Status of this Memo

By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3667.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt.

The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html.

This Internet-Draft will expire on September 18, 2004.

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.

Table of Contents

1.  Introduction
2.  Timed-Status Element
3.  Example
4.  Schema
5.  IANA Considerations
5.1  URN Sub-Namespace Registration for 'urn:ietf:params:xml:ns:pidf:timed-status'
5.2  Schema Registration for Schema urn:ietf:params:xml:ns:pidf:timed-status'
6.  Security Considerations
§  Normative References
§  Informative References
§  Author's Address
A.  Contributors
B.  Acknowledgments
§  Intellectual Property and Copyright Statements

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.

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.

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

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

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

Registrant Contact:

IESG

XML:

See Figure 2

6. Security Considerations

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

Normative References

Informative References

Author's Address

Appendix A. Contributors

Jonathan Rosenberg
dynamicsoft
600 Lanidex Plaza
Parsippany, NJ 07054-2711
USA
Email: jdrosen@dynamicsoft.com

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.

Intellectual Property Statement

The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the IETF's procedures with respect to rights in IETF Documents can be found in BCP 78 and BCP 79.

Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr.

The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org.

Disclaimer of Validity

This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Copyright Statement

Copyright (C) The Internet Society (2004). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights.

Acknowledgment

Funding for the RFC Editor function is currently provided by the Internet Society.