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SIMPLE WG                                                     M. Isomaki
Internet-Draft                                     Nokia Research Center
Expires: August 6, 2004                                      E. Leppanen
                                                                   Nokia
                                                        February 6, 2004


   An Extensible Markup Language (XML) Configuration Access Protocol
        (XCAP) Usage for Manipulating Presence Document Contents
          draft-isomaki-simple-xcap-pidf-manipulation-usage-00

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

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   This Internet-Draft will expire on August 6, 2004.

Copyright Notice

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

Abstract

   This document describes a usage of the Extensible Markup Language
   (XML) Configuration Access Protocol (XCAP) for manipulating the
   contents of Presence Information Data Format (PIDF) based presence
   document. It is mainly intended to be used in Session Initiation
   Protocol (SIP) based presence systems, where the Event State
   Compositor can use the XCAP-manipulated presence document as one of
   the inputs based on which it builds the overall presence state for
   the presentity.





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Table of Contents

   1.   Introduction . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.   Conventions  . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.   Relationship with presence state published using SIP
        PUBLISH  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.   Application Unique ID  . . . . . . . . . . . . . . . . . . .   5
   5.   Structure of Published Presence Information  . . . . . . . .   5
   6.   Computed Data  . . . . . . . . . . . . . . . . . . . . . . .   6
   7.   Additional Constraints . . . . . . . . . . . . . . . . . . .   6
   8.   Naming Conventions . . . . . . . . . . . . . . . . . . . . .   6
   9.   Authorization Policies . . . . . . . . . . . . . . . . . . .   6
   10.  XML Schema . . . . . . . . . . . . . . . . . . . . . . . . .   6
   11.  Example Document . . . . . . . . . . . . . . . . . . . . . .   6
   12.  Security Considerations  . . . . . . . . . . . . . . . . . .   7
   13.  IANA Considerations  . . . . . . . . . . . . . . . . . . . .   7
   13.1 XCAP Application Usage ID  . . . . . . . . . . . . . . . . .   8
   14.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . .   8
        Normative References . . . . . . . . . . . . . . . . . . . .   8
        Informative References . . . . . . . . . . . . . . . . . . .   8
        Authors' Addresses . . . . . . . . . . . . . . . . . . . . .   9
        Intellectual Property and Copyright Statements . . . . . . .  10





























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1. Introduction

   The Session Initiation Protocol (SIP) for Instant Messaging and
   Presence (SIMPLE) specifications allow a user, called a watcher, to
   subscribe to another user, called a presentity [6], in order to learn
   their presence information [7].

   A SIP based mechanism, SIP PUBLISH method, has been defined for
   publishing presence state [13]. However, SIP PUBLISH has a limited
   scope and does not address all the requirements for setting presence
   state. First, it only allows a single Presence User Agent (PUA) to
   publish its view of the presence state, independently of and without
   the possibility to learn about the states set by other PUAs. Since
   each PUA is typically tied to a single physical device, this means
   that it is hard to set device independent presence state using SIP
   PUBLISH. Second, SIP PUBLISH creates a soft state which expires after
   the negotiated lifetime unless it is refreshed. This makes it
   unsuitable for setting state that should prevail even without active
   refreshing. There are several use cases where setting of permanent
   presence state that can be manipulated independent of any device is
   needed. For instance presentity's e-mail (mailto: URI) and WWW
   homepage (http: URI) address are this kind of information. Similarly
   a user might want to set information, such as note, that should
   constitute his presence in the absence of any active publications,
   i.e. serve as a sort of default presence state. SIMPLE based presence
   systems thus require a mechanism to complement SIP PUBLISH in order
   to address these use cases.

   XML Configuration Access Protocol (XCAP) [2] allows a client to read,
   write and modify application configuration data, stored in XML format
   on a server. The data has no expiration time, so it must be
   explicitly inserted and deleted. The protocol allows multiple clients
   to manipulate the data, provided that they are authorized to do so.
   XCAP is already used in SIMPLE based presence systems for
   manipulation of presence lists and presence authorization policies.
   This makes XCAP an ideal choice for doing device independent presence
   document manipulation.

   This document defines an XML Configuration Access Protocol (XCAP)
   application usage for manipulating the contents of presence document.
   CPIM PIDF [3] is used as the presence document format, since event
   state compositor already has to support it, as it is used in SIP
   PUBLISH.

   Section 3 describes in more detail how the presence document
   manipulated with XCAP is related to soft state publishing done with
   SIP PUBLISH.




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   XCAP requires application usages to standardize several pieces of
   information, including an application unique ID (AUID), and an XML
   schema for the manipulated data. These are specified starting from
   the Section 4.

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.

   Comprehensive terminology of presence and event state publishing is
   provided in [13].

3. Relationship with presence state published using SIP PUBLISH

   The framework for publishing presence state is introduced in [12]. A
   central part of the framework is the event state compositor element
   whose function is to compose presence information received from
   serveral sources.

   The presence state manipulated with XCAP can be seen as one of the
   information sources for the compositor to be combined with the soft
   state information published using SIP PUBLISH. This is illustrated in
   the figure below. It is expected that in the normal case there can be
   several PUAs publishing their separate views, but only single XCAP
   manipulated presence document.























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               +---------------+         +------------+
               |   Event State |         |  Presence  |--> SIP SUBSCRIBE
               |   Compositor  +---------+  Agent     |<-- SIP NOTIFY
               |               |         |   (PA)     |
               +-------+-------+         +------------+
                 ^     ^     ^
                 |     |     |
                 |     |     |       +---------------+
        +--------+     |     +-------|  XCAP server  |
        |              |             +-------+-------+
        |              |                 ^         ^
        | SIP Publish  |                 |  XCAP   |
        |              |                 |         |
     +--+--+        +--+--+         +-------+   +-------+
     | PUA |        | PUA |         | XCAP  |   | XCAP  |
     |     |        |     |         | client|   | client|
     +-----+        +-----+         +-------+   +-------+


      Figure 1: Framework for Presence Publishing and Event State
                              Composition


   How the compositor combines the hard state information with the soft
   state information to form a coherent presence document is entirely a
   matter of local policy, and is beyond the scope of this document.
   Also the exact protocol interface between XCAP server and the event
   state compositor is not specified here. The obvious requirement is
   that such interface exists, and that the presentity indeed has an
   XCAP server supporting the usage defined in this specification
   provisioned for him.

4. Application Unique ID

   XCAP requires application usages to define a unique application usage
   ID (AUID) in either the IETF tree or a vendor tree. This
   specification defines the 'pidf-manipulation' AUID within the IETF
   tree, via the IANA registration in the Section 13.

5. Structure of Published Presence Information

   The XML [5] format of the presence information (PIDF) is defined in
   [3] and its extensions. The PIDF defines the presence information to
   consist of the root element 'presence' including 'tuples' which
   contain a mandatory status element, a communication mean specific
   presence attribute and other markups. Additionally, the presence
   information can contain other presentity level information outside
   tuples.



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   The namespace URI for PIDF is defined in [3].

6. Computed Data

   There are no computed data on the document beyond those described in
   the schema.

7. Additional Constraints

   There are no constraints on the document beyond those described in
   the XML schemas and [3].

8. Naming Conventions

   There are no naming conventions beyond the possible conventions
   defined in [3] that need to be defined for this application usage.

9. Authorization Policies

   This application usage does not modify the default XCAP authorization
   policy, which allows only a user (owner) to read, write or modify
   their own documents. A server can allow privileged users to modify
   documents that they don't own, but the establishment and indication
   of such policies is outside the scope of this document.

10. XML Schema

   The XML schema definition for the presence information can be found
   from [3] and its extensions.

11. Example Document

   The following example document illustrates the situation where the
   (human) presentity has left for vacation, and before that has set his
   presence state such that he is only available via cellular phone and
   e-mail. In the absence of any published soft state information, this
   would be the sole input to the compositor forming the presence
   document. The example document contain PIDF extensions specified in
   [10] and [11].


   <?xml version="1.0" encoding="UTF-8"?>
         <presence xmlns="urn:ietf:params:xml:ns:cpim-pidf"
              xmlns:es="urn:ietf:params:xml:ns:pidf:rpid-status"
              xmlns:et="urn:ietf:params:xml:ns:pidf:rpid-tuple"
              xmlns:ci="urn:ietf:params:xml:ns:pidf:cipid"
              entity="pres:someone@example.com">

           <tuple id="18x765">
             <et:type>presentity</et:type>



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             <status>
               <basic>open</basic>
               <es:activity>Vacation</ep:activity>
             </status>
             <timestamp>2004-02-06T16:49:29Z</timestamp>
             <note>I'm available only by e-mail and GSM phone.</note>
             <ci:homepage>http://www.example.com/~someone</ci:homepage>
           </tuple>

           <tuple id="8eg92m">
             <et:class>auth-1</et:class>
             <et:type>service</et:type>
             <status>
               <basic>open</basic>
             <es:idle/>
             </status>
             <note>cellphone</note>
             <contact priority="0.5">tel:+358506767</contact>
           </tuple>

           <tuple id="8eg92n">
             <et:class>auth-1</et:class>
             <et:type>service</et:type>
             <status>
               <basic>open</basic>
             <es:idle/>
             </status>
             <note>I'm reading mail a couple of times a week</note>
             <contact priority="1.0">mailto:someone@example.com</contact>
           </tuple>
         </presence>



12. Security Considerations

   The configuration information defined by this application usage is
   particularly sensitive. It represents the set of presence information
   which is delivered to watchers according to specific authorization
   policies. As a result, clients SHOULD use TLS when contacting servers
   in order to fetch this information. Also if the server delivers
   presence information using the XCAP protocol it must be done
   according to the defined authorization policy.

13. IANA Considerations

   There are an IANA consideration associated with this specification.




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13.1 XCAP Application Usage ID

   This section registers a new XCAP Application Usage ID (AUID)
   according to the IANA procedures defined in [2].

   Name of the AUID: pidf-manipulation

   Description: Pidf-manipulation application usage defines how XCAP is
   used to manipulate the contents of presence documents in Session
   Initiation Protocol (SIP) based presence systems.

14. Acknowledgements

   The authors would like to thank Jonathan Rosenberg, Aki Niemi,
   Krisztian Kiss and Jose Costa-Requena for their comments.

Normative References

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

   [2]  Rosenberg, J., "The Extensible Markup Language (XML)
        Configuration Access Protocol (XCAP)",
        draft-rosenberg-simple-xcap-01 (work in progress), October 2003.

   [3]  Sugano, H., "CPIM presence information data format",
        draft-ietf-impp-cpim-pidf-08 (work in progress), May 2003.

Informative References

   [4]   Mealling, M., "The IETF XML Registry",
         draft-mealling-iana-xmlns-registry-05 (work in progress), June
         2002.

   [5]   Bray, T., "Extensible Markup Language (XML) 1.0 (Second
         edition)", W3C REC REC-xml-20001006, October 2000.

   [6]   Day, M., "A model for presence and instant messaging", RFC
         2778, February 2000.

   [7]   Rosenberg, J., "Session Initiation Protocol (SIP) Extensions
         for Presence",  draft-ietf-simple-presence-10.txt (work in
         progress), January 2003.

   [8]   Roach, A., "Session Initiation Protocol (SIP)-Specific Event
         Notification", RFC 3265, June 2002.

   [9]   Peterson, J., "Common profile for presence (CPP)",



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         draft-ietf-impp-pres-03.txt (work in progress), May 2003.

   [10]  Schulzrinne, H., "RPID -- Rich Presence Information Data
         Format",  draft-ietf-simple-rpid-00.txt (work in progress),
         July 2003.

   [11]  Schulzrinne, H., "CIPID: Contact Information in Presence
         Information Data Format",  draft-ietf-simple-cipid-00.txt (work
         in progress), August 2003.

   [12]  Campbell, B., "SIMPLE Presence Publication Requirements",
         draft-ietf-simple-publish-reqs-00 (work in progress), February
         2003.

   [13]  Niemi, A., "Session Initiation Protocol (SIP) Extension for
         Event State Publication",  draft-ietf-sip-publish-02.txt (work
         in progress), January 2004.

   [14]  Rosenberg, J., "A Session Initiation Protocol (SIP) Event
         Package for Modification Events for the Extensible Markup
         Language (XML) Configuration Access Protocol (XCAP) Managed
         Documents",  draft-rosenberg-simple-xcap-package-00 (work in
         progress), May 2003.


Authors' Addresses

   Markus Isomaki
   Nokia Research Center
   Itamerenkatu 11-13
   00180 Helsinki
   Finland

   Phone:
   EMail: markus.isomaki@nokia.com


   Eva Leppanen
   Nokia
   P.O BOX 785
   Tampere
   Finland

   Phone:
   EMail: eva-maria.leppanen@nokia.com






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   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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Acknowledgment

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











































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