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'6' on line 371 looks like a reference -- Missing reference section? '1' on line 348 looks like a reference -- Missing reference section? '7' on line 375 looks like a reference -- Missing reference section? '8' on line 379 looks like a reference Summary: 6 errors (**), 0 flaws (~~), 1 warning (==), 10 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force P. Koskelainen 3 Internet Draft Nokia 4 draft-koskelainen-mmusic-floor-req-01.txt H. Schulzrinne 5 October 31, 2002 Columbia U. 6 Expires: May 2003 J. Ott 7 Universitaet Bremen 9 Requirements for Floor Control 11 STATUS OF THIS MEMO 13 This document is an Internet-Draft and is in full conformance with 14 all provisions of Section 10 of RFC2026. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six months 22 and may be updated, replaced, or obsoleted by other documents at any 23 time. It is inappropriate to use Internet-Drafts as reference 24 material or to cite them other than as "work in progress". 26 The list of current Internet-Drafts can be accessed at 27 http://www.ietf.org/ietf/1id-abstracts.txt 29 To view the list Internet-Draft Shadow Directories, see 30 http://www.ietf.org/shadow.html. 32 Abstract 34 This document defines the requirements for floor control. 36 1 Introduction 38 Multimedia conferences often contain shared resources such as the 39 right to talk, input access to a limited-bandwidth video channel, or 40 a pointer or input focus in a shared application. 42 In many cases, it is desirable to be able to control who can provide 43 input (send/write/control, depending on the application) to the 44 shared resource. 46 Floor control enables applications or users to gain safe and mutually 47 exclusive or non-exclusive input access to the shared object or 48 resource. We define a floor as the temporary permission for a 49 conference participant to access or manipulate a specific shared 50 resource or group of resources [2]. 52 Floor control is an optional feature of conferences. SIP [4] 53 conferencing applications may decide not to support this feature at 54 all. Some applications of floor control, such as write access to a 55 shared document, are useful even for "conferences" with two members, 56 while other resources, such as an audio channel, may only make floor 57 control worthwhile for larger groups. 59 Earlier work on this topic (e.g., [3], [5], [6], [2]) can serve as 60 useful input for the SIP standardization efforts. 62 In general, floor control is closely related to the management of 63 shared resources in operating systems and distributed systems. 64 Synchronization, mutual exclusion and the reader-writer problem have 65 become standard tools in those areas. However, floor control differs 66 in that it generally involves managing access by human participants, 67 with a much stronger emphasis on policies. 69 This work supports on-going SIPPING conferencing work [1], and [7]. 71 2 Conventions of This Document 73 In this document, the key words "MUST", "MUST NOT", "REQUIRED", 74 "SHALL", "SHALLNOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", 75 and "OPTIONAL" are to be interpreted as described in RFC 2119 [8]. 77 3 Definitions 79 Focus: The focus is a SIP user agent that is addressed by a 80 conference URI. The focus maintains a SIP signaling 81 relationship with each participant in the conference. The 82 focus is responsible for ensuring, in some way, that each 83 participant receives the media that make up the conference. 84 The focus also implements conference policies. The focus 85 is a logical role. 87 Floor: A floor is a set of shared resources within a conference. 88 A single conference may have multiple floors. 90 Conference members: A conference member or participant that has 91 a signaling relationship with the conference focus and 92 receives one or more of the media streams that are part of 93 the conference. 95 Conference owner: A conference owner is a privileged user who 96 defines rules for running the conference. By default, the 97 conference creator becomes the owner, but the role can be 98 delegated to another entity. Among other roles, the 99 conference owner also establishes rules for floor control, 100 by creating floors, assigning and removing floor chairs. 101 The conference owner may delegate some of these 102 responsibilities to another party. The conference owner 103 does not have to be a member in the conference. 105 Chair: A user (or an entity) who manages one floor by granting, 106 denying or revoking access privileges. The chair does not 107 have to be a member of the conference. The chair is 108 sometimes also referred to as the moderator. Different 109 floors within a conference may have different chairs. 110 Chairs may change during a conference. 112 Floor control: Floor control is a mechanism that enables 113 applications or users to gain safe and mutually exclusive 114 or non-exclusive access to the shared object or resource. 116 Floor controller: A floor controller is a logical entity that 117 manages floors. It receives requests from conference 118 participants, the conference owner and the floor chair and 119 issues protocol requests to affect conference and floor 120 status. Depending on floor policy, the floor controller may 121 ask the chair to approve decisions. 123 Floor policy: The floor policy is the set of rules and 124 attributes governing operation of the floor controller. The 125 floor policy is defined upon creation of a floor and may be 126 modified by an authorized participant. 128 4 Model 130 A floor control protocol is used to convey the floor control messages 131 among the floor chairs (moderators) of the conference, the floor 132 controller, the focus and the participants of the conference. 134 Floor control can operate at the origin of data, at a redistribution 135 point or at the destination. At the origin of data, floor control can 136 ask the sender, via signaling, to surpress the generation of data. At 137 the redistribution point, the floor controller can modify the mixing 138 matrix, so that only media streams from certain participants are 139 delivered to other participants. At the destination, floor control 140 can filter incoming media or messages, so that only floor holders can 141 affect the state of the shared resource. 143 We can also distinguish cooperative and coercive floor control. 145 Cooperative floor control relies on the cooperation of the data 146 source, while coercive floor control does not; it can function even 147 if a participant is malicious or malfunctioning. Among the three 148 locations of floor control, floor control at the redistribution point 149 and at the receiver can be made coercive, while floor control at the 150 sender is by necessity cooperative. 152 A floor is always coupled to one or more media sessions. The manner 153 of creating a media session itself is defined elsewhere. A 154 participant with appropriate privileges may create a floor by 155 defining that one or more media sessions are now floor-controlled. As 156 part of the creation of a floor, a chair needs to be appointed. (In 157 some cases, the chair is an automaton, rather than a human 158 participant.) 160 5 Integration with Conferencing 162 We assume that the ability of users to create floors is governed by 163 the conference policy. For simplicity, we assume that a chair can 164 delegate his or her responsibility to any other member of the 165 conference. 167 The conference policy and thus, indirectly, the conference owner 168 defines whether or not floor control is in use and for which 169 resources. If floor control is enabled for a particular resource or 170 set of resources, the conference policy also defines for which 171 resources the use of floor control is mandatory and for which it is 172 optional. [TBD: Not clear what mandatory and optional means.] 174 Typically, the conference owner creates a floor using a yet-to-be- 175 defined mechanism and appoints the floor chair. The conference owner 176 can remove the floor at any time (so that the resources are no longer 177 floor-controlled), change the chair or the floor parameters. 179 The chair just controls the access to the floor, according to the 180 conference policy. 182 Figure 1 depicts how floor control integrates into the overall 183 conferencing architecture. 185 6 Requirements 187 REQ-1: It MUST be possible to announce to participants that a 188 particular media session (or group of media session) is 189 floor-controlled and where requests for the floor should be 190 addressed to. 192 +------------------------+ 193 | | 194 +-------+ | +------------------+ | 195 |Floor | | | Conference Policy| | 196 |Control| --- | | Server | | 197 |Server | ------ | +------------------+ | 198 +-------+ ----- | | 199 . . . ---+-- +-------------+ | 200 . . .. | --- | Media Policy| | 201 . .. .. | | Server | | 202 . . . | +-------------+ | 203 . . .. | | 204 Floor . . .. | +---------+ +-----+ | 205 Control . .. . | |Focus | |Mixer| | 206 Protocols. . .. | +---------+ +-----+ | 207 (SUB/NOT & . . .. +-----/-----------------+ 208 controls) . . .---- / | 209 . . ----.. / | 210 . ---- ./ dialogs 211 . ---- . /. | 212 . ---- . / .. | 213 --- / .. | 214 +-------+ +-------+ . +-------+ 215 | | | | .. | | 216 | Client| | Client| .. | Client| 217 | | | | . | | 218 | | | | | | 219 | | | | | | 220 +-------+ +-------+ +-------+ 222 Figure 1: Floor control integration into Conferencing 224 SDP's "a" line offers one possible indication. 226 REQ-2: It MUST be possible to group more than one media sessions 227 together so that one floor applies to the group. 229 The SDP "fid" extension may serve this purpose. 231 REQ-3: It MUST be possible to define who is allowed to create, 232 change and remove a floor in a conference. We assume that 233 the conference owner always has this privilege and may also 234 authorize other entities, via conference policy. 236 REQ-4: A participant with appropriate privileges MUST be able to 237 create a floor with specific parameters, such as how many 238 simultaneous users are allowed to access the resource. It 239 MUST be possible to modify these parameters during the 240 lifetime of a floor. 242 REQ-5: It MUST be possible to use a chair-controlled floor 243 policy in which the floor controller notifies the floor 244 chair and waits for the chair to make a decision. This 245 enables the chair to fully control who has the floor. The 246 server MAY forward all requests immediately to chair, or it 247 may do filtering and send only occasional notifications to 248 chair. 250 REQ-6: Participants MUST be able to request (claim) a floor and 251 give additional information about the request, such as the 252 topic of the question for an audio floor. 254 REQ-7: A floor holder MUST be able to release a floor. 256 REQ-8: The chair or controller MUST be able to revoke a floor 257 from its current holder. 259 REQ-9: It MUST be possible to grant a floor to a participant. 261 REQ-10: It MUST be possible to get and set at least the 262 following floor parameters: 264 - who is floor control chair (this does not have to be the 265 conference owner); 267 - floor control policy (such as chair-controlled, first- 268 come first-served, random); 270 - the number of simultaneous floor holders. 272 REQ-11: Floor policies MAY support time limits that 273 automatically pass the floor to the next-in-line after a 274 preset time interval. 276 REQ-12: It MUST be possible for a user with appropriate 277 conference privileges to change the chair for a floor. 279 REQ-13: It MAY be possible for a user to request that a media 280 session should be floor-controlled. The requestor does not 281 necessarily become the floor chair. (For example, a 282 conference creator may designate a set of media as a latent 283 floor that automatically becomes floor controlled as soon 284 as a member requests it.) 286 REQ-14: Different floors may have different chairs. 288 REQ-15: Bandwidth and terminal limitations SHOULD be taken into 289 account in order to ensure that floor control can be 290 efficiently used in mobile environments. 292 REQ-16: Conference members and the chair MUST be able to 293 determine who has the floor and who has requested the 294 floor. 296 REQ-17: Conference members and the chair MUST be able to be 297 notified when the floorholder changes and when a new floor 298 request is being made. 300 REQ-18: It should be possible to name custom floor control 301 policies, both with local meaning only and global 302 registration. 304 REQ-19: It may be desirable to support a floor control mechanism 305 where users without specialized software can request the 306 floor. (For example, a floor control mechanism could 307 utilize specific instant messages.) 309 7 Open Issues 311 o Support multiple simultaneous chairs for one floor? 313 o Support for privacy (especially for REQ-16) 315 8 Acknowledgements 317 The authors would like to thank Xiaotao Wu, Sanjoy Sen, Jonathan 318 Rosenberg, Brian Rosen, Nermeen Ismail, Rohan Mahy, and Orit Levin 319 for their comments. 321 9 Authors' Addresses 323 Petri Koskelainen 324 Nokia 325 Visiokatu 1, 326 33720 Tampere 327 Finland 328 electronic mail: petri.koskelainen@nokia.com 329 Henning Schulzrinne 330 Dept. of Computer Science 331 Columbia University 332 1214 Amsterdam Avenue, MC 0401 333 New York, NY 10027 334 USA 335 electronic mail: hgs@cs.columbia.edu 337 Joerg Ott 338 Universitaet Bremen 339 MZH 5180 340 Bibliothekstr. 1 341 D-28359 Bremen 342 Germany 343 tel:+49-421-201-7028 344 sip:jo@tzi.org 346 10 Bibliography 348 [1] J. Rosenberg, "A Framework for Conferencing with the Session 349 Initiation Protocol, " Internet Draft, Internet Engineering Task 350 Force, Oct 2002, Work in progress. 352 [2] Dommel, H.-P., and Garcia-Luna-Aceves, J., "Floor control for 353 activity coordination in networked multimedia applications.," In 354 Proc. of 2nd Asian-Pacific Conference on Communications (APCC (Osaka, 355 Japan, June 1995). 357 [3] P. Koskelainen, H. Schulzrinne, and X. Wu, "A sip-based 358 conference control framework," in The 12nd International Workshop on 359 Network and Operating System Support for Digital Audio and Video 360 (NOSSDAV) , (Miami Beach, Florida), May 2002. 362 [4] J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. 363 Peterson, R. Sparks, M. Handley, and E. Schooler, "SIP: session 364 initiation protocol," RFC 3261, Internet Engineering Task Force, June 365 2002. 367 [5] C. Bormann, D. Kutscher, J. Ott, and D. Trossen, "Simple 368 conference control protocol service specification," Internet Draft, 369 Internet Engineering Task Force, Mar. 2001. Work in progress. 371 [6] X. Wu, P. Koskelainen, H. Schulzrinne, and C. Chen, "Use SIP and 372 SOAP for conference floor control," Internet Draft, Internet 373 Engineering Task Force, Apr. 2002. Work in progress. 375 [7] O. Levin et al. , "Requirements for tightly coupled SIP 376 conferencing," Internet Draft, Internet Engineering Task Force, July 377 2002. Work in progress. 379 [8] S. Bradner, "Key words for use in RFCs to indicate requirement 380 levels," RFC 2119, Internet Engineering Task Force, Mar. 1997. 382 Full Copyright Statement 384 Copyright (c) The Internet Society (2002). All Rights Reserved. 386 This document and translations of it may be copied and furnished to 387 others, and derivative works that comment on or otherwise explain it 388 or assist in its implementation may be prepared, copied, published 389 and distributed, in whole or in part, without restriction of any 390 kind, provided that the above copyright notice and this paragraph are 391 included on all such copies and derivative works. However, this 392 document itself may not be modified in any way, such as by removing 393 the copyright notice or references to the Internet Society or other 394 Internet organizations, except as needed for the purpose of 395 developing Internet standards in which case the procedures for 396 copyrights defined in the Internet Standards process must be 397 followed, or as required to translate it into languages other than 398 English. 400 The limited permissions granted above are perpetual and will not be 401 revoked by the Internet Society or its successors or assigns. 403 This document and the information contained herein is provided on an 404 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 405 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 406 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION 407 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 408 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 410 Table of Contents 412 1 Introduction ........................................ 1 413 2 Conventions of This Document ........................ 2 414 3 Definitions ......................................... 2 415 4 Model ............................................... 3 416 5 Integration with Conferencing ....................... 4 417 6 Requirements ........................................ 4 418 7 Open Issues ......................................... 7 419 8 Acknowledgements .................................... 7 420 9 Authors' Addresses .................................. 7 421 10 Bibliography ........................................ 8