Last Modified: 2003-10-20
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.
|Oct 03||Submit Requirements for Membership Manipulation for publication as Informational|
|Oct 03||Submit Requirements for Basic Floor Control for publication as Informational|
|Nov 03||Submit Conferencing Scenarios document for publication as Informational|
|Nov 03||Submit Use Cases for Media Topology Control for publication as Informational|
|Dec 03||Submit Requirements for Media Topology Control for publication as Informational|
|Feb 04||Submit Basic Floor Control Protocol for publication as PS|
|Mar 04||Submit Notification Event package extension for conference related events for publication as PS|
|May 04||Submit Membership Manipulation Protocol for publication as PS|
|Jul 04||Submit Protocol for Media Topology Control for publication|
-Adam, Could you post these notes (after reviewing) on the supplemental page and forward to the IESG. Thanks, Alan. - - - - - - Reviewed charter milestones. Noted that this is first meeting of the WG and we're already behind. Discussed draft-even-xcon-conference-scenarios-00. There were questions about adequacy of scenarios, especially regarding text media. * Cullen Jennings agreed to contribute some text on that subject. * Room polled for consensus: should we accept this draft as a WG item? Hum indicated support. Joerg Ott discussed draft-koskelainen-xcon-floor-control-req-00. There was question by Jonathan Rosenberg about relationship to focus - not covered by document. Roni Even and Rohan Mahy also asked about positioning re the conferencing framework. (There seemed to be sentiment for better positioning of this doc) Dean Willis asked if the protocol will allow selection of a particular floor - Joerg said yes. Juhe Garg raised concern with the number of protocols that conference participants must implement. Answer was that this doc is just requirements, not specification of a protocol. Nermeen Ismail asked whether participants are notified who has the floor. Answer was there is a requirement for this. Cullen Jennings asked for way for requestor to know what status is of request for floor. Marcus Brunner discussed draft-brunner-xcon-fc-issues-00. This draft asserts floor control mechanism must be independent of policy; policy is instead part of the conference application. Question by chair if this could be incorporated into the floor control requirements document. Joerg and author had discussion of fine points of this. Decided this should be taken to the mailing list. Brian Rosen expressed opinion that the requirements were verging on too much for initial work - should remove rather than add requirements. * On hum, agreed to accept the combination of these two documents as WG doc. * Room polled for consensus: should we accept the combinations of these two documents a WG item? Hum indicated support. Hisham Khartabil presented draft-koskelainen-xcon-cpcp-reqs-01. Juhe Garg requested addition of requirement to control when a conference ends. * Room polled for consensus: should we accept this draft as a WG item? Hum indicated support. Hisham also discussed draft-koskelainen-xcon-xcap-cpcp-usage-01: asked for opinions on use of XCAP for this. The people present were not prepared to commit on this. Orit Levin presented draft-levin-xcon-cpcp-00 (apparently an alternative to draft-koskelainen-xcon-xcap-cpcp-usage-01.) She had some issues with XCAP - expressed opinion it would unduly influence schema - preferred focusing on xml schema independent of transport used to manage it - open to http, sip, soap. Discussion continued on both documents. Cullen Jennings thought things don't hang together very well yet - need more work. Alan Johnston complained that he hadn't seen anything on list about it - asserted not ready to decide on one approach vs the other - need to take this to the list. Lisa Dusseault mentioned new ACL Webdav extensions. Chairs requested people to read and comment on the requirements. * Cullen Jennings, Eric Burger, and others agreed to do so. Rohan discussed draft-mahy-xcon-media-policy-control-00. It raises issue of what level of abstraction does the wg want to work at. There was very lively discussion of this, only slightly captured here. Got to question of whether the application deals with application specific roles, and they are the subjects in interaction with media policy, or whether the application must itself map its notion of role onto some non-application-specific notation of media streams, etc. Cullen Jennings thought roles of participants can change - wasn't sure if everybody on same page. Doesn't want it to be hard to figure out roles. He also doesn't know how an "application" relates to the model, but apparently it is important. Nermeen Ismail reiterated desire to make policy engine unaware of significance of particular roles. She feels "media policy" is a bad term. Eric Burger wanted something fairly high level - gave analogy - assembly language is more flexible than Java, but would prefer to use Java. Eric also said even MGCP would be preferred to the logical model proposed. Rohan and Eric debated on connections between media and conference policy. Rohan thinks there are cases where changes to role of a participant in conf policy also affect media policy. Eric says "not necessarily" - it is up to "application" to decide if both should be changed. Alan raised issue that changes to media policy must be able to be reflected back to users - need some way to reverse engineer the changes to something user meaningful. Also commented that the "application" is the user interface. Thought that the conceptual approach was better than the logical (Rohan) approach for this. Juhe Garg wanted to remove term "roles" - focus only on "permissions". Eric really didn't like this. Rohan felt use cases are needed. Nermeen wanted better requirements. Rohan then showed a strawman definition of a subconference - asserting it is a conversation. Brian Rosen then showed a couple of slides (jennings-xconMediaPolicyRan.pdf) of rebutal to Rohan's, asking what is the problem we are trying to solve. Asserted draft-mahy-xcon-media-policy-control-00 is too complicated, and doesn't address the problem directly. Its a language to describe media flow graphs, not one to control them. Not facilitating interoperable implementations. Brian proposed templates instead. Rohan was concerned with how to map templates for media control onto conference control. Brian gave an example of a mix-minus mixer. Said #input audio streams, #output audio streams (max) are bound at conf creation. This raised a lot of concerns from audience. People felt this was almost what Rohan was proposing. Rohan asserted that any proposal must address how it interacts with conf policy. And Cullen wanted to be sure it covers all the requirements. Jonathan didn't think it was necessary to solve all problems as long as there is extensibility. Media policy requirements draft by Roni Even mentioned: hasn't changed since last meeting. See everyone next time!