One document matched: draft-boulton-xcon-msrp-conferencing-02.txt
Differences from draft-boulton-xcon-msrp-conferencing-01.txt
XCON Working Group C. Boulton
Internet-Draft Ubiquity Software Corporation
Expires: March 26, 2006 M. Barnes
Nortel
September 22, 2005
Centralized Conferencing (XCON) Using the Message Session Relay
Protocol (MSRP)
draft-boulton-xcon-msrp-conferencing-02
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
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 March 26, 2006.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
A Centralized Conference as defined by the XCON working group is both
signaling and protocol agnostic. The primary focus of the XCON work
has been centered on the Session Initiation Protocol for signaling
and Audio/Video for the media types. This document defines the
mechanisms, in the context of the XCON framework, required when using
the Message Session Relay Protocol (MSRP) in a Centralized Conference
Boulton & Barnes Expires March 26, 2006 [Page 1]
Internet-Draft MSRP Conferencing September 2005
(XCON).
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 3
3. Protocol and Framework Overview . . . . . . . . . . . . . . . 3
3.1. Framework operations . . . . . . . . . . . . . . . . . . . 5
4. Text Sidebar . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Private Message . . . . . . . . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
Intellectual Property and Copyright Statements . . . . . . . . . . 12
Boulton & Barnes Expires March 26, 2006 [Page 2]
Internet-Draft MSRP Conferencing September 2005
1. Introduction
A Centralized Conference as defined by the XCON working group is both
signaling and protocol agnostic. The primary focus of the XCON work
has been centered on the Session Initiation Protocol for signaling
and Audio/Video for the media types. The requirements to support
conferences of session-based instant messages, private messaging, and
sidebars are introduced in [6]. This document defines the mechanisms
and associated framework elements involved when using the Message
Session Relay Protocol(MSRP) in a Centralized Conference(XCON) in
support of those requirements.
[Editors Note: This document is still in early stages of development
and is intended to invoke discussion. It is not intended to provide
exact solutions at his stage, but rather explores a potential
approach to a solution.]
This document has been constructed in full compliance with both the
XCON Framework[2] document and the SIPPING Conference Framework [3]
document. The XCON Framework provides the data model and interfaces
to be used while the SIPPING Framework provides details of the SIP
signaling protocol operations. For the purpose of this document,
MSRP will be discussed in the context of SIP being the carrying
protocol, as defined in the core MSRP [4] specification.
2. Conventions and Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT
RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as
described in BCP 14, RFC 2119 [1] and indicate requirement levels for
compliant implementations.
3. Protocol and Framework Overview
MSRP is defined as a peer-to-peer protocol that enables a direct
connection between two compliant endpoints, unless an MSRP relay is
inserted in the MSRP signaling path. The MSRP Relay specification
[5] details the associated functionality with a relay in the
signaling path. Centralized conferencing using MSRP can be achieved
by the Conference Server appearing as an MSRP endpoint for Conference
Participants, with the Conference server distributing the messages by
relaying them to each of the conference participants.
Figure 1 provides an illustration of MSRP clients having a direct,
1:1 connection to the Conference server. The MSRP Conference Server
Boulton & Barnes Expires March 26, 2006 [Page 3]
Internet-Draft MSRP Conferencing September 2005
can be roughly categorized as a hybrid MSRP entity that combines both
MSRP client and MSRP relay functionality. An MSRP SEND sent to the
conference will arrive at the conference server and then be
replicated to all appropriate MSRP sessions.
+--------+
| MSRP |
| Client |
| |
+--------+
|
|
|
|
|
|
v
+-----------+
+--------+ | | +--------+
| MSRP | | MSRP | | MSRP |
| Client |-------------->|Conference |<--------------| Client |
| | | Server | | |
+--------+ | | +--------+
+-----------+
^
|
|
|
|
|
|
+--------+
| XCON |
| Client |
| |
+--------+
Figure 1: Client Connection
The approach in this document is to minimize the impact no the MSRP
protocol, while taking full advantage of the functionality provided
by the XCON and SIPPING Conferencing frameworks. The solution
proposal in this document, as described in Section 3.1, meets many of
the requirements identified in the requirements document for
Multiparty MSRP [6]. Some of the requirements introduce additional
Boulton & Barnes Expires March 26, 2006 [Page 4]
Internet-Draft MSRP Conferencing September 2005
concepts that are not yet fully addressed within the context of the
XCON framework or associated protocol documents, however, they are
general enough that they should be addressed. For example, the
notion of privacy and anonymity of participants is introduced in the
framework in the context of security, but no discussion of mechanism
is provided. [Editor's Note: Further elaboration of how this
solution proposal meets those requirements is likely required,
although a simple checklist in the appendix, or inline references to
those requirements (e.g. ...solution text...(REQ-GEN-10) might
suffice. ]
A basic solution for IM chat sessions, also meeting the Multiparty
MSRP requirements, is documented in [7]. The solution proposed in
that document requires extensions to the base MSRP protocol. It uses
the concept of an "MSRP switch" as the centralized component, whose
role is very similar to the MSRP Conferencing Server in this
document. The solution in [7] doesn't explicitly take advantage of
the XCON FW data model, as it primarily intends to make use of the
basic SIP conferencing framework to provide the basic chat
functionality. However, that solution approach is compatible with
the solution components described in this document, with no impact on
that basic solution proposal. One of the advantages of applying the
two solutions in concert would be a reuse of the XCON FW model for
sidebars and private conferences and manipulation of the conference
data. [Editor's Note: Ideally, discussion of this document can be
used to further the model for sidebars and private conferences within
the XCON FW document, which is currently very sketchy].
3.1. Framework operations
As mentioned in the overview, an MSRP client connecting to a
Conference server has a 1:1 relationship with the MSRP signaling
entity, each having a unique MSRP session ID (session ID's are
contained in MSRP URLs). When referring to MSRP session ID's the
document is making reference to the locally (at Conference Server)
generated Session ID that is inserted into the local Path SDP
attribute and used for MSRP session signaling identification. An
important concept in this proposal is the creation and management of
MSRP sessions. It is important that each MSRP session created, as
identified by the unique session ID, is explicitly tied to an
associated Conference, represented by the Conference Identifier (as
defined in the XCON Conference Framework [3]). This provides the
relevant association between MSRP and an XCON Conference. An example
representation is illustrated by the rows contained in Figure 2
Boulton & Barnes Expires March 26, 2006 [Page 5]
Internet-Draft MSRP Conferencing September 2005
---------------------------------------------
| Conference Identifier |
---------------------------------------------
| MSRP Session ID=8asjdhk |
| MSRP Session ID=38iuhds |
| MSRP Session ID=djiowid |
| MSRP Session ID=389hewu |
---------------------------------------------
Figure 2: Simple Session Association
The XCON Framework[3] introduces the concept of a Conference User
Identifier, which is also defined in [TODO]. When a user joins an
Conference Instance through the signaling protocol, it is allocated
an appropriate Conference User Identifer either through
authentication or system allocation. The Conference User Identifer
MUST be used in conjunction with the MSRP sessions identifier to
internally represent a participant in an Conference Instance.
Figure 2 is then expanded to look like Figure 3. Again a row in the
table representing a single entry.
-------------------------------------------------------------------
| Conference Identifier |
-------------------------------------------------------------------
| MSRP Session ID=8asjdhk | Conf User ID=839ULjj |
| MSRP Session ID=38iuhds | Conf User ID=0283hHu |
| MSRP Session ID=djiowid | Conf User ID=ncH37H |
| MSRP Session ID=389hewu | Conf User ID=pakdjjH |
-------------------------------------------------------------------
Figure 3: Advanced Session Association
A more complex session association is necessary due to potential for
a user to have multiple MSRP sessions in a single conference instance
e.g. multi-lingual conference support. The conference representation
in Figure 3 allows for such functionality when separate SIP dialogs
represent MSRP sessions. This process becomes complex when multiple
SDP MSRP media sessions (m=) are defined in a single payload. This
internal representation now needs expanding to enable a Conference
System to explicitly associate a media session (m=). This involves
including the media label, as defined in [8], to maintain the
internal conference association. An example is illustrated in
Figure 4
Boulton & Barnes Expires March 26, 2006 [Page 6]
Internet-Draft MSRP Conferencing September 2005
----------------------------------------------------------------------------
| Conference Identifier |
----------------------------------------------------------------------------
| MSRP Session ID=8asjdhk | Conf User ID=839ULjj | Label=iede3 |
| MSRP Session ID=38iuhds | Conf User ID=0283hHu | Label=8heus |
| MSRP Session ID=838unaH | Conf User ID=0283hHu | Label=3cnu7 |
| MSRP Session ID=djiowid | Conf User ID=ncH37Hs | Label=jd38J |
| MSRP Session ID=389hewu | Conf User ID=pakdj7H | Label=U83hd |
| MSRP Session ID=Ko03jdk | Conf User ID=pakdj7H | Label=ehy3h |
----------------------------------------------------------------------------
Figure 4: Advanced Session Association + Media Label
In Figure 4 Conference User Identifiers '0283hHu' and 'pakdj7H'
appear twice. The combination of multiple Conference User
Identifiers and a unique MSRP session ID enables the conference
system to clearly identify a specific MSRP instance. The
representation also includes the media label, as defined in [8],for
identification purposes. This added property, which is extracted
from the SDP media line, enables clear identification when multi SDP
media (m=) lines appear in the same SDP payload.
On issuing an MSRP SEND request to an MSRP media session that is a
member of an XCON Conference instance, the SEND request will be
replicated and forwarded, in the relevant context, to all other MSRP
media sessions that are participants of the Conference Instance.
An MSRP capable client wishing to join a conference uses standardized
XCON mechanisms for creating and joining a Conference. SIP signaling
mechanisms for creating and joining a conference are defined in
SIPPING Conference Framework [3] and non signaling specific
mechanisms are defined in the XCON Framework [2]. A client MUST
include the media label attribute defined in [8] when including
multiple MSRP sessions in the same SDP payload.
Even in the simplest Conference System, where users are allowed to
enter anonymously, the internal representation described in this
section should be observed. In this case the Conference System would
still internally create a Conference User Identifier for participant
reference purposes.
4. Text Sidebar
The Session Based Messaging Conferencing requirements document [6]
identifies the requirement (REQ-GEN-12) to set up a sidebar
conference with one or more participants of the conference.
Boulton & Barnes Expires March 26, 2006 [Page 7]
Internet-Draft MSRP Conferencing September 2005
The concept of a 'sidebar' in an XCON compliant conference system is
fully described in section 7.3 of the XCON Framework document [2].
The creation, manipulation and deletion of sidebars for MSRP based
sessions has the same principles.
[Editors note: see current sidebar proposal in the XCON FW relating
to cloning a conference object with no associated time reference.
This provides a current sub-conference.]
Creating a sidebar representation for MSRP would have internal
ramifications in a Conference System. It would involve the creation
of a cloned conference object (see editor's note above) that
associates the appropriate Conference users. This would then involve
a new session being established to convey the Sidebar information.
[Editors note: Lots more detail to insert.]
5. Private Message
[Editors note: This section needs updating to align with updates to
niemi-simple-chat.]
6. Security Considerations
As discussed in the XCON Framework, there are a wide variety of
potential attacks related to conferencing, due to the natural
involvement of multiple endpoints and the many, often user-invoked,
capabilities provided by the conferencing system. Examples of
attacks in the context of MSRP conferencing would include the
following: an endpoint attempting to receive the messages for
conferences in which it is not authorized to participate, an endpoint
attempting to disconnect other users, and theft of service, by an
endpoint, in attempting to create conferences it is not allowed to
create.
Since this solution makes use of existing protocols (e.g. MSRP,
Conference Control Protocol, SIP), it also re-uses the security
solutions for those protocols and the associated authorization
mechanisms. There are security issues associated with the
authorization to specifically perform the MSRP conferencing
capability. Since, this solution makes use of the XCON framework, it
makes use of the policy associated with the Conference Object to
ensure that only authorized entities are able to manipulate the data
to access the capabilities. This solution also makes use of the
privacy and security of the identity of a user in the conference, as
discussed in the XCON Framework.
Boulton & Barnes Expires March 26, 2006 [Page 8]
Internet-Draft MSRP Conferencing September 2005
[Editor's Note: Are there any security issues unique to MSRP
conferencing that aren't covered by based MSRP, MSRP relays or the
conferencing framework? ]
7. Acknowledgements
The authors would like to thank Miguel Garcia-Martin for his comments
on this document and discussion of the solution options.
8. References
8.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
8.2. Informative References
[2] Barnes, M., "A Framework and Data Model for Centralized
Conferencing", draft-ietf-xcon-framework-01 (work in progress),
July 2005.
[3] Rosenberg, J., "A Framework for Conferencing with the Session
Initiation Protocol",
draft-ietf-sipping-conferencing-framework-05 (work in progress),
May 2005.
[4] Campbell, B., "The Message Session Relay Protocol",
draft-ietf-simple-message-sessions-11 (work in progress),
July 2005.
[5] Jennings, C., "Relay Extensions for the Message Sessions Relay
Protocol (MSRP)", draft-ietf-simple-msrp-relays-05 (work in
progress), July 2005.
[6] Niemi, A. and M. Garcia-Martin, "Requirements for Private
Messaging in Centralized Conference Environments",
draft-garcia-xcon-private-messaging-reqs-01 (work in progress),
June 2005.
[7] Niemi, A. and M. Garcia-Martin, "Multi-party Instant Message
(IM) Sessions using the Message Session Relay Protocol (MSRP)",
draft-niemi-simple-chat-03 (work in progress), July 2005.
[8] Levin, O. and G. Camarillo, "The SDP (Session Description
Protocol) Label Attribute", draft-ietf-mmusic-sdp-media-label-01
Boulton & Barnes Expires March 26, 2006 [Page 9]
Internet-Draft MSRP Conferencing September 2005
(work in progress), January 2005.
Boulton & Barnes Expires March 26, 2006 [Page 10]
Internet-Draft MSRP Conferencing September 2005
Authors' Addresses
Chris Boulton
Ubiquity Software Corporation
Building 3
Wern Fawr Lane
St Mellons
Cardiff, South Wales CF3 5EA
Email: cboulton@ubiquitysoftware.com
Mary Barnes
Nortel
2201 Lakeside Blvd
Richardson, TX
Email: mary.barnes@nortel.com
Boulton & Barnes Expires March 26, 2006 [Page 11]
Internet-Draft MSRP Conferencing September 2005
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
Boulton & Barnes Expires March 26, 2006 [Page 12]
| PAFTECH AB 2003-2026 | 2026-04-23 17:22:12 |