Metadata lecture 5 part 2


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  • Really just a brief overview of it, pointing out highlights of the system
  • These terms are identified in Chapter 8, MAL Problems: some elements are ambiguous or overlap: creator and contributor. Is the creator the one who created the digital object or the original print version? (Problem with multiple versions) This is easily dealt with in the library community/AACR2, but in the web environment there is no authority (other than Dc) and the system has been simplified for a purpose.
  • The first three greatly simplify the metadata creation process (as opposed to AACR2/MARC, which specifiies these aspects for many, many fields). Could create metadata with only title, or with only title and creator. Repeatability also enables elements to be used for somewhat different purposes (as in both title and parallel title being recorded in two title elements. Extensible: ability to apply the core element set to various circumstances by extending the meaning of elements through the use of qualifiers International in scope: translated into several other languages; can be used in other languages because of its simplicity
  • Point out: encoding schemes can be identified by use of the attribute “scheme” (see DCMIType) element refinement can be done via “dot” representation (see 2003 for date created)
  • Last point: metadata not always embedded in documents, sometimes exist as separate records. For these purposes XML is the exchange syntax of choice
  • Namespace: set of values defined by a metadata scheme
  • Example of 2 nd : OSU’s digitial library collections (which we saw earlier in class) Example of last: Open Archives Institute’s protocol for metadata harvesting
  • Metadata lecture 5 part 2

    1. 1. Dublin Core and DigitalCollectionsMarch 18, 2013Richard Sapon-White 1
    2. 2. Overview Dublin Core (DC) History Elements, Principles and Qualifiers Syntax Uses Digital Collections and DC Discussion of DC and Controlled Vocabularies 2
    3. 3. DC History 2nd International WWW Conference, Chicago, 1994 1st Dublin Core Workshop, OCLC headquarters, Dublin, Ohio, USA Development by Dublin Core Metadata Initiative – 3
    4. 4. DC History Rapid increase in the number of WWW resources Problem: retrieval of relevant documents Solution: a metadata schema that is Simple enough for resource creators to use Flexible enough to allow for more detailed description Not restricted to any one exchange syntax 4
    5. 5. Fifteen DC Elements Identifier Language Source Relation Rights Coverage Format Type Publisher Description Date Contributor Subject Title Creator 5
    6. 6. Characteristics of the DublinCore •All elements are optional •All elements are repeatable •Elements may be displayed in any order •Extensible •International in scope 6
    7. 7. Dublin Core Principles Dumb-Down One-to-One Appropriate Values 7
    8. 8. Dumb-Down The fifteen core elements are usable with or without qualifiers Qualifiers make elements more specific: Element Refinements narrow meanings, never extend Encoding Schemes give context to element values If software encounters an unfamiliar qualifier, look it up –or just ignore it! 8
    9. 9. The One-to-One Principle • Describe one manifestation of a resource with one record Example: a digital image of the Mona Lisa is not described as if it were the same as the original painting • Separate descriptions of resources from descriptions of the agents responsible for those resources Example: email addresses and affiliations of creators are attributes of the creator, not the resource 9
    10. 10. Appropriate Values “Best practice for a particular element or qualifier may vary by context, but in general an implementer cannot always predict that the interpreter of the metadata will always be a machine. This may impose certain constraints on how metadata is constructed, but the requirement of usefulness for discovery should be kept in mind.”--from Using Dublin Core by Diane Hillman 10
    11. 11. Qualified Dublin Core Includes: Additional element: Audience Element Refinements Value Encoding Schemes 11
    12. 12. Element Refinements Make element meanings narrower, more specific: a Date Created versus Date Modified an Is Replaced By versus Replaces Relation Depending on syntax chosen, refinements may appear as stand-alone tags instead of with elements: <dct:created>2002-10-04</dct:created>,instead of: <dc:date><dct:created>2002-10-04 </dct:created></dc:date> •Requires a schema to dumb-down Date Created to Date Dublin Core is simple enough to support both usages 12
    13. 13. Encoding Metadata Records Mid-1990s: HTML tags embedded in Web pages Simple, easy to deploy, but inflexible, hard to maintain Bad tags like DC.Creator.eyecolor imply a non- existent support for nesting and for entity distinctions 2000+: Better XML/RDF alternatives RDF metadata supports complex structures without breaking simple DC grammar Open Archives Initiative promotes mass adoption of an XML schema for simple, unqualified Dublin Core records - along with a protocol to make them available 13
    14. 14. HTML-Encoded DC <link rel=“schema.DC” href= title=“Dublin Core Metadata Element Set, version 1.1”> <meta name=“DC.Element_name” content=“element_value”> Example: <meta name=“DC.Title” content=“Using Dublin Core”> 14
    15. 15. HTML-Encoded DC (cont.) <link rel=“schema.DC” href= title=“Dublin Core Metadata Element Set, version 1.1”> <meta name=“DC.Title” content=“Using Dublin Core”> <meta name=“DC.Creator” content=“Hillman, Diane”> <meta name=“DC.Identifier” content=“”> <meta name=“DC.Type” scheme=“DCMIType” content=“text”> <meta name=“DC.Date.created” content=“2003”> 15
    16. 16. Problems with using HTML forDC Useful only when web crawlers and search engine indexers can detect <meta> tags HTML not useful for complex constructions (e.g., when repeated elements need to be grouped) HTML only useful with metadata embedded in documents 16
    17. 17. RDF/XML-Encoded DC Allows multiple metadata schemes to be read by humans and parsed by machines Allows multiple objects to be described All namespaces must first be defined 17
    18. 18. RDF/XML-Encoded DC Example <rdf:RDF xmlns:rdf=" syntax-ns#" xmlns:dc=""> <rdf:Description rdf:about=""> <dc:creator>Rose Bush</dc:creator> <dc:title>A Guide to Growing Roses</dc:title> <dc:description>Describes process for planting and nurturing different kinds of rose bushes.</dc:description> <dc:date>2001-01-20</dc:date> </rdf:Description> 18
    19. 19. Value Encoding Schemes Indicate that the value is: a term from a controlled vocabulary (e.g., Library of Congress Subject Headings) a string formatted in a standard way (e.g., that "05/02" means May 2nd, not February 5th) 19
    20. 20. Uses of Dublin Core Subject gateways and portals Description of resources generated from DC Digitization projects where full cataloging would be too time consuming or problematic ons/ Union catalogs, search engine indexes, external databases Converted from more detailed metadata in a local database 20