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

 Charter
 Last Modified: 2009-11-12

 Current Status: Active Working Group

 Chair(s):
     Alan Johnston  <alan.b.johnston@gmail.com>
     Richard Barnes  <rbarnes@bbn.com>

 Real-time Applications and Infrastructure Area Director(s):
     Robert Sparks  <rjsparks@nostrum.com>
     Cullen Jennings  <fluffy@cisco.com>

 Real-time Applications and Infrastructure Area Advisor:
     Robert Sparks  <rjsparks@nostrum.com>

 Mailing Lists: 
     General Discussion:xcon@ietf.org
     To Subscribe:      https://www.ietf.org/mailman/listinfo/xcon
     Archive:           http://www.ietf.org/mail-archive/web/xcon/index.html

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:

   Done         Submit Requirements for Basic Floor Control for publication as 
                Informational 

   Done         Submit Conferencing Scenarios document for publication as 
                Informational 

   Done         Submit Basic Floor Control Protocol for publication as PS 

   Done         Submit Framework for publication as PS 

   Done         Submit Event Notification Package for publication as PS 

   Aug 2009       Submit Conference Data Model for publication as PS 

   Aug 2009       Submit Conference Control Protocol for publication as PS 

   Apr 2010       Submit Conferencing Call Flows Document for publication as 
                Informational 


 Internet-Drafts:

Posted Revised         I-D Title   <Filename>
------ ------- --------------------------------------------
Apr 2006 Nov 2009   <draft-ietf-xcon-common-data-model-14.txt>
                Conference Information Data Model for Centralized Conferencing 
                (XCON) 

Feb 2008 Sep 2008   <draft-ietf-xcon-event-package-01.txt>
                Conference Event Package Data Format Extension for Centralized 
                Conferencing (XCON) 

Jun 2008 Dec 2009   <draft-ietf-xcon-ccmp-05.txt>
                Centralized Conferencing Manipulation Protocol 

Jul 2009 Dec 2009   <draft-ietf-xcon-examples-02.txt>
                Centralized Conferencing Manipulation Protocol (CCMP) Call Flow 
                Examples 

 Request For Comments:

  RFC   Stat Published     Title
------- -- ----------- ------------------------------------
RFC4376 I    Feb 2006    Requirements for Floor Control Protocol 

RFC4597 I    Aug 2006    Conferencing Scenarios 

RFC4582 PS   Nov 2006    The Binary Floor Control Protocol (BFCP) 

RFC5018 PS   Sep 2007    Connection Establishment in the Binary Floor Control 
                       Protocol (BFCP) 

RFC5239 PS   Jun 2008    A Framework for Centralized Conferencing