Subject: Re: [Sipping] label in Conference package

From: "Johnston, Alan" <[email-masked]>
Date: Wed, 02 Feb 2005 14:56:22 +0000

Brian,

I am only going to address your first paragraph.  The rest of your comments should be redirected to the XCON list where it is in scope.

There is no dependencies between the SIP Conference Package and XCON.  There are many users of this spec that will never incorporate any XCON spec.  There is running code and actual products based on this spec.

As you know XCON does not even have a framework document.  Consensus on details like those you mention are likely a year off.  We can not wait for XCON to publish SIP conferencing specs.

Right now there are exactly 0 RFCs that say how to do SIP conferencing.  Delaying this work any further is not an option.

Thanks,
Alan Johnston
Sip:[email-masked]

-----Original Message-----
From: [email-masked] <[email-masked]>
To: [email-masked] <[email-masked]>
Sent: Wed Feb 02 13:48:39 2005
Subject: [Sipping] label in Conference package

And we continue, in my opinion, to push things like the conference package
forward without understanding how the pieces, including the xcon framework,
and the "template" concept interact with all of this.

Generally, I agree with you that if you have two audio streams, you need to
label them separately, say stereo-left and stereo-right.  

The reference to the xcon framework and template work is that I believe you
DECLARE a stream in the template, which means it defines what a stream does,
and gives it a name.  Then in the SDP, you label a stream with a name so
that you can specify that "this stream is an instance of the stream defined
in the template", then you get to see the status of these streams in the
conference package, and you need a name to distinguish them.

They all have to have the same notion of "label".

This means that the framework has to describe how that works, and the
definitions of the names in the template, SDP, and conference package have
to align with each other.

We can't reasonably do the conference package before we agree on the
framework.  For example, should there be a name hierarchy (ie
masterAudio.Left)?  I suspect we want such a thing.  When we started work on
templates, hierarchy had some nice characteristics.

Brian

________________________________________
From: [email-masked] [mailto:[email-masked]] On Behalf
Of Even, Roni
Sent: Tuesday, February 01, 2005 4:06 PM
To: SIPPING WG
Subject: [Sipping] label in Conference package

Hi,
In the example session I noticed that each user media type had a different
label for the same media type. I thought that the idea of label was to have
the same label for the same stream for all participants. This means that the
label of the audio stream should be the same.
The issue of the label raises a question - If the conference allows two
audio streams, how do I identify in the users part which stream is which and
if the user only sends one how do I know which one. Again I thought that the
"label" should identify the streams explained in the mmusic label daft. My
suggestion would be to have label at the conference allowed streams level.
Thanks
Roni
*************************************************************
Roni Even
Polycom Israel
 
Tel: +972-3-9251200
Cell: +972-54-5481099
Fax: +972-3-9211571
*****************************************************************

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Use [email-masked] for questions on current sip
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---

From: "Brian Rosen" <[email-masked]>
Date: Wed, 2 Feb 2005 11:20:55 -0500

Alan

I'm sorry, but there are a ton of dependencies between xcon and the SIP
conference package, and we're discovering that we can't do the SIP stuff
first and then try to deal with inconsistencies later.  We have to do the
XCON, the SDP work and the SIP work TOGETHER, because they are dealing with
EXACTLY the same thing.  

The ONLY thing you need to conference in SIP is a simple UA that calls a
conference server.  We do that now, and there is no problem.  There is no
pressing need for anything else except maybe a roster.  What we actually
need is a complete mechanism to make a conference service, including the SIP
and SDP mappings to that service.  

The conference package defines what a conference aware SIP UA means, and it
has to work in conjunction with the XCON defined conference service.  Doing
one end without the other never makes any sense, and it doesn't make any
sense here.  You can't define the mapping to something before you define
what you are mapping to. 

The specifics we are talking about in this thread: how to refer to one
stream of many streams in a conference, is exactly the discussion in the SDP
label, and is exactly the discussion in the definition of streams in the
template, all of which should be summarized in the framework.  

Precisely, conference-package-08 defines label as:
5.7.4  label of string type

   The element <label> carries a unique identifier for this stream among
   all streams in the conference and is assigned by the focus.  The
   value of this element corresponds to the SDP "label" media attribute
   defined in [21].

Which relates label in conference package to label in SDP.  The label
document SPECIFICALLY links SDP labels and XCON:
   Additionally, XCON identifies the need to uniquely
   identify a media stream in terms of its role in a conference
   regardless of its media type, transport protocol, and media format.
   This can be acomplished by using an external document that points to
   the appropriate media stream and provides information (e.g., the
   media stream's role in the conference) about it.

So conference-package-08 links label in media-type to label in SDP, and
mmusic-sdp-media-label links the label to XCON.  This is a proper linkage,
and nothing is going to work without that linkage.  We're designing this
elephant by committee, and we have more than a few members of this
committee.

Many conference efforts in the IETF have failed.  I don't want this one to,
and pushing sip mapping to conference state before defining conference state
is wrong.  This is but one example of many similar problems.

Brian

________________________________________
From: Johnston, Alan [mailto:[email-masked]] 
Sent: Wednesday, February 02, 2005 9:56 AM
To: [email-masked]; [email-masked]
Subject: Re: [Sipping] label in Conference package

Brian,

I am only going to address your first paragraph.  The rest of your comments
should be redirected to the XCON list where it is in scope.

There is no dependencies between the SIP Conference Package and XCON.  There
are many users of this spec that will never incorporate any XCON spec. 
There is running code and actual products based on this spec.

As you know XCON does not even have a framework document.  Consensus on
details like those you mention are likely a year off.  We can not wait for
XCON to publish SIP conferencing specs.

Right now there are exactly 0 RFCs that say how to do SIP conferencing. 
Delaying this work any further is not an option.

Thanks,
Alan Johnston
Sip:[email-masked]