Web Services Overview

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Web Services Overview

• Thomas Hickey

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What are Web Services?

• Machine-to-machine communication
• Run over standard Web protocols
• XML syntax, HTTP packaging
• Several approaches
• REST
• Representational State Transfer
• SOAP
• Simple Object Access Protocol

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REST

• REST is simplest
• Send an HTTP request
• Get back a response (XML, HTML)
• Examples
• Web browser
• OpenURL
• Z39.50 as a Web service SRU
• http//sfx.bath.ac.uk/sfxmenu?genrebookisbn1234
  -5678
• http//www.kb.nl/
• cgi-zoek/srw.pl?querytestmaxRec10recSchemadc
  _record

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REST OAI-PMH

• Now in version 2.0
• Allows synchronization of databases
• Other services can be layered
• ODL Open Digital Libraries
• XTCat name authority service

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SOAP is more complex

• Simple Object Access Protocol
• Z39.50 as a SOAP service SRW
• http//www.loc.gov/z3950/agency/zing/srwu/wsdl/zin
  g_srw_binding.wsdl
• WSDL
• UDDI

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Classes of Services

• Register
• Search
• Resolve
• Navigate
• Decompose
• Enhance
• Transform

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Registration Services

• Metadata about metadata
• Dublin Core extensions
• Digital format descriptions
• Metadata about objects
• Books
• Web resources
• Metadata about agents
• People
• Institutions

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Search Services

• Go from data to links
• Name to preferred form
• Search terms to record list

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Resolution Services

• From links to data
• Record numbers to records
• Controlled names to name metadata
• Class number to textual description

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Navigation Services

• Movement within hierarchies
• Classification, e.g. DDC
• FRBR (work, expression, manifestation, item)
• General network movement
• Link selection and following

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Decomposition Services

• DDC Numbers
• Names within a list
• Citations within a paper
• Structure of a document
• Letters within an image

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Enhancement Services

• Normalization
• Linkage to registered forms
• Addition of DDC numbers
• Authority control on agents
• Content augmentation
• Add information to a brief record from a matching
  longer record

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Transformation Services

• Syntax translation
• MARC21 to MARC XML
• Semantic translation
• Qualified Dublin Core to MARC21
• Library of Congress SH to FAST
• Content translation
• English to French?

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An Example ePrints UK

• Records harvested from archives
• Web services to enhance metadata

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Personal e-print archives
Institutional e-print archives
Non-institutional e-print archives
OAI-PMH
Subject Classification Service
e-Prints UK
SOAP
Name Authority Service
SOAP HTTP Z39.50
RDN Gateway/portal Service
Citation Analysis Service
RDN Gateway/portal Service
RDN Gateway/portal Service
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Web Services for ePrints UK

• Personal name authorities
• Subject classification
• Citation analysis

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Example XTCat

• Union catalog of thesis and dissertation metadata
• Records extracted from WorldCat
• Available via OAI-PMH
• Separate set for electronic theses
• We harvest from other repositories
• Integrate with existing records
• Allow re-harvesting (e.g. by VTLS)

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Issues

• Syntax
• Semantics
• Content

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• No one promised us tomorrow
• Hawaiian proverb