A URN Namespace for XML.org
Assigning persistent names to XML resources.
Best, K. and N. Walsh, "A URN Namespace for XML.org", RFC 3120, DOI 10.17487/RFC3120, June 2001, <https://www.rfc-editor.org/info/rfc3120>.
@misc{rfc3120,
series = {Request for Comments},
number = 3120,
howpublished = {RFC 3120},
publisher = {RFC Editor},
doi = {10.17487/RFC3120},
url = {https://www.rfc-editor.org/info/rfc3120},
author = {K. Best and N. Walsh},
title = {{A URN Namespace for XML.org}},
pagetotal = 5,
year = 2001,
month = jun,
} RFC text
Contents
Network Working Group K. Best
Request for Comments: 3120 OASIS, Inc.
Category: Informational N. Walsh
Sun Microsystems, Inc.
June 2001
A URN Namespace for XML.org
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 Internet Society (2001). All Rights Reserved.
Abstract
This document describes a URN (Uniform Resource Name) namespace that
is engineered by the Organization for the Advancement of Structured
Information Standards (OASIS) for naming persistent resources stored
in the XML.org repository (such as XML (Extensible Markup Language)
Document Type Definitions, XML Schemas, Namespaces, Stylesheets, and
other documents).
1. Introduction
The XML.org Registry is provided by XML.org as a public service where
XML schemas, DTDs, stylesheets, and other documents can be shared.
Documents are submitted to a repository then retrieved by others who
may want to use them. These documents require unique identifiers.
Motivated by these observations, XML.org would like to assign URNs to
some resources in order to retain unique, permanent location-
independent names for them.
This namespace specification is for a formal namespace.
2. Specification Template
Namespace ID:
"xmlorg" requested.
Registration Information:
Registration Version Number: 3
Registration Date: 2001-02-05
Declared registrant of the namespace:
Karl Best
OASIS - Organization for the Advancement of Structured
Information Standards
Post Office Box 455
Billerica, MA USA 01821
Phone: +1 (978) 667 5115
Declaration of structure:
The Namespace Specific String (NSS) of all URNs assigned by
XML.org will have the following hierarchical structure:
There is one branch at the top of the hierarchy: "objects".
The Objects Hierarchy
The general structure of the NSS in the names hierarchy has the
form:
urn:xmlorg:objects:{type}{:subtype}?:{object-id}
where "type" identifies the document type (document, schema,
stylesheet, entity, xmlns, etc.), the optional "subtype"
provides additional information about the document type (for
example, stylesheet or schema language), and "object-id" is a
unique identifier for the document.
The Director of Technical Operations at OASIS assigns document
types, subtypes, and all unique identifiers.
Relevant ancillary documentation:
None
Identifier uniqueness considerations:
Identifier uniqueness will be enforced by the Director of
Technical Operations who assigns unique identifiers to all
documents identified by URN.
Identifier persistence considerations:
OASIS is committed to maintaining the accessibility and
persistence of all the resources that are assigned URNs.
Process of identifier assignment:
Assignment is limited to the owner and those authorities that are
specifically designated by the owner. OASIS may assign portions
of its namespace for assignment by other parties.
Process of identifier resolution:
The owner will distribute catalogs (OASIS TR9401 Catalogs) that
map the assigned URNs to resource identifiers (e.g., URLs). A
more interactive, online resolution system will also be deployed
in the near future.
The owner will authorize additional resolution services as
appropriate.
Rules for Lexical Equivalence:
URNs are lexically equivalent if they are lexically identical.
Conformance with URN Syntax:
No special considerations.
Validation mechanism:
None specified. The owner will publish OASIS TR9401 Catalogs.
The presence of a URN in a catalog indicates that it is valid.
Scope:
Global
3. Examples
The following examples are not guaranteed to be real. They are
listed for pedagogical reasons only.
urn:xmlorg:objects:schema:xmlschema:xcatalog
urn:xmlorg:objects:dtd:xml:docbook:v4.1.2
4. Security Considerations
There are no additional security considerations other than those
normally associated with the use and resolution of URNs in general.
References
[1] Goldfarb, C. F., "ISO (International Organization for
Standardization) ISO 8879:1986(E) Information Processing -- Text
and Office Systems -- Standard Generalized Markup Language
(SGML)", 1986.
[2] W3C, XML WG, "Extensible Markup Language (XML) 1.0", February
1998, <http://www.w3.org/TR/REC-xml>.
[3] W3C, Namespaces WG, "Namespaces in XML", January 1999,
<http://www.w3.org/TR/REC-xml-names>.
[4] OASIS, Entity Mgmt. TC, "Entity Management: OASIS Technical
Resolution 9401:1997 (Amendment 2 to TR 9401)", January 1994,
<http://www.oasis-open.org/html/a401.htm>.
[5] Moats, R., "URN Syntax", RFC 2141, May 1997.
[6] Mealling, M. and R. Daniel, "URI Resolution Services Necessary
for URN Resolution", RFC 2483, January 1999.
Authors' Addresses
Karl Best
OASIS, Inc.
P.O. Box 455
Billerica, MA 01821
US
EMail: karl.best@oasis-open.org
Norman Walsh
Sun Microsystems, Inc.
One Network Drive
MS UBUR02-201
Burlington, MA 01803-0902
US
EMail: Norman.Walsh@East.Sun.COM
Full Copyright Statement
Copyright (C) The Internet Society (2001). All Rights Reserved.
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
AI ELI5
On this page
§1XML Resources Need Permanent Names
The XML.org Registry is a public repository where XML schemas, DTDs, stylesheets and other documents can be shared and reused. Documents in the repository need unique, permanent identifiers so that applications can refer to them reliably, even if the physical location or server changes.
This RFC defines a URN (Uniform Resource Name) namespace for assigning such identifiers to XML.org resources. URNs are location-independent names, unlike URLs which point to a specific server.
Imagine a library where books get moved around. You need a permanent library card number that works no matter which shelf the book is on.
§2How the xmlorg Namespace Works
All URNs in the xmlorg namespace follow the form urn:xmlorg:objects:{type}{:subtype}?:{object-id}. The namespace has one top-level branch called objects. The type field identifies what kind of document it is: schema, dtd, stylesheet, entity, xmlns, or others.
The optional subtype provides additional detail, such as the schema language. The object-id is a unique identifier assigned by the Director of Technical Operations at OASIS. For example: urn:xmlorg:objects:schema:xmlschema:xcatalog or urn:xmlorg:objects:dtd:xml:docbook:v4.1.2.
A name has a form like urn:xmlorg:objects:schema:xmlschema:mycatalog. Each part tells you what the file is and gives it a unique ID that never changes.
§3Resolution and Use
OASIS distributes catalogs (OASIS TR9401 Catalogs) that map URNs to actual URLs where the resources can be found. A more interactive online resolution service is also planned. The presence of a URN in a catalog indicates that it is valid. URNs are lexically equivalent only if they are exactly identical; there is no special comparison.
Applications and XML tools can use URNs as import statements and entity references, decoupling the XML source from any particular server location.
OASIS keeps a catalog that says 'this URN can be found at this web address'. When you ask for a resource by name, the catalog tells you where to get it.