Attached is an update to my Draft on using Dublin Core in
WebDAV, which addresses the question of subelements
(currently under debate in the Meta2 group).

--
/====================================================================\
|John (Francis) Stracke    |My opinions are my own.|S/MIME supported |
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WEBDAV Working Group                    J. Stracke, Netscape
INTERNET DRAFT                          October 5, 1998
<draft-ietf-webdav-dublin-core-01>

Expires April, 1999

                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.

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

9.1 INFORMATIONAL REFERENCES

10 AUTHORS' ADDRESSES


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.

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 <URL: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>
 <ol>
  <li>S. Weibel, OCLC Online Computer Library Center, Inc.</li>
  <li>J. Kunze, University of California, San Francisco</li>
  <li>C. Lagoze, Cornell University</li>
  <li>M. Wolf, Reuters Limited</li>
 </ol>
</DUBLIN:Creator>

(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.

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.

4 Security Considerations

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

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].

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.

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
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   has made any effort to identify any such rights.  Information on the
   IETF's procedures with respect to rights in standards-track and
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   claims of rights made available for publication and any assurances
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   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
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   this standard.  Please address the information to the IETF Executive
   Director.

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.

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.

10 AUTHORS' ADDRESSES

J. Stracke
Netscape Communications Corporation
501 E. Middlefield Rd.
Mountain View, CA  94043
Email: [log in to unmask]