1 CS 502: Computing Methods for Digital Libraries Lecture 17 Descriptive Metadata: Dublin Core

2 Administration Wireless network Expanded to Willard Straight Discussion classes Regular schedule continues tomorrow -- sessions at 7:30 and 8:30. Assignment 3 Testing your ability to evaluate evidence

3 Descriptive metadata Information discovery is often most effective when applied to metadata rather than raw information Allows fielded searching author = "Goethe" Suitable for non-textual material type = "picture" and subject = "Ithaca" Can be used with controlled vocabulary language = "en"

4 Dublin Core Simple set of metadata elements for online information 15 basic elements intended for all types and genres of material all elements optional all elements repeatable Developed by an international group chaired by Stuart Weibel since 1995

5 Dublin Core elements 1. Title The name given to the resource by the creator or publisher. 2. Creator The person or organization primarily responsible for the intellectual content of the resource. For example, authors in the case of written documents, artists, photographers, or illustrators in the case of visual resources. 3. Subject The topic of the resource. Typically, subject will be expressed as keywords or phrases that describe the subject or content of the resource. The use of controlled vocabularies and formal classification schemes is encouraged.

6 Dublin Core elements 4. Description A textual description of the content of the resource, including abstracts in the case of document-like objects or content descriptions in the case of visual resources. 5. Publisher The entity responsible for making the resource available in its present form, such as a publishing house, a university department, or a corporate entity. 6. Contributor A person or organization not specified in a creator element who has made significant intellectual contributions to the resource but whose contribution is secondary to any person or organization specified in a creator element (for example, editor, transcriber, and illustrator).

7 Dublin Core elements 7. Date A date associated with the creation or availability of the resource. 8. Type The category of the resource, such as home page, novel, poem, working paper, preprint, technical report, essay, dictionary. 9. Format The data format of the resource, used to identify the software and possibly hardware that might be needed to display or operate the resource. 10. Identifier A string or number used to uniquely identify the resource. Examples for networked resources include URLs and URNs.

8 Dublin Core elements 11. Source Information about a second resource from which the present resource is derived. 12. Language The language of the intellectual content of the resource. 13. Relation An identifier of a second resource and its relationship to the present resource. This element permits links between related resources and resource descriptions to be indicated. Examples include an edition of a work (IsVersionOf), or a chapter of a book (IsPartOf).

9 Dublin Core elements 14. Coverage The spatial locations and temporal durations characteristic of the resource. 15. Rights A rights management statement, an identifier that links to a rights management statement, or an identifier that links to a service providing information about rights management for the resource.

10 Dublin Core with Meta Tags

11 Qualifiers Element qualifier Example: Date DC.Date -> Created: DC.Date -> Issued: DC.Date -> Available: / DC.Date -> Valid: /

12 Dublin Core with qualifiers Digital Libraries and the Problem of Purpose David M. Levy Corporation for National Research Initiatives January 2000 article /january2000-levy English Copyright (c) David M. Levy

13 Qualifiers Value qualifiers Example: Subject DC.Subject -> DDC: DC.Subject -> LCSH: Digital libraries-United States

14 Limits of Dublin Core Complex objects Article within a journal A thumbnail of another image The March 28 final edition of a newspaper

15 Flat v. linked records Flat record All information about an item is held in a single Dublin Core record, including information about related items convenient for access and preservation information is repeated -- maintenance problem Linked record Related information is held in separate records with a link from the item record less convenient for access and preservation information is stored once Compare with normal forms in relational databases

16 Dublin Core with flat record extension Continuation D-Lib Magazine

17 Events Version 1 New material Version 2 Should Version 2 have its own record or should extra information be added to the Version 2 record? How are these represented in Dublin Core

18 Minimalist versus structuralist Minimalist 15 elements, no qualifiers, suitable for non-professionals encourage creators to provide metadata Structuralists 15 elements, qualifiers, RDF, detailed coding rules will require trained metadata experts

19 Personal opinion Dublin Core is a simple way to describe digital content that: is a single, self-contained object ("document-like") is static with time has few relationships Some web sites satisfy these criteria Dublin Core is not suitable for digital content that: is heavily structured changes dynamically

20 Dublin Core in many languages See: Thomas Baker, Languages for Dublin Core, D-Lib Magazine December 1998,