Network Working Group D. Orchard Internet-Draft BEA Systems, Inc. Expires: June 9, 2005 R. Salz DataPower Technology, Inc. December 9, 2004 The QName URN Namespace draft-rsalz-qname-urn-00.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she become aware will be disclosed, in accordance with RFC 3668. 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 June 9, 2005. Copyright Notice Copyright (C) The Internet Society (2004). 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. Orchard & Salz Expires June 9, 2005 [Page 1] Internet-Draft UUID URN December 2004 Table of Contents 1. Introduction and Motivation . . . . . . . . . . . . . . . . . 3 2. Namespace Registration Template . . . . . . . . . . . . . . . 3 3. Security Considerations . . . . . . . . . . . . . . . . . . . 5 4. Normative References . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . 7 Orchard & Salz Expires June 9, 2005 [Page 2] Internet-Draft UUID URN December 2004 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 [2] 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 [3]. Namespace ID: qname Registration Information: Version number: 1 Registration date: 2004-11-30 Declared registrant of the namespace: The W3C Technical Architecture Group (TAG) [5], reachable at tag@w3.org [6]. Orchard & Salz Expires June 9, 2005 [Page 3] Internet-Draft UUID URN December 2004 Declaration of syntactic structure: The QName URN is structured as four colon-separated fields. Note that colons within the fourth field, the URI part, are not significant; the entire fourth field is treated as a single opaque entity by this URN scheme. A QName URN is defined by the following ABNF [4]: qnameURN = "qname" ":" prefix ":" localname ":" uri prefix = ncname / "" / "*" localname = ncname uri = ncname = Here are three examples of a QName URN: urn:qname:xkms:Reject:http://w3.org/2002/xkms# urn:qname:Reject:http://w3.org/2002/xkms# urn:qname:*:Reject:http://w3.org/2002/xkms# The first correspond to the following element content QNames (the element name is not significant): xkms:Reject Reject The third QName URN example would match at least both of the XML QNames, as well as an inifinite number of others, since the namespace prefix is explicitly marked as "don't-care." Relevant ancillary documentation: [1][2] Identifier uniqueness considerations: An XML QName is semantically defined as a (namespace-uri, localname) pair; the namespace prefix is not significant. For some applications, such as signature functions, the prefix is important and must not be preserved. The QName URN provides both a one-to-one mapping, that preserves the uniquess of the underlying QName, and an explicit many-to-one mapping, that does not preserve the uniquess when it is not important to do so. Identifier persistence considerations: QName URN's have the same persistance as the underlying XML QName from which they are derived. Process of identifier assignment: Assignment of identifiers depends on the original XML QName, typically deferring to the namespace URI. Anyone with access to an XML QName can create an equivalent QName URN; no registration Orchard & Salz Expires June 9, 2005 [Page 4] Internet-Draft UUID URN December 2004 is required. Process for identifier resolution: Inherited from the QName resolution rules (typically the namespace URI) from which the QName URN is created. Rules for Lexical Equivalence: If necessary, convert each QName URN to the same encoding. The encoding of a QName URN is determined by context, and depends on the encoding of the document in which it appears. To be lexically equivalent the resultant QName URN's must be identical when compared byte-for-byte. To be semantically equivalent, ignore the prefix field when comparing bytes. Conformance with URN Syntax: Fully conformant. Validation mechanism: Inherited from the namespace URI of the original QName. Scope: Inherited from the original QName. 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 [1] Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E. and F. Yergeau, "Extensible Markup Language (XML) 1.0 (Third Edition)", W3C Recommendation, February 2004, . [2] Bray, T., Hollander, D. and A. Layman, "Namespaces in XML", W3C Recommendation, January 1990, . [3] Daigle, L., van Gulik, D., Iannella, R. and P. Faltstrom, "URN Namespace Definition Mechanisms", BCP 33, RFC 2611, June 1999. [4] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. [5] [6] Orchard & Salz Expires June 9, 2005 [Page 5] Internet-Draft UUID URN December 2004 Authors' Addresses David Orchard BEA Systems, Inc. 625 W 22nd Ave Vancouver, BC V5Z 1Z5 Canada Phone: +1 778-772-8425 EMail: dorchard@bea.com URI: http://www.bea.com Rich Salz DataPower Technology, Inc. 1 Alewife Center Cambridge, MA 02142 US Phone: +1 617-864-0455 EMail: rsalz@datapower.com URI: http://www.datapower.com Orchard & Salz Expires June 9, 2005 [Page 6] Internet-Draft UUID URN December 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat 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 implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2004). 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Orchard & Salz Expires June 9, 2005 [Page 7]