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Making Metadata Work for the NSDL
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Starting from Sept. 2001 with... A prototype with not much behind it that was re-usable (http://siteforscience.org)http://siteforscience.org Lots of good ideas based on that prototype An Oracle license A very small group of people with many different visions of what we were doing The management structure of a research project (e.g., none)
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... jump to Dec. 2, 2002, when you will see (http://nsdl.org): A Metadata Repository with roughly 250,000 metadata records (items and collections) A uPortal-based user interface, containing: a search service a simple topic browse of collections featured collection exhibits views of future enhancements A developing plan for the future
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Getting from there to here Designing the Metadata Repository Working with unfinished standards Dublin Core in transition XML schema for qualified DC in early stages OAI 2.0 not yet cooked Concerns from partners and funders around quality issues Envisioning Simple Metadata-Based Services (SiMBaS)
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The Metadata Repository Designed to scale Based on an automated harvest/expose model with OAI at each end A notion of “normalized metadata” with qualified Dublin Core as its base Transformations on the way in, native and transformed re-exposed
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Standards at the bleeding edge Metadata strategy based on crosswalking from 8 formats to one (NSDL-DC) The reality: a Baskin-Robbins model of “standard metadata” Standards badly documented, little organized support, very little training available at any price Projects not obligated to offer metadata, even if they had it (in whatever form)
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OAI in transition—the story in 2002 Version 1.1 was not yet widely used Version 2 not yet available; NSDL became beta-tester (!) Final version of OAI 2.0 delayed by NSDL needs (definition of change) Now working with collection partners to bring up servers, ensure validation Lower end option for OAI on the way
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The DC schema wars DC-Architecture group working primarily on RDF schema Gang of Five began work outside DC, presented version for comment to DC- Architecture Oct. 2002 Process of approval not yet complete, NSDL using “final” version
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A few schema issues... Three namespaces Restricted to “simple literal” values Refinements expressed as elements Encoding schemes expressed as new complexTypes (schemes not limited to a single element) NSDL Schema types: NSDL-DC NSDL-Search NSDL-All
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The Process Data harvesting Data evaluation Transform specification DB_insert file creation Database ingest OAI re-exposure
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Data evaluation XML validity DC conformance (whether simple or qualified) Emphasis on Date, Type, Format, Identifier Potential problem areas: Special characters “funky text” Tools: XML Spy, Spotfire
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Specifying transform Simple transforms (DC simple—>DC qualified) Scheme identification for standard values (date, type, format, language) Quality transforms improving functionality of search limits by ensuring appropriate values for type and format improving user experience by deleting funky text and special characters that affect display
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DB_Insert file Header First harvest? Category (item, collection, annotation...) Harvest date Source Link to “native” metadata
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OAI exposure OAI “About” OAI “Provenance” Metadata origin and rights assertions Alterations to originally harvested data Re-harvest information Collection (& brand) association
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Still to do... Currently running on “manual” Ingest process not yet completed or documented data validation routines additional metadata types (annotation) and services linked to metadata
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Automation opportunities Collection registration assignment of unique identities “responsible entities” harvest/re-harvest, transform/re- transform, and associated record keeping integrating/linking new information with metadata record (service model)
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Other challenges Educating data providers and aggregators about GOOD METADATA Better techniques for evaluation and transformation Coping with users? (Uh, oh)
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For more information The NSDL Metadata Primer (http://metamanagement.comm.nsdlib.o rg/outline.html)http://metamanagement.comm.nsdlib.o rg/outline.html NSDL XML schema (http://ns.nsdl.org/schemas/nsdl_dc/nsdl _dc_v1.00.xsd)http://ns.nsdl.org/schemas/nsdl_dc/nsdl _dc_v1.00.xsd
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