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Network Working Group P. Saint-Andre Request for Comments: 4854 XSF Category: Informational April 2007

            A Uniform Resource Name (URN) Namespace for
Extensions to the Extensible Messaging and Presence Protocol (XMPP)

Status of This Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

Copyright Notice

 Copyright (C) The IETF Trust (2007).


 This document describes a Uniform Resource Name (URN) namespace for
 uniquely identifying Extensible Markup Language (XML) formats and
 protocols that provide extensions to the Extensible Messaging and
 Presence Protocol (XMPP) and are defined in specifications published
 by the XMPP Standards Foundation (XSF).

Saint-Andre Informational [Page 1] RFC 4854 URN Namespace for XMPP Extensions April 2007

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
 2.  Specification Template  . . . . . . . . . . . . . . . . . . . . 3
 3.  Namespace Considerations  . . . . . . . . . . . . . . . . . . . 6
 4.  Community Considerations  . . . . . . . . . . . . . . . . . . . 6
 5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 7
 6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
 7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 8
   7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 8
   7.2.  Informative References  . . . . . . . . . . . . . . . . . . 8

Saint-Andre Informational [Page 2] RFC 4854 URN Namespace for XMPP Extensions April 2007

1. Introduction

 While the Extensible Messaging and Presence Protocol (XMPP), as
 specified in [XMPP-CORE] and [XMPP-IM], provides basic messaging and
 presence functionality, the fact that XMPP is at root a technology
 for streaming Extensible Markup Language [XML] data makes it possible
 to include virtually any structured information within XMPP, as long
 as such information is qualified by appropriate XML namespaces
 [XML-NAMES].  When sent over XMPP, such structured data formats and
 protocols are generally referred to as "XMPP extensions".
 A large number of such XMPP extensions exist.  The main standards
 development organization in which such extensions are defined is the
 XMPP Standards Foundation (XSF) (formerly the Jabber Software
 Foundation), which contributed XMPP to the Internet Standards
 process.  Typically, such extensions are defined within the XSF's
 XMPP Extension Protocol (XEP) specification series.  To date, the XML
 namespaces defined within the Jabber/XMPP community have used names
 of the form "jabber:*" (deprecated since early 2002) and
 "*" (not including names of the form
 "urn:ietf:params:xml:ns:xmpp-*" specified in the XMPP RFCs).
 However, it is desirable that names associated with future XMPP
 extensions be both unique and persistent, which is not necessarily
 the case with names that are also HTTP URLs.  Therefore, in
 accordance with the process defined in [MECHANISMS], this document
 registers a formal namespace identifier (NID) for Uniform Resource
 Names [URN] associated with XMPP extensions published in the XSF's
 XEP series and for XML namespaces registered with the XSF's XMPP
 Registrar function [REGISTRAR].

2. Specification Template

 Namespace ID:
    The Namespace ID "xmpp" is requested.
 Registration Information:
    Version 1
    Date: 2007-04-27
 Declared Registrant of the Namespace:
    Registering organization
       Organization: XMPP Standards Foundation
       Address: P.O. Box 1641, Denver, CO 80201 USA

Saint-Andre Informational [Page 3] RFC 4854 URN Namespace for XMPP Extensions April 2007

    Designated contact
       Role: XMPP Registrar
 Declaration of Syntactic Structure:
    The Namespace Specific String (NSS) of all URNs that use the
    "xmpp" NID shall have the following structure:
    The keywords have the following meaning:
       (1) the "ShortName" is a required US-ASCII string that
       conforms to the URN syntax requirements (see RFC 2141)
       and defines a particular protocol or format that is used
       as an XMPP extension.
       (2) the "SubName" is an optional US-ASCII string that
       conforms to the URN syntax requirements (see RFC 2141)
       and defines a particular subset of the relevant protocol
       or format.
    The XSF's XMPP Registrar function shall be responsible for
    managing the assignment of both "ShortName" and "SubName"
    strings and maintaining a registry of resulting namespaces
    at <>.  The
    XMPP Registrar may also assign URNs in sub-trees below the
    level of the ShortName or SubName as needed for use in various
    XMPP extensions.
 Relevant Ancillary Documentation:
    Information about the XSF's XMPP Registrar function can be
    found at <>
    and <>.
 Identifier Uniqueness Considerations:
    The XMPP Registrar is already responsible for managing
    the assignment of XML namespace names of the form
    "{ShortName}" and
    (e.g., "" and
    "").  In order to
    assign namespace names in the context of the "xmpp"
    NID, the XMPP Registrar shall simply modify the syntax
    of the namespace names it assigns from

Saint-Andre Informational [Page 4] RFC 4854 URN Namespace for XMPP Extensions April 2007

    "{ShortName}" and
    "{ShortName}#{SubName}" to
    "urn:xmpp:{ShortName}" and "urn:xmpp:{ShortName}:{SubName}".
    The XMPP Registrar shall ensure the uniqueness of all
    XMPP URNs by checking such names against the list of
    existing namespace names, as documented in XEP-0053
    (the controlling specification for the XMPP Registrar
    function).  The XMPP Registrar shall, in all cases, directly
    ensure the uniqueness of the assigned strings and shall
    not assign secondary responsibility for management of any
    sub-trees.  However, the XMPP Registrar may assign URNs
    in sub-trees below the level of the ShortName or SubName
    as needed for use in various XMPP extensions.  The
    resulting URNs shall not be re-assigned.
 Identifier Persistence Considerations:
    The XMPP Registrar shall provide clear documentation of
    the registered uses of the "xmpp" NID in the form of
    XMPP Extension Protocol (XEP) specifications published
    at <>, as well as a
    registry of the namespace names themselves at
 Process of Identifier Assignment:
    The XMPP Registrar's processes and procedures for
    identifier assignment are documented in XEP-0053,
    which is the controlling specification for the XMPP
    Registrar function.  In particular, identifiers shall
    be issued only upon advancement of the relevant protocol
    specification to a status of Draft within the standards
    process, followed by the XMPP Standards Foundation (as
    specified in XEP-0001).  The XMPP Registrar shall check
    all identifiers against the list of existing namespace
    names to ensure uniqueness and to encourage relevance
    and memorability.  Assignment of URNs within the "xmpp"
    tree is reserved to the XMPP Standards Foundation,
    specifically to its XMPP Registrar function.
 Process for Identifier Resolution:
    The namespace is not currently listed with a Resolution
    Discovery System (RDS), but nothing about the namespace
    prohibits the future definition of appropriate resolution
    methods or listing with an RDS.

Saint-Andre Informational [Page 5] RFC 4854 URN Namespace for XMPP Extensions April 2007

 Rules for Lexical Equivalence:
    No special considerations; the rules for lexical
    equivalence specified in RFC 2141 apply.
 Conformance with URN Syntax:
    No special considerations.
 Validation Mechanism:
    None specified.

3. Namespace Considerations

 The XMPP Standards Foundation has been developing Internet protocols
 since August 2001 and that work is expected to continue for the
 foreseeable future.  The old-style "jabber:*" namespace names
 originally used in the Jabber open-source community were not proper
 URNs or URIs and thus were deprecated in early 2002.  Since then, the
 namespace names assigned by the XMPP Registrar function of the XMPP
 Standards Foundation have been (equivalent to) specialized HTTP URLs
 whose authority component is "".  While that domain is
 currently under the control of the XMPP Standards Foundation, there
 is no guarantee that it will always remain so, thus potentially
 threatening the reliability and permanence of the assigned namespace
 names.  The use of Uniform Resource Names with an appropriate
 Namespace ID will enable the XMPP Standards Foundation to assign
 cleaner, more general, more permanent, more reliable, and more
 controllable namespace names related to the XMPP extensions it
 defines, while keeping the tree of XMPP extensions produced by the
 XMPP Standards Foundation properly separate from the IETF tree used
 to define some of the core XMPP namespaces as well as namespaces
 related to XMPP extensions that may be produced in the future by the

4. Community Considerations

 The XMPP standards development community will benefit from
 publication of this namespace by having more permanent and reliable
 names for the XML namespaces defined in XMPP Extension Protocol
 specifications produced by the XMPP Standards Foundation.

Saint-Andre Informational [Page 6] RFC 4854 URN Namespace for XMPP Extensions April 2007

 The standards process followed by the XSF is open to contributions
 from any interested individual; such a contribution takes the form of
 a proposal submitted to the XMPP Extensions Editor
 <>, accepted by the XMPP Council
 <>, and published in the XSF's XMPP
 Extension Protocol (XEP) series at <>.
 Use of the proposed space for a particular XML format or protocol
 extension will be contingent upon advancement of the appropriate
 specification within the XSF's standards process (as documented in
 [XEP]) and issuance of a namespace name within the "xmpp" tree by the
 XMPP Registrar (as documented in [REGISTRAR]).

5. Security Considerations

 This document introduces no additional security considerations beyond
 those associated with the use and resolution of URNs in general.

6. IANA Considerations

 This document defines a URN NID registration of "xmpp", which has
 been entered into the IANA registry located at

Saint-Andre Informational [Page 7] RFC 4854 URN Namespace for XMPP Extensions April 2007

7. References

7.1. Normative References

 [MECHANISMS]  Daigle, L., van Gulik, D., Iannella, R., and P.
               Faltstrom, "Uniform Resource Names (URN) Namespace
               Definition Mechanisms", BCP 66, RFC 3406, October 2002.
 [URN]         Moats, R., "URN Syntax", RFC 2141, May 1997.

7.2. Informative References

 [REGISTRAR]   Saint-Andre, P., "XMPP Registrar Function", XSF
               XEP 0053, December 2006.
 [XEP]         Saint-Andre, P., "XMPP Extension Protocols", XSF
               XEP 0001, December 2006.
 [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", 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
 P.O. Box 1641
 Denver, CO  80201

Saint-Andre Informational [Page 8] RFC 4854 URN Namespace for XMPP Extensions April 2007

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 Copyright (C) The IETF Trust (2007).
 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.
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Saint-Andre Informational [Page 9]

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