Subject: [dispatch] Technical issues on SIP/XMPP co-existence so far

From: <[email-masked]>
Date: Wed, 28 Oct 2009 12:31:42 +0100

Hi,
I've tried to summarize the issues raised during the discussion on SIP-XMPP co-existence charter proposal (http://www.ietf.org/mail-archive/web/dispatch/current/msg00560.html).  Several folks participated in the discussion, so if I have missed any comments, please let me know.

The purpose is the keep the list of issues as food for thought both for the planned SIP-XMPP co-existence ad-hoc meeting in Hiroshima, and for whatever forum that (hopefully) follows as a result of the ad-hoc meeting.

The following issues were raised on the DISPACH WG list:
 
- Relationship to disaggregated media. How is this work related to http://tools.ietf.org/html/draft-loreto-dispatch-disaggregated-media-00 ?

- Relationship to SIP/XMPP interworking. There are several drafts (draft-saintandre-sip-xmpp-*) available that deal with SIP/XMPP interworking (protocol translation). Should this work be handled together with the proposed SIP-XMPP co-existence (using SIP and XMPP in a complementary fashion).

- Video vs. voice. Video media should be included as an additional use case in addition to voice media.

- Multiparty. http://tools.ietf.org/html/draft-veikkolainen-sip-voip-xmpp-im-01 talks only about one-to-one sessions. Should the scope also cover multiparty cases?

- Call transfer. How should call transfer be considered in this work?

- Real-time text. There are XMPP implementations that transmit text character-by-character. Should standardizing such a feature be considered. If yes, should it be part of this effort, or is a better home the XSF?

- Call-id usage. Effects of B2BUA's to call-id and correlation id need to be considered.

- Scope, other IM protocols. Are other IM protocols (than XMPP) in the scope of this work?

- Learning addresses, vCard, E.164. What are the mechanisms for learning other endpoints' addresses? Can vCard be used? Most SIP deployments use E.164 addresses. What are the effects of E.164 address format to this work?

- How does correlation between IM and Jingle sessions work in XMPP? How does XMPP negotiatie the use of Jingle?

We can identify at least three categories on how to classify these issues. There is no particular purpose for this categorization other than it might help people to focus the discussion later on.

* Role of SIP vs XMPP
  - What medias or modes of communication each one would support?
  - Disjoint vs. overlapping feature sets (esp. presence and IM)?
  - What to do about overlapping functionality?

* Address correlation
  - How to find the user addresses in the other protocol domain?
  - Via directories, presence, specific query (e.g. SIP OPTIONS), session setup, IM conversation, etc.

* Protocol translation
  - SIP/XMPP "gateway" functionality

Regards,
Simo