As I and others on this blog have mentioned on several occasions, the SIMPLE (or the more formal and rather awkward: “SIP for Instant Messaging and Presence Leveraging Extensions”) working group of the IETF has been responsible for defining how to do Presence and Instant Messaging applications using SIP and related protocols. The SIMPLE working group has existed for some time; in fact, it’s one of the oldest ongoing working groups in the Real-time Applications and Infrastructure (RAI) area of the IETF. I am currently a co-chair for SIMPLE.
I write to tell you that SIMPLE’s work is almost done. We are finally seeing the light at the end of this long tunnel. Of the four remaining work items, one is in the AUTH48 state. (This means that the RFC editor has presented a candidate for the final RFC version back to the authors for any last minute edits and approval.) One entered Working Group Last Call (WGLC) last week. There are only two work items that may still see controversy, and one of those is in IESG review.
The first draft extends the MSRP protocol to allow the endpoints to negotiate which one will open a TCP connection to its peer. I blogged about this draft some time ago. We should see publication of the resulting RFC any day now. In fact, it’s already been assigned a number: RFC 6135. [Update: RFC 6135 was officially published on February 28.]
The second, draft-ietf-simple-simple (aka “SIMPLE made Simple”), is an informational draft that acts as a road-map and secret-decoder-ring for the various specifications produced by the SIMPLE working group. (Keep in mind, that there is no one protocol known as SIMPLE. But we still tend to use the term SIMPLE informally to refer to the resulting suite of protocols and architecture.) The fact that this draft is in WGLC means the author believes that this draft is essentially ready to be sent to the IESG for final review and publication. It’s possible that the last call review could uncover some controversial point that would require more work. But given the nature of this draft, I expect that any WGLC feedback is more likely be clarification and editorial comments.
We do know in advance, however, that draft-ietf-simple-simple may require minor editing to reflect the final disposition of the last two drafts below. This means that, regardless of its current completion state, draft-ietf-simple-simple will be the last draft to be published by SIMPLE.
Draft-ietf-simple-msrp-sessmatch describes an extension to MSRP to make it more friendly to Session Border Controllers (SBCs). The way that MSRP devices match TCP connections to message sessions means that, if an MSRP session traverses an SBC, that SBC has to re-write the To-Path and From-Path header fields in a manner similar to an MSRP Relay. Some working group participants expressed concern that this requirement could impact SBC performance. The sessmatch draft would allow supporting endpoints to work across SBCs that do not change MSRP messages en route. However, there are still ongoing discussions concerning the impact on security and interoperability.
Assuming that the sessmatch draft has not become a moot point by then, I plan to go into considerably more detail on it and the surrounding controversy in my next blog entry.
Then, finally, there’s draft-ietf-simple-chat. This draft defines how to create MSRP “chatrooms” with conference servers. There’s still some controversy over how this draft interacts with some similar work from the XCON working group.
Hopefully, we will resolve the issues around these last two drafts soon–at which time I hope to be able to entitle a blog entry as “SIMPLE Finally Done!”