SIMPLE                                                    H. Schulzrinne
Internet-Draft                                               Columbia U.
Expires: September 18, 2004                               March 20, 2004


   Timed Presence Extensions to the Presence Information Data Format
    (PIDF) to Indicate Presence Information for Past and Future Time
                               Intervals
                      draft-ietf-simple-future-01

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Copyright Notice

   Copyright (C) The Internet Society (2004). All Rights Reserved.

Abstract

   The timed presence extension adds elements to the Presence
   Information Data Format (PIDF) that allow a presentity to declare
   their status for a time interval fully in the future or the past.









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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Timed-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:timed-status' . . . . . . . . . .  7
   5.2 Schema Registration for Schema
       urn:ietf:params:xml:ns:pidf:timed-status'  . . . . . . . . . .  7
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
       Normative References . . . . . . . . . . . . . . . . . . . . . 10
       Informative References . . . . . . . . . . . . . . . . . . . . 11
       Author's Address . . . . . . . . . . . . . . . . . . . . . . . 11
   A.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 12
   B.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 13
       Intellectual Property and Copyright Statements . . . . . . . . 14

































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1. Introduction

   Presence information, e.g., represented as PIDF [5] and RPID [3],
   describes the current state of the presentity.  RPID also 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 published and
   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 or past status cannot be expressed with <status> elements that
   use optional attributes or elements indicating such past or future
   time ranges. If they did, PIDF parsers would ignore those optional
   attributes or elements, and would not be able to distinguish current
   information from past or future information.

   This document defines the <timed-status> element that describes
   status information that is either no longer valid or covers some
   future timeperiod.





















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2. Timed-Status Element

   The <timed-status> element can only appear within a PIDF <tuple>
   element.  More than one such element MAY appear within a <tuple>
   element.  Sources of <timed-status> information should avoid
   overlapping elements, but since overlapping appointments are common
   in calendars, for example, receivers MUST be able to render such
   overlapping <timed-status> indications.

   The <timed-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.

   The <timed-status> element may contain any PIDF status extension,
   such as RPID [3].  However, not all elements in PIDF extensions are
   sensible in this context.  For example, information such as contact
   information [4] that does not change as a function of time is
   inappropriate for use with timed status.

   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.  Implementations SHOULD ascertain
   whether the time values in the <timed-status> elements are plausible,
   for example, by checking whether the time stamp in a notification
   protocol message corresponds to local time and by making sure that
   they are fully in the past or future, both relative to real time and
   the time contained in the optional PIDF <timestamp> element.





















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3. Example

   An example combining PIDF and timed-status is shown in Fig.  Figure
   1.


   <?xml version="1.0" encoding="UTF-8"?>
      <presence xmlns="urn:ietf:params:xml:ns:pidf"
           xmlns:fs="urn:ietf:params:xml:ns:pidf:timed-status"
           entity="pres:someone@example.com">

        <tuple id="7c8dqui">
          <contact>sip:someone@example.com</contact>
          <status>
            <basic>open</basic>
          </status>
          <fs:time-status from="2003-08-15T10:20:00.000-05:00"
             until="2003-08-22T19:30:00.000-05:00">
             <basic>closed</basic>
          </fs:timed-status>
        </tuple>
        <note>I'll be in Tokyo next week</note>
     </presence>

   An Example of Timed 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:timed-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 timed-status tuple extensions for PIDF.
       </xs:documentation>
     </xs:annotation>

     <xs:element name="timed-status" type="timed-status"/>

     <xs:complexType name="timed-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 Timed-Status Schema

                                Figure 2













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5. IANA Considerations

   This document calls for IANA to register a new XML namespace URN and
   schema per [2].

5.1 URN Sub-Namespace Registration for
    'urn:ietf:params:xml:ns:pidf:timed-status'

   URI: urn:ietf:params:xml:ns:pidf:timed-status

   Description: This is the XML namespace for XML elements defined by
      RFCXXXX to describe timed-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>Timed-Status Information in Presence Information Data Format</title>
      </head>
      <body>
          <h1>Namespace for timed-status presence extension</h1>
          <h2>urn:ietf:params:xml:ns:pidf:timed-status</h2>
          <p>See <a href="URL of published RFC">RFCXXXX</a>.</p>
       </body>
       </html>
      END



5.2 Schema Registration for Schema
    urn:ietf:params:xml:ns:pidf:timed-status'

   URI: please assign






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   Registrant Contact: IESG

   XML: See Figure 2
















































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6. Security Considerations

   The security issues are similar to those for RPID [3].
















































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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]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January
        2004.












































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Informative References

   [3]  Schulzrinne, H., Gurbani, V., Kyzivat, P. and J. Rosenberg,
        "RPID: Rich Presence: Extensions to the Presence Information
        Data Format  (PIDF)", draft-ietf-simple-rpid-02 (work in
        progress), March 2004.

   [4]  Schulzrinne, H., "CIPID: Contact Information in Presence
        Information Data Format", draft-ietf-simple-cipid-00 (work in
        progress), February 2004.

   [5]  Sugano, H. and S. Fujimoto, "Presence Information Data Format
        (PIDF)", draft-ietf-impp-cpim-pidf-08 (work in progress), May
        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 provided helpful comments.














































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