Transport Area P. Koskelainen Internet-Draft Nokia Expires: December 22, 2003 H. Schulzrinne Columbia University J. Ott Bremen Univ. June 23, 2003 Requirements for Floor Control draft-koskelainen-xcon-floor-control-req-00 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on December 22, 2003. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document defines the requirements for floor control in a multi-party conference environment. Koskelainen, et al. Expires December 22, 2003 [Page 1] Internet-Draft CPCP-req June 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions Used in This Document . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Integration with Conferencing . . . . . . . . . . . . . . . . 7 6. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 8 7. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 10 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 Normative References . . . . . . . . . . . . . . . . . . . . . 12 Informative References . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 13 Intellectual Property and Copyright Statements . . . . . . . . 15 Koskelainen, et al. Expires December 22, 2003 [Page 2] Internet-Draft CPCP-req June 2003 1. Introduction Conference applications often have shared resources such as the right to talk, input access to a limited-bandwidth video channel, or a pointer or input focus in a shared application. In many cases, it is desirable to be able to control who can provide input (send/write/control, depending on the application) to the shared resource. Floor control enables applications or users to gain safe and mutually exclusive or non-exclusive input access to the shared object or resource. Floor is an individual temporary access or manipulation permission for a specific shared resource (or group of resources) [7]. Floor control is an optional feature for conferencing applications. SIP [2] conferencing applications may also decide not to support this feature at all. Two-party applications may use floor control outside conferencing, although the usefulness of this kind of scenario is limited. Floor control may be used together with conference policy control protocol (CPCP) [8], or it may be used as standalone separate protocol, e.g. with SIP but without CPCP. Floor control has been studied extensively over the years, (e.g. [9], [7], [6]) therefore earlier work can be utilized here. This document can be used with other documents, such as Conferencing framework document [3]. Koskelainen, et al. Expires December 22, 2003 [Page 3] Internet-Draft CPCP-req June 2003 2. Conventions Used in This Document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119. Koskelainen, et al. Expires December 22, 2003 [Page 4] Internet-Draft CPCP-req June 2003 3. Terminology This document uses the definitions from [3]. Additional definitions: Floor: A permission to temporarily access or manipulate a specific shared resource or set of resources. Conference owner: A privileged user who controls the conference, creates floors and assigns and deassigns floor chairs. Conference owner does not have to be a member in a conference. Floor chair: A user (or an entity) who manages one floor (grants, denies or revokes a floor). Floor chair does not have to be a member in a conference. Floor control: A mechanism that enables applications or users to gain safe and mutually exclusive or non-exclusive input access to the shared object or resource. Koskelainen, et al. Expires December 22, 2003 [Page 5] Internet-Draft CPCP-req June 2003 4. Model A floor control protocol is used to convey the floor control messages among the floor chairs (moderators) of the conference, the floor control server and the participants of the conference. Centralized architecture is assumed in which all messages go via one point. The centralized conference server controls the floors at least in the signaling level. Controlling also the actual (physical) media resources (e.g. audio mixer) is highly recommended, but beyond the scope of this document. Note that the floor is a concept coupled with one or more media streams. The creation of the media session itself is defined elsewhere. A participant with appropriate privileges may create a floor by defining that existing media session(s) is now floor- controlled, and apppoint a floor chair. Koskelainen, et al. Expires December 22, 2003 [Page 6] Internet-Draft CPCP-req June 2003 5. Integration with Conferencing Floor control itself does not support privileges such as handing over chair privileges to another users (or taking them away). Instead, some external mechanism, such as conference management (e.g. CPCP or internal web-interface for policy manipulation) is used for that. Conference policy (and conference owner or creator) decides whether floor control is in use or not. Actual conference media enforcing (e.g. controlling audio bridge) are beyond the scope of this document. Floor control itself does not define media enforcing. It is also conference policy about what media streams can be in a conference, and which ones are floor controlled. Typically, conference owner creates the floor(s) using floor control protocol (or some other mechanism) and appoints the floor chair. Conference owner can remove the floor anytime (so that media is not floor controlled anymore), or change floor chair or floor parameters. Floor chair just controls the access to the floor(s), according to the conference policy. Floor control server is a separate logical entity, typically co-located with focus and conference policy server. Therefore, communication between floor control server and other conferencing entities (except with the client) does not need to be defined. Koskelainen, et al. Expires December 22, 2003 [Page 7] Internet-Draft CPCP-req June 2003 6. Requirements REQ-1: It MUST be possible to announce to participants that a particular media session (or group of media session) is floor-controlled and where requests for the floor should be addressed to. (This is a requirement for session protocol, i.e. SIP. SDP's "a" line offers one possible indication.) REQ-2: It MUST be possible to group more than one media sessions together so that one floor applies to the group. (The SDP "fid" extension may serve this purpose.) REQ-3: It MUST be possible to define who is allowed to create, change and remove a floor in a conference. We assume that the conference owner always has this privilege and may also authorize other entities, via conference policy. REQ-4: A participant with appropriate privileges MUST be able to create a floor with specific parameters, such as how many simultaneous users are allowed to access the resource. It MUST be possible to modify these parameters during the lifetime of a floor and terminate a floor. REQ-5: It MUST be possible to use a chair-controlled floor policy in which the floor controller notifies the floor chair and waits for the chair to make a decision. This enables the chair to fully control who has the floor. The server MAY forward all requests immediately to chair, or it may do filtering and send only occasional notifications to the chair. REQ-6: Participants MUST be able to request (claim) a floor and give additional information about the request, such as the topic of the question for an audio floor. REQ-7: A floor holder MUST be able to release a floor. REQ-8: The chair or controller MUST be able to revoke a floor from its current holder. REQ-9: It MUST be possible to grant a floor to a participant. REQ-10: It MUST be possible to get and set at least the following floor parameters: - who is floor control chair (this does not have to be the conference Koskelainen, et al. Expires December 22, 2003 [Page 8] Internet-Draft CPCP-req June 2003 owner); - what is the floor control policy (such as chair-controlled, first- come first-served, random); - the number of simultaneous floor holders. REQ-11: Floor policies MAY support time limits that automatically pass the floor to the next-in-line after a preset time interval. REQ-12: It MUST be possible for a user with appropriate conference privileges to change the chair for a floor. REQ-13: It MAY be possible for a user to request that a media session should be floor-controlled. The requestor does not necessarily become the floor chair. (For example, a conference creator may designate a set of media as a latent floor that automatically becomes floor controlled as soon as a member requests it.) REQ-14: Different floors may have different chairs. OPEN ISSUE: Is this needed? REQ-15: Bandwidth and terminal limitations SHOULD be taken into account in order to ensure that floor control can be efficiently used in mobile environments. REQ-16: Conference members and the chair MUST have the capability to learn who has the floor and who has requested the floor. (Note: Conference policy may prevent members seeing this.) REQ-17: It MUST be possible to notify conference members and chair about the floorholder changes and when a new floor request is being made. (Note: Conference policy may prevent members seeing this.) REQ-18: It may be desirable to support a floor control mechanism where users without specialized software can request the floor. (For example, a floor control mechanism could utilize specific instant messages.) Koskelainen, et al. Expires December 22, 2003 [Page 9] Internet-Draft CPCP-req June 2003 7. Open Issues - separation of floor creation and floor granting - support for privacy (esp. REQ-16) Koskelainen, et al. Expires December 22, 2003 [Page 10] Internet-Draft CPCP-req June 2003 8. Acknowledgements The author would like to thank IETF conferencing design team and Xiaotao Wu, Sanjoy Sen, Eric Burger, Brian Rosen, and Nermeen Ismail for their feedback. Koskelainen, et al. Expires December 22, 2003 [Page 11] Internet-Draft CPCP-req June 2003 Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, BCD 14, March 1997. [2] Rosenberg et al., J., "SIP: Session Initiation Protocol", RFC 3261, June 2002. [3] Rosenberg, J., "A Framework for Conferencing with the Session Initiation Protocol", draft-rosenberg-sipping-conferencing-framework-01 (work in progress), February 2003. Koskelainen, et al. Expires December 22, 2003 [Page 12] Internet-Draft CPCP-req June 2003 Informative References [4] Koskelainen, P., Schulzrinne, H. and X. Wu, "Additional Requirements to Conferencing", October 2002. [5] Wu, X., Schulzrinne, H. and P. Koskelainen, "Use of SIP and SOAP for conference floor control", January 2003. [6] Koskelainen, P., Schulzrinne, H. and X. Wu, "A sip-based conference control framework", Nossdav'2002 Miami Beach, May 2002. [7] Dommel, H. and J. Garcia-Luna-Aceves, "Floor control for activity coordination in networked multimedia applications", Proc. of 2nd Asian-pacific Conference on Communications APPC, Osaka Japan, June 1995. [8] Koskelainen, P. and H. Khartabil, "An Extensible Markup Language (XML) Configuration Access Protocol (XCAP) Usage for Conference Policy Manipulation", draft-koskelainen-xcon-xcap-cpcp-usage-00 (work in progress), June 2003. [9] Borman, C., Kutchner, D., Ott, J. and D. Trossen, "Simple conference control protocol service specification", draft-ietf-mmusic-sccp-00 (work in progress), March 2001. Authors' Addresses Petri Koskelainen Nokia P.O. Box 100 (Visiokatu 1) Tampere FIN-33721 Finland EMail: petri.koskelainen@nokia.com Henning Schulzrinne Columbia University 1214 Amsterdam Avenue New York 10027 USA EMail: hgs@columbia.edu Koskelainen, et al. Expires December 22, 2003 [Page 13] Internet-Draft CPCP-req June 2003 Joerg Ott Bremen Univ. Germany EMail: jo@tzi.uni-bremen.de Koskelainen, et al. 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