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OAI and Metadata Aggregation

OAI and Metadata Aggregation

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OAI and Metadata Aggregation

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  1. OAI and Metadata Aggregation Sarah Shreeves University of Illinois at Urbana-Champaign LIS 450 RO: Representing and Organizing Information Resources March 7, 2004

  2. Outline What is the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH)? OAI Projects at the University of Illinois and what we’ve learned 450 RO

  3. OAI is a tool • Set of rules that defines the communication between systems (like FTP and HTTP) • All about moving metadata (not data) around • Assumes widely distributed content, but centralized services • A building block for digital library services The purpose of OAI is to foster interoperability 450 RO

  4. OAI is not…. • Metadata • A search tool • A database 450 RO

  5. DATABASE H A R VESTER HTTP Request (OAI Verb) REPOSITORY OAI OAI HTTP Response (Valid XML) How OAI Works Data providers and service providers OAI requests are sent via HTTP Responses are sent in valid XML Service Provider Data Provider 450 RO

  6. OAI Use of Dublin Core DC is OAI’s lowest common denominator BUT OAI supports & encourages use of other community-driven metadata schemas 450 RO

  7. Harvesting vs. Federation Different approaches to interoperability • Federation: services are run remotely on remote data (e.g. Broadcast Searching) • Harvesting: metadata is transferred from the remote source to the destination where the services are located OAI is a harvesting tool. 450 RO

  8. OAI Compared to Z39.50 450 RO

  9. Why Use OAI? • Content in non-Z39.50 enabled locations • Metadata provider more lightweight than Z39.50 and scales well. • Service provider wishes to augment search services or metadata normalization is needed. Portals can use both Z39.50 & OAI 450 RO

  10. Who uses OAI? • Approximately 400 data providers • Basic building block of the National Science Digital Library (NSDL) • Incorporated into D-Space and • Part of ContentDM, Michigan’s DLXS, and other products • International use: Open Archives Forum in Europe, UK and EU 450 RO

  11. OAI Projects at UIUC • NSF funded Second Generation Digital Mathematics Resources • Mellon funded OAI Metadata Harvesting Project • • IMLS Digital Collections and Content Project 450 RO

  12. 450 RO

  13. Challenges of Metadata Aggregation • Heterogeneity of items described • Loss of Context / Information loss • Knowledge structures differ So…. • Native metadata schemas differ • Controlled vocabularies differ • Use and presentation of items differ 450 RO

  14. Challenges of Metadata Aggregation Metadata quality issues emphasized • Completeness • Provenance • Accuracy • Conformance to expectations • Logical consistency/coherence • Timeliness • Accessibility 450 RO

  15. Metadata for different communities 450 RO

  16. Metadata for different communities 450 RO

  17. Loss of Context: Record in OAI aggregation 450 RO

  18. Context: Record in native database 450 RO

  19. Loss of context / data 450 RO

  20. Loss of context / data 450 RO

  21. Completeness of Metadata • identifier:;subview=detail;cc=fish3ic;entryid=X-0802;viewid=1004_112 • publisher: UMMZ Fish Division • format: jpeg • type: image • subject: 1926-05-18 • subject: 1926;0812;18;Trib. to Sixteen Cr. Trib. Pine River, Manistee R.;R10W;S26; S27;JAM26-460;05;T21N;1926/05/18 • language: UND • description: Flora and Fauna of the Great Lakes Region; 450 RO

  22. 450 RO

  23. Description:Digital image of a single-sized cotton coverlet for a bed with embroidered butterfly design. Handmade by Anna F. Ginsberg Hayutin. Source:Materials: cotton and embroidery floss. Dimensions: 71 in. x 86 in. Markings: top right hand corner has 1 1/2 in. x 1/2 in. label cut outs at upper left and right hand side for head board; fabric is woven in a variation of a rib weave; color each of yellow and gray; hand-embroidered cotton butterflies and flowers from two shades of each color of embroidery floss - blue, pink, green and purple and single top 20 in. bordered with blue and black cotton embroidery thread; stitches used for embroidery: running stitch, chain stitch, French knot and back stitches; selvage edges left unfinished; lower edges turned under and finished with large gray running stitches made with embroidery floss. Format:Epson Expression 836 XL Scanner with Adobe Photoshop version 5.5; 300 dpi; 21-53K bytes. Available via the World Wide Web. Coverage:— Date Created: 2001-09-19 09:45:18; Updated: 20011107162451; Created: 2001-04-05; Created: 1912-1920? Type:Image Granularity of Description: Excerpt of Metadata Record Describing "Cotton coverlet with embroidered butterfly design" 450 RO

  24. Granularity of Description: Excerpt of Metadata Record Describing “American Woven Coverlet” Description:Materials: Textile--Multi, Pigment—Dye; Manufacturing Process: Weaving--Hand, Spinning, Dyeing, Hand-loomed blue wool and white linen coverlet, worked in overshot weave in plain geometric variant of a checkerboard pattern.Coverlet is constructed from finely spun, indigo-dyed wool and undyed linen, woven with considerable skill. Although the pattern is simpler, the overall craftsmanship is higher than 1934.01.0094A. - D. Schrishuhn, 11/19/99 This coverlet is an example of early "overshot" weaving construction, probably dating to the 1820's and is not attributable to any particular weaver. -- Georgette Meredith, 10/9/1973 Source:— Format:228 x 169 x 1.2 cm (1,629 g) Coverage:Euro-American; America, North; United States; Indiana? Illinois? Date:Early 19th c. CE Type:cultural; physical object; original 450 RO

  25. Challenge: Range of vocabularies in use Controlled Vocabularies in use for IMLS NLG projects (results from survey of 65 NLG projects with digital content) 450 RO

  26. Data providers can: • Create metadata for interoperability • Reusable metadata - think beyond your local users and environment • Use well structured and defined schemas; move beyond simple DC • Use and identify controlled vocabularies 450 RO

  27. Service Providers can… • Analyze metadata and cluster and normalize some aspects • Build indexes based on type of resource (image, text, physical object) rather than collection • Custom interfaces and selective views for target audiences / domains 450 RO

  28. Recap OAI is a tool OAI is easy - metadata is hard Better metadata = better interoperability 450 RO

  29. Resources Open Archives Initiative Mellon Illinois OAI project IMLS Digital Collections and Content Project 450 RO

  30. Contact Information Sarah Shreeves Project Coordinator, IMLS Digital Collections and Content Visiting Assistant Professor of Library Administration University of Illinois Library at Urbana-Champaign Email: Phone: 217.244.7809 450 RO