Expressing Simple Dublin Core™ in RDF/XML

1.Introduction and Goals

The Dublin Core™ Metadata Element Set V1.1 (DCMES) [DCMES] can be represented in many syntax formats. This document gives an encoding for the DCMES in XML[XML-SPEC] using simple RDF[RDFMS], provides a DTD and XML Schema[XMLSCHEMA] to validate the documents and describes a method to link them from web pages.

This document describes an encoding for the DCMES in XML subject to these restrictions:

• The Dublin Core™ elements described in the DCMES V1.1 reference can be used
• No other elements can be used
• No element qualifiers can be used
• The resulting RDF/XML cannot be embedded in web pages

The primary goal for this document is to provide a simple encoding, where there are no extra elements, qualifiers, optional or varying parts allowed. This allows the resulting data to be validated against a DTD and guaranteed usable by XML parsers. A secondary goal was to make the encoding also be valid RDF[RDFMS] which allows the document to be manipulated using the RDF model. We have tried to limit the RDFconstructsto the minimum, and the result is a standard header and footer for every document.

我们承认,将有进一步的文档s describing other encodings for DC without these restrictions however this one is for the simplest possible form. One result of the restrictions is that the encoding does not create documents that can be embedded in HTML pages. Please refer toExpressing Qualified Dublin Core™ in RDF / XML[DCQ-RDF-XML] for the details of expressing the full DC in RDF/XML.

This document is based on previous work such as [EM-DTD], [CIMI-XML-TB] and [CIMI-DC-DTD].

2.An Encoding of Dublin Core™ in XML

This section describes step by step, this method of how to create a document for the DCMES in XML.

2.1.XML declaration

Any well-formed XML document must include a statement of the version of XML used (and content encoding). At present, the only valid version of XML, as defined in the W3C Recommendation, is 1.0. Thus the document must start with

on the first line.

2.2.Referencing the XML DTD

2.3.Declaring the use of RDF

It is necessary to declare that RDF[RDFMS] is being used so that applications can recognise this is an RDF/XML document. This declares the outerrdf:RDFcontaining tag with its XML namespace and the XML namespace for the DCMES elements.

2.4.Describing the resources

This encoding can describe multiple resources in a single document. Each resource described is enclosed in a container element, a pair ofrdf:Descriptiontags. Resources may have no, one or several identifiers and some of these may be URIs.

If a resource has at least one URI, the most appropriate one should be used as the value of therdf:aboutattribute of therdf:Descriptiontag like this:

 ... 

Inside therdf:Descriptioncontainer, put each of the Dublin Core™ elements with thedc:namespace prefix before it, so for example theTitleelement becomesdc:titleall in lowercase and used inside therdf:Descriptioncontainer like this:

 My Home Page 

This can be repeated for all other DCMES elements that are needed with the standard Dublin Core™ guidelines - all elements are repeatable and optional. Note that there is no requirement on applications consuming this document to preserve the order of elements in the container and therefore you should not expect this to be preserved.

If the value of the Dublin Core™ element is a resource which has a URI rather than plain text, it should be recorded in the value of therdf:resourceattribute on the tag, with empty tag content. For example, if the value of thesourcewas a URI, it would be recorded like this:

There may be more than oneIdentifierelement for the resource containing URIs or other identifiers. If a URI identifier is available and appropriate to use, it should be made the value of therdf:aboutattribute of therdf:Descriptionelement as described above. The otherIdentifier编码的元素值应该在同一个曼勒r as the other elements as described below. Here is a fragment of a description of a book which has a non-URI identifier:

 Internet Ethics Duncan Langford Book ISBN 0333776267 

It may be that there is no identifier for the resource, in which case neither of the above methods should be used and both therdf:aboutattribute andIdentifierelement left out. This is used something like this:

 The Mona Lisa A painting by ... 

2.5.Language and character encoding

XML provides anxml:langattribute that can be used on any element. This provides a way to describe the language used for thecontentof the element. The DCMES provides aLanguageelement which is used to describe the language of theresource.

The values of the elements and attributes will need to be encoded using the rules of XML when there are special characters in the value. The special characters that need to be encoded, and when they need to be are summarised here for reference:

XML Encoding Required in   & &amp; Element and attribute values   < &lt; Element and attribute values   > &gt; Element and attribute values   ' (apostrophe / single quote) &apos; Attribute values   " (double quote) &quot; Attribute values    

注意”和“只需要用于those characters inside attribute values, which are only needed for therdf:resourceattribute (see Section 2.4) and thexml:langattribute (see Section 2.5).

All other characters outside the core US-ASCII range of 32-126 shouldnotbe encoded with the HTML entities such as é since these are not defined in XML. Numeric entities for the characters should be used which are written as &#ddd; in decimal or ઼ in hexadecimal. Alternatively they can be encoded as Unicode in one of the formats such as UTF-8 which is widely supported.

2.6.Finishing off the document

The final thing that needs to be done is to close therdf:RDFelement opened at the top of the document by adding the following line:

3.Examples (For Information Only)

    Dave Beckett's Home Page Dave Beckett ILRT, University of Bristol 2000-06-06  

     
 
 
 
Example 2
 
 
 

         
    Dublin Core™ Metadata Initiative - Home Page The Dublin Core™ Metadata Initiative Web site. 1998-10-10 text/html en The Dublin Core™ Metadata Initiative  L'Initiative de métadonnées du Dublin Core der Dublin-Core Metadata-Diskussionen  
         
 
 
 
 

4.Linking to Dublin Core™ metadata in XML from HTML

Dublin Core™ encoded in the method described here can be referred to from an HTML document and associated with it by means of the HTMLelement. The recommended relation type for this purpose isrel="meta", used like this:

wheremydoc.dcxmlis the URI of the XML document being refered to. This is described inEncoding Dublin Core™ Metadata in HTML[DC-HTML].

Appendix A- DTD for Simple Dublin Core™ Metadata Element Set 1.1 in RDF/XML (For Information Only)

This section is for information only and not part of the standard.

The URI for this DTD is//www.voudr.com/specifications/dublin-core/dcmes-xml/2002-04-22/dcmes-xml-dtd.dtd

Appendix B- XML Schema for Simple Dublin Core™ Metadata Element Set 1.1 in RDF/XML (For Information Only)

This section is for information only and not part of the standard.

The URI for this XML Schema is//www.voudr.com/specifications/dublin-core/dcmes-xml/2002-04-22/dcmes-xml-xsd.xsd

     XML Schema 2000-12-01 for Dublin Core™ Metadata Element Set version 1.1 //www.voudr.com/specifications/dublin-core/2000/11/dcmes-xml/dcmes-xml-xsd.xsd by Dave Beckett[email protected]看到一个XML编码的简单都柏林核心™Metadata - 2000-12-01 //www.voudr.com/specifications/dublin-core/2000/11/dcmes-xml/ Based on Dublin Core™ Metadata Element Set, Version 1.1: Reference Description //www.voudr.com/specifications/dublin-core/rec/dces-19990702.shtml This schema is INFORMATIVE and not part of the standard. It has passed the http://www.w3.org/2000/09/webdata/xsv validator for XML Schema 20000922 version as of 2001-03-14 Converted using the dtd2xsd.pl script posted to xml-dev http://lists.xml.org/archives/xml-dev/200101/msg00481.html      Get access to the xml: attribute groups for xml:lang as declared on various elements below       Get access to the XML Schema 2000-10-24 draft definitions      Get access to the RDF Model and Syntax 1999-02-22 definitions                                                                                                

References

[DCMES]Dublin Core™ Metadata Element Set, Version 1.1: Reference Description
//www.voudr.com/specifications/dublin-core/dces/1999-07-02/

[XML-SPEC]Extensible Markup Language (XML) 1.0, W3C Recommendation, 10 February 1998
http://www.w3.org/TR/REC-xml

[EM-DTD]DTD's for the Dublin Core™ Element Set, Eric Miller
//www.voudr.com/specifications/dublin-core/dcmes-xml/2002-04-22/dcmes-xml-dtd.dtd

[DCQ-RDF-XML]Expressing Qualified Dublin Core™ in RDF / XML : Stefan Kokkelink and Roland Schwänzl, DCMI Proposed Recommendation,//www.voudr.com/specifications/dublin-core/dcq-rdf-xml/2002-04-14/(latest version)

[DC-HTML]Encoding Dublin Core™ Metadata in HTML: John Kunze, DCMI, December 1999, RFC 2731,http://www.ietf.org/rfc/rfc2731.txt.

[CIMI-XML-TB]The use of XML as a transfer syntax for museum records during the CIMI Dublin Core™ test bed : some practical experiences, Bert Degenhart Drenth
MS Word (no non-proprietary format available):http://www.cimi.org/wg/xml_spectrum/XML_for_DC_testbed_rev.doc

[CIMI-DC-DTD]CIMI Dublin Core™ DTD
MS Word (no non-proprietary format available):http://www.cimi.org/public_docs/CIMI-DC-DTD_210400.doc

[RDFMS]Resource Description Framework (RDF) Model and Syntax Specification, W3C Recommendation, 22 February 1999http://www.w3.org/TR/REC-rdf-syntax

[XMLSCHEMA]XML Schema, W3C Recommendation, 2 May 2001http://www.w3.org/TR/xmlschema-1/