XML Schemas for Dublin Core Metadata Pete Johnston, UKOLN, University of Bath DC Architecture WG Meeting, DC-2004, Shanghai, China, Wednesday 13 October 2004 http://www.ukoln.ac.uk/

XML Schemas for Dublin Core Metadata Guidelines for Encoding DC in XML Conventions for representing DC metadata in XML Two sets of schemas Simple DC only (simple content model, used by OAI-PMH oai_dc schema) Qualified DC (more flexible content model, used by various implementers) Versioning Container elements The “simpleLiteral” type Abstract Model

Versioning Terms are continually added to the DCMI metadata vocabularies as result of Usage Board decisions DC Terms vocabulary DCMI Type Vocabulary (?) Requires changes to corresponding XML Schema to provide XML component declaration XML Schema used for structural validation Change to XML Schema may change validity of instance e.g. <dcterms:provenance> XML element invalid on Friday night, valid on Monday morning

Versioning Currently Request to be able to reference “latest version” URLs of all XML Schemas include datestamp User references specific version Must change references to access new version Request to be able to reference “latest version” Proposal Make available both “latest version” and “date-stamped” versions Impact Applications choose which to reference N.B. Must manage expectations re validation accordingly

Container XML elements DC-in-XML Guidelines do not require use of specific XML container element Applications choose XML container element Request to provide container XML element(s) associated with DCMI XML Namespace Proposal Provide container XML elements corresponding to description and description set in DCMI Abstract Model Question Separate container XML elements for Simple DC description and Qualified DC description? Or same XML element with different content models? What XML Namespace should be used? Also N.B. DC-in-XML doc adopts more restrictive notion of Qualified DC than DCMI AM

SimpleLiteral Datatype dc:SimpleLiteral complexType defined so as to provide flexibility Derive types based on simpleContent Derive types based on complexContent (with child elements) Derivation of complexType with simpleContent from complexType with complexContent allowable in XML Schema But not supported by some parsers/processors Questions from implementers Some implementers do make use of derived types based on complexContent

DC-in-XML Guidelines and DCMI Abstract Model (Not strictly a “schema issue”!) DC-in-XML guidelines pre-date DCMI Abstract Model Based on a simpler model of a DC metadata description Do not support resource URIs value URIs rich values related descriptions resource class URIs Value strings sometimes being interpreted as value URIs

DC-in-XML Guidelines and DCMI Abstract Model Either Accept/emphasise current limitations Or Decide which features of DCMI AM should be supported in syntax Revise syntax accordingly (e.g. to distinguish value strings and value URIs) Produce new set of schemas

Acknowledgements UKOLN is funded by the UK Museums, Libraries and Archives Council (MLA), the Joint Information Systems Committee (JISC) of the UK higher and further education funding councils, as well as by project funding from the JISC and the European Union. UKOLN also receives support from the University of Bath where it is based. http://www.ukoln.ac.uk/

XML Schemas for Dublin Core Metadata Pete Johnston, UKOLN, University of Bath DC Architecture WG Meeting, DC-2004, Shanghai, China, Wednesday 13 October 2004 http://www.ukoln.ac.uk/