Subject: WG Action: Centralized Conferencing (xcon)

From: The IESG <[email-masked]>
Date: Tue, 07 Oct 2003 15:53:05 -0400

A new IETF working group has been formed in the Transport Area.  
For additional information, please contact the Area Directors or the WG Chairs.

Centralized Conferencing (xcon)
-------------------------------

Current Status: Active Working Group  

Chair(s):
Adam Roach <[email-masked]>
Alan Johnston <[email-masked]>

Transport Area Director(s):
Allison Mankin <[email-masked]>
Jon Peterson <[email-masked]>

Transport Area Advisor:
Allison Mankin <[email-masked]>

Mailing Lists:
General Discussion: [email-masked]
To Subscribe: http://www.softarmor.com/mailman/listinfo/xcon
Archive: http://www.softarmor.com/pipermail/xcon

Description of Working Group:

The focus of this working group is to develop a standardized suite of
protocols for tightly-coupled multimedia conferences, where strong
security and authorization requirements are integral to the solution.
Tightly-coupled conferences have a central point of control and
authorization (known as a focus) so they can enforce specific media and
membership relationships, and provide an accurate roster of 
participants. The media mixing or combining function of a 
tightly-coupled conference need not be performed centrally, however.

The scope of this effort is intentionally more narrow than previous
attempts to standardize conferencing (e.g. centralized control), and is
intended to enable interoperability in a commercial environment which
already has a number of non-standard implementations using some of the
protocols.

Privacy, security, and authorization mechanisms are integral to the
solution generated by the working group. This includes allowing
participants to be invisible to all but the conference owner, or to be
visible but participate anonymously with respect to some or all of
the other participants.

Authorization rules allow for participants and non-participants
to have roles (ex: speaker, moderator, owner), and to be otherwise
authorized to perform membership and media manipulation for or on
behalf of other participants. In order to preserve these properties,
the protocols used will require implementation of channel security
and authentication services.

Due to the centralized architecture of the WG, XCON's mechanisms will 
place requirements on the signaling protocol used between the focus and 
the participants. At a high level, the signaling protocol must be able 
to establish, tear down, modify, and perform call control operations on
multimedia streams, including voice, video, and instant messaging, in 
both a centralized and distributed mixing architecture. SIP will be the 
reference session signaling protocol used for examples; however, none of 
the XCON solutions themselves will be signaling protocols, nor will XCON 
extend existing signaling protocols. Other signaling protocols than SIP 
may be used between the focus and participants, including non-IETF 
protocols, but the requirements and possible extensions needed for other 
signaling protocols to utilize the full functionality of the XCON 
architecture is outside the scope of XCON.

The deliverables for the group will be:
- A mechanism for membership and authorization control
- A mechanism to manipulate and describe media "mixing" or "topology" 
  for multiple media types (audio, video, text)
- A mechanism for notification of conference related events/changes (for
  example a floor change)
- A basic floor control protocol

The initial set of protocols will be developed for use in unicast media
conferences. The working group will perform a second round of work to
enhance the set of protocols as necessary for use with multicast media
after their initial publication.

The following items are specifically out-of-scope:
- Voting
- Fully distributed conferences
- Loosely-coupled conferences (no central point of control)
- Far-end device control
- Protocol used between the conference controller and the mixer(s)
- Capabilities negotiation of the mixer(s)
- Master-slave cascaded conferences

The working group will coordinate closely with the SIPPING and
MMUSIC working groups. In addition the working group will cooperate
with other groups as needed, including SIP, MSEC, AVT, and the W3C
SMIL working groups. In addition, the working group will consider
a number of existing drafts as input to the working group.

Goals and Milestones:

       Oct 2003 Submit Requirements for Membership Manipulation for
                         publication as Informational

       Oct 2003 Submit Requirements for Basic Floor Control for
                         publication as Informational

       Nov 2003 Submit Conferencing Scenarios document for publication
                         as Informational

       Nov 2003 Submit Use Cases for Media Topology Control for publication
                         as Informational

       Dec 2003 Submit Requirements for Media Topology Control for
                         publication as Informational

       Feb 2004 Submit Basic Floor Control Protocol for publication as PS

       Mar 2004 Submit Notification Event package extension for conference
                         related events for publication as PS

       May 2004 Submit Membership Manipulation Protocol for publication
                         as PS

       Jul 2004 Submit Protocol for Media Topology Control for publication
                         as PS