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Metadata Interaction, Integration, and Interoperability

NISO Workshop: Metadata Practices on the Cutting Edge, May 20, 2004, Washington, DC. Metadata Interaction, Integration, and Interoperability. William E. Moen <wemoen@unt.edu> School of Library and Information Sciences Texas Center for Digital Knowledge University of North Texas Denton, TX 72603.

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Metadata Interaction, Integration, and Interoperability

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  1. NISO Workshop: Metadata Practices on the Cutting Edge, May 20, 2004, Washington, DC Metadata Interaction, Integration, andInteroperability William E. Moen<wemoen@unt.edu>School of Library and Information SciencesTexas Center for Digital KnowledgeUniversity of North TexasDenton, TX 72603

  2. Overview • The problem space • Interoperability and communities • Mechanisms to address interoperability NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  3. Is there a problem? • Many metadata schemes and element sets • Well known & documented • Less known and little public documentation • Similar/same content described by different metadata schemes and vocabularies • No canonical metadata record for an object • Varied syntaxes for encoding metadata • No canonical syntax • A vital and diverse metadata ecology! • No problem, unless…. NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  4. Metadata in the networked environment • Interaction between systems that use metadata • Harvesting • Searching • Integrating different types of metadata for local information management • Technical metadata for digital asset mgmt • Reusing metadata in local applications • ONIX metadata in library systems • Interoperability? NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  5. Importance of interoperability Systems and organizations will interoperate One should actively be engaged in the ongoing process of ensuring that the systems, procedures and culture of an organisation are managed in such a way as to maximise opportunities for exchange and re-use of information, whether internally or externally. Paul Miller, 2000 Metadata interoperability has to be the underlying principle of networked information management. Marcia Lei Zeng, 2001 NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  6. Interoperability System-oriented definition: • The ability of two or more systems or components to exchange information and use the exchanged information without special effort on either system User-oriented definition: • The condition achieved when two or more technical systems can exchange information directly in a way that is satisfactory to users of the systems (AAP) NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  7. Interoperability factors • In the context of networked information retrieval • Multiple and disparate systems (operating systems, information retrieval systems, etc.) • Multiple protocols • Multiple formats of data • Multiple metadata schemes • Multiple vocabularies, ontologies, disciplines • Multiple languages • Multiple character sets NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  8. Preliminary framework for interoperability • In the context of networked information retrieval • Within and across communities • Information communities/Communities of practice • Focal community • Extended community • Extra community • Costs to achieve interoperability vary NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  9. Interop Among and Across Communities Extra Community Extended Community (e.g., Cultural Heritage) Focal Community (e.g., Geospatial ) Focal Community (e.g., Libraries) Focal Community (e.g., Archives) Extended Community Focal Community (e.g., Geospatial) Focal Community (e.g., Museum) Focal Community (e.g., Natural HistoryMuseums) NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  10. Communities • Communities of practice (Wenger) • Network of professionals • work on common problems • speak a common language • share similar values • produce shared meanings • Information communities • Looser affiliation of people • creators • information managers • users • Membership in multiple information communities NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  11. Rust’s people & stuff (& agreements) model Create People Stuff Manage Use • People creating stuff for specific information community; stuff used by multiple communities • People managing stuff within context of community of practice • Different communities of practice interested in same stuff NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  12. Cost of acceptance Few adopters Many adopters Functionality Interoperability cost vs. functionality • Adoption of common standard • low cost with low functionality • higher functionality but with a greater cost of adoption • No best point on the curve – every point is optimal for some purpose Arms, et al., 2002 NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  13. So we have … • Many metadata schemes and element sets • Similar/same content described by different metadata schemes and vocabularies • Varied syntaxes for encoding metadata • Which reflect: • Community practices, needs, meaning • Cost barriers to adopting common standards • Lack of knowledge of available standards • Not invented here syndrome NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  14. Mechanisms for addressing interoperability • Crosswalks and mapping • Application profiles • Registries • Resource Description Framework (RDF) NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  15. Mapping and crosswalks • Mapping: Intellectual activity that identifies semantically equivalent elements in different metadata schemes • Crosswalk: Documentation resulting from mapping showing the equivalencies and conversion specifications • 1998 NISO White Paper on Crosswalks Unfortunately, the specification of a crosswalk is a difficult and error-prone task requiring in-depth knowledge and specialized expertise in the associated metadata standards St. Pierre & LaPlant, 1998 NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  16. Mapping issues • Semantic, structural, and data conversion • One-way or reversible mappings? • Mapping between any two elements: • One-to-one • One-to-many (repeatable elements; unique more narrowly defined elements) • Many-to-one (complete mapping; incomplete mapping) • One-to-zero (no semantically equivalent element) • Data conversion • From less inclusive to more inclusive format • From uncontrolled to controlled vocabulary Correct and efficient mapping of metadata elements among various formats is the essential condition for ensuring metadata interoperability Zeng & Xiao, 2001 NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  17. Mapping to an interoperable core • OCLC Office of Research’s Metadata Switch Project • Experimental modular services that add value to metadata • Metadata Schema Transformation Web Service (Godby, et al., 2003) • An interoperable core • Translations between metadata standards via mapping to and from the core • Reducing the number of separate mappings between metadata standards • Design of the interoperable core is an open issue NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  18. Application profiles • Reuse of elements from different sets, but cannot define new elements • Specify permitted schemes (e.g., date/time formats, controlled vocabulary) for data values • Can refine standard definitions Application profiles consist of data elements drawn from one or more namespace schemas combined together by implementors and optimised for a particular local application. Heery & Patel, 2000 By defining application profiles and, most importantly by declaring them, implementers can start to share information about their schemas in order to inter-work with wider groupings. Heery & Patel, 2000 NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  19. Registries The term "registry" covers a broad range of databases, documentation services, or Web-based portals providing access to schemas. • Metadata registry: • An index of metadata terms, official definitions, local variations extensions • Can enable the reuse of existing elements rather than users/communities reinventing their own • UK Schemas Project: Includes registry of several metadata element sets • EU Cores Project: Includes registry of core vocabularies and profiles; a schema creation tool and Web interface to register schemas • Dublin Core Metadata Registry: Authoritative source for DC; Designed to promote the discovery and reuse of exiting metadata definitions; Baker, et al., 2001 Almost universally, registries are seen as our best hope in the medium term for a scalable solution to the problem of mapping and translating between a diversity of schemas. Baker, et al., 2001 NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  20. Resource Description Framework (RDF) • Provides a basic grammar for representing metadata terms, their semantics, relationships, etc. • Use of Uniform Resource Identifiers (URIs) to identify namespace schemas where terms are declared and defined • RDF Schemas and XML Schemas, see: • Heery & Johnston, 2003 • Hunter and Lagoze, 2001 • Baker, et al., 2001 • SchemaWeb: gathers information about schemas published on the web NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  21. Metadata interoperability? • In this context, interoperability means • Effective reuse and integration of existing metadata from various sources • Ability to discover and act on authoritative specifications of metadata vocabularies • Support for interaction with one or more metadata sets created for other communities • The diverse metadata ecology presents challenges but reflects real-world needs of diverse information communities NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  22. References • Application Profiles: Mixing and Matching Metadata Schemas. Heery & Patel. 2000. • http://www.ariadne.ac.uk/issue25/app-profiles/ • Combining RDF and XML Schemas to Enhance Interoperability Between Metadata Application Profiles. Hunter & Lagoze. 2001. • http://archive.dstc.edu.au/RDU/staff/jane-hunter/www10/paper.html • CORES Project: A Forum on Share Metadata Vocabularies • http://www.cores-eu.net/ • The Dublin Core Metadata Registry • http://www.dublincore.org/dcregistry/ • Issues in Crosswalking Content Metadata Standards. St. Pierre & LaPlant. 1998 • http://www.niso.org/press/whitepapers/crsswalk.html • Mapping Metadata Elements of Different Formats. Zeng, M. L. & Xiao, L. 2001. • A Metadata Registry for the Semantic Web. Heery & Wagner. 2002. • http://www.dlib.org/dlib/may02/wagner/05wagner.html NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

  23. References • Metadata Schema Registries in the Partially Semantic Web: The CORES Experience. Heery & Johnston. 2003. • http://www.oclc.org/research/projects/mswitch/default.htm • Metadata Switch Project. OCLC. 2004. • http://www.oclc.org/research/projects/mswitch/default.htm • SCHEMAS Project: Forum for Metadata Schema Implementers • http://www.schemas-forum.org/ • SchemaWeb. • http://www.schemaweb.info/default.aspx • A Spectrum of Interoperability. Arms, et al. 2002 • http://www.dlib.org/dlib/january02/arms/01arms.html • Two Paths to Interoperable Metadata. Godby, et al. 2003. • http://www.siderean.com/dc2003/103_paper-22.pdf • What Terms Does Your Metadata Use? Application Profiles as Machine-Understandable Narratives. Baker, et al. 2001. • http://jodi.ecs.soton.ac.uk/Articles/v02/i02/Baker/ NISO Workshop: Metadata Practices on the Cutting Edge -- May 20, 2004 -- Washington, DC

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