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Enhancing Web Services with Z39.50: Roadmap for SRW/SRU Adoption

Explore the transition from classic Z39.50 to SRW/SRU, identifying strengths and weaknesses, featuring the benefits of SRW, SRU implementation, CQL usage, and the Outlook for SRW/SRU adoption. Learn how the integration of Z39.50 can improve web services. Discover the potential shift in various communities, such as MetaSearch and Geospatial, and the challenges and opportunities that come with it.

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Enhancing Web Services with Z39.50: Roadmap for SRW/SRU Adoption

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  1. Z39.50 as a Web Service Ralph LeVan Research Scientist

  2. Roadmap • Why Z39.50 as a Web Service? • The Weaknesses of Classic Z39.50 • The Strengths of Classic Z39.50 • SRW: Search and Retrieve on the Web • SRU: Search and Retrieve with URL’s • Outlook for SRW/SRU

  3. The Weaknesses of Classic Z39.50 • Not popular with the Web community • Connection-based Sessions • Binary Encoding • Transmitted directly over TCP/IP • Complicated

  4. Z39.50 Complicated? • 11 Native Services • Init, Search, Present, DeleteResultSet, AccessControl, ResourceControl, TriggerResourceControl, ResourceReport, Scan, Sort, Segment. • 7 Extended Services • PersistentResultSet, PersistentQuery, PeriodicQuerySchedule, ItemOrder, DatabaseUpdate, ExportSpecification, ExportInvocation

  5. Z39.50 Complicated? • 156 page standard • 147 in the 2002 draft • Vocabulary from the OSI community • Target, Origin, APDU, A-association, Z-association.. • Records described with ASN.1 • Attribute Sets

  6. The Strengths of Classic Z39.50 • Result Sets (a.k.a. Statefulness) • Abstraction • Abstract Access Points (Attribute Sets) • Abstract Record Schemas • Explain

  7. SRW: Search and Retrieve on the Web • SOAP (Simple Object Access Protocol) Based • HTTP • XML • Records Described in WSDL (Web Service Description Language) • 1 Service: SearchAndRetrieve • No Documentation :-)

  8. Semantically equivalent to classic Z39.50 • Gateways Trivial • Preserves the experience of the ZIG without the baggage of the standard • Syntactic equivalence discounted

  9. SRW: The Basics • Only one database per request • String (not structure) based queries • Index Sets, not Attribute Sets • One Record Syntax (XML)

  10. The SRW Request • String Query • Integer StartRecord • Integer MaximumRecords • String RecordSchema

  11. The SRW Response • String ResultSetReference • ResultSetName • ResultSetTimeToLive • Integer TotalHits • Records • Status (Status Code & Diagnostic)

  12. CQL: Common Query Language • Loosely based on CCL Search • Boolean & Proximity Operators • Index Sets & Indexes • Truncation Characters ‘*’, ‘#’ & ‘?’ • Example: dc.title=“harry potter” or bib1.isbn=123-456-78x

  13. Explain Now Possible • Not practical for classic Z39.50 • List of supported Schemas • List of supported Indexes

  14. SRU: Search and Retrieve with URL’s • SRW Without the SOAP Wrapper • Intended for Thin Clients • Adds ResponseSchema Parameter • Example http://deimos.oclc.org/SRW/etdcat?query=nuclear&maxRecords=10

  15. Outlook for SRW/SRU • A solution looking for a problem? • Not likely to be quickly adopted by the library community • Could show up first in other communities: MetaSearch, Geospatial, Biodiversity, OAI(?) • Will be seen as a competitor with XML Query

  16. Links • http://www.loc.gov/z3950/agency/zing/zing.html • http://staff.oclc.org/~levan/docs/SRW-RAC20030814.ppt

  17. & Questions nswers A

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