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SIMPLE WG                                                    M. Lonnfors
Internet-Draft                                               E. Leppanen
Expires: August 5, 2005                                            Nokia
                                                            H. Khartabil
                                                                   Telio
                                                           J. Urpalainen
                                                   Nokia Research Center
                                                           February 2005


     Presence Information Data format (PIDF) Extension for Partial
                                Presence
                draft-ietf-simple-partial-pidf-format-04

Status of this Memo

   This document is an Internet-Draft and is subject to all provisions
   of Section 3 of RFC 3667.  By submitting this Internet-Draft, each
   author represents that any applicable patent or other IPR claims of
   which he or she is aware have been or will be disclosed, and any of
   which he or she become aware will be disclosed, in accordance with
   RFC 3668.

   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 August 5, 2005.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   The Presence Information Document Format (PIDF) specifies the



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   baseline XML based format for describing presence information.  One
   of the characteristic of the PIDF is that document always needs to
   carry all presence information available for the presentity.  In some
   environments where low bandwidth and high latency links can exist it
   is often beneficial to limit the amount of transported information
   over the network.  This document introduces a new MIME type which
   enables transporting of either only the changed parts or the full
   PIDF based presence information.

Table of Contents

   1.   Introduction . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.   Conventions  . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.   Structure of PIDF diff documents . . . . . . . . . . . . . .   3
     3.1  'version' attribute  . . . . . . . . . . . . . . . . . . .   4
     3.2  'entity' attribute . . . . . . . . . . . . . . . . . . . .   4
   4.   Usage of 'application/pidf-diff+xml' . . . . . . . . . . . .   4
   5.   IANA Considerations  . . . . . . . . . . . . . . . . . . . .   5
     5.1  Content-type registration for
          'application/pidf-diff+xml'  . . . . . . . . . . . . . . .   5
     5.2  URN sub-namespace registration for
          'urn:ietf:params:xml:ns:pidf-diff' . . . . . . . . . . . .   6
     5.3  XML Schema Registration  . . . . . . . . . . . . . . . . .   7
   6.   Examples . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   7.   XML Schema . . . . . . . . . . . . . . . . . . . . . . . . .  11
   8.   Interoperability Considerations  . . . . . . . . . . . . . .  12
   9.   Security Considerations  . . . . . . . . . . . . . . . . . .  12
   10.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . .  12
   11.  References . . . . . . . . . . . . . . . . . . . . . . . . .  13
     11.1   Normative references . . . . . . . . . . . . . . . . . .  13
     11.2   Informative references . . . . . . . . . . . . . . . . .  13
        Authors' Addresses . . . . . . . . . . . . . . . . . . . . .  14
        Intellectual Property and Copyright Statements . . . . . . .  15


















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1.  Introduction

   The Presence Information Document Format (PIDF) [3] specifies the
   baseline XML based format for describing presence information.  One
   of the characteristic of the PIDF is that document always needs to
   carry all presence information available for the presentity.  In some
   environments where low bandwidth and high latency links can exist, it
   is often beneficial to limit the amount of transported information
   over the network.

   This document introduces a new MIME-Type 'application/pidf-diff+xml'
   which enables transporting of either only the changed parts or the
   full PIDF based presence information.  The root element of the
   document distinguishes whether the partial or full PIDF document
   content was transported.

2.  Conventions

   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.

   This memo makes use of the vocabulary defined in RFC2778 [2].  In
   addition, the following terms are defined:

   Full presence document: A presence document that contains all the
      presentity's presence information that is available to a
      particular watcher.

   Partial presence document: A presence document that represents a
      fragment of the full presence document.  A partial presence
      documents can only be understood in the context of the full
      presence document, i.e.  a partial presence document modifies a
      local copy of the full presence document.


3.  Structure of PIDF diff documents

   A new MIME type 'application/pidf-diff+xml' defines this content
   type.

   The XML Schema imports the PIDF [3] schema so that the full PIDF
   document content with the addition of a 'version' attribute can be
   transported.  The root element of the document is then <pidf-full>
   and the 'version' attribute information is included within it.
   Otherwise the content of <pidf-full> element is exactly the same than
   what would have been if 'application/pidf+xml' content type had been



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   used.  Although the XML Schema allows using also <presence> as the
   document root element it is disallowed from applications utilizing
   this content type.

   When only the changes of the presence document are transported, the
   model described in XML patch operations [7] is used.  The root
   element of the document is then <pidf-diff>.  The patch operation
   elements: <add>, <remove> and <replace> allow changing the fragments
   of the local copy of the full presence document.  The <add> element
   is used to add new content, the <replace> element updates and the
   <remove> element removes existing content.

   The 'version' attribute within the two possible document root
   elements contains a sequence number that is progressively incremented
   by one between subsequent document updates, i.e.  a more recent
   document update has a higher 'version' value than the previous one.
   This is used to ensure consistent updates as the recipient of the
   document can use the 'version' number to properly order received
   documents.  This number increments independently regardless of
   whether the <pidf-full> or <pidf-diff> content is transported.

   Implementations using this document format must follow guidelines
   specified in the PIDF [3].  Specifically, the XML document MUST be
   well formed and SHOULD be valid.  Presence documents MUST be based on
   XML 1.0 and MUST be encoded using UTF-8.  This specification makes
   use of XML namespaces for identifying presence documents and document
   fragments.  The namespace URI for elements defined by this
   specification is a URN [4], using the namespace identifier 'ietf'
   specified in RFC 2648 [5] and extended by RFC3688 [6].  This URN is:

   urn:ietf:params:xml:ns:pidf-diff

3.1  'version' attribute

   Every presence document compliant with this specification contains a
   'version' attribute within the <pidf-diff> and <pidf-full> element.

3.2  'entity' attribute

   Every presence document compliant with this specification can contain
   an 'entity' attribute within the <pidf-diff> element.  It's content
   MUST then be the same than that of the full presence document.

4.  Usage of 'application/pidf-diff+xml'

   The partial presence document SHOULD only contain those elements or
   attributes that have changed.  However, when there are a lot of
   queued changes the full presence document content can then be



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   transported instead.

5.  IANA Considerations

   This memo calls for IANA to:

   o  register a new XML namespace URN per [6].

   o  register a new content type 'application/pidf-diff+xml' per
      RFC2048 [10].

   o  register a new XML Schema URN per [6].


5.1   Content-type registration for 'application/pidf-diff+xml'

      MIME media type name: application

      MIME subtype name: pidf-diff+xml

      Mandatory parameters: none

      Optional parameters: charset
      Indicates the character encoding of enclosed XML.  Default is
      UTF-8.

      Encoding considerations:
      Uses XML, which can employ 8-bit characters, depending on the
      character encoding used.  See RFC 3023 [8], section 3.2.

      Security considerations:
      This content type is designed to carry presence data, which may be
      considered private information.  Appropriate precautions should be
      adopted to limit disclosure of this information.  Please refer to
      [[[RFCXXXX]]] security considerations section for more
      information.

      Interoperability considerations: none

      Published specification: [[[RFCXXXX]]]

      Applications which use this media type: SIP-based presence systems

      Additional information:

         Magic Number: None

         File Extension: .xml



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         Macintosh file type code: "TEXT"

      Personal and email address for further information: Mikko
      Lonnfors, mikko.lonnfors@nokia.com

      Intended usage: LIMITED USE

      Author/Change controller:
      This specification is a work item of the IETF SIMPLE working
      group, with mailing list address <simple@ietf.org>.


5.2  URN sub-namespace registration for
    'urn:ietf:params:xml:ns:pidf-diff'

      URI:
      urn:ietf:params:xml:ns:pidf-diff

      Description:
      This is the XML namespace for XML elements defined by
      [[[RFCXXXX]]] to describe the 'application/pidf-diff+xml' content
      type for partial PIDF.

      Registrant Contact:
      IETF, SIMPLE working group, <simple@ietf.org>
      Mikko Lonnfors, <mikko.lonnfors@nokia.com>

   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>PIDF extension for partial PIDF</title>
         </head>
         <body>
             <h1>Namespace for PIDF extension for partial
                  notifications</h1>
             <h2>urn:ietf:params:xml:ns:pidf-diff</h2>
             <p>See <a href="[[[URL of published RFC]]]">
             RFCXXXX</a>.</p>
          </body>
          </html>
     END



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5.3  XML Schema Registration

   This section registers a new XML Schema.

      URI:
      urn:ietf:params:xml:schema:pidf-diff

      Registrant Contact:
      IETF, SIMPLE working group, <simple@ietf.org>
      Mikko Lonnfors, <mikko.lonnfors@nokia.com>


6.  Examples

   An 'application/pidf-diff+xml' document that contains the full state
   presence information:

   <?xml version="1.0" encoding="UTF-8"?>
   <p:pidf-full xmlns="urn:ietf:params:xml:ns:pidf"
          xmlns:p="urn:ietf:params:xml:ns:pidf-diff"
          xmlns:r="urn:ietf:params:xml:ns:pidf:rpid"
          xmlns:c="urn:ietf:params:xml:ns:pidf:caps"
          entity="pres:someone@example.com"
          version="567">

    <tuple id="sg89ae">
     <status>
      <basic>open</basic>
      <r:relationship>assistant</r:relationship>
     </status>
     <c:servcaps>
      <c:audio>true</c:audio>
      <c:video>false</c:video>
      <c:message>true</c:message>
     </c:servcaps>
     <contact priority="0.8">tel:09012345678</contact>
    </tuple>

    <tuple id="cg231jcr">
     <status>
      <basic>open</basic>
     </status>
     <contact priority="1.0">im:pep@example.com</contact>
    </tuple>

    <tuple id="r1230d">
     <status>
      <basic>closed</basic>



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      <r:activity>meeting</r:activity>
     </status>
     <r:homepage>http://example.com/~pep/</r:homepage>
     <r:icon>http://example.com/~pep/icon.gif</r:icon>
     <r:card>http://example.com/~pep/card.vcd</r:card>
     <contact priority="0.9">sip:pep@example.com</contact>
    </tuple>

    <note xml:lang="en">Full state presence document</note>

    <r:person>
     <r:status>
      <r:activities>
       <r:on-the-phone/>
       <r:busy/>
      </r:activities>
     </r:status>
    </r:person>

    <r:device id="urn:esn:600b40c7">
     <r:status>
      <c:devcaps>
       <c:mobility>
        <c:supported>
         <c:mobile/>
        </c:supported>
       </c:mobility>
      </c:devcaps>
     </r:status>
    </r:device>

   </p:pidf-full>


    An example partial update document with the <pidf-diff> root
   element:















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   <?xml version="1.0" encoding="UTF-8"?>
   <p:pidf-diff xmlns="urn:ietf:params:xml:ns:pidf"
                xmlns:p="urn:ietf:params:xml:ns:pidf-diff"
                xmlns:r="urn:ietf:params:xml:ns:pidf:rpid"
             entity="pres:someone@example.com"
             version="568">

    <p:add sel="presence/note" pos="before"><tuple id="ert4773">
     <status>
      <basic>open</basic>
     </status>
     <contact priority="0.4">mailto:pep@example.com</contact>
     <note xml:lang="en">This is a new tuple inserted
           between the last tuple and note element</note>
    </tuple>

    </p:add>

    <p:replace sel="*/tuple[@id='r1230d']/status/basic/text()"
     >open</p:replace>

    <p:remove sel="*/r:person/r:status/r:activities/r:busy"/>

    <p:replace sel="*/tuple[@id='cg231jcr']/contact/@priority"
     >0.7</p:replace>

   </p:pidf-diff>


    An updated local composition presence document after applying the
   patches:

   <?xml version="1.0" encoding="UTF-8"?>
   <p:pidf-full xmlns="urn:ietf:params:xml:ns:pidf"
          xmlns:p="urn:ietf:params:xml:ns:pidf-diff"
          xmlns:r="urn:ietf:params:xml:ns:pidf:rpid"
          xmlns:c="urn:ietf:params:xml:ns:pidf:caps"
          entity="pres:someone@example.com"
          version="568">

    <tuple id="sg89ae">
     <status>
      <basic>open</basic>
      <r:relationship>assistant</r:relationship>
     </status>
     <c:servcaps>
      <c:audio>true</c:audio>
      <c:video>false</c:video>



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      <c:message>true</c:message>
     </c:servcaps>
     <contact priority="0.8">tel:09012345678</contact>
    </tuple>

    <tuple id="cg231jcr">
     <status>
      <basic>open</basic>
     </status>
     <contact priority="0.7">im:pep@example.com</contact>
    </tuple>

    <tuple id="r1230d">
     <status>
      <basic>open</basic>
     </status>
     <r:homepage>http://example.com/~pep/</r:homepage>
     <r:icon>http://example.com/~pep/icon.gif</r:icon>
     <r:card>http://example.com/~pep/card.vcd</r:card>
     <contact priority="0.9">sip:pep@example.com</contact>
    </tuple>

    <tuple id="ert4773">
     <status>
      <basic>open</basic>
     </status>
     <contact priority="0.4">mailto:pep@example.com</contact>
     <note xml:lang="en">This is a new tuple inserted
         between the last tuple and note element</note>
    </tuple>

    <note xml:lang="en">Full state presence document</note>

    <r:person>
     <r:status>
      <r:activities>
       <r:on-the-phone/>
      </r:activities>
     </r:status>
    </r:person>

    <r:device id="urn:esn:600b40c7">
     <r:status>
      <c:devcaps>
       <c:mobility>
        <c:supported>
         <c:mobile/>
        </c:supported>



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       </c:mobility>
      </c:devcaps>
     </r:status>
    </r:device>

   </p:pidf-full>



7.  XML Schema

   The XML schema for the 'application/pidf-diff+xml' data format.  The
   included schema "patch-ops.xsd" is defined in [7] and the PIDF Schema
   "pidf.xsd" is imported from [3].


   <?xml version="1.0" encoding="UTF-8"?>
   <xsd:schema
       targetNamespace="urn:ietf:params:xml:ns:pidf-diff"
       xmlns:tns="urn:ietf:params:xml:ns:pidf-diff"
       xmlns:pidf="urn:ietf:params:xml:ns:pidf"
       xmlns:xsd="http://www.w3.org/2001/XMLSchema"
       elementFormDefault="qualified">

    <xsd:include schemaLocation="patch-ops.xsd"/>

    <xsd:import namespace="urn:ietf:params:xml:ns:pidf"
                schemaLocation="pidf.xsd"/>

    <xsd:element name="pidf-diff">
     <xsd:complexType>
      <xsd:sequence minOccurs="0" maxOccurs="unbounded">
       <xsd:choice>
        <xsd:element name="add" type="tns:add"/>
        <xsd:element name="replace" type="tns:replace"/>
        <xsd:element name="remove" type="tns:remove"/>
       </xsd:choice>
      </xsd:sequence>

      <xsd:attribute name="version" type="xsd:unsignedInt"
                     use="required"/>
      <xsd:attribute name="entity" type="xsd:anyURI"/>
     </xsd:complexType>
    </xsd:element>

    <xsd:element name="pidf-full">
     <xsd:complexType>
      <xsd:complexContent>



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       <xsd:extension base="pidf:presence">

       <xsd:attribute name="version" type="xsd:unsignedInt"
                      use="required"/>
       </xsd:extension>
      </xsd:complexContent>
     </xsd:complexType>
    </xsd:element>

   </xsd:schema>


8.  Interoperability Considerations

   Systems compliant with CPP [9] will not be by default able to use
   this specification.  However, this will not cause any
   interoperability problems because all endpoints and gateways must
   support the default MIME type (application/pidf+xml) regardless if
   they support this specification.  Thus if a gateway or another end
   point does not understand this specification it will not be used.  In
   SIMPLE based systems use of this MIME type is nagotiated using SIP
   contect type nagotiation mechanism as specified in partial
   notification [14].

   Other CPP compliant (other than SIP based) systems can also support
   this specification if they have a mechanism to indicate support for
   it.  If they do it is possible to build a gateway which will preserve
   end-to-end integrity with usage of partial PIDF.

9.  Security Considerations

   All security considerations identified for PIDF [3] apply unchanged
   for this document as presence information may contain highly
   sensitive information.  In addition, once the partial content is
   transformed, a malicious man-in-the-middle MAY easily mess up the
   patching process.  The protocol used to distribute this content
   SHOULD ensure privacy, message integrity and authentication.
   Furthermore, the protocol should provide access controls which
   restrict who can see who else's presence information.

10.  Acknowledgments

   The authors would like to thank Jose Costa-Requena, Jyrki Aarnos,
   Jonathan Rosenberg, Dean Willis, Miguel Garcia, Krisztian Kiss, Ben
   Cambell, Robert Sparks, Anders Kristenssen and Aki Niemi for their
   valuable comments and contributions.





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11.  References

11.1  Normative references

   [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

   [2]  Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and
        Instant Messaging", RFC 2778, February 2000.

   [3]  Sugano, H., "CPIM presence information data format", RFC 3863,
        May 2003.

   [4]  Moats, R., "URN syntax", RFC 2141, May 1997.

   [5]  Moats, R., "A URN namespace for IETF documents", RFC 2648, Aug.
        1999.

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

   [7]  Urpalainen, J., "An Extensible Markup Language (XML) Patch
        Operations Framework Utilizing XML Path Language (XPath)
        Selectors",  draft-urpalainen-simple-xml-patch-ops-00, March
        2005.

11.2  Informative references

   [8]   Murata, M., "XML media types", RFC 3023, January 2001.

   [9]   Peterson, J., "Common Profile for Presence (CPP)", RFC 3859.

   [10]  Freed, N., Klensin, J. and J. Postel, "Multipurpose Internet
         Mail Extensions (MIME) Part Four: Registration Procedures",
         RFC 2048, November 1996.

   [11]  Rosenberg, J., "A Data Model for Presence",
          draft-ietf-simple-presence-data-model-02 (work in progress),
         February 2005.

   [12]  Schulzrinne, H., Gurbani, V., Kyzivat, P. and J. Rosenberg,
         "RPID: Rich Presence Extensions to the Presence Information
         Data Format (PIDF)",  draft-ietf-simple-rpid-05 (work in
         progress), February 2004.

   [13]  Schulzrinne, H., "CIPID: Contact Information in Presence
         Information Data Format",  draft-ietf-simple-cipid-03 (work in
         progress), July 2004.



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   [14]  Lonnfors, M., Costa-Requena, J., Leppanen, E. and H. Khartabil,
         "Session Initiation Protocol (SIP) extension for Partial
         Notification of Presence Information",
          draft-ietf-simple-partial-notify-04 (work in progress),
         February 2005.


Authors' Addresses

   Mikko Lonnfors
   Nokia
   Itamerenkatu 11-13 00180
   Helsinki
   Finland

   Phone: +358 71 8008000
   Email: mikko.lonnfors@nokia.com


   Eva Leppanen
   Nokia
   P.O BOX 785
   Tampere
   Finland

   Phone: +358 7180 77066
   Email: eva-maria.leppanen@nokia.com


   Hisham Khartabil
   Telio
   P.O. Box 1203 Vika
   Oslo
   Norway

   Phone: +47 2167 3544
   Email: hisham.khartabil@telio.no


   Jari Urpalainen
   Nokia Research Center
   Itamerenkatu 11-13 00180
   Helsinki
   Finland

   Phone: +358 7180 37686
   Email: jari.urpalainen@nokia.com




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Acknowledgment

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