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Lecture 18 Descriptive Metadata: Metadata Models. CS 502: Computing Methods for Digital Libraries. Administration. Metadata Models. Challenge Are there general principles of metadata? Applicable to wide varieties of formats, genres and types.
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Lecture 18 Descriptive Metadata: Metadata Models CS 502: Computing Methods for Digital Libraries
Metadata Models • Challenge • Are there general principles of metadata? • Applicable to wide varieties of formats, genres and types. • Useful for information discovery, collection management, preservation, e-commerce. • Applicable to different creations, versions, etc. • Balance cost against utility
Perceived Problems with Dublin Core Separate metadata elements for Creator, Contributor, and Publisher. Confusion between Genre and Format. Many qualifiers have been proposed for Date. Apparent redundancy of the element "Source". Reasons for the 1:1 relationship between metadata and an information resource.
Creations Work Expression IsRealizedThrough Manifestation IsEmbodiedIn Item IsExemplifiedBy
Agents Person Work Corporate body Expression Manifestation Item Agent or IsOwnedBy IsProducedBy IsRealizedBy IsCreatedBy
Actions Work Expression Manifestation Item Transforms PlaysRoleIn Agent Actions
Actions • Originate • Compile • Excerpt • Reformat • Use • Acquire/relinquish object • Acquire/relinquish rights
Extras Creations may have relations between each other Actions may have time or place Creations may have subjects
Relations References / Is Referenced By to point to other information resources IsBasedOn / IsBasisFor to express intellectual derivation IsVersionOf / HasVersion to express historical evolution Is Format Of / Has Format to identify transformations of media or layout Is Part of / Has Part to record Part/Whole
Relations Is IsMetadataAuthorOf / HasMetadataAuthoredBy to name the creator of the metadata IsDefinitionOf / IsDefinedBy to point to the URI of the definition of the semantics IsOwnerOf/ IsOwnedBy to name the owner/repository with custody of a physical thing
Resolution of Problems with Dublin Core Separate metadata elements for Creator, Contributor, and Publisher. All are Agents related to Works, Expressions, Manifestations or Items. Confusion between Genre and Format. Both are Form, related to either Work/Expression or Manifestation/Item. Many qualifiers have been proposed for Date. A Work, its Expression, a Manifestation and an Item can each have a particular Date. Apparent redundancy of the element "Source". Source is expressed more clearly as a particular Relation.
Unresolved problems 1 • Complex objects • Indecs view is confused between: • single package of material for e-commerce • trails of rights and payments of indefinite complexity • Dublin Core view is limited to: • document-like objects with simple relationships
Unresolved problems 2 • Cost • No system provides useful guidelines to balance cost of metadata against utility • Indecs model of e-commerce requires complex metadata that is not needed for information discovery and other applications • Dublin Core is struggling with the tension between minimalists and structuralists
Unresolved problems 3 • Documentation and training • Both Indecs and Dublin Core will require a detail set of instructions and codes. • Despite many years of effort they are a long way from having such guidelines. • In a rapidly changing world, the guidelines will always be out of date. • The guidelines will need trained people to understand them. The dream of metadata generated by untrained creators and publishers is far away.
Personal Opinion • Metadata is valuable only because it enables specific services • Information discovery (descriptive) • Rendering and display (structural and technical) • Commerce (administrative) • Long-term preservation (descriptive, structural and technical) • All metadata depends on its context • "Author" is: • descriptive metadata for information discovery • administrative metadata for commerce
Personal Opinion • Metadata is expensive • Costs must be balanced against value for specific services • There is no correct place and time to gather metadata • At source v. by cataloguer or indexer • By professional v. automatically • At time of creation v. when needed