Internet DRAFT - draft-levin-xcon-conference-package-ext
draft-levin-xcon-conference-package-ext
XCON O. Levin
Internet-Draft Microsoft Corporation
Expires: April 20, 2006 October 17, 2005
Extensions to the Session Initiation Protocol (SIP) Event Package for
Conference State
draft-levin-xcon-conference-package-ext-00
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document introduces global elements into the SIP Conference
Event Package XML schema to make the conference objects and sub-
objects easily accessible by schemas external to the event package,
such as the XCON conference control protocols. This document also
defines the way to introduce XCON extensions into the SIP Conference
Event Package in a backwards compatible manner. This document also
defines a set of extensions to the SIP Conference Event Package XML
schema being used in the XCON conferencing architecture.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Global Objects . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Conference Event Package Schema Extensibility . . . . . . . . 4
5. XCON Extensions to Conference Event Package Schema . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7.1. URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:xcon-conference-info . . . . . . . 9
7.2. XML Schema Registration . . . . . . . . . . . . . . . . . 9
7.3. URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:conference-info-separator . . . . . 9
7.4. XML Schema Registration . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12
Intellectual Property and Copyright Statements . . . . . . . . . . 13
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1. Introduction
The SIP Conference State Event Package [8] defines a means for
describing a conference object with its sub-objects, such as users,
endpoints, sidebars, etc. with optional detailed information for
each. This document introduces global elements into the SIP
Conference State Event Package XML schema to make the conference
objects and the sub-objects easily accessible by schemas external to
the event package, such as of the XCON conference control protocols.
This allows for uniform definition of the conference elements and
sub-elements without replicating them for each XCON sub-system.
This document also defines the way to introduce XCON extensions into
the SIP Conference Event Package in a backwards compatible manner.
The defined technique is compatible with the SIP Conference State
Event Package [8] XML definitions and allows for automatic standard
XML parsing of the extensions.
This document is also being used as a repository for the XCON
extensions to the SIP Conference Event Package XML schema.
2. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 [1] and
indicate requirement levels for compliant implementations.
3. Global Objects
The SIP Conference State Event Package [8] defines a conference
object which contains the information about many conference
components, such as users, endpoints, sidebars, etc. Using the SIP
Events Mechanism RFC 3265 [6], the conference information is always
distributed as a single document (full or partial) containing the
Conference Object. In order to manipulate the conference information
or state, it is desirable to be able to access a sub-object of a
conference directly - without the need for processing the whole
document. In order to achieve this granularity, this document
introduces global elements into the SIP Conference State Event
Package XML schema for each major object. This allows for uniform
definition of the conference elements and sub-elements without
replicating them for each XCON sub-system.
This document extends the XML definition of the
urn:ietf:params:xml:ns:conference-info namespace as follows:
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<?xml version="1.0" encoding="UTF-8" ?>
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:conference-info"
xmlns:tns="urn:ietf:params:xml:ns:conference-info"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns="urn:ietf:params:xml:ns:conference-info"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<!--
Elements and Attributes to be used outside the event package
-->
<xs:attribute name="state" type="state-type"/>
<xs:element name="media" type="media-type"/>
<xs:element name="endpoint" type="endpoint-type"/>
<xs:element name="user-roles" type="user-roles-type"/>
<xs:element name="user" type="user-type"/>
<!--
The original Conference Event Package schema goes below
-->
</xs:schema>
4. Conference Event Package Schema Extensibility
The conference event package allows a user to subscribe to the
information relating to a conference. This document doesn't affect
any of the assumptions, procedures, and considerations present in the
SIP Conference State Event Package [8]. These include the package
name, XML namespace, default filtering policy, subscription duration,
the data format name, and the data format.
The SIP Conference State Event Package [8] XML definition mandates
that any package extension elements belong a name space different
from the original schema. The SIP Conference State Event Package
schema does allow for extensions from multiple namespaces being
simultaneously included. It is envisioned that the extensions will
be introduced gradually (i.e. through multiple extension versions)
and potentially from different sources. In order to automatically
process the extended XML document, it must comply with a standard and
therefore deterministic XML schema, which means that a parser
recognizing document element contents has to be able to decide,
without look ahead, which content model token to match with the
current input token, while processing the document from left to
right.
By simply introducing a new element or elements into the allowed
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places of the SIP Conference State Package schema, each extended
sequence seizes to be extensible due to the known "non-deterministic"
(i.e., ambiguous) content model.
In order to mitigate the problem, this document introduces a concept
of a "separator" being defined in a separate name space. The
namespace URI for the separator is a URN [2], using the namespace
identifier 'ietf' defined by [4] and extended by RFC 3688 [10]. This
URN is:
urn:ietf:params:xml:ns:conference-info-separator
This document introduces the XML definition of the
urn:ietf:params:xml:ns:conference-info-separator namespace as
follows:
<?xml version="1.0" encoding="UTF-8" ?>
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:conference-info-separator"
xmlns:tns="urn:ietf:params:xml:ns:conference-info-separator"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns="urn:ietf:params:xml:ns:conference-info-separator"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<!--
This defines a separator marking the beginning of extensions
-->
<xs:element name="separator">
<xs:complexType/>
</xs:element>
</xs:schema>
For example, if XCON decides to add a <disclaimer> free text element
to the <conference-description>, the extended <conference-info>
schema needs to include the <disclaimer> element defined just after
the XCON extension(s). The example below illustrates the technique:
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:conference-info"
xmlns:tns="urn:ietf:params:xml:ns:conference-info"
xmlns:cis="urn:ietf:params:xml:ns:conference-info-separator"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns="urn:ietf:params:xml:ns:conference-info"
xmlns:cix="urn:ietf:params:xml:ns:xcon-conference-info"
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elementFormDefault="qualified"
attributeFormDefault="unqualified">
<!--
This imports the standard separator
-->
<xs:import namespace="urn:ietf:params:xml:ns:conference-info-separator" schemaLocation="ms-ci-separator.xsd"/>
<!--
This import brings in the XCON Conference Package extensions
-->
<xs:import namespace="urn:ietf:params:xml:ns:xcon-conference-info" schemaLocation="xcon-ci-ext.xsd"/>
<!--
The beginning of the SIP Conference Event Package definitions is skipped ...
-->
<!--
CONFERENCE DESCRIPTION TYPE
-->
<xs:complexType name="conference-description-type">
<xs:sequence>
<xs:element name="display-text" type="xs:string" minOccurs="0"/>
<xs:element name="subject" type="xs:string" minOccurs="0"/>
<xs:element name="free-text" type="xs:string" minOccurs="0"/>
<xs:element name="keywords" type="keywords-type" minOccurs="0"/>
<xs:element name="conf-uris" type="uris-type" minOccurs="0"/>
<xs:element name="service-uris" type="uris-type" minOccurs="0"/>
<xs:element name="maximum-user-count" type="xs:unsignedInt" minOccurs="0"/>
<xs:element name="available-media" type="conference-media-type" minOccurs="0"/>
<xs:element ref="cix:disclaimer" minOccurs="0"/>
<xs:sequence minOccurs="0">
<xs:element ref="cis:separator"/>
<xs:any namespace="##other" processContents="lax" maxOccurs="unbounded"/>
</xs:sequence>
</xs:sequence>
<xs:anyAttribute namespace="##other" processContents="lax"/>
</xs:complexType>
<!--
The rest of the SIP Conference Event Package definitions are skipped ...
-->
</xs:schema>
An XML document example compliant with the extended schema is shown
below:
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<?xml version="1.0" encoding="UTF-8"?>
<conference-info
xmlns="urn:ietf:params:xml:ns:conference-info"
entity="sips:conf233@example.com"
state="full" version="1">
<!--
CONFERENCE INFO
-->
<conference-description>
<subject>Agenda: This month's goals</subject>
<service-uris>
<entry>
<uri>http://sharepoint/salesgroup/</uri>
<purpose>web-page</purpose>
</entry>
</service-uris>
<!--
XCON Extensions Version 1.0
-->
<cix:disclaimer>THIS CONFERENCE MAY BE RECORDED!
</cix:disclaimer>
<cis:separator/>
<!--
Other potential extensions unknown to the receiver
-->
<foo:bar/>
</conference-description>
<!--
CONFERENCE STATE
-->
<conference-state>
<user-count>33</user-count>
</conference-state>
</conference-info>
By using the technique above, a receiver of the XML document can
deterministically parse multiple blocks of unknown extensions and
skip them as long as the known extensions appear in the known order.
In the example above but without the <cis:separator>, the schema
would have been ambiguous, since the newly added element can be
parsed as either matching the <cix:disclaimer> or as part of the <xs:
any>.
5. XCON Extensions to Conference Event Package Schema
The SIP Conference State Event Package [8] XML definition mandates
that any package extension elements need to be defined in a name
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space different from the original schema. This document registers a
new namespace URI where all XCON extensions to the SIP Conference
Event Package MUST be defined. The namespace URI for XCON extensions
is a URN [2], using the namespace identifier 'ietf' defined by [4]
and extended by RFC 3688 [10]. This URN is:
urn:ietf:params:xml:ns:xcon-conference-info
The XCON extensions are defined in the schema below:
EDITOR's NOTE: The schema below is just an example of how the XCON
extensions need to be schematized. The real extensions TBD based on
the requirements.
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:xcon-conference-info"
elementFormDefault="qualified"
attributeFormDefault="unqualified"
xmlns:tns="urn:ietf:params:xml:ns:xcon-conference-info"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns="urn:ietf:params:xml:ns:xcon-conference-info">
<xs:element name="disclaimer" type="xs:string"/>
</xs:schema>
6. Security Considerations
Subscriptions to conference state information can reveal very
sensitive information. Moreover, manipulation of this information
through conference control protocols requires a strong means for
authentication, conference information protection, and applying
comprehensive authorization rules by a focus. Users of this
specification MUST comply with the security considerations discussed
in the SIP Event Package for Conference State [8] and the conference
control protocol specifications, such as CCCP [11].
7. IANA Considerations
This document registers two new XML namespaces and two new XML
schemas.
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7.1. URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:xcon-conference-info
This section registers a new XML namespace, as per the guidelines in
RFC 3688 [10].
URI: The URI for this namespace is
urn:ietf:params:xml:ns:xcon-conference-info
Registrant Contact: IETF XCON Working Group <xcon@ietf.org>, as
designated by the IESG <iesg@ietf.org>
XML:
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Centralized Conference Information Namespace</title>
</head
<body>
<h1>Namespace for Centralized Conference Information</h1>
<h2>urn:ietf:params:xml:ns:xcon-conference-info</h2>
<p>See <a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
7.2. XML Schema Registration
This specification registers a schema, as per the guidelines in RFC
3688 [10].
URI: please assign
Registrant Contact: IETF XCON Working Group <xcon@ietf.org>, as
designated by the IESG <iesg@ietf.org>
XML: The XML can be found as the sole content of Section 5
7.3. URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:conference-info-separator
This section registers a new XML namespace, as per the guidelines in
RFC 3688 [10].
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URI: The URI for this namespace is
urn:ietf:params:xml:ns:conference-info-separator
Registrant Contact: IETF XCON Working Group <xcon@ietf.org>, as
designated by the IESG <iesg@ietf.org>
XML:
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Separator for Conference Information Namespace</title>
</head
<body>
<h1>Namespace for Separator for Conference Information</h1>
<h2>urn:ietf:params:xml:ns:conference-info-separator</h2>
<p>See <a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
7.4. XML Schema Registration
This specification registers a schema, as per the guidelines in RFC
3688 [10].
URI: please assign
Registrant Contact: IETF XCON Working Group <xcon@ietf.org>, as
designated by the IESG <iesg@ietf.org>
XML: The XML can be found as the sole content of Section 4
8. Acknowledgements
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.
[2] Moats, R., "URN Syntax", RFC 2141, May 1997.
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[3] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
[4] Moats, R., "A URN Namespace for IETF Documents", RFC 2648,
August 1999.
[5] 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.
[6] Roach, A., "Session Initiation Protocol (SIP)-Specific Event
Notification", RFC 3265, June 2002.
[7] Yergeau, F., "UTF-8, a transformation format of ISO 10646",
STD 63, RFC 3629, November 2003.
[8] Rosenberg, J., "A Session Initiation Protocol (SIP) Event
Package for Conference State",
draft-ietf-sipping-conference-package-12 (work in progress),
July 2005.
[9] Barnes, M., "A Framework and Data Model for Centralized
Conferencing", draft-ietf-xcon-framework-01 (work in progress),
July 2005.
9.2. Informative References
[10] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
[11] Levin, O. and G. Kimchi, "Centralized Conference Data Model",
draft-levin-xcon-cccp-02 (work in progress), February 2005.
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Author's Address
Orit Levin
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052
US
Email: oritl@microsoft.com
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