CORES Annual Report 2002
The central aim of the CORES project is to support enhancement of semantic interoperability between the various metadata element sets that underlie the Web. CORES is working towards this target firstly by bringing standards makers together in a Standards Interoperability Forum to agree on a common approach to declaring their elements, and secondly by providing implementers with the means to 'publish' information about the element sets in use in their projects and applications.
The project envisions 'core vocabularies' as the basis for shared semantics in the future Web. Such core vocabularies will use a common model for identifying data elements and declaring schemas, and will be shared by means of a distributed network of schemas registries.
Summary of 2002 Activities
The CORES Standards Interoperability Forum brought together major metadata standardisation activities to discuss the practicalities of cross-standard interoperability.
Highlights of the past year included
- Survey to gather the opinions from metadata standardisation initiatives, and umbrella organisations
- Discussion paper for consideration by Standards Interoperability Forum participants
- CORES Resolution on the use of URIs to identify data elements agreed by various standards representatives
The CORES resolution emerged from a meeting of the Standards Interoperability Forum in Brussels, November 2002. The signatories agreed to promote the implementation of this resolution over the next year. The project will be reporting at the project end on the results of cross-standard discussions.
Fig.1: Standards Interoperability Forum, Brussels
Development work has progressed on the CORES Registry and the Schema Creation Tool. The Schema Creation Tool works interactively with a complementary Schema Registry enabling implementers to declare their local application profiles as RDF schemas, and register them in the CORES Registry. The Registry is intended to help implementors of information projects and services find out about metadata terms in use (both official definitions and local variations) thereby encouraging harmonisation of metadata usage within particular fields and applications. Specifications are now available including
- Functional Requirements
- Installation Guide
- Developer's manual
- User's Manual
Over the next few months the project will be evaluating use of these tools in collaboration with the user community.
Work areas
CORES Resolution
The Semantic Web requires an infrastructure of identifiers for data elements, identifiers that are machine-processable by semantic technology tools, and are unique. CORES is promoting the use of URIs for this purpose following recommended practice emerging from the Semantic Web activity within the World Wide Web Consortium. Use of URIs will enable data elements to be cited unambiguously whether in human readable documents or machine-readable schema. For example the Dublin Core element "title" can be cited as "http://purl.org/dc/terms/title".
The text of the CORES Resolution stated that signatories agreed:
Whereas:
our metadata standards have "elements" -- units of meaning comparable and mappable to elements of other standards,
We agree:
to assign Uniform Resource Identifiers to our elements;
to articulate and publish specific policies regarding the stability, persistence, and maintenance of the URIs assigned to the elements.
The resolution was signed by representatives of a number of standards organisations: GILS, ONIX, MARC 21, CERIF, the DOI Foundation, IEEE LTSC, and DCMI.
Wide scale deployment of URIs to identify data elements in this way will facilitate both sharing and re-use of data elements in application profiles, and also creation of instance metadata that identifies data elements in a predictable fashion ensuring the metadata can be understood and re-used by systems across the Web.
CORES Registry and Schema Creation Tool
The variety of new and emerging Web based services and initiatives has led to a proliferation of metadata. Such metadata is based on diverse schemas, and whilst a certain level of diversity is inevitable and allows for differentiation between services, needless duplication and re-invention of schema is not effective. CORES is supporting effectiveness and interoperability in the creation and use of metadata by encouraging sharing of metadata semantics by means of a complementary Schema Creation Tool and Schema Registry.
These complementary tools allow an implementer to search the Registry for suitable existing data elements and, by means of a simple 'drag and drop' mechanism, identify elements to be included in their local schema or application profile. The Registry will be populated with terms from well-known metadata element sets such as the Dublin Core and IEEE LOM.
The CORES Registry and Schema Creation tool both use the same data model, based on work carried out in previous European projects DESIRE and SCHEMAS, and developed in association with related efforts in the MEG Registry project and the DCMI Registry work. Both tools will describe elements by means of machine-understandable schemas, using the conventions of the Resource Description Framework (RDF). The CORES Schema Creation Tool enables the managers of metadata vocabularies to construct schemas by providing information on the terms they declare and on the terms they reuse from existing vocabularies. The tool generates a schema which can be submitted to the CORES Schema Registry and may also be saved locally as an RDF/XML file for use by other applications. The Schema Creation Tool is intended for use by information workers, project staff, system implementers or others who are familiar with the requirements for metadata within their system. The schema creation tool is designed so that users do not have to have expertise in the underlying RDF schema specification.
Fig. 2: Simplified data model for CORES tools
Future Work
The CORES Schema Creation/Registration Workshop, SZTAKI, Budapest, 6-7 March 2003 will provide an introduction to the use of RDF to describe metadata vocabularies in the form of machine-understandable schemas. Practical sessions will allow participants to learn to use the CORES Schema Creation Tool to prepare schemas and submit them to the Registry, and to navigate the schemas submitted via the Registry's Web interface.
The aims of the workshop are:
- to provide a brief introduction to RDF and specifically to the use of RDF to describe metadata vocabularies;
- to introduce the CORES Registry data model: the classes of resource described, their attributes and relationships, and their representation using RDF;
- to allow participants to use the CORES Schema Creation Tool to create and register schemas;
- to allow participants to navigate schemas via the CORES Registry HTML interface and via some other tools;
- to explore the effectiveness of the CORES data model for representing a variety of vocabularies;
- to evaluate the functionality of the CORES Schema Creation Tool.
Further Information
Further information is available from the project web site see http://www.cores-eu.net