The Use of Dublin Core™ Metadata in WebDAV

Status of this Memo

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Abstract

This document specifies a standard mapping for using the metadata vocabulary of Dublin Core™ ([DUBLIN]) in a WebDAV ([WEBDAV]) server.

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Contents

STATUS OF THIS MEMO
ABSTRACT
CONTENTS
1 INTRODUCTION
2 MAPPING
2.1 NAMESPACE
2.2 PROPERTY NAMES
2.3 PROPERTY FORMAT
2.4 SUBELEMENTS
3 INTERNATIONALIZATION CONSIDERATIONS
4 SECURITY CONSIDERATIONS
5 IANA CONSIDERATIONS
6 COPYRIGHT
7 INTELLECTUAL PROPERTY
8 ACKNOWLEDGEMENTS
9 REFERENCES
9.1 NORMATIVE REFERENCES
9.2 INFORMATIONAL REFERENCES
10 AUTHORS' ADDRESSES

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1 Introduction

This document specifies a standard mapping for using the metadata vocabulary of Dublin Core™ ([DUBLIN]) in a WebDAV ([WEBDAV]) server. WebDAV defines a protocol for manipulating metadata on a Web resource; in WebDAV, an element of metadata is called a property. Dublin Core™ defines several metadata elements, with standard names and standard meanings. A server which stores Dublin Core™ metadata for its content may wish to make the metadata available as WebDAV properties; to forestall the emergence of nonstandard ways to provide this functionality, this document defines a standard mapping from Dublin Core™ element labels into WebDAV property names.

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2 Mapping

2.1 Namespace

WebDAV properties are expressed as XML elements ([XML]), using XML namespaces ([XMLNS]) to permit different groups to define sets of properties without interfering with each other. XML namespaces are named by URIs. This document defines a namespace for use by Dublin Core; its URI is ftp://ftp.isi.edu/in-notes/rfc2413.txt. This is a URI for [DUBLIN], so it seemed like a reasonable choice. Note that, although this URI may one day not be a valid mechanism for fetching [DUBLIN], that will not make it unusable for the purpose of defining this namespace.

2.2 Property Names

A WebDAV property representing a Dublin Core™ element has the same name as the Dublin Core™ element label.

2.3 Property Format

Since a WebDAV property can occur on a resource only once, while a content item may bear more than one instance of a Dublin Core™ element, some mechanism is needed to represent the multivalued elements in the singlevalued property syntax. Since WebDAV properties are expressed in XML, there is a simple mechanism available: an ordered list element, where each list item corresponds to an element. For example, the Creator elements of [DUBLIN] might be expressed as follows:

`DUBLIN:Creator

1. S. Weibel, OCLC Online Computer Library Center, Inc.
2. J. Kunze, University of California, San Francisco
3. C. Lagoze, Cornell University
4. M. Wolf, Reuters Limited

`

(assuming that a namespace declaration PI has appeared to define DUBLIN: to refer to the Dublin Core™ namespace.)

2.4 Subelements

As of this writing, the Dublin Core™ group is debating how and whether to provide subelements (that is, a technique for structuring metadata elements). Since subelements are not yet standardized, this document cannot yet give a definitive answer on how to integrate them into WebDAV; a future document may be needed.

One approach under consideration, set out in [GUENTHER], is to use structured element names (e.g., Creator becomes structured into Creator.PersonalName and Creator.CorporateName); if this approach is adopted, then this document can be applied unchanged, because Creator.CorporateName is a perfectly legal XML tag name. Alternative approaches could include storing structured data in an element; this approach would require a future document specifying a mapping from that structure into XML.

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3 Internationalization Considerations

XML is an inherently internationalizable format, able to express any language or character set; as a result, all WebDAV properties, including the Dublin Core™ properties defined here, are internationalizable.

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4 Security Considerations

The security considerations of this mapping are those of [DUBLIN] plus those of [WEBDAV].

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5 IANA Considerations

The namespace defined here is isomorphic to the element namespace defined in [DUBLIN], so this document introduces no new IANA considerations beyond those of [DUBLIN].

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6 Copyright

The following copyright notice is copied from RFC 2026 [Bradner, 1996], section 10.4, and describes the applicable copyright for this document. Copyright (C) The Internet Society April 5, 1998. 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 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

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7 Intellectual Property

The following notice is copied from RFC 2026 [Bradner, 1996], section 10.4, and describes the position of the IETF concerning intellectual property claims made against this document.

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 other 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.

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8 Acknowledgements

The triviality of this specification is due to the hard work put into [WEBDAV], [DUBLIN], [XML], and [XMLNS] by their respective authors and working groups.

The need for this specification was pointed out (by Jim Whitehead, I think) during the variants discussion held after a meeting of the versioning design team of the WebDAV working group.

Thanks to Liz Parrot for alerting me to the question of subelements. 

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9 References

9.1 Normative References

[DUBLIN] S. Weibel, J. Kunze, C. Lagoze, M. Wolf, "Dublin Core™ Metadata for Resource Discovery." RFC 2413. Online Computer Library Center; University of California, San Francisco; Cornell; Reuters. September, 1998.

[WEBDAV] Y. Y. Goland, E. J. Whitehead, Jr., A. Faizi, S. R. Carter, D. Jensen, "Extensions for Distributed Authoring on the World Wide Web - WebDAV." Draft-ietf-webdav-protocol-08. Internet Draft, work in progress. Microsoft, U.C. Irvine, Netscape, Novell. April, 1998.

[XML] T. Bray, J. Paoli, C. M. Sperberg-McQueen, "Extensible Markup Language (XML)." World Wide Web Consortium Recommendation REC-xml-19980210. < http://www.w3.org/TR/1998/REC-xml-19980210>.

9.2 Informational References

[XMLNS] T. Bray, D. Hollander, A. Layman, "Name Spaces in XML" World

Wide Web Consortium Working Draft, < http://www.w3.org/TR/WD-xml-names>.

[GUENTHER] R. Guenther, "Dublin Core™ Qualifiers/Substructure", < http://www.loc.gov/marc/dcqualif.html>. October, 1997.

October, 1997.

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10 AUTHORS' ADDRESSES

J. Stracke
Netscape Communications Corporation
501 E. Middlefield Rd.
Mountain View, CA 94043
Email: [email protected]