A Uniform Resource Name (URN) Namespace for Extensions to the Extensible Messaging and Presence Protocol (XMPP)
draft-saintandre-xmpp-urn-00

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Copyright Notice

Copyright © The Internet Society (2006).

Abstract

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 Jabber Software Foundation (JSF).

Table of Contents

1.  Introduction
2.  Specification Template
3.  Namespace Considerations
4.  Community Considerations
5.  Security Considerations
6.  IANA Considerations
7.  References
    7.1.  Normative References
    7.2.  Informative References
§  Author's Address
§  Intellectual Property and Copyright Statements

1.  Introduction

While the Extensible Messaging and Presence Protocol (XMPP) as specified in [XMPP‑CORE] (Saint-Andre, P., “Extensible Messaging and Presence Protocol (XMPP): Core,” October 2004.) and [XMPP‑IM] (Saint-Andre, P., “Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and Presence,” October 2004.) provides basic messaging and presence funtionality, the fact that XMPP is at root a technology for streaming Extensible Markup Language [XML] (Bray, T., Paoli, J., Sperberg-McQueen, C., and E. Maler, “Extensible Markup Language (XML) 1.0 (2nd ed),” October 2000.) 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] (Bray, T., Hollander, D., and A. Layman, “Namespaces in XML,” January 1999.). 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 Jabber Software Foundation (JSF), which contributed XMPP to the Inernet Standards Process. Typically, such extensions are defined within the JSF'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 "http://jabber.org/protocol/*" (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] (Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom, “Uniform Resource Names (URN) Namespace Definition Mechanisms,” October 2002.), this document registers a formal namespace identifier (NID) for Uniform Resource Names [URN] (Moats, R., “URN Syntax,” May 1997.) associated with XMPP extensions published in the JSF's XEP series and XML namespaces registered with the JSF's XMPP Registrar function [REGISTRAR] (Saint-Andre, P., “XMPP Registrar,” May 2004.).

2.  Specification Template

Namespace ID:

   The Namespace ID "xmpp" is requested.

Registration Information:

   Version 1
   Date: <when submitted>

Declared Registrant of the Namespace:

   Registering organization
      Organization: Jabber Software Foundation
      Address: P.O. Box 1641, Denver, CO 80201 USA

   Designated contact
      Role: XMPP Registrar
      Email: registrar@jabber.org

Declaration of Syntactic Structure:

   The Namespace Specific String (NSS) of all URNs that use the
   "xmpp" NID shall have the following structure:

      urn:xmpp:{ShortName}:{SubName}

   The keywords have the following meaning:

      (1) the "ShortName" is a 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 a 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 JSF'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 <http://www.xmpp.org/registrar/namespaces.html>.  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 JSF's XMPP Registrar function can be
   found at <http://www.xmpp.org/extensions/xep-0053.html>
   and <http://www.xmpp.org/registrar/>.

Identifier Uniqueness Considerations:

   The XMPP Registrar is already responsible for managing the
   assignment of XML namespace names of the form
   "http://jabber.org/protocol/{ShortName}" and
   "http://jabber.org/protocol/{ShortName}#{SubName}"
   (e.g., "http://jabber.org/protocol/pubsub" and
   "http://jabber.org/protocol/disco#info").  If the "xmpp"
   NID is approved, the XMPP Registrar shall simply modify the
   syntax of the namespace names it assigns from
   "http://jabber.org/protocol/{ShortName}" and
   "http://jabber.org/protocol/{ShortName}#{SubName}" to
   "urn:xmpp:{ShortName}" and "urn:xmpp:{ShortName}:{SubName}".

   The XMPP Registrar shall ensure the uniqueness of all
   ShortName strings and of all SubName strings within the
   context of a given ShortName through checking such names
   against the list of existing namespace names (this process
   is not currently documented, but documentation may be added
   to XEP-0053, which is the controlling specification for the
   XMPP Registrar).  It is envisioned that the XMPP Registrar
   shall in all cases directly ensure the uniqueness of the
   assigned strings and that the XMPP Registrar 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
   <http://www.xmpp.org/extensions/> as well as a
   registry of the registered namespaces themselves at
   <http://www.xmpp.org/registrar/namespaces.html>.

Process of Identifier Assignment:

   The XMPP Registrar's processes for ShortName and SubName
   assignment are not currently documented, but such strings
   are typically generated by the author of the relevant XMPP
   Extension Protocol specification and checked by the XMPP
   Registrar against the list of existing namespace names to
   ensure relevance, memorability, and uniqueness
   (documentation of this process may be added to XEP-0053,
   which is the controlling specification for the XMPP
   Registrar).  Assignment of URNs within the "xmpp" tree is
   reserved to the Jabber Software Foundation, specifically
   to its XMPP Registrar function as specified in XEP-0053.

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.

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.

Scope:

   Global.

3.  Namespace Considerations

The standards work of the Jabber Software Foundation has been in progress since August 2001 and 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 Jabber Software Foundation have been (equivalent to) specialized HTTP URLs whose authority component is "jabber.org". While that domain is currently under the control of the Jabber Software 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 Jabber Software 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 properly separate from the IETF tree used to define some of the core XMPP namespaces.

4.  Community Considerations

The Jabber/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 JSF.

The standards process followed by the JSF is open to contributions from any interested individual; such a contribution takes the form of a proposal submitted to the XMPP Extensions Editor <mailto:editor@jabber.org>, accepted by the XMPP Council <http://www.xmpp.org/council/>, and published in the JSF's XMPP Extension Protocol (XEP) series at <http://www.xmpp.org/extensions/>. It is envisioned that, as at present, use of the proposed space for a particular XML format or protocol extension will be contingent upon advancement of the appropriate specification within the JSF's standards process as documented in XEP-0001 <http://www.xmpp.org/extensions/xep-0001.html>.

5.  Security Considerations

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

6.  IANA Considerations

This document defines a URN NID registration of "xmpp", which shall be entered into the IANA registry located at <http://www.iana.org/assignments/urn-namespaces>.

7.  References

7.1. Normative References

7.2. Informative References

Author's Address

Full Copyright Statement

Copyright © The Internet Society (2006).

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