XCON WG P. Koskelainen
Internet-Draft H. Khartabil
Expires: July 29, 2004 Nokia
January 29, 2004
Requirements for Conference Policy Control Protocol
draft-ietf-xcon-cpcp-reqs-02
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Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
The conference policy server allows clients to manipulate and
interact with the conference policy. One mechanism to manipulate the
policy is to use conference policy control protocol (CPCP). This
document gives the requirements for CPCP.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Integration with Floor Control . . . . . . . . . . . . . . . . 6
5. Conference Policy Data Model . . . . . . . . . . . . . . . . . 7
6. CPCP Requirements . . . . . . . . . . . . . . . . . . . . . . 8
6.1 Conference creation, termination and joining . . . . . . . . . 8
6.2 Manipulating general conference attributes . . . . . . . . . . 8
6.3 Authentication and Security . . . . . . . . . . . . . . . . . 9
6.4 Application and media manipulation . . . . . . . . . . . . . . 9
6.5 ACL manipulation . . . . . . . . . . . . . . . . . . . . . . . 9
6.6 Floor control . . . . . . . . . . . . . . . . . . . . . . . . 10
6.7 Inviting and ejecting users . . . . . . . . . . . . . . . . . 11
6.8 User Privileges . . . . . . . . . . . . . . . . . . . . . . . 11
6.9 General Protocol Requirements . . . . . . . . . . . . . . . . 12
7. Changes since draft-ietf-xcon-cpcp-reqs-01 . . . . . . . . . . 13
8. Changes since draft-ietf-xcon-cpcp-reqs-00 . . . . . . . . . . 14
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15
Normative References . . . . . . . . . . . . . . . . . . . . . 16
Informative References . . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 17
Intellectual Property and Copyright Statements . . . . . . . . 18
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1. Introduction
The conferencing framework document [3] describes the overall
architecture, terminology, and protocol components needed for multi-
party conferencing. It defines a logical function called a conference
policy server (CPS) which can store and manipulate rules associated
with participation in a conference. These rules include directives
on the lifespan of the conference, who can and cannot join the
conference, definitions of roles available in the conference and the
responsibilities associated with those roles.
The conference policy control protocol (CPCP) is a client-server
protocol that can be used by users to manipulate the rules associated
with the conference.
The conference policy is represented by a URI. There is a unique
conference policy for each conference. The conference policy URI
points to a conference policy server which can manipulate that
conference policy.
Conferencing framework describes also conference notification service
that is a logical function provided by the focus. It means that the
focus can act as a notifier, accepting subscriptions to the
conference state.
Note that CPCP is not the only mechanism to manipulate conference
policy, but other mechanisms exists as well, such as a Web interface.
This document can be used with other documents, such as Conferencing
framework document [3]. Moreover, [5] and [7] give useful background
information about conferencing and floor control.
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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.
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3. Terminology
This document uses the definitions from [3].
Additional definitions:
ACL
Access control list (ACL) defines users who can join a
conference. Users may have allow, blocked or pending status in
the list. Each conference has its own ACL.
Moderator
A special (privileged) role for a user that is allowed to
manipulate conference policy and override policy decisions made
by other users.
Floor control
Floor control is a mechanism that enables applications or users
to gain safe and mutually exclusive or non-exclusive access to
the shared object or resource in a conference.
Privilege
A privilege is a right to perform a manipulation operation in a
conference. It is user permission such as the right to modify
ACL or expel users.
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4. Integration with Floor Control
Floor control is an optional feature often used by conferencing
applications. It enables applications or users to gain safe and
mutually exclusive or non-exclusive input access to a shared object
or resource. We define a floor as the temporary permission for a
conference participant to access or manipulate a specific shared
resource or group of resources.
We assume that the ability of users to create floors is governed by
the conference policy. Conference user may use floor control protocol
(see e.g. [6]) or some other mechanism to request floors.
The conference policy also defines the floor control policy (e.g.
moderator-controlled or server grants the floor randomly) and the
floor moderator, if the floor policy is moderator-controlled.
The privileged user in a conference (such as the creator) can remove
the floor at any time by modifying the conference policy (so that the
resources are no longer floor- controlled), or change the floor
chair.
The floor moderator just controls the access to the floor, according
to the floor policy, defined by the conference policy at a time when
the floor is created.
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5. Conference Policy Data Model
Conference policy data is relatively static. It is not updated
frequently as e.g. participant list is not part of the conference
policy. Users with sufficient privileges are able to manipulate
conference policy. For example, a user with sufficient privileges
may manipulate conference's access control list by adding a user into
the ACL allowed list.
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6. CPCP Requirements
This section describes requirements for the conference policy control
protocol (CPCP).
6.1 Conference creation, termination and joining
REQ-A1: It MUST be possible to create a new conference addressable by
a URI.
REQ-A2: It MUST be possible to associate policy attributes to a
conference URI.
REQ-A3: It MUST be possible to reserve a conference URI for future
use with or without associating policy attributes to it.
REQ-A4: It MUST be possible for a privileged user to read conference
policy for a given conference URI, during and before joining the
conference.
REQ-A5: It MUST be possible to delete existing conference policy.
This results in terminating the conference, deleting conference URI
and releasing all resources associated with it.
REQ-A6: It MUST be possible to anonymously participate in a
conference.
REQ-A7: It MUST NOT be possible for a user to authenticate himself as
an anonymous user.
Note: A conference focus must not accept users to authenticate
themselves with a username "anonymous" (like in Digest
authentication).
REQ-A8: It MUST be possible to assign multiple conference URIs to a
conference, one for each session signaling protocol scheme that the
conference server supports.
REQ-A9: It MUST be possible to define the start and stop times for
the conference.
6.2 Manipulating general conference attributes
REQ-B1: It MUST be possible to set, modify and delete a conference
Subject.
REQ-B2: It MUST be possible to set, modify and delete conference URI
display name.
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REQ-B3: It MUST be possible to set, modify and delete conference
creator information (as is seen e.g. in SDP o line).
REQ-B4: It MUST be possible to set, modify and delete conference URI
link for more information (as used e.g. in SDP u line).
REQ-B5: It MUST be possible to set, modify and delete conference host
contact information (as used e.g. in SDP e and p lines).
REQ-B6: It MUST be possible to set, modify and delete short
conference session description (as used e.g. in SDP i line). This
can be per session or per media.
REQ-B7: It MUST be possible to set, modify and delete the parameter
for max number of conference participants. This defines the maximum
number of participants present at the same time.
REQ-B8: It MUST be possible to hide conference related information
from non-privileged users.
Note: This defines the level of visibility of the basic conference
information (e.g. visible only to participants). This feature may be
needed e.g. in search operations.
REQ-B9: It MUST be possible to set, modify and delete conference
Keywords.
Note: (This may be useful e.g. for search engines).
6.3 Authentication and Security
REQ-C1: It MUST be possible to define appropriate authentication for
joining users.
6.4 Application and media manipulation
REQ-D1: It MAY be possible to define media policy within conference
policy.
REQ-D2: It MUST be possible to define the media types for the
conference.
Note: This means MIME main types, such as audio and video. The
conference server can use this information e.g when placing m lines
in SIP/SDP dial-outs.
6.5 ACL manipulation
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REQ-E1: It MUST be possible to define which users are not allowed to
join the conference.
REQ-E2: It MUST be possible to define which users are not allowed to
join a conference in a single operation.
REQ-E3: It MUST be possible to define which users are allowed to join
the conference.
REQ-E4: It MUST be possible to define which users are allowed to join
a conference in a single operation.
REQ-E5: It MUST be possible to define which users are places into
pending list, waiting for further approval e.g. from moderator.
REQ-E6: It MUST be possible to use wildcards in ACL (such as
sip:*@example.com is allowed to join).
REQ-E7: ACL conflicts MUST be solved in a well-defined way (e.g. what
if user appears both in blocked list and in allowed list) e.g. by
mandating the order in which ACL definitions are evaluated (e.g. most
specific expression first).
REQ-E8: Conference MUST have default policy for those users that no
matching rule is found in ACL.
REQ-E9: It MUST be possible to allow and disallow anonymous
membership in a conference.
6.6 Floor control
REQ-F1: It MUST be possible to define whether floor control is in use
or not.
REQ-F2: It MUST be possible to define the algorithm to be used in
granting the floor.
Note: Example algorithms might be e.g. moderator-controlled, FCFS,
random.
REQ-F3: It MUST be possible to define how many users can have the
floor at the same time.
REQ-F4: It MUST be possible to have one floor for one or more media
types.
REQ-F5: It MUST be possible to have multiple floors in a conference.
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REQ-F6: It MUST be possible to define whether a floor is
moderator-controlled or not.
REQ-F7: If the floor is moderator-controlled, it MUST be possible to
assign and replace the floor moderator.
6.7 Inviting and ejecting users
REQ-G1: It MUST be possible to define a dial-out list of users that
the conference focus invites.
REQ-G2: It MUST be possible to set a dial-out list in a single
operation.
REQ-G3: It MUST be possible to expel users from a currently occurring
conference.
REQ-G4: It MUST be possible to expel many users in a single
operation.
REQ-G5: It MUST be possible to define list of users who the focus
should refer to the conference (so that the referred users will dial
in the conference).
REQ-G6: It MUST be possible to set the list of referred users in a
single operation.
6.8 User Privileges
REQ-H1: It MUST be possible to give a privilege to a user.
REQ-H2: It MUST be possible to give privileges to many users in a
single operation.
REQ-H3: It MUST be possible to remove a privilege from a user.
REQ-H4: It MUST be possible to remove privileges from many users in a
single operation.
REQ-H5: It MUST be possible to define users who are allowed to
subscribe to the conference event package [4]
REQ-H6: It MUST be only be possible for a users with sufficient
privileges to manipulate conference policy.
Note: For example, the creator of the conference may manipulate
conference policy.
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6.9 General Protocol Requirements
REQ-CP-1: Protocol behaviour: CPCP protocol MUST be a reliable
client-server protocol. Hence, it MUST have a positive response
indicating that the request has been received, or error response if
an error has occurred.
REQ-CP-2: Manipulations of the policy collection MUST exhibit the
ACID property; that is, they MUST be atomic, be consistent, durable,
and operate independently.
REQ-CP-3: It MAY be possible for the client to batch multiple
operations (such as add a user to ACL blocked list, or remove a user
from ACL allowed list) into a single request that is processed
atomically.
REQ-CP-4: It MUST be possible for the server to authenticate the
client.
REQ-CP-5: It MUST be possible for the client to authenticate the
server.
REQ-CP-6: It MUST be possible for message integrity to be ensured
between the client and the server.
REQ-CP-7: It MUST be possible for privacy to be ensured between the
client and server.
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7. Changes since draft-ietf-xcon-cpcp-reqs-01
- time definition changed: only start/stop times required
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8. Changes since draft-ietf-xcon-cpcp-reqs-00
- floor control aligned with floor control requirements document
- removed the concept of hidden user
- anonymous membership modified
- removed "inactive"
- added media type requirement (e.g. audio, video)
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9. Acknowledgements
The authors would like to thank Eric Burger, Keith Drage, Brian
Rosen, Xiaotao Wu, Henning Schulzrinne, Simo Veikkolainen and IETF
conferencing design team for their feedback.
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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.
[4] Rosenberg, J., "A Session Initiation Protocol (SIP) Event
Package for Conference State",
draft-ietf-sipping-conference-package-01 (work in progress),
June 2003.
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Informative References
[5] Koskelainen, P., Schulzrinne, H. and X. Wu, "Additional
Requirements to Conferencing", October 2002.
[6] Wu, X., Schulzrinne, H. and P. Koskelainen, "Use of SIP and SOAP
for conference floor control", January 2003.
[7] Koskelainen, P., Schulzrinne, H. and X. Wu, "A sip-based
conference control framework", Nossdav'2002 Miami Beach, May
2002.
Authors' Addresses
Petri Koskelainen
Nokia
P.O. Box 100 (Visiokatu 1)
Tampere FIN-33721
Finland
EMail: petri.koskelainen@nokia.com
Hisham Khartabil
Nokia
P.O. Box 321
Helsinki FIN-00045
Finland
EMail: hisham.khartabil@nokia.com
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