Network Working Group                                     P. Saint-Andre
Internet-Draft                                                       XSF
Expires: October 11, 2007                                  April 9, 2007


                       The Jabber-ID Header Field
                      draft-saintandre-jabberid-05

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Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document defines a header field that enables a sender to include
   a Jabber Identifier in the header block of an email message for the
   purpose of associating the email message or sender with a particular
   Extensible Messaging and Presence Protocol (XMPP) address.








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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Jabber-ID Syntax  . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
     6.2.  Informative References  . . . . . . . . . . . . . . . . . . 5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 6
   Intellectual Property and Copyright Statements  . . . . . . . . . . 7







































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1.  Introduction

   The Extensible Messaging and Presence Protocol (XMPP), documented in
   [XMPP-CORE], is a streaming XML technology that enables any two
   entities on a network to exchange well-defined but extensible XML
   elements (called "XML stanzas") in close to real time.  Given XMPP's
   heritage in the Jabber open-source community, one of the primary uses
   for XMPP is instant messaging and presence as documented in
   [XMPP-IM], and XMPP addresses are still referred to as Jabber
   Identifiers or Jabber IDs.

   Because almost all users of Jabber/XMPP instant messaging and
   presence systems are users of email systems, it can be helpful for
   such users to specify their Jabber Identifiers in the email messages
   they send.  The Jabber-ID header defined in this document provides a
   standard location for that information.


2.  Jabber-ID Syntax

   The syntax of the Jabber-ID header is defined below using Augmented
   Backus-Naur Form (as specified by [ABNF]), where the "pathxmpp" rule
   is defined in [XMPP-URI] and the remaining rules are defined in
   [MESSAGE]:

   "Jabber-ID:" [FWS] pathxmpp (*WSP / obs-FWS) CRLF

   Note: Although a native XMPP address may contain virtually any
   [UNICODE] character, an electronic mail header may contain only
   printable [US-ASCII] characters (see Section 2 of [MESSAGE]).
   Therefore, any non-US-ASCII characters in an XMPP address must be
   converted to US-ASCII before inclusion in a Jabber-ID header, in
   accordance with the rules specified in [XMPP-URI].  In addition,
   characters allowed in XMPP node identifiers and XMPP resource
   identifiers but disallowed by the relevant URI rules must be percent-
   encoded in accordance with the rules specified in [URI]; for details,
   see [XMPP-URI].


3.  Examples

   For a user whose XMPP address is "juliet@example.com", the
   corresponding Jabber-ID header would be:

   Jabber-ID: juliet@example.com

   As noted, non-US-ASCII characters in XMPP addresses must be converted
   into US-ASCII before inclusion in a Jabber-ID header.  Consider the



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   following XMPP address:

   jiři@čechy.example

   Note: The string "ř" stands for the Unicode character LATIN
   SMALL LETTER R WITH CARON and the string "č" stands for the
   Unicode character LATIN SMALL LETTER C WITH CARON, following the "XML
   Notation" used in [IRI] to represent characters that cannot be
   rendered in ASCII-only documents (note also that these characters are
   represented in their stringprep canonical form; see [STRINGPREP]).
   For those who do not read Czech, this example could be Anglicized as
   "george@czech-lands.example".

   Following the rules in [XMPP-URI] and the Jabber-ID header syntax,
   the resulting header would be:

   Jabber-ID: ji%C5%99i@%C4%8Dechy.example


4.  IANA Considerations

   In accordance with [REG], the IANA registers the "Jabber-ID" header
   field in the Permanent Message Header Field Registry.  The
   registration template is as follows:

   Header field name:  Jabber-ID
   Applicable protocol:  mail
   Status:  standard
   Author/Change controller:  IETF
   Specification document(s):  XXXX
   Related information:  For details regarding the native usage and
      format of Jabber Identifiers, see Extensible Messaging and
      Presence Protocol (RFC 3920).


5.  Security Considerations

   Message headers are an existing standard and are designed to easily
   accommodate new types.  Although the Jabber-ID header may be forged,
   this problem is inherent in Internet email; however, because a forged
   Jabber-ID header may break automated processing, applications should
   not depend on the Jabber-ID header to indicate the authenticity of an
   email message or the identity of its sender.

   Advertising XMPP addresses in email headers may make it easier for
   malicious users to harvest XMPP addresses and therefore to send
   unsolicited bulk communications to the users or applications
   represented by those addresses.  Care should be taken in balancing



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   the benefits of open information exchange against the potential costs
   of unwanted communications.  An email user agent that is capable of
   including the Jabber-ID header field in outgoing email messages
   should provide an option for its user to disable inclusion of the
   Jabber-ID header field generally, on a per-recipient basis, or on a
   per-message basis.


6.  References

6.1.  Normative References

   [ABNF]     Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 4234, October 2005.

   [MESSAGE]  Resnick, P., "Internet Message Format", RFC 2822,
              April 2001.

   [XMPP-URI]
              Saint-Andre, P., "Internationalized Resource Identifiers
              (IRIs) and Uniform Resource  Identifiers (URIs) for the
              Extensible Messaging and Presence Protocol (XMPP)",
              draft-saintandre-rfc4622bis-00 (work in progress),
              April 2007.

6.2.  Informative References

   [IRI]      Duerst, M. and M. Suignard, "Internationalized Resource
              Identifiers (IRIs)", RFC 3987, January 2005.

   [REG]      Klyne, G., Nottingham, M., and J. Mogul, "Registration
              Procedures for Message Header Fields", BCP 90, RFC 3864,
              September 2004.

   [STRINGPREP]
              Hoffman, P. and M. Blanchet, "Preparation of
              Internationalized Strings ("stringprep")", RFC 3454,
              December 2002.

   [UNICODE]  The Unicode Consortium, "The Unicode Standard, Version
              3.2.0", 2000.

              The Unicode Standard, Version 3.2.0 is defined by The
              Unicode Standard, Version 3.0 (Reading, MA, Addison-
              Wesley, 2000.  ISBN 0-201-61633-5), as amended by the
              Unicode Standard Annex #27: Unicode 3.1
              (http://www.unicode.org/reports/tr27/) and by the Unicode
              Standard Annex #28: Unicode 3.2



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              (http://www.unicode.org/reports/tr28/).

   [URI]      Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [US-ASCII]
              American National Standards Institute, "Coded Character
              Set - 7-bit American Standard Code for Information
              Interchange", ANSI X3.4, 1986.

   [XMPP-CORE]
              Saint-Andre, P., "Extensible Messaging and Presence
              Protocol (XMPP): Core", RFC 3920, October 2004.

   [XMPP-IM]  Saint-Andre, P., "Extensible Messaging and Presence
              Protocol (XMPP): Instant Messaging and Presence",
              RFC 3921, October 2004.


Author's Address

   Peter Saint-Andre
   XMPP Standards Foundation

   Email: stpeter@jabber.org
   URI:   xmpp:stpeter@jabber.org
























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   Administrative Support Activity (IASA).





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