Network Working Group C. Boulton
Internet-Draft Ubiquity Software Corporation
Intended status: Informational M. Barnes
Expires: April 16, 2007 Nortel
October 13, 2006
A Universal Resource Identifier (URI) for Centralized Conferencing
(XCON)
draft-boulton-xcon-uri-00
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Copyright (C) The Internet Society (2006).
Abstract
A Uniform Resource Identifier (URI) is defined as a compact string of
characters for identifying an abstract or physical resource. This
document defines a URI scheme and syntax for the conference object
identifier, as defined in "A Framework and Data Model for Centralized
Conferencing".
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. URI Mapping . . . . . . . . . . . . . . . . . . . . . . . 6
4. Conference URI Definition . . . . . . . . . . . . . . . . . . 7
5. Conference Object Identifier Distribution . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
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
A Uniform Resource Identifier (URI) is defined as a compact string of
characters for identifying an abstract or physical resource. This
document defines a URI scheme and syntax for the conference object
identifier, as defined in "A Framework and Data Model for Centralized
Conferencing" [3]
A Conference Object, defined in [3], provides the data representation
of a conference instance during its varying life-cycle stages. A
conference object is unique within a conferencing system and requires
a mechanism for identifying and associating varying components/
interfaces that construct and manipulate a conference instance. The
XCON-URI scheme defined in this document provides a unique top-level
conference object identifier that provides such functionality. The
conference object identifier can then be used by the conferencing
system and related protocols to gain access and reference a specific
conference object (for example, used by a Conference Control
Protocol). It is expected that a Conference Object may be accessed
by a number of future mechanisms. It is the intention of this
document to also provide appropriate guidelines for mapping to future
extensions.
2. Conventions and Terminology
In this document, BCP 14/RFC 2119 [1] defines the key words "MUST",
"MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL". In
addition, BCP 15 indicates requirement levels for compliant
implementations.
This document uses the terminology defined in [3] and also defines
the following additional terms:
TODO : TODO.
3. Overview
The conference object identifier can be viewed as a key to accessing
a specific conference object. It is used by the conference control
protocol as described in (TBD) to access, manipulate and delete a
conference object. A conference object identifier is provided to the
conferencing client to enable such functions to be carried out. This
can either be returned through the conference control protocol while
creating a conference object, be provided by the conference
notification service or through out-of-band mechanisms (e.g.
E-Mail).
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Editors Note: Part of the extension to the Conference Package for
XCON?
A centralized conferencing (XCON) system, as defined in the
Conference Framework [3], has potential to expose a range of
interfaces and protocols. It is also possible that future additions
to the centralized conferencing framework might place requirements to
provide further additional protocols and interfaces. A conference
object can consist and be associated with many identifiers that are
in some way related to a conference object. Good examples include
the Binary Floor Control Protocol (BFCP)[4] and call signaling
protocols, such as SIP. Each use unique identifiers to represent a
protocol instance associated with a conference object.
A conferencing system may maintain a relationship between the
conference object identifiers and the identifiers associated with
each of the complimentary centralized conferencing protocols (e.g.,
call signaling protocols, BFCP, etc.). To facilitate the maintenance
of these relationships, the conference object identifier acts as a
top level identifier within the conferencing system for the purpose
of identifying the interfaces for these other protocols. This
implicit binding provides a structured mapping of the various
protocols with the associated conference object Identifier. Figure 1
illustrates the relationship between the identifiers used for the
protocols within this framework and the general conference object
identifier.
+--------------+
| Conference |
| Object |
| Identifier |
+------+-------+
|
|
|
+-----------------+---------------+
| |
+-------+---------+ +-------+-------+
|CSP Conference ID| | BFCP 'confid' |
+-----------------+ +---------------+
Figure 1: Conference Object Mapping.
In Figure 1, the conference object identifier acts as the top level
key in the identification process. The call signaling protocols have
an associated conference user identifier, often represented in the
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form of URIs. The binary floor control protocol, as defined in [5],
defines the 'conf-id' identifier which represents a conference
instance within floor control. When created within the conferencing
system, the 'conf-id' has a 1:1 mapping to the unique conference
object Identifier. Operations associated with the conference control
protocols are directly associated with the conference object, thus
the primary identifier associated with these protocols is the
conference object identifier. The mappings between additional
protocols/interface is not strictly 1:1 and does allow for multiple
occurrences. For example, multiple call signaling protocols will
each have a representation that is implicitly linked to the top level
conference object identifier e.g. H323 and SIP URIs that represent a
conference instance. It should be noted that a conferencing system
is free to structure such relationships as required and this
information is just included as a guideline that can be used.
The following example illustrates the representation and
relationships that might occur in a typical conference instance. The
table in Figure 2 lists a typical conference instance and related
properties.
+------------------------+------------------------+------------------------+
| Conf Obj URI | CSP URI | BFCP Conf-ID |
+------------------------+------------------------+------------------------+
| xcon:Ji092i | sip:Ji092i@example.com | Ji092i |
| | tel:+44(0)2920930033 | |
| | h323:Ji092i@example.com| |
+------------------------+------------------------+------------------------+
Figure 2: Conference Table Representation
The information from Figure 2 can then be applied to the
representation introduced in Figure 1. This results in Figure 3.
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+--------------+
| Conference |
| Object |
| Identifier |
+--------------+
| xcon:Ji092i |
+------+-------+
|
|
|
+-----------------+---------------+
| |
+-----------+-----------+ +-------+-------+
| CSP Conference IDs | | BFCP 'confid' |
+-----------------------+ +---------------+
|h323:Ji092i@example.com| | Ji092i |
|tel:+44(0)2920930033 | +-------+-------+
|sip:Ji092i@example.com | |
+-----------------------+ +-------|-------+
| BFCP 'floorid |
+---------------+
| UEK78d |
| 09cnJk |
+---------------+
Figure 3: Conference Tree Representation
Further elements can be added to the tree representation in Figure 3
to enable a complete representation of a conference instance within a
conferencing system.
This style of association can be applied to any supplementary
mechanisms that are applied to the centralized conferencing model
defined in this document as long as a unique reference per conference
instance is available that can be mapped to a conference object.
3.1. URI Mapping
As mentioned in the previous section, it is possible to map an 'xcon'
URI from this specification for multiple usages. Identification of a
conference instance within related protocols can be derived from the
appropriate 'xcon' URI. It is expected that any future additions to
centralized conferencing will make use of the mappings provided in
this section.
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A basic XCON URI looks as follows:-
xcon:83Hd79qhjsd@example.com
The left hand side of the URI (to the left of the '@') represents the
unique token. This token can be used by any protocol wishing to gain
access to functionality associated with a specific conference object.
For example, when used to construct a SIP INVITE request, the token
would be used to populate the 'user' part of the SIP URI - as defined
in RFC 3261[2]. The right hand side of the URI, as with any URI,
provides domain level information ('example.com' in previous
example). So continuing the previous example, the SIP URI domain
part would be equal to this domain information. This would result in
the following SIP URI that would enable a request to be sent to the
conference instance (to join) at a conferencing system:
sip:83Hd79qhjsd@example.com
Another example would be the mapping of the previous 'xcon' URI for
the purpose of BFCP. Again, the previously described 'left side' of
the URI would be extracted and used as the 'confid' defined in [5].
The 'right side' of the URI provides the required connection
information to construct a BFCP connection. The hostname can be used
to provide either a an IP address or use DNS resolution to provide a
connection location (and optionally port). A port can be explicitly
defined if required.
[Editors Note: Describe mapping for Conference Control - TODO].
The syntax defined in Section 4 also allows additional URI parameters
to be defined. This specification does not define any parameters or
usages but future documentation MAY require additional functionality.
All unknown parameters SHOULD be ignored when used for mapping
purposes but MAY be included if specifically documented.
[Editors Note: This is currently for discussion. Strict mapping
rules will be defined based on discussion].
4. Conference URI Definition
XCON-URI = "xcon" "://" [conf-object-id "@"] hostport
*( ";" url-parameter)
; hostport as defined in RFC3261
conf-object-id = 1*( unreserved / "+" / "=" / "/" )
; unreserved as defined in RFC3986
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url-parameter = token ["=" token]
5. Conference Object Identifier Distribution
The actual distribution of conference object identifiers is
considered out of scope for this document. It is expected that they
will be delivered to clients compliant to the centralized
conferencing framework through a number of mechanisms. This could be
through the conference control mechanism, the data model and
conference package or out of band mechanisms such as E-Mail.
6. Security Considerations
Security Considerations to be included in later versions of this
document.
7. IANA Considerations
8. Acknowledgments
TODO.
9. References
9.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
9.2. Informative References
[2] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002.
[3] Barnes, M., "A Framework and Data Model for Centralized
Conferencing", draft-ietf-xcon-framework-05 (work in progress),
September 2006.
[4] Camarillo, G., "The Binary Floor Control Protocol (BFCP)",
draft-ietf-xcon-bfcp-06 (work in progress), December 2005.
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[5] Camarillo, G., "Session Description Protocol (SDP) Format for
Binary Floor Control Protocol (BFCP) Streams",
draft-ietf-mmusic-sdp-bfcp-03 (work in progress), December 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
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