SIMPLE H. Schulzrinne
Internet-Draft Columbia U.
Expires: August 8, 2004 February 8, 2004
Future Presence: Extensions to the Presence Information Data Format
(PIDF)
draft-ietf-simple-future-00
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Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
The Future Presence extension adds elements to the Presence
Information Data Format (PIDF) that allow a presentity to declare
their status for a time in the future.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Future-Status Element . . . . . . . . . . . . . . . . . . . . 4
3. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5.1 URN Sub-Namespace Registration for
'urn:ietf:params:xml:ns:pidf:future-status' . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
Normative References . . . . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 9
A. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 10
B. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
Intellectual Property and Copyright Statements . . . . . . . . 12
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1. Introduction
Presence information, e.g., represented as PIDF [3] and RPID [2],
describes the current state of the presentity. RPID allows to
indicate how long certain aspects of the status have been valid and
how long they are expected to be valid, but the time range has to
include the time when the presence information is delivered to the
watcher. (This restriction is necessary to avoid
backwards-compatibility problems with plain PIDF implementations.)
In some cases, the watcher can better plan communications if it knows
about the presentity's future plans. For example, if a watcher knows
that the presentity is about to travel, it might place a phone call
earlier.
It is also occasionally useful to represent past information since it
may be the only known presence information; it may give watchers an
indication of the current status. For example, indicating that the
presentity was at a meeting that ended an hour ago indicates that the
presentity is likely in transit at the current time.
Future status cannot be expressed with <tuples> elements with
optional extensions since PIDF parsers would not be able to
distinguish current from future or past information.
This document defines the <future-status> element that describes
status information that is either no longer valid or covers some
future timeperiod.
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2. Future-Status Element
The <future-status> element MUST be qualified with the 'from'
attribute and MAY be qualified with an 'until' attribute to describe
the time when the status assumed this value and the time until which
is element is expected to be valid. The time range MUST NOT encompass
the present time, as that would provide an unnecessary and confusing
alternate mechanism to describe presence.
Note that this document chooses absolute rather than relative times,
since relative times would be too hard to keep properly updated when
spacing notifications, for example. Implementors are advised to
ascertain whether the time values in the <future-status> elements are
plausible, for example, by checking whether the time stamp in a
notification protocol message corresponds to local time.
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3. Example
An example combining PIDF and future-status is shown in Fig. Figure
1.
<?xml version="1.0" encoding="UTF-8"?>
<presence xmlns="urn:ietf:params:xml:ns:pidf"
xmlns:ts="urn:ietf:params:xml:ns:pidf:future-status"
entity="pres:someone@example.com">
<tuple id="7c8dqui">
<contact>sip:someone@example.com</contact>
<status>
<basic>open</basic>
</status>
<future-status from="2003-08-15T10:20:00.000-05:00"
until="2003-08-22T19:30:00.000-05:00">
<basic>closed</basic>
</future-status>
</tuple>
<note>I'll be in Tokyo next week</note>
</presence>
An Example of Future Status
Figure 1
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4. Schema
The schema is shown in Fig. Figure 2.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns="urn:ietf:params:xml:ns:pidf:future-status"
xmlns:pidf="urn:ietf:params:xml:ns:pidf"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<!-- This import brings in the XML language attribute xml:lang-->
<xs:import namespace="http://www.w3.org/XML/1998/namespace"
schemaLocation="http://www.w3.org/2001/xml.xsd"/>
<xs:annotation>
<xs:documentation xml:lang="en">
Describes future-status tuple extensions for PIDF.
</xs:documentation>
</xs:annotation>
<xs:element name="future-status" type="future-status"/>
<xs:complexType name="future-status">
<xs:sequence>
<xs:element name="basic" type="pidf:basic" minOccurs="0"/>
<xs:element name="note" type="pidf:note"/>
<xs:any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute name="from" type="xs:dateTime"/>
<xs:attribute name="until" type="xs:dateTime"/>
</xs:complexType>
</xs:schema>
The Future-Status Schema
Figure 2
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5. IANA Considerations
This document calls for IANA to register a new XML namespace URNs per
[4].
5.1 URN Sub-Namespace Registration for
'urn:ietf:params:xml:ns:pidf:future-status'
URI: urn:ietf:params:xml:ns:future-status
Description: This is the XML namespace for XML elements defined by
RFCXXXX to describe future-status presence information extensions
for the status element in the PIDF presence document format in the
application/cpim-pidf+xml content type.
Registrant Contact: IETF, SIMPLE working group, simple@ietf.org;
Henning Schulzrinne, hgs@cs.columbia.edu
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>Future-Status Information in Presence Information Data Format</title>
</head>
<body>
<h1>Namespace for future-status presence extension</h1>
<h2>urn:ietf:params:xml:ns:future-status</h2>
<p>See <a href="URL of published RFC">RFCXXXX</a>.</p>
</body>
</html>
END
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6. Security Considerations
The security issues are similar to those for RPID [2].
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Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Schulzrinne, H., "RPID -- Rich Presence Information Data
Format", draft-ietf-simple-rpid-00 (work in progress), July
2003.
[3] Sugano, H. and S. Fujimoto, "Presence Information Data Format
(PIDF)", draft-ietf-impp-cpim-pidf-08 (work in progress), May
2003.
[4] Mealling, M., "The IETF XML Registry",
draft-mealling-iana-xmlns-registry-05 (work in progress), June
2003.
Author's Address
Henning Schulzrinne
Columbia University
Department of Computer Science
450 Computer Science Building
New York, NY 10027
US
Phone: +1 212 939 7042
EMail: hgs+simple@cs.columbia.edu
URI: http://www.cs.columbia.edu
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Appendix A. Contributors
Jonathan Rosenberg
dynamicsoft
600 Lanidex Plaza
Parsippany, NJ 07054-2711
USA
Email: jdrosen@dynamicsoft.com
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Appendix B. Acknowledgments
This document is based on the discussions within the IETF SIMPLE
working group. Vijay Gurbani, Paul Kyzivat, Jon Peterson and
Jonathan Rosenberg have provided helpful comments.
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