Network Working Group M. Mealling
Internet-Draft VeriSign, Inc.
Expires: December 16, 2003 June 17, 2003
The IETF XML Registry
draft-mealling-iana-xmlns-registry-05.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at http://
www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on December 16, 2003.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document describes an IANA maintained registry for IETF
standards which use Extensivle Markup Language (XML) related items
such as Namespaces, Document Type Declarations (DTDs), Schemas, and
Resource Description Framework (RDF) Schemas.
1. Introduction
Over the past few years the Extensible Markup Language (XML)
[W3C.REC-xml] has become a widely used method for data markup. There
have already been several IETF Working Groups that have produced
standards that define XML Document Type Definitions (DTDs), XML
Namespaces [W3C.REC-xml-names] and XML Schemas [W3C.REC-xmlschema-1].
Each one of these technologies uses Uniform Resource Identifiers
Mealling Expires December 16, 2003 [Page 1]
Internet-Draft The IETF XML Registry June 2003
(URIs) [RFC2396] and other standardized identifiers to identify
various components.
For example, while it has been the practice within some standards
that use Document Type Definitions (DTDs) to forego the use of the
PUBLIC identifiers in favor of 'well known' SYSTEM identifiers, it
has proven to be more trouble than its worth to attempt to
standardize SYSTEM identifiers. The result is that several IETF
standards that have simply created non-resolvable URIs in order to
simply identify but not resolve the DTD for some given XML document.
This document seeks to standardize and improve these practices by
creating an IANA maintained registry of XML element identifiers so
that document authors and implementors have a well maintained and
authoritative location for their XML elements. As part of this
standard, the IANA will maintain
o the public representation of the document,
o the URI for the elements if one is provided at the time of
registration,
o a registry of Public Identifiers as URIs.
In the case where the registrant does not request a particular URI,
the IANA will assign it a Uniform Resource Name that follows
[RFCXXXX].
2. Terminology
The 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.
3. Registerable Documents
3.1 The Assigned/Registered URI
All elements (except PUBLIC identifiers) in this registry will
require a URI in order to be registered. If the registrant wishes to
have a URI assigned then a URN of the form:
urn:ietf:params:xml:<class>:<id>
will be assigned where <class> is the type of the document being
registered (see below). <id> is a unique id generated by the IANA
based on any means the IANA deems necessary to maintain uniqueness
Mealling Expires December 16, 2003 [Page 2]
Internet-Draft The IETF XML Registry June 2003
and persistence. NOTE: in order for a URN of this type to be
assigned, the item being registered MUST have been through the IETF
concensus process. Practically this means it must be documented in an
RFC. The RFC XXXX [RFCXXXX] URN registration template is found in
Section 6.
The IANA will also maintain a file server available via at least HTTP
and FTP that contains all of the registered elements in some publicly
accessible file space in the same way that all of the IANA's
registered elements are available via
http://www.iana.org/assignments/. While the directory structure of
this server is up to the IANA, it is suggested that the files be
organized by the <class> and the individual files have the <id> as
their filename.
Implementors are warned that they should not programatically rely on
those resources being available or the directory structure remaining
static for any reason. It is explicitly recognized that some software
tools attempt to download DTDs, schema, etc 'on the fly' and that
developers should understand when this is done and to not reference
IANA network resources as a 'schema download repository'. This is the
reason that the IANA will not register or provide SYSTEM identifiers.
3.2 Registerable Classes
The list of types of XML elements that can be registered with the
IANA are:
publicid -- An XML document that contains a DOCTYPE declaration or
any other external reference can identify that reference via both
a PUBLIC identifier and a SYSTEM identifier. The SYSTEM identifier
is system-specific information that enables the entity manager of
an XML system to locate the file, memory location, or pointer
within a file where the entity can be found. It should also be
noted that a system identifier could be an invocation of a program
that controls access to an entity that is being identified. Thus
they are not registered items. In many cases, SYSTEM identifiers
are also URIs but in these cases the URI is still only used for
system-specific information. In the case where a PUBLIC Identifier
is also a URI it is possible for the SYSTEM Identifier to contain
the same URI but this behavior is not recommended unless its side
effects are well known and understood to not cause any
unacceptable harm.
A PUBLIC identifier is a name that is intended to be meaningful
across systems and different user environments. Typically it will
be a name that has a registered owner associated with it, so that
public identifiers will be guaranteed unique and no two entities
Mealling Expires December 16, 2003 [Page 3]
Internet-Draft The IETF XML Registry June 2003
will have the same public identifier. In practice, PUBLIC
identifiers are typically Formal Public Identifers [ISO.8879.1986]
but they are not restricted to just that set. As said in
[RFC3151]:
"Any string which consists only of the public identifier
characters (defined by Production 13 of Extensible Markup
Language (XML) 1.0 Second Edition) is a legal public
identifier."
Therefore it is legal for a PUBLIC identifier to be a URN if it
adheres to the character set restrictions.
Thus, the identifier registered along with a DTD is its PUBLIC
identifier. The only restriction being that it must adhere to the
character set restrictions. In the case where the registrant does
not provide one, the IANA will assign one of the form
'urn:ietf:params:xml:pi:<id>'. Registrants are encouraged to
investigate RFC 3151 [RFC3151] as a recommended method for
minting a URN that can also be represented as an FPI.
ns -- XML Namespaces [W3C.REC-xml-names] are named by a URI. They
have no real, machine-parseable representation. Thus the
registered document will be either the specification or a
reference to it. In the case where a URI is not provided by the
registrant, the IANA will assign a URN of the form
'urn:ietf:params:xml:ns:<id> which will be the XML Namespace's
name.
schema -- XML Schemas [W3C.REC-xmlschema-1] are also identified by a
URI but their contents are machine parseable. The IANA registered
document will be the XML Schema file. The URN the IANA assigns can
be used as the URI for the schema and is of the form
'urn:ietf:params:xml:schema:<id>'.
rdfschema -- The Resource Description Format (RDF)
[W3C.CR-rdf-schema] is an XML serialization of a connected graph
based data model used for metadata expression. RDF makes use of
schemas for RDF that express grammars about relationships between
URIs. These grammars are identified by URIs. The URN assigned by
the IANA can be used as the identifying URI and is of the form
'urn:ietf:params:xml:rdfschema:<id>'.
4. Registration Procedures
Until such time as the IANA requests or implements an automated
process for the registration of these elements, any specifications
Mealling Expires December 16, 2003 [Page 4]
Internet-Draft The IETF XML Registry June 2003
wishing to do so must make that request part of the IANA
considerations section of their respective documents. That request
must be in the form of the following template:
URI
The URI or PUBLIC identifier that identifies the XML component.
If the registrant is requesting that the IANA assign a URI then
this field should be specified as "please assign"
Registrant Contact
The individual/organization that is the registration contact for
the component being registered. Ideally this will be the name and
pertinent physical and network contact information. In the case of
IETF developed standards the Registrant will be the IESG.
XML
The exact XML to be stored in the registry. Unless otherwise
obvious what the beginning and end of the file are, the document
should use the text "BEGIN" to mark the beginning of the file and
"END" to mark the end of the file. The IANA will insert any text
between those two strings (minus any page breaks and RFC
formatting inserted by the RFC Editor) into the file kept in the
repository.
5. Security Considerations
The information maintained by the IANA will be authoritative and thus
will be a target for attack. In some cases, such as XML Schema and
DTDs, the content maintained by the IANA may be directly input into
software. Thus, extra care should be taken by the IANA to maintain
the security precautions required for an important reference location
for the Internet.
Beyond this concern there are no other security considerations not
already found with any other IANA registry.
6. IANA Considerations
This documents seeks to create a rather large registry for which the
IANA (at the direction of the IESG) will be primarily responsible.
The amount of effort required to maintain this registry is not
insignificant and the policies and procedures surrounding any
approval process are non-trivial. The registry is on a First Come
First Served basis but at this time a Specification is Required. Once
the IETF has some experience with this registry these policies may
change.
Mealling Expires December 16, 2003 [Page 5]
Internet-Draft The IETF XML Registry June 2003
RFC XXXX [RFCXXXX] specifies that any new registry that requires a
name to be assigned below the 'urn:ietf:params' namespace must
specify the structure of that space in template form. The IANA is
directed to create and maintain this new sub-namespace:
Registry-name: xml
Specification: This document contains the registry specification. The
namespace is organized with one sub-namespace which is the <id>.
Repository: To be assigned according to the guidelines found above.
Index value: The class name
Normative References
[ISO.8879.1986]
International Organization for Standardization,
"Information processing - Text and office systems -
Standard generalized markup language (SGML)", ISO Standard
8879, 1986.
[RFC2396] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396,
August 1998.
[RFC3151] Walsh, N., Cowan, J. and P. Grosso, "A URN Namespace for
Public Identifiers", RFC 3151, August 2001.
[RFCXXXX] Mealling, M., Masinter, L., Hardie, T. and G. Klyne, "An
IETF URN Sub-namespace for Registered Protocol
Parameters", draft-mealling-iana-urn-02.txt (work in
progress), August 2001.
[W3C.CR-rdf-schema]
Brickley, D. and R. Guha, "Resource Description Framework
(RDF) Schema Specification 1.0", W3C CR-rdf-schema, March
2000, <http://www.w3.org/TR/2000/CR-rdf-schema-20000327>.
[W3C.REC-xml]
Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler,
"Extensible Markup Language (XML) 1.0 (2nd ed)", W3C
REC-xml, October 2000, <http://www.w3.org/TR/REC-xml>.
[W3C.REC-xml-names]
Bray, T., Hollander, D. and A. Layman, "Namespaces in
XML", W3C REC-xml-names, January 1999, <http://www.w3.org/
TR/REC-xml-names>.
Mealling Expires December 16, 2003 [Page 6]
Internet-Draft The IETF XML Registry June 2003
[W3C.REC-xmlschema-1]
Thompson, H., Beech, D., Maloney, M. and N. Mendelsohn,
"XML Schema Part 1: Structures", W3C REC-xmlschema-1, May
2001, <http://www.w3.org/TR/xmlschema-1/>.
Author's Address
Michael Mealling
VeriSign, Inc.
Mountain View, CA
US
URI: http://www.research.verisignlabs.com
Mealling Expires December 16, 2003 [Page 7]
Internet-Draft The IETF XML Registry June 2003
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
Full Copyright Statement
Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assignees.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
Mealling Expires December 16, 2003 [Page 8]
Internet-Draft The IETF XML Registry June 2003
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Mealling Expires December 16, 2003 [Page 9]