Network Working GroupD. Orchard
Internet-DraftAyogo Games, Inc.
Intended status: InformationalR. Salz
Expires: September 8, 2010IBM
J. Reschke, Editor
greenbytes
March 7, 2010

The QName URN Namespace
draft-rsalz-qname-urn-02

Abstract

This specification defines a Uniform Resource Name namespace for XML namespace-qualified names, QNames. As long as the URN is encoded in the same character set as the document containing the original QName, the Qname URN provides enough information to maintain the semantics, and optionally the exact syntax, of the original name.

Editorial Note (To be removed by RFC Editor before publication)

Please send comments to the xml-dev mailing list (<http://www.xml.org/xml-dev/>).

XML versions, latest edits and the issues list for this document are available from <http://greenbytes.de/tech/webdav/#draft-rsalz-qname-urn>.

Status of this Memo

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Table of Contents

Issues list

IdTypeStatusDateRaised By
contactseditclosed2009-12-11julian.reschke@greenbytes.de
mailing-listeditclosed2009-12-12julian.reschke@greenbytes.de
registranteditclosed2009-12-11julian.reschke@greenbytes.de
xml11changeclosed2009-12-11julian.reschke@greenbytes.de
any-urichangeopen2009-12-12julian.reschke@greenbytes.de
curieeditopen2009-12-12julian.reschke@greenbytes.de
editeditopen2010-03-07julian.reschke@greenbytes.de
exampleschangeopen2009-12-11julian.reschke@greenbytes.de
i18nchangeopen2009-12-11julian.reschke@greenbytes.de
qname-vs-expnameeditopen2009-12-12julian.reschke@greenbytes.de
reg-infoeditopen2009-12-11julian.reschke@greenbytes.de
 I  edit   (type: edit, status: open)
julian.reschke@greenbytes.de2010-03-07 Umbrella issue for editorial changes.
Associated changes in this document: A.
 I  contacts   (type: edit, status: closed)
julian.reschke@greenbytes.de2009-12-11 Update author information.
2010-03-07Resolution: Done in -01.
 I  mailing-list   (type: edit, status: closed)
julian.reschke@greenbytes.de2009-12-12 In the boilerplate, state where this Internet Draft should be discussed. Proposal: xml-dev.
2010-03-07Resolution: Done in -01.
 I  curie   (type: edit, status: open)
julian.reschke@greenbytes.de2009-12-12 Maybe we should clarify the relation with CURIEs (which can be confused with QNames)?
 I  qname-vs-expname   (type: edit, status: open)
julian.reschke@greenbytes.de2009-12-12 There's a risk that we confuse people by claiming this is about QNames. What we map to URNs is the triple (namespace-name, local-name, prefix), where the prefix is optional. The tuple (namespace-name, local-name) is the *expanded name*, not the QName. Options: (1) just clarify the prose, (2) rename the URN scheme (is it in use already?) to something like "xmlname".
 I  i18n   (type: change, status: open)
julian.reschke@greenbytes.de2009-12-11 Need to state how non-ASCII characters are mapped to the URN.

1. Introduction and Motivation

This specification defines a Uniform Resource Name namespace for XML namespace-qualified names, QNames. As long as the URN is encoded in the same character set as the document containing the original QName, the Qname URN provides enough information to maintain the semantics, and optionally the exact syntax, of the original name.

There are a variety of situations when a QName may need to be mapped to a URI. For example, when exchanging (or referencing) an identifier for an XML element contained within a document, and the medium of exchange prefers URIs to QNames, such as an XML Schema anyURI data type. Another scenario is for comparing the identifiers, which can be simpler by comparing just a string without having to also compare the context setting XML namespace attribute that may be declared arbitrarily earlier in the document.

The XML Namespaces specification [XMLNS] does not provide a canonical mapping between QNames and URIs. Any XML specification that wants to enable identifier exchanges must define a language specific QName to URI mapping. There have emerged a variety of different algorithms and solutions for the mapping. To date, there have been no standardized algorithms available that they can re-use, which has increased their efforts. A standardized mapping, such as this, should provide increased productivity.

Almost all of the algorithms for Qname to URI mappings are based upon concatenation of the URI and the name with variations based upon prefix inclusion, namespace name and name separator, etc. These are typically problematic because it is difficult to recover the QName from the URI as the namespace name and name separator may have already been used in the namespace name. Having the namespace name at the end of the identifier string avoids these and other problems.

2. Namespace Registration Template

The following paragraphs contain the URN namespace registration data, as defined in [RFC3406].

Namespace ID:

 I  reg-info   (type: edit, status: open)
julian.reschke@greenbytes.de2009-12-11 Update registration info.
Associated changes in this document: 2, 2.

Registration Information:

 I  registrant   (type: edit, status: closed)
julian.reschke@greenbytes.de2009-12-11 Update registrant info.
2010-03-07Resolution: Make the editor the registrant.
Associated changes in this document: 2.

Declared registrant of the namespace:

Declaration of syntactic structure:

Relevant ancillary documentation:

Identifier uniqueness considerations:

Identifier persistence considerations:

Process of identifier assignment:

Process for identifier resolution:

Rules for Lexical Equivalence:

Conformance with URN Syntax:

Validation mechanism:

Scope:

 I  xml11   (type: change, status: closed)
julian.reschke@greenbytes.de2009-12-11 Consider removing any material related to XML 1.1.
2010-03-07Resolution: Done.
Associated changes in this document: <#rfc.change.xml11.1>, 4, 4.
 I  

del-1. XML and Namespaces 1.1

This scheme can also support the XML 1.1 [XML11] and XML namespaces 1.1 [XMLNS11] standards.

In the 1.1 Namespace specification, namespace URI's (universal resource identifiers; see ...xref...) become IRI's (internationalized resource identifiers, see ...xref...). Although currently an Internet-Draft, and therefore not feasible to use as a normative reference here, it is expected that the final RFC will continue to define a way to map IRI's to URI's. To apply this specification to IRI's, then, first apply that mapping before using the syntax here.

3. Security Considerations

QName URN's provide a way to transcribe XML QName's into and out of URN syntax. Any security considerations are inherited from the original QName.

4. Normative References

[XML]Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and F. Yergeau, “Extensible Markup Language (XML) 1.0 (Fifth Edition)”, W3C REC-xml-20081126, November 2008, <http://www.w3.org/TR/2008/REC-xml-20081126/>.
[XML11]Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., Yergeau, F., and J. Cowan, “Extensible Markup Language (XML) 1.1 (Second Edition)”, W3C REC-xml11-20060816, August 2006, <http://www.w3.org/TR/2006/REC-xml11-20060816/>.
[XMLNS]Bray, T., Hollander, D., Layman, A., Tobin, R., and H. Henry, “Namespaces in XML 1.0 (Third Edition)”, W3C REC-xml-names-20091208, December 2009, <http://www.w3.org/TR/2009/REC-xml-names-20091208/>.
[XMLNS11]Bray, T., Hollander, D., Layman, A., and R. Tobin, “Namespaces in XML (Second Edition)”, W3C REC-xml-names11-20060816, August 2006, <http://www.w3.org/TR/2006/REC-xml-names11-20060816/>.
[RFC3406]Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom, “Uniform Resource Names (URN) Namespace Definition Mechanisms”, BCP 33, RFC 3406, October 2002.
[RFC5234]Crocker, D., Ed. and P. Overell, “Augmented BNF for Syntax Specifications: ABNF”, STD 68, RFC 5234, January 2008.

A. Change Log (to be removed by RFC Editor before publication)

A.1 Since draft-rsalz-qname-urn-00

Updated references and fix reference to XMLNS which was meant to reference XMLNS11. Add a set of issues: "any-uri", "contacts", "curie", "examples", "i18n", "mailing-list", "qname-vs-expname", "reg-info", "registrant", "xml11".

 I  

A.2 Since draft-rsalz-qname-urn-01

Close issues "contacts" and "mailing-list" as resolved (already in -01). Close issues "registrant" and "xml11". Update registration info ("reg-info").

Authors' Addresses

David Orchard
Ayogo Games, Inc.
EMail: orchard@pacificspirit.com

Rich Salz
IBM
EMail: rsalz@us.ibm.com

Julian F. Reschke (editor)
greenbytes GmbH
Hafenweg 16
Muenster, NW 48155
Germany
EMail: julian.reschke@greenbytes.de
URI: http://greenbytes.de/tech/webdav/