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Enhancing Information Retrieval with Z39.50 & RDF Web Integration

Learn benefits & limitations of combining Z39.50 & RDF for precise searching and metadata organization. Explore search architectures, syntax, and potential synergies for efficient retrieval.

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Enhancing Information Retrieval with Z39.50 & RDF Web Integration

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  1. Z39.50, RDF and the Web ZIG Tutorial August 1999 Poul Henrik Jørgensen, Danish Library Centre, www.dbc.dk

  2. Contents • WWW Benefits and Limitations • Z39.50 Benefits and Limitations • Resource Description Framework, RDF Z39.50 & Web / DBC-PHJ

  3. Web Harvesters • Web Harvesters follow links to find HTML documents on selected Web Servers • Fetches documents and extracts words from the text • Meta tags are (sometimes) ignored • Maintains databases of words with URLs of corresponding Web pages Z39.50 & Web / DBC-PHJ

  4. Web Search Overview • Displays search-form in a Web browser • Search-words are submitted to index- database • List of Web pages with hyperlinks is returned to Web browser • User clicks on URLs to fetch original HTML documents from the source Z39.50 & Web / DBC-PHJ

  5. Web Search Architecture Web Har-vester Web Server Source Docu-ments 1. Fetch words 3. Fetch documents Web Index 2. Search index Index Search Web Server Web Browser Z39.50 & Web / DBC-PHJ

  6. Web Search Example Z39.50 & Web / DBC-PHJ

  7. Web Search Benefits and Issues • Utilize standard Web browsers • Returns many URLs to Web pages • Information within databases is ignored • Tied to special search forms • Imprecise search on free-text words • Limited control over presentation formats Z39.50 & Web / DBC-PHJ

  8. Z39.50 Overview • Z39.50 Targets (Z-Servers) share a standard system interface to Z39.50 Origins (Z-Clients) • Z-Clients support specialised user interfaces • Z-Clients submit metadata Search- and Present requests etc. to Z-Servers • Z39.50 search metadata and retrieve information from databases Z39.50 & Web / DBC-PHJ

  9. Z39.50 Architecture Z-Server front-end Search & Retrieve User interface Z-Client back-end Z39.50 Data-base Z39.50 & Web / DBC-PHJ

  10. Z39.50 Example Z39.50 & Web / DBC-PHJ

  11. Z-Web Gateway Architecture Web browser Web front-end Z-Client back-end Z-Server front-end Data-base HTTP Z39.50 Z39.50 & Web / DBC-PHJ

  12. Z39.50 Benefits and Issues • Precise searching with metadata attributes • Z39.50 includes Extended Services to retrieve, order and update information. • Information systems require standard Z-Server front-ends • Require speciel Z-Clients • Standard system interface between Z-Clients and Servers Z39.50 & Web / DBC-PHJ

  13. RDF Overview • Resource Description Framework • Developed by W3C from PICS • General information model based on Directed Labeled Graphs (DLG) – and NIAM • Serilization and Schema based on XML • XML Namespace defines vocabularies • Document Object Model (DOM) as API Z39.50 & Web / DBC-PHJ

  14. RDF Elements • An RDF Resource is an instance of one or more Classes • Resources have Properties • A Class may be a Subclass of another Class • Properties are values or Relations to other Resources • Statements: Resource (Subject) + Property (Predicate) + Value (Object) Z39.50 & Web / DBC-PHJ

  15. RDF Statement • Poul Henrik Jørgensen (Value) • is the creator (Property) • of the resource http://neptun.dbc.dk/efila/documents/zigmar1999/zigmarch1999b.htm (Subject). Ref.: http://www.w3.org/TR/REC-rdf-syntax/ Z39.50 & Web / DBC-PHJ

  16. RDF XML Syntax <?xml version="1.0" ?> -<RDF xmlns=http://www.w3.org/1999/02/22-rdf-syntax-ns# xmlns:s="http://description.org/schema/"> <Description about= • "http://neptun.dbc.dk/efila/documents/zigmar1999/zigmarch1999b.ht”> <s:Creator>Poul Henrik Jørgensen</s:Creator> </Description> </RDF> Z39.50 & Web / DBC-PHJ

  17. Possible RDF and Z39.50 Synergy • Z39.50 Services • Z39.50/HTTP Profile: • HTTP transmission protocol • XML Transfer Syntax • XML Namespace as search attributes • XSL based Query Language (XQL) Z39.50 & Web / DBC-PHJ

  18. XQL Example <xsl:for-each select = "book[publisher/name = 'Addison-Wesley'] /author"> <xsl:value-of /> </xsl:for-each> http://www.w3.org/TandS/QL/QL98/pp/xql.html Z39.50 & Web / DBC-PHJ

  19. Summary • Web Search engines have two drawbacks: • No standard interface (human or otherwise) • No standard service models • RDF offers general method to describe objects and relationships (i.e. Metadata) • Z39.50/HTTP + XMLNS + RDF + DOM + XQL may be a winning combination Z39.50 & Web / DBC-PHJ

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