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Network Working GroupP. Saint-Andre
Internet-DraftJabber Software Foundation
Expires: August 6, 2004February 6, 2004

Transporting Presence Information Data Format (PIDF) over the Extensible Messaging and Presence Protocol (XMPP)
draft-saintandre-xmpp-pidf-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 defines how to send information encoded in the CPIM Presence Information Data Format (PIDF) over the Extensible Messaging and Presence Protocol (XMPP).



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Table of Contents




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1. Introduction

The Presence Information Data Format ([PIDF]) defines a common presence data format for presence protocols that conform to the Common Profile for Presence ([CPP]), enabling presence information to be transferred across CPP-compliant protocol boundaries without modification, with attendant benefits for security and performance. Because the syntax for PIDF is XML[XML], it should be straightforward to send PIDF data over the Extensible Messaging and Presence Protocol [XMPP-CORE], since XMPP is simply an XML streaming protocol. This memo defines a mechanism for encapsulating PIDF data within an "extended namespace" contained in an XMPP presence stanza.

1.1 Terminology

This document inherits terminology defined in [PIDF], [XMPP-CORE], and [XMPP-IM].

The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119[TERMS].

1.2 Discussion Venue

The author welcomes discussion and comments related to the topics presented in this document. The preferred forum is the <xmppwg@jabber.org> mailing list, for which archives and subscription information are available at <http://www.jabber.org/cgi-bin/mailman/listinfo/xmppwg/>.



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2. Protocol

The PIDF format is defined in [PIDF]. Briefly, the XML namespace name is 'urn:ietf:params:xml:ns:pidf', the root element is <presence/>, the <presence/> element must possess an 'entity' attribute, and the <presence/> element may contain any number of <tuple/> child elements specying information about an entity.

The recommended method for encapsulating PIDF data within an XMPP presence stanza is by including the PIDF <presence/> element as a child of the XMPP <presence/> stanza. Although it may appear that this is potentially confusing, the inclusion of the 'urn:ietf:params:xml:ns:pidf' namespace ensures that PIDF data is kept separate from XMPP presence data (in accordance with [XML-NAMES]). The following is a simple example of encapsulating PIDF data within an "extended namespace" in XMPP:

A basic example of PIDF over XMPP:

<presence from='romeo@example.net/orchard' xml:lang='en'>
  <show>dnd</show>
  <status>Wooing Juliet</status>
  <presence xmlns='urn:ietf:params:xml:ns:pidf'
            entity='pres:romeo@example.net'>
    <tuple id='orchard'>
      <status>
        <basic>open</basic>
      </status>
    </tuple>
  </presence>
</presence>
        

Because base PIDF data does not encapsulate any additional information over and above XMPP presence stanzas, there is little point to including it in native XMPP systems when it is not encrypted (obviously, encrypting PIDF data can help to ensure end-to-end encryption of presence information, as described in [XMPP-E2E]). The power of PIDF in the context of XMPP derives from extensions thereto, such as the rich presence formats described in [RPID] and the geographical location formats described in [GEOLOC]. Any such extension to PIDF can be included in an XMPP presence stanza, since, according to the definition of "extended namespaces" in [XMPP-IM], the format of such extended data is defined by the extension rather than by the base XMPP specification itself. Thus the ability to include PIDF data and PIDF data extensions in XMPP enables XMPP-aware applications to include any PIDF-compatible data that is currently defined or that may be defined in the future. Naturally, there is no guarantee that all XMPP entities will be able to understand such PIDF data, and entities that do not understand the data MUST ignore it; however, this memo at least defines a mechanism for including PIDF data, which XMPP applications are encouraged to implement if they desire to make use of PIDF data extensions for rich presence, geographical location, and other kinds of presence-related information.



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3. IANA Considerations

This document requires no action on the part of the IANA.



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4. Security Considerations

Detailed security considerations for XMPP are given in XMPP Core[XMPP-CORE].



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Normative References

[CPP] Peterson, J., "Common Profile for Presence (CPP)", draft-ietf-impp-pres-04 (work in progress), August 2003.
[PIDF] Fujimoto, S., Sugano, H., Klyne, G., Bateman, A., Carr, W. and J. Peterson, "Presence Information Data Format (PIDF)", draft-ietf-impp-cpim-pidf-08 (work in progress), May 2003.
[TERMS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[XML] Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler, "Extensible Markup Language (XML) 1.0 (2nd ed)", W3C REC-xml, October 2000.
[XML-NAMES] Bray, T., Hollander, D. and A. Layman, "Namespaces in XML", W3C REC-xml-names, January 1999.
[XMPP-CORE] Saint-Andre, P., "Extensible Messaging and Presence Protocol (XMPP): Core", draft-ietf-xmpp-core-22 (work in progress), January 2004.
[XMPP-E2E] Saint-Andre, P., "End-to-End Object Encryption in the Extensible Messaging and Presence Protocol (XMPP)", draft-ietf-xmpp-e2e-07 (work in progress), December 2003.
[XMPP-IM] Saint-Andre, P., "Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and Presence", draft-ietf-xmpp-im-21 (work in progress), January 2004.


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Informative References

[GEOLOC] Peterson, J., "A Presence-based GEOPRIV Location Object Format", draft-ietf-geopriv-pidf-lo-00 (work in progress), January 2004.
[RPID] Schulzrinne, H., "RPID -- Rich Presence Information Data Format", draft-ietf-simple-rpid-00 (work in progress), July 2003.


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Author's Address

  Peter Saint-Andre
  Jabber Software Foundation
EMail:  stpeter@jabber.org


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Intellectual Property Statement

Full Copyright Statement

Acknowledgment