose suggested that modularization of the SIP document set (paring down RFC2543) would greatly simplify the matter. It was universally acknowledged at the conclusion of the conversation that, whatever form this work would take, it should be conducted not in SIMPLE but within the SIP WG. As a major revision of RFC2543 is already underway in that WG, it was noted by Jonathan Rosenberg that this work would most likely obviate the need for a framework distinct from the standard. There was consensus that the framework deliverable should be removed from the charter.

Christian Huitema requested that the actual charter be displayed on the overhead. The entire charter was then displayed page by page for review.

Jonathan Lennox commented that the dates currently listed in the charter were perhaps unreasonably close - the point was generally conceded by the assembly. Jonathan Rosenberg noted that the charter had not been updated recently to reflect the passage of time - the dates are to be pushed forward by one month each.

Jon Peterson asked for any further comments on the charter, indicating that the lack of any further comments would be taken as consensus. No further comments on the charter followed.

- Open issues

Two particular open issues were discussed, and two were acknowledged to be closed:

The security and privacy implications of waiting to send a 200 to SUBSCRIBE until the user approves - considering that by doing so, the user may unintentionally reveal part of their presence status. Henning Schulzrinne stressed that this was not a terribly difficult problem. Jonathan Rosenberg suggested that since presence is carried in a NOTIFY, rather than a 200, one should always send the 200 to SUBSCRIBE immediately.

Forking of MESSAGE and SUBSCRIBE was also briefly examined - it was suggested that the properties of SUBSCRIBE in this regard mirrored that of REGISTER.

Closed issues included limiting the number of Contacts in a SUBSCRIBE message to one, and sending presence in response to SUBSCRIBE in a NOTIFY rather than in a 200.


SIP for Instant Messaging and Presence Leveraging Extensions
Update on IMPP and CPIM
SIP for Instant Messaging and Presence