Subject: [siprec] Draft minutes from interim virtual meeting

From: "Elwell, John" <[email-masked]>
Date: Tue, 10 May 2011 09:34:00 +0200

Unfortunately, in my hurry I misinterpreted the Webex controls and thought the meeting was being recorded when it was not. So we have no recording, and I have put the minutes together based on notes from Andy and my own notes / memory. I suspect some of the points raised have been lost, but I hope the main conclusions are about right.

Please send your changes/additions within one week.

John

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Minutes of the SIPREC WG Interim Virtual Meeting
2011-05-09, 14.00-16.00 GMT/UTC
===============================================
Meeting chaired by Brian Rosen and John Elwell.

Participants: Brian Rosen, John Elwell, Ken Rehor, Leon Portman, Henry Lum, Ram Mohen, Andy Hutton, Paul Kyzivat, Parthasarathi, Dan Romascanu, Charles Eckel, Mary Barnes, Arul Muthu

Minutes produced by John Elwell based on notes from Andy Hutton.

Jabber log: None of the meeting participants were on Jabber.

Recording: Owing to misoperation, the meeting was not recorded.

Meeting started at 14.05.

Topic - Administrivia (chairs)
==============================
Slides: http://kenrehor.com/ietf/siprec/IETF80.1/Chairs.pdf

No changes to published agenda.

Topic - Architecture (Andy Hutton)
draft-ietf-siprec-architecture-02
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Draft: https://datatracker.ietf.org/doc/draft-ietf-siprec-architecture/
Slides: http://kenrehor.com/ietf/siprec/IETF80.1/201105_SIPREC_Interim_Draft-ietf-siprec-architecture-Status.pdf

Slides 4/5 - There was a discussion on SRC Decomposition and Partha's comment that the figures in the document should show the SRC split into two separate UA's one on the CS side and one on the RS side. Andy stated that he did not fully understand the need for showing such a decomposition but maybe further study of the RTP Model might indicate a reason why this might be needed. No other views were expressed and it was agreed that Andy would keep the discussion going on the list to get consensus.

Topic - RTP Model (Charles Eckel)
================================
Slides: http://kenrehor.com/ietf/siprec/IETF80.1/RTP%20model.pdf

Charles had sent out on the list some proposed text on the RTP model (incorporating text from Andy Hutton merged with earlier text from himself). The text was targeted at incorporation into the architecture draft.

Arul pointed out that the RTP translator model did not allow the SRC to add any value in terms of synchronising streams, therefore the model might need augmenting (in the area of RTCP handling) or considered not applicable.

The text certainly needs more discussion to gain WG consensus before incorporation in the architecture draft, and therefore Charles kindly agreed to put it into a separate individual draft (with the help of others as necessary) for further discussion. Also, when this is available, the chairs will try to get some involvement of experts in AVTCORE and try to avoid clashes with AVTxxx meetings in Quebec City, so that experts can attend if needed.

Topic - Metadata model(Parthasarasi R)
draft-ietf-siprec-metadata-00
================================================
Draft: https://datatracker.ietf.org/doc/draft-ietf-siprec-metadata/
Slides: http://kenrehor.com/ietf/siprec/IETF80.1/SIPREC%20Metamodel%20-%20Virtual%20Interim-May09_2011.pdf

Slide 6 - On the open issue concerning any additional direct associates with the RS block, there were no proposals for additions.

Slide 7 - There was considerable discussion on the need for a Recording Session object. Paul Kyzivat doubted that we really need to refer to an RS object from elsewhere, and if not, why model an RS in metadata? Henry asked whether we have a requirement for pausing a whole RS, as opposed to media streams, since this might be justification for an RS object. Although the meeting was tending towards considering pause of the entire RS as not needed, more discussion is required on the need for this and on the consequences for the model if it is needed.

Notwithstanding the pause issue, can we move forward without an RS object and without any other object representing a Recording or Recording Group (an object we had previously but discarded)? Charles pointed out two cases: when two SRCs need to create separate recordings of the same CS; and when something goes wrong during recording of a CS and the SRC wants to initiate a new RS to continue recording the same CS. Although the unique CS object identifier is sufficient for either case, it is not sufficient to distinguish the two cases.

The meeting was probably tending towards not needing an RS object (or any other object representing a recording or group of recordings), but more list discussion is needed. Charles kindly agreed to start a new thread and list his summary of the situation and his views.

There was agreement that the attributes of an RS are not needed (there had been email discussion stating why not).

There was insufficient time to review the remaining issues in the slides.

Topic - Metadata format(Parthasarasi R)
draft-ram-siprec-metadata-format-01
================================================
Draft: https://datatracker.ietf.org/doc/draft-ram-siprec-metadata-format/
Slides: http://kenrehor.com/ietf/siprec/IETF80.1/SIPREC%20Metamodel%20Format-Interim-May9-2011.pdf

Slide 5, open issue 1 - There was no disagreement on allowing a many-to-many relationship between RS and CS objects.

Slide 6, open issue 2 - Skipped, as this relates to the ongoing discussion on the model.

Slide 7, open issue 3 - There was no disagreement that both CSG and CS objects should have globally unique IDs.

Slide 8, open issue 4 - The issue of whether a Media Stream (MS) object needs a globally unique ID seems to depend on whether a single MS can have a lifetime outside the context of a single CS. Needs further list discussion.

Slide 9, open issue 5 - Although some thought it would be sufficient for a Participant object to be unique within the context of a CS or CSG, Charles was concerned we may need a means of identifying the same Participant in several CSs, e.g., over a call transfer.

Charles noted that the general concept of globally unique identifiers and ramifications for back-end storage had arisen at the Prague meeting, but those with concerns on that occasion were not present on this occasion. Paul suggested that the use of globally unique identifiers on the SIPREC interface does not necessarily prevent the SRS finding other solutions for back-end storage or retrieval.

More list discussion needed.

Slide 10, open Issue 6 - There was only time for limited discussion. This is not really an XML extensibility issue.

There was insufficient time to review the remaining issues in the slides.

Topic - Protocol (Henry Lum)
draft-portman-siprec-protocol-04
================================================
Draft: https://datatracker.ietf.org/doc/draft-portman-siprec-protocol/
Slides: http://kenrehor.com/ietf/siprec/IETF80.1/SIPREC%20Protocol%20-%20Virtual%20Interim%20-%2020110509.pdf

There was no time for this topic.

Wrap-up
================================
In view of failing to finish the agenda, it was suggested we have another interim virtual meeting during the second half of June. This should cover the protocol as well as some specific topics that are still open following list discussion. However, the aim should be to try to resolve as much as possible on the list during the next few weeks. The chairs will try to arrange a second interim virtual meeting, which can be cancelled if not needed.

The meeting was closed at 16.05.