RE: [XCON] draft on MSRP conferencing

[Aki Niemi <aki.niemi at nokia.com>]

Hi,

I think that unfortunately this discussion is heading towards the same
deadlock we reached around IETF-61. I would suggest that when we
actually have a proposal for the XCON sidebar mechanism, we return to
this issue, and investigate whether all requirements are fulfilled with
this XCON sidebar mechanism alone, or whether both sidebars and private
MSRP messages are required.

That said, my belief still is that we need both, and I have a use case
to back this up below. Otherwise, I have yet to hear an argument proving
for example that in IRC people are only using sidebars and not the
PRIVMSG method, or that the PRIVMSG and INVITE methods are not analogous
to a private MSRP message and establishment of a sidebar in XCON in the
multiparty MSRP setting. Feel free to correct me if my understanding
there is not correct.

The use-case
------------

Consider a chat room, in which N tv-stations are negotiating with the
Olympic committee for purchasing the broadcast rights to the different
sports in the next olympic games. Each station's delegation consists of
one member.

As often happens with these fictional negotiations, at any point during
the negotiations, tv-stations may start to swap and trade amongst each
other with the broadcast rights of sports they've already secured. These
unofficial negotiations happen in private, randomly and un-structured.

To accomplish this using only a sidebar mechanism, in addition to the
main conference (N+1 participants), we would need a full mesh of N x N
sidebars at least (for each pair of tv-stations) so that the delegates
could each send a private communication to each other whenever they feel
the urge. 

With our mechanism, you don't have to have any sidebars to enable one
delegate to send a private communication to another delegate. 

Of course, sometimes in thes enegotiations a sidebar is set-up, e.g.,
among the North-American tv-stations to further negotiate the broadcast
rights to baseball since none of the Europeans are interested. Even
then, any North-American tv-station delegate would benefit being able to
send a *single* private message to another North-American tv-station
delegate whenever they feel like it -- without having to establish a
sidebar.

Cheers,
Aki

On Wed, 2005-02-23 at 15:59, ext Brian Rosen wrote:
> Miguel
> 
> This is a conference - you send your media to a mixer, and it sends it to a
> group of others.  Normally, in a chat room, you send to the mixer, and it
> sends to ALL others.
> 
> In an audio conference, normally, you send your media to the mixer, it sends
> it to ALL others.
> 
> You have the capability to send to a subset of ALL.  In an audio conference,
> that is a sidebar.  
> 
> What you are discussing is how you indicate who is in your sidebar, right?
> The mixer knows the SIP URIs.  What you are indicating is that you want the
> participant identifiers used to select the participants in the sidebar to
> not necessarily be SIP URIs, but be nicknames.
> 
> That has nothing to do with IM vs audio; it's how participants are
> identified in a conference.  You want at least an option to be identified
> solely by nicknames.  I think you would agree that if you know the SIP URIs
> of the participants in the conference as well as their nicknames, then it's
> a UA issue to select sidebars by nicknames.  You seem to want to make sure
> that participants' URIs are not necessarily known to other participants.
> 
> That is a reasonable requirement, but we have to word it so that it covers
> all media forms.
> 
> I'll note that nicknames may well be useful in other contexts besides IM.
> It may make a more appropriate label for, say, a small video window.
> 
> Brian
> 
> 
> 
> >

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