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Timed Presence Extensions to the Presence Information Data Format (PIDF) to Indicate Status Information for Past and Future Time Intervals :: RFC4481








Network Working Group                                     H. Schulzrinne
Request for Comments: 4481                                   Columbia U.
Category: Standards Track                                      July 2006


                    Timed Presence Extensions to the
               Presence Information Data Format (PIDF) to
     Indicate Status Information for Past and Future Time Intervals

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   The Presence Information Data Format (PIDF) defines a basic XML
   format for presenting presence information for a presentity.  This
   document extends PIDF, adding a timed status extension
   ( element) that allows a presentity to declare its
   status for a time interval fully in the future or the past.

Table of Contents

   1. Introduction ....................................................2
   2. Terminology and Conventions .....................................2
   3. Timed-Status Element ............................................3
   4. Example .........................................................4
   5. The XML Schema Definition .......................................5
   6. IANA Considerations .............................................6
      6.1. URN Sub-Namespace Registration for
           'urn:ietf:params:xml:ns:pidf:timed-status' .................6
      6.2. Schema Registration for Schema
           'urn:ietf:params:xml:ns:pidf:timed-status' .................7
   7. Security Considerations .........................................7
   8. References ......................................................7
      8.1. Normative References .......................................7
      8.2. Informative References .....................................7
   Contributor's Address ..............................................8
   Acknowledgements ...................................................8




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1.  Introduction

   Traditionally, presence information, e.g., represented as Presence
   Information Data Format [3] (PIDF) and augmented by Rich Presence
   Information Data format [9] (RPID), describes the current state of
   the presentity.  However, a 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.

   In this document, we use terms defined in RFC 2778 [7].  In
   particular, a "presentity", abbreviating presence entity, provides
   presence information to a presence service.  It is typically a
   uniquely-identified person.

   RPID already allows a presentity to indicate the period when a
   particular aspect of its presence is valid.  However, the 
   element in the PIDF  does not have this facility, so that it
   is not possible to indicate that a presentity will be OPEN or CLOSED
   in the future, for example.

   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 an off-site meeting that ended an hour ago
   indicates that the presentity is likely in transit at the current
   time.

   It is unfortunately not possible to simply add time range attributes
   to the PIDF  element, as PIDF parsers without this capability
   would ignore these attributes and thus not be able to distinguish
   current from future presence status information.

   This document defines the  element that describes the
   status of a presentity that is either no longer valid or covers some
   future time period.

2.  Terminology and Conventions

   The key words MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT,
   RECOMMENDED, MAY, and OPTIONAL in this document are to be interpreted
   as described in BCP 14, RFC 2119 [1].









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3.  Timed-Status Element

   The  element is a child of the  element and MUST
   NOT appear as a child of a PIDF  element or another
    element.  More than one such element MAY appear within
   a PIDF  element.

   Sources of  information should avoid elements that
   overlap in time, but since overlapping appointments are common in
   calendars, for example, receivers MUST be able to render such
   overlapping  indications.


   The  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
   this element is expected to be valid.  If the 'until' attribute is
   missing, the information is assumed valid until the tuple is
   explicitly overridden or expires as defined by the publication
   mechanism used.  The time range MUST NOT encompass the present time,
   i.e., the PIDF  value, as that would provide an
   unnecessary and confusing alternate mechanism to describe presence.
   Thus, the 'from' attribute for tuples without an 'until' attribute
   MUST refer to the future.

   During composition, a presence agent (PA) may encounter a stored
    element that covers the present time.  The PA MAY
   either discard that element or MAY convert it to a regular 
   element if it considers that information more credible.

   The  element may contain the  and 
   elements, as well as any other element that is appropriate as a PIDF
    extension and that has a limited validity period.  Examples
   include the PIDF-LO [8] extensions for location objects.

   This extension chose absolute rather than relative times, since
   relative times would be too hard to keep properly updated when
   spacing notifications, for example.  Originators of presence
   information MUST generate time values in the  elements
   that are fully in the past or future relative to local real
   (wallclock) time and the time information contained in the optional
   PIDF  element.









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RFC 4481                     Timed Presence                    July 2006


4.  Example

   An example combining PIDF and timed-status is shown below:

   

     
       
         open
       
       
          closed
       
       sip:someone@example.com
     
     I'll be in Tokyo next week
   































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RFC 4481                     Timed Presence                    July 2006


5.  The XML Schema Definition

   The XML [4] schema [5][6] is shown below.

   
   

     

     
        
          Describes timed-status tuple extensions for PIDF.
        
     
     
     
       
         
         
         
       
       
       
     
   





















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RFC 4481                     Timed Presence                    July 2006


6.  IANA Considerations

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

6.1.  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
      RFC 4481 to describe timed-status presence information extensions
      for the status element in the PIDF presence document format in the
      application/pidf+xml content type.

   Registrant Contact:  IETF, SIMPLE working group, simple@ietf.org;
      Henning Schulzrinne, hgs@cs.columbia.edu

   XML:

    BEGIN
      
     
      
           Timed Presence Extensions to the Presence
           Information Data Format (PIDF) to Indicate Status
           Information for Past and Future Time Intervals
      
      
          

Namespace for timed-status presence extension

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

See RFC4481.

END Schulzrinne Standards Track [Page 6] RFC 4481 Timed Presence July 2006 6.2. Schema Registration for Schema 'urn:ietf:params:xml:ns:pidf:timed-status' URI: urn:ietf:params:xml:ns:pidf:timed-status Registrant Contact: IESG XML: See Section 5 7. Security Considerations The security issues are similar to those for RPID [9]. 8. References 8.1. 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. [3] Sugano, H., Fujimoto, S., Klyne, G., Bateman, A., Carr, W., and J. Peterson, "Presence Information Data Format (PIDF)", RFC 3863, August 2004. [4] Yergeau, F., Paoli, J., Sperberg-McQueen, C., Bray, T., and E. Maler, "Extensible Markup Language (XML) 1.0 (Third Edition)", W3C REC REC-xml-20040204, February 2004. [5] Maloney, M., Beech, D., Thompson, H., and N. Mendelsohn, "XML Schema Part 1: Structures Second Edition", W3C REC REC- xmlschema-1-20041028, October 2004. [6] Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes Second Edition", W3C REC REC-xmlschema-2-20041028, October 2004. 8.2. Informative References [7] Day, M., Rosenberg, J., and H. Sugano, "A Model for Presence and Instant Messaging", RFC 2778, February 2000. [8] Peterson, J., "A Presence-based GEOPRIV Location Object Format", RFC 4119, December 2005. Schulzrinne Standards Track [Page 7] RFC 4481 Timed Presence July 2006 [9] Schulzrinne, H., Gurbani, V., Kyzivat, P., and J. Rosenberg, "RPID: Rich Presence Extensions to the Presence Information Data Format (PIDF)", RFC 4480, July 2006. Contributor's Address Jonathan Rosenberg dynamicsoft 600 Lanidex Plaza Parsippany, NJ 07054-2711 USA EMail: jdrosen@dynamicsoft.com Acknowledgements This document is based on the discussions within the IETF SIMPLE working group. Mary Barnes, Avri Doria, Miguel Garcia, Vijay Gurbani, Hisham Khartabil, Paul Kyzivat, Mikko Lonnfors, Yannis Pavlidis and Jon Peterson provided helpful comments. Author's Address Henning Schulzrinne Columbia University Department of Computer Science 450 Computer Science Building New York, NY 10027 US Phone: +1 212 939 7004 EMail: hgs+simple@cs.columbia.edu URI: http://www.cs.columbia.edu Schulzrinne Standards Track [Page 8] RFC 4481 Timed Presence July 2006 Full Copyright Statement Copyright (C) The Internet Society (2006). 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. 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. Intellectual Property 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 procedures with respect to rights in RFC 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. Acknowledgement Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Schulzrinne Standards Track [Page 9]

 

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