XCON Working Group C. Boulton
Internet-Draft Avaya
Intended status: Standards Track M. Barnes
Expires: February 21, 2009 Nortel
August 20, 2008
An XCON Client Conference Control Package for the Media Control Channel
Framework
draft-boulton-xcon-conference-control-package-03
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Abstract
The Centralized Conferencing framework defines a model whereby client
initiated interactions are required for creation, deletion,
manipulation and querying the state of a of conference. This
document defines a Media Control Channel Package for XCON client
initiated Conference Control. The Package is based on the Media
Control Channel Framework, which is also used for media server
control, thus optimizing the implementation for some entities
participating in an XCON system.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Control Package Detail . . . . . . . . . . . . . . . . . . . . 6
5.1. Control Package Name . . . . . . . . . . . . . . . . . . . 6
5.2. Framework Message Usage . . . . . . . . . . . . . . . . . 6
5.3. Common XML Support . . . . . . . . . . . . . . . . . . . . 6
5.4. Control Message Bodies . . . . . . . . . . . . . . . . . . 7
5.5. REPORT Message Bodies . . . . . . . . . . . . . . . . . . 7
5.6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . . . 10
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1. Introduction
As part of the Centralized Conferencing (XCON) work group in the IETF
a Data Model[I-D.ietf-xcon-common-data-model] has been created for
the purpose of modeling conference based services in a standard way.
The XCON group also requires a standards based mechanism that will
enable third party conference clients participating to interoperate
with conference servers and manipulate conference parameters.
The Media Control (MEDIACTRL) Work Group within the IETF has the
explicit goal of creating an architecture and framework for
controlling Media Servers. As part of this work a Control Channel
Framework[I-D.boulton-sip-control-framework] has been created that is
based on the Session Initiation protocol (SIP). It uses SIP to
setup, maintain and terminate a reliable control channel for the
purpose of exchanging control based interactions. The Control
Framework provides an extension template for creating extensions that
specify the semantic detail associated with the operations. The
extension documents are known as Control Packages and an example is
the 'Basic IVR Control Package'[I-D.boulton-ivr-control-package].
This document will specify a Control Package for Conference Control
by participating clients using the SIP Control Framework.
The Media Control Channel Framework provides the ideal mechanism for
reliably exchanging control messages between a conference client and
server. It provides inherent properties such as:
o Reliable delivery of control messages.
o Lightweight Protocol Data Units (PDU).
o Linked asynchronous transactional mechanism.
o Asynchronous event mechanism.
The SIP Control Framework uses SIP as its overlying rendezvous
mechanism. This provides all the inherent benefits like:
o SIP Service Location - Use SIP Proxies or Back-to-Back User Agents
for discovering Control Servers..
o SIP Security Mechanisms - Leverage established security mechanisms
such as Transport Layer Security (TLS) and Client Authentication.
o Connection Maintenance - The ability to re-negotiate a connection,
ensure it is active, audit parameters, and so forth.
o Agnostic - Allows for ease of extension.
Not only is the Media Control Channel Framework an ideal mechanism
for controlling conference instances by participating clients, it
also provides the property of re-use by conferencing systems of
functionality implemented for controlling Media Servers etc. This
includes re-using the SIP stack for control channel setup as well as
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the Control Channel Framework stack for receiving/sending the PDUs
for multiple control packages in an XCON conference system.
It should be noted that this mechanism is a complementary technology
to that specified in the document 'A Centralized Conferencing
Manipulation Protocol (CCMP)'[I-D.barnes-xcon-ccmp]. In fact this
specification simply re-uses the SOAP bindings created in that
document for a consistent view (so just the transport mechanism is
different). While the mechanism defined in [I-D.barnes-xcon-ccmp] is
ideal for certain network deployments (for example Service Orientated
Architectures), it is important to offer an alternative access method
for clients with non SOA based technologies. Using the SIP Control
Framework provides consistency across both XCON and MEDIACTRL work
groups.
2. Conventions
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 [RFC2119] and indicate requirement
levels for compliant implementations.
3. Terminology
This document reuses the terminology defined in the framework and
data model for centralized conferencing [I-D.ietf-xcon-framework].
In addition, the following acronyms and terms are used in this
document:
SOAP: Simple Object Access Protocol.
WSDL: Web Services Description Language. WSDL is an XML format for
describing network services as a set of endpoints operating on
messages containing either document-oriented or procedure-oriented
information.
4. Overview
The use of the Media Control Channel Framework offers an ideal
mechanism for creating, deleting and manipulating XCON conference
instances by participating clients. As the Control Channel Framework
is a generic mechanism, this section provides non-normative detail
showing how the Control Channel Framework can be applied to this
particular use-case. In [I-D.ietf-xcon-framework], two distinct
roles are defined - A 'Control Client' and a 'Control Server'. Such
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roles are interchangeable between entities within a session depending
on package requirements. A simple diagram is illustrated in Figure 1
+--------------SIP Traffic--------------+
| |
v v
+-----+ +--+--+
| SIP | | SIP |
|Stack| |Stack|
+---+-----+---+ +---+-----+---+
| Control | | Control |
| Client |<----Control Channel---->| Server |
+-------------+ +-------------+
Figure 1: Basic Architecture
The XCON Conference Control package will cast a participating XCON
compliant User Agent that wishes to control a conference instance as
a 'Control Client' as defined in the SIP Control Framework. It will
have permission to generate and issue commands in CONTROL messages as
defined in Section 5.2 of this document. It will also have the
ability to receive responses to Conference Package CONTROL requests
that are contained in either appropriate responses or subsequent
REPORT messages, also specified in Section 5.2. The specific format
of the conference control messages and responses are defined in
Section 5.4 and Section 5.5. They re-use the format specified in
CCMP[I-D.barnes-xcon-ccmp]. This provides a common binding set with
alternative access mechanism depending on client requirements. The
previous diagram can be updated as illustrated in Figure 2.
+--------------SIP Traffic--------------+
| |
v v
+-----+ +--+--+
| SIP | | SIP |
|Stack| |Stack|
+---+-----+---+ +---+-----+---+
| XCON | | XCON |
| Control | | Conference |
| Client |<----Control Channel---->| System |
+-------------+ +-------------+
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Figure 2: Conference Control Architecture
Editor's Note: The Overview section will be expanded in later
versions of the document.
5. Control Package Detail
The Media Control Channel Framework defines rules that Control
Package extensions must provide mandatory information as described in
section 10 of [I-D.boulton-sip-control-framework]. This section
fulfills the obligation.
5.1. Control Package Name
The SIP Control Framework requires a Control Package definition to
specify and register a unique package name. The name and version of
this Control Package is "xcon-conf-control/1.0".
5.2. Framework Message Usage
The Conference Control package uses the SOAP WSDL
[W3C.CR-wsdl20-20051215] defined in CCMP[I-D.barnes-xcon-ccmp]. To
maintain the consistency with the design of the WSDL the SIP Control
Framework messages will be applied in a similar manner. The CONTROL
message will be used to contain requests that enable conference
manipulation - as specified in Section 5.4 and can only travel from
the client to a Conferencing System. Responses, as specified in
Section 5.5, can only travel from the Conferencing System to an
expectant client. Depending on the time it takes to process the
request (as specified in [I-D.boulton-sip-control-framework]),
responses can either be contained in a Control Framework 200 response
or subsequent REPORT method.
5.3. Common XML Support
The Control Framework requires a Control Package definition to
specify if the attributes for media dialog or conference references
are required.
This package requires that the XML Schema in Section 16.1 of
[I-D.boulton-sip-control-framework] MUST NOT be supported for media
dialogs and conferences.
EDITOR'S NOTE: This document could make use of the Conf common schema
TBD.
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5.4. Control Message Bodies
A valid CONTROL body message MUST conform to the WSDL defined in
[I-D.barnes-xcon-ccmp]. To be precise, the CONTROL message body MUST
comply only to the 'input' element of the WSDL portType
(CCMPPortType).
5.5. REPORT Message Bodies
A valid CONTROL body message MUST conform to the WSDL defined in
[I-D.barnes-xcon-ccmp]. To be precise, the REPORT message body MUST
comply only to the 'output' element of the WSDL portType
(CCMPPortType).
5.6. Examples
TODO
6. IANA Considerations
TODO
7. Security Considerations
Access to conference control functionality needs to be tightly
controlled to avoid attackers disrupting conferences, adding
themselves to conferences or engaging in theft of services.
The Framework for Centralized Conferencing [I-D.ietf-xcon-framework]
specifies that the protocols used for manipulation and retrieval of
confidential information MUST support a confidentiality and integrity
mechanism. To support the confidentiality and integrity
requirements, all conference control information included in the
package defined in this document SHOULD be carried over TLS.
Editor's Note: once the security requirements for the control
packages are further specified in the Control Framework for SIP
[I-D.boulton-sip-control-framework] additional information may be
added to this section.
There are also security issues associated with the authorization to
perform actions on the conferencing system to invoke specific
capabilities. Implementers SHOULD deploy standard SOAP
authentication and authorization mechanisms to ensure that only
authorized entities are able to manipulate the data.
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8. Acknowledgments
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[W3C.CR-wsdl20-20051215]
Chinnici, R., Moreau, J., Ryman, A., and S. Weerawarana,
"Web Services Description Language (WSDL) Version 2.0 Part
1: Core Language", W3C CR CR-wsdl20-20051215,
December 2005.
[W3C.REC-soap12-part1-20030624]
Hadley, M., Gudgin, M., Nielsen, H., Mendelsohn, N., and
J. Moreau, "SOAP Version 1.2 Part 1: Messaging Framework",
World Wide Web Consortium FirstEdition REC-soap12-part1-
20030624, June 2003,
<http://www.w3.org/TR/2003/REC-soap12-part1-20030624>.
[W3C.REC-soap12-part2-20030624]
Mendelsohn, N., Moreau, J., Nielsen, H., Hadley, M., and
M. Gudgin, "SOAP Version 1.2 Part 2: Adjuncts", World Wide
Web Consortium FirstEdition REC-soap12-part2-20030624,
June 2003,
<http://www.w3.org/TR/2003/REC-soap12-part2-20030624>.
9.2. Informative References
[I-D.ietf-xcon-common-data-model]
Novo, O., Camarillo, G., Morgan, D., and R. Even,
"Conference Information Data Model for Centralized
Conferencing (XCON)", draft-ietf-xcon-common-data-model-11
(work in progress), June 2008.
[I-D.ietf-xcon-framework]
Barnes, M., Boulton, C., and O. Levin, "A Framework for
Centralized Conferencing", draft-ietf-xcon-framework-11
(work in progress), April 2008.
[I-D.boulton-sip-control-framework]
Boulton, C., "A Control Framework for the Session
Initiation Protocol (SIP)",
draft-boulton-sip-control-framework-05 (work in progress),
February 2007.
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[I-D.boulton-ivr-control-package]
Boulton, C., Melanchuk, T., and S. McGlashan, "A Basic
Interactive Voice Response (IVR) Control Package for the
Media Control Channel Framework",
draft-boulton-ivr-control-package-06 (work in progress),
February 2008.
[I-D.barnes-xcon-ccmp]
Barnes, M., Boulton, C., and H. Schulzrinne, "Centralized
Conferencing Manipulation Protocol",
draft-barnes-xcon-ccmp-04 (work in progress),
February 2008.
Authors' Addresses
Chris Boulton
Avaya
Building 3
Wern Fawr Lane
St Mellons
Cardiff, South Wales CF3 5EA
Email: cboulton@avaya.com
Mary Barnes
Nortel
2380 Performance Drive
Richardson, TX
Email: mary.barnes@nortel.com
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