Modularization and Interoperability: Dublin Core and the Warwick Framework Sandra D. Payette Digital Library Research Group Cornell University November 19, 1997

Dublin Core: Motivations Problems with resource discovery –full-text indexing ineffective (false hits, irrelevancy, overload) –full-text approaches not useful for non-textual data (e.g., audio, video, executable programs) Impracticality of traditional cataloging on large scale –time consuming, labor intensive, special skills –limited coverage - only “selected” items

Dublin Core: Intentions Description of networked objects (document-like) Simple, yet usable, set of elements Facilitate automated indexing to support networked resource discovery Enable authors and maintainers to provide metadata without specialized skills

Dublin Core Metadata Element Set Title name given to the work by the author Author or Creator person(s) responsible for the intellectual content Subject and Keywords the topic of the work, keywords, or formal classification schemes Description textual description of the content (abstract, prose describing an image, etc.) Publisher the organization making the work available in its present form Other Contributor person(s) other than the author who have made significant contributions to the intellectual content Date the date the work was made available Resource Type category of the resource Format Data representation of the resource Resource Identifier Unique Identification string (e.g. URL, URN, ISBN...) Source object from which this object is derived (if applicable) Language language of the intellectual content of the object Relation relationship of the object to other objects or collections Coverage spatial locations and temporal duration characteristics Rights Management a pointer to a copyright notice, a rights management statement, or a rights server.

Warwick Workshop Dublin Core issues acknowledged: Semantics and Syntax Trade-offs –Loosely-defined “Core” vs. standards requirements –Rich semantics (more elements) vs. ease of use –Less definition of syntax vs. high interoperability “Core” restricted to descriptive data elements –excludes rights management, administrative, structural, and other specialized metadata What about “Core’s” relationship to other emerging metadata schemes

Warwick Workshop : Goals Semantic interoperability –cross-disciplinary –multi-lingual Promote interoperability among: – content providers – catalogers and indexers – automated resource discovery systems

Warwick Framework A larger framework for Dublin Core that allows for : Co-existence –DC can co-exist, be combined with, and complement others sets of metadata Community-specific standards –Groups/communities can develop and maintain standard metadata sets that serve their unique needs. Consistency –Metadata of different types can be handled consistently Growth/extensibility –New and emerging metadata schemes can be incorporated –Framework transcends existing networked infrastructure

Warwick Framework: Container Architecture Containers –an entity for aggregating multiple sets of metadata (packages) Packages –typed sets of metadata that are either logically or physically distinct General principles: –one container operation: return a sequence of contained packages –packages are opaque at the container level –access to package contents subject to terms and conditions

Metadata Container Container Package Dublin Core Package MARC record Package Indirect Reference Package Terms and Conditions URI Typed Metadata Set Indirect Package

Warwick Framework: Modularity Promotes Interoperability Away from monolithic universals Value in components that can be interpreted and can work together in common framework

Implementing the Warwick Framework How can a Warwick container be associated with a content object? –Embed in document (RDF/XML, HTML META tags) –External to document and supplied by transport mechanism during resource retrieval (RDF) –Link to from within document (e.g., HTML) –Component of a Digital Object in a distributed object repository architecture (e.g. CORBA)

Back to the Dublin Core So why create Dublin Core records if I can create my own metadata package?

Dublin Core Records as “Anchors” Dublin Core is good bet for a “baseline descriptive package” that can be supplemented by other specialized packages in a container 15 fundamental descriptive elements that can be the common ground for discovery across disparate resources Dublin Core records are flexible through qualifiers

Dublin Core Qualifiers Scheme Language Type (note RDF work on extending the Dublin Core in particular)

Proposed Dublin Core Qualifiers Subject: LCC (Library of Congress Classification) LCSH (Library of Congress Subject Headings) NLM (National Library of Medicine Classification) MeSH (Medical Subject Headings Identifier: (URL is default) URN (Uniform Resource Name) ISBN (International Standard Book Number) ISSN (International Standard Serial Number) SICI (Serial Item and Contribution Identifier) SCHEME: a formal data content standard to refine the meaning of an element’s data, for example: Source: Rebecca Guenther, The Qualifiers Proposal (

Proposed Dublin Core Qualifiers Author: DC.Creator (unqualified) DC.Creator.PersonalName DC.Creator.CorporateName Date: DC.Date.Creation_of_intellectual_content DC.Date.Creation/Modification_of_present_form DC.Date.Formal_publication TYPE : a sub-element used to refine the definition of an element itself, for example: Source: Rebecca Guenther, The Qualifiers Proposal (

Learning Objects in the Warwick Framework URN 2 Dublin Core Record Package 1Package 2 Package 3Package 4 LOMG Access Control Record LOMG Content Record URN 2 MARC Record URN 1

Extending Warwick to Repository Architectures Data and metadata are indistinguishable at the architectural level –both are intellectual content –both are first-class objects Digital Objects are aggregations of content packages Relationships can be first-class objects

Implementations in Progress Collaborative effort on CORBA based distributed repository architecture: –Cornell (FEDORA) –CNRI –LANL Reference: Lagoze, Carl and Daniel, Ron Jr., “Extending the Warwick Framework: From Metadata Containers to Active Digital Objects”, D-lib Magazine, November 1997

Relationships between Distributed Objects Relationship Package Dublin Core Record “Content” Package Access Control List P0P0 P1P1 P2P2 P3P3 R 0 : (bibliographic-description P 1 P 2 ) R 1 : (access-rules P 3 P 2 ) R 2 : (MARC-record URN 1 #P 1 P 2 ) R0R0 R1R1 MARC Record Other Package P0P0 P1P1 R2R2 URN 1

Questions?