--- 1/draft-ietf-webdav-dublin-core-00.txt 2006-02-05 02:10:50.000000000 +0100 +++ 2/draft-ietf-webdav-dublin-core-01.txt 2006-02-05 02:10:50.000000000 +0100 @@ -1,266 +1,491 @@ +WEBDAV Working Group J. Stracke, eCal Corp. +INTERNET DRAFT + +Expires December, 1999 June 8, 1999 -WEBDAV Working Group J. Stracke, Netscape - - + Use of Dublin Core Metadata in WebDAV -Expires April, 1999 +1 Status of this Document - Use of Dublin Core Metadata in WebDAV + This document is an Internet-Draft and is in full conformance with + all provisions of Section 10 of RFC2026. -Status of this Memo + 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. - This document is an Internet-Draft. 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.'' - Internet-Drafts are draft documents valid for a maximum of six - months and may be updated, replaced, or made obsolete 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 + - To view the entire list of current Internet-Drafts, please check - the "1id-abstracts.txt" listing contained in the Internet-Drafts - Shadow Directories on ftp.is.co.za (Africa), ftp.nordu.net - (Northern Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au - (Pacific Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu - (US West Coast). + The list of Internet-Draft Shadow Directories can be accessed at + Distribution of this document is unlimited. Please send comments to - the Distributed Authoring and Versioning (WEBDAV) working group at - , which may be joined by sending a message - with subject "subscribe" to . + francis@ecal.com or to the w3c-dist-auth@w3.org discussion list. - Discussions of the WEBDAV working group are archived at - . +2 Abstract -Abstract + This document specifies a mapping for using the metadata vocabulary + of Dublin Core ([DUBLIN]) in a WebDAV ([WEBDAV]) server. - This document specifies a standard mapping for using the metadata - vocabulary of Dublin Core ([DUBLIN]) in a WebDAV ([WEBDAV]) server. +3 Introduction -Contents + This document specifies a mapping for using the metadata vocabulary + of Dublin Core ([DUBLIN]) in a WebDAV ([WEBDAV]) server. -STATUS OF THIS MEMO 1 -ABSTRACT 1 -CONTENTS 2 + 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 incompatible ways to + provide this functionality, this document defines a mapping from + Dublin Core element labels into WebDAV property names. -1 INTRODUCTION 2 + The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALLNOT", + "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and"OPTIONAL" in this + document are to be interpreted as described in [MUSTS] . -2 MAPPING 3 +4 Mapping -2.1 NAMESPACE 3 + The approach taken in this mapping is to leverage the RDF encoding + ([DC-RDF]) of Dublin Core. An [RDF] document encoding Dublin Core + data would look something like this: -2.2 PROPERTY NAMES 3 + + + + + + Crocker, David + + + + + -2.3 PROPERTY FORMAT 3 + The mapping defined here works by identifying each subelement of + with a single WebDAV property. Since WebDAV + properties are expressed as XML elements ([XML]), using XML + namespaces ([XMLNS]) allow different groups to define sets of + properties without interfering with each other, the mapping is direct + and one-to-one. In this case, the namespaces being used are + , + , and + , as specified in + [RDF] and [DC-RDF]. To obtain the Dublin Core creator for the + resource , a WebDAV client would + issue a PROPFIND method to the resource, requesting the dc:creator + property: -2.4 SUBELEMENTS 3 + PROPFIND /rfc/rfc822.txt HTTP/1.1 + Host: www.ietf.org + Content-type: text/xml; charset="utf-8" + Content-Length: xxxx -3 INTERNATIONALIZATION CONSIDERATIONS 4 + + + + + + -4 SECURITY CONSIDERATIONS 4 + The response to the request would provide the element, + and all its contents, just as in the RDF document above. -5 IANA CONSIDERATIONS 4 +4.1 Correspondences -6 COPYRIGHT 4 + The following table illustrates the relationship between [DUBLIN] + element names and [WEBDAV] property names. The dc: prefix is assumed + to be mapped to the namespace http://purl.org/dc/elements/1.0/. -7 INTELLECTUAL PROPERTY 5 + Dublin Core element WebDAV property -8 ACKNOWLEDGEMENTS 5 + DC.Title dc:title + DC.Creator dc:creator + DC.Subject dc:subject + DC.Description dc:description + DC.Publisher dc:publisher + DC.Contributor dc:contributor + DC.Date dc:date + DC.Type dc:type + DC.Format dc:format + DC.Identifier dc:identifier + DC.Source dc:source + DC.Language dc:language + DC.Relation dc:relation + DC.Coverage dc:coverage + DC.Rights dc:rights -9 REFERENCES 6 +4.2 Abbreviated Syntax -9.1 NORMATIVE REFERENCES 6 + The Abbreviated Syntax of [DC-RDF] MUST NOT be used in this encoding, + since it requires packing separate properties into a single XML + element, which is incompatible with the DAV property model. -9.1 INFORMATIONAL REFERENCES 6 +4.3 Complications -10 AUTHORS' ADDRESSES 6 + A previous version of this document had some difficulties with + advanced sections of the Dublin Core model. This version addresses + these problems, but it may be useful to enumerate them for future + reference. -1 Introduction +4.3.1 Multivalued Properties - This document specifies a standard mapping for using the metadata - vocabulary of Dublin Core ([DUBLIN]) in a WebDAV ([WEBDAV]) server. + 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. The + previous document defined an ad hoc XML syntax for listing multiple + values, which drew criticism from people who wanted more general + multivalued property support for WebDAV. This document is able to + sidestep the problem because Dublin Core now has its own solution, + and it is not necessary to create a new one. In the above example, if + RFC-822 had multiple authors, the element might contain + an element containing elements. - 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. +4.3.2 Qualification (Subelements) -2 Mapping + When the previous document was written, some members of the Dublin + Core group had plans to support more structure in their metadata, but + had not yet defined a syntax for it. At this time, the debate over + subelements is still not fully resolved, but the syntax in the RDF + encding has been established: to add extra data on a dc: element, one + nests a dcq: element within it, as a qualifier, as in the + element in the RDF example above. -2.1 Namespace +5 Examples - 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. The Dublin Core datamodel group is defining a - namespace for XML tags representing Dublin Core elements; WebDAV - properties should use that same namespace. The - URI currently proposed for that namespace is - . Note that this is - currently only a proposal within the datamodel group; if the Dublin - Core group as a whole picks a different URI, WebDAV should use that - URI. + The examples in this section are based on Example 14 of [DC-RDF], + showing how [WEBDAV] would be used to set and get the properties + presented there. (Note that non-ASCII characters in Example 14 have + been elided for the sake of the ASCII Internet-Draft format.) -2.2 Property Names +5.1 Set with PROPPATCH - A WebDAV property representing a Dublin Core element has the same - name as the Dublin Core element label. +5.1.1 Request -2.3 Property Format + PROPPATCH /metadata/resources/dc/datamodel/WD-dc-rdf/ HTTP/1.1 + Host: www.ukoln.ac.uk + Content-type: text/xml + Content-length: xxxx - 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. The Dublin Core - datamodel group is working on defining an XML DTD for this - representation; WebDAV properties should use that DTD when it is - ready. + + + + + + + + Guidance on expressing the Dublin Core + within the Resource Description Framework (RDF) + Veiledning a uttrykke Dublin Core innenfor + rammen av Resource Description Framework (RDF) + Dublin Core in RDF: Eine Anleitung + + + + + Eric Miller + Paul Miller + Dan Brickley + + + + + This document describes work carried out by + the Data Model Working Group of the Dublin Core Metadata + Initiative. Specifically, the document discusses means by which + the fifteen elements of the Dublin Core (as defined in RFC 2413) + may be expressed using the Resource Description Framework (RDF) + and encoded with the eXtensible Markup Language (XML). RDF-based + mechanisms by which the 15 elements may be qualified are also + introduced. + Dette dokumentet beskriver arbeide utfort av + arbeidsgruppen for datamodellering knyttet til Dublin + Core-initiativet. Spesifikt diskuterer dokumentet hvordan de + femten elementene i Dublin Core (slik disse er definert i RFC + 2413) kan uttrykkes ved hjelp av Resource Description Framework + (RDF) og kodes ved hjelp av eXtensible Markup Language (XML). + Videre introduseres RDF-baserte mekanismer for a kvalifisere de 15 + elementene. + + + Dublin Core; Resource Description Framework; RDF; + eXtensible + Markup Language; XML + Dublin Core Metadata Initiative + Dublin Core Data Model Working Group + + + + WTN8601 + 1999-05-26 + + + + + IMT + text/html + + + + + RFC1766 + en + + + + + + -2.4 Subelements +5.1.2 Response - 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. + HTTP/1.1 200 OK - 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. +5.2 Retrieving a single Dublin Core property with PROPFIND -3 Internationalization Considerations + This example shows how to fetch the DC.Title property. - XML is an inherently internationalizable format, able to express - any language or character set; as a result, all WebDAV properties, +5.2.1 Request + + PROPFIND /metadata/resources/dc/datamodel/WD-dc-rdf/ HTTP/1.1 + Host: www.ukoln.ac.uk Content-type: text/xml; charset="utf-8" + Content-Length: xxxx + + + + + + + + +5.2.2 Response + + HTTP/1.0 200 OK + Content-Type: text/xml + Content-Length: xxxx + + + + + + + Guidance on expressing the Dublin Core + within the Resource + Description Framework (RDF) + Veiledning a uttrykke Dublin Core + innenfor rammen av + Resource Description Framework (RDF) + Dublin Core in RDF: Eine Anleitung + + + + + +5.3 Retrieving multiple Dublin Core properties with PROPFIND + + This example shows how to fetch the DC.Title, DC.Creator, and + DC.Publisher properties in a single request. + +5.3.1 Request + + PROPFIND /metadata/resources/dc/datamodel/WD-dc-rdf/ HTTP/1.1 + Host: www.ukoln.ac.uk Content-type: text/xml; charset="utf-8" + Content-Length: xxxx + + + + + + + + + + +5.3.2 Response + HTTP/1.0 200 OK + Content-Type: text/xml + Content-Length: xxxx + + + + + + + Guidance on expressing the Dublin Core + within the Resource + Description Framework (RDF) + Veiledning a uttrykke Dublin Core + innenfor rammen av + Resource Description Framework (RDF) + Dublin Core in RDF: Eine Anleitung + + + + + + Eric Miller + Paul Miller + Dan Brickley + + + + Dublin Core Metadata Initiative + + + +6 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 +7 Security Considerations The security considerations of this mapping are those of [DUBLIN] plus those of [WEBDAV]. -5 IANA Considerations +8 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 +9 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 + 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. 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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. 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Please address the information to the IETF Executive Director. -8 Acknowledgements +11 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 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 + 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. + Thanks to Liz Parrot for alerting me to the question of subelements. -9 References + Thanks to Paul Miller for clarifying to me how [DC-RDF] handles + multivalued properties. -9.1 Normative References +12 References + +12.1 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. + 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. + [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." RFC 2518. 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. . + [XML] T. Bray, J. Paoli, C. M. Sperberg-McQueen, "Extensible Markup + Language (XML)." World Wide Web Consortium Recommendation + Rec-xml-19980210. . -9.2 Informational References + [RDF] Resource Description Framework Model and Syntax Specification, + February 1999, World Wide Web Consortium Recommendation + Rec-rdf-syntax/. .. - [XMLNS] T. Bray, D. Hollander, A. Layman, "Name Spaces in XML" - World Wide Web Consortium Working Draft, + [DC-RDF] E. Miller, P. Miller, D. Brickley, "Guidance on expressing + the Dublin Core within the Resource Description Framework", May 1999, + http://www.ukoln.ac.uk/metadata/resources/dc/datamodel/WD-dc-rdf/ + + [MUSTS] Bradner, S., "Key words for use in RFCs to Indicate + Requirement Levels," RFC 2119, Harvard University, March 1997. + +12.2 Informational References + + [XMLNS] T. Bray, D. Hollander, A. Layman, "Name Spaces in XML" World + Wide Web Consortium Working Draft, . [GUENTHER] R. Guenther, "Dublin Core Qualifiers/Substructure", . October, 1997. -10 AUTHORS' ADDRESSES +13 Authors' Addresses J. Stracke - Netscape Communications Corporation - 501 E. Middlefield Rd. - Mountain View, CA 94043 - Email: francis@netscape.com + eCal Corp. + 234 N. Columbus Blvd., 2nd Floor + francis@ecal.com