Z39.50

1
Z39.50 XML

• Poul Henrik Jørgensen, phj_at_dbc.dk
• Danish Bibliographic Centre
• www.dbc.dk

2
Background

• Moderate number of Z39.50 Servers
• Little take-up outside major research libraries
• Many limited to basic search and retrieval
• Mostly used for Web-to-Z gateways
• Requirements for related services, e.g. Item
  Order or Circulation
• Time-consuming to implement Z39.50

3
Issues

• Technology is alien to mainstream IT
  infrastructure
• Limited development tools
• Few developers
• Proprietary C-libraries
• Inaccessible specifications.
• Plethora of esoteric features
• No common (object-based) API
• BER data format is not eye-readable

4
Objectives

• Leverage investments in existing Z39.50 Services
  and specifications
• Simplify Z39.50 implementation
• Facilitate interoperability with other relevant
  standards
• Foster migration of Z39.50 functionality to
  mainstream IT technologies

5
First Steps

• Introduce XML as Z39.50 Transfer Syntax
• Specify new Z39.50 data structures as XML Schemas
• Encode complex hierarchical data within XML
  documents
• Use XML as alternative to GRS-1

6
XML structures in Z39.50

• Holdings XML Schema
• www.portia.dk/zholdings/Holdings6a/HoldingsSchema6
  a.xsd
• ExplainLite Server information
• www.one-2.org
• Dublin Core/RDF
• Extended Services Task Packages

7
SOAP Overview

• SOAP is a protocol to transport XML data
• Initially designed for Remote Procedure Calls
• Utilise normal HTTP POST to send a Request and
  receive Response from a Web (SOAP) Server
• Parameters are carried as XML structures within
  normal HTTP body
• Primary input to W3C XML Protocol work
• http//www.w3.org/TR/SOAP/

8
ZML Z39.50 over SOAP

• Existing ASN.a protocol elements encoded as XER
  Structures
• Relevant Z39.50 Services mapped to SOAP
  Request/Response functions over HTTP
• Protocol parameters encoded as XML SOAP
  parameters via XER
• Existing Web-to-Z gateways may be enhanced with
  SOAP-to-Z gateways

9
Init Request Example

• ltSOAPEnvelope xmlnsSOAP"http//schemas.xmlsoap.
  org/soap/envelope/"
• xmlnsxsi"http//www.w3.org/1999/X
  MLSchema-instance"
• xmlnsxsd"http//www.w3.org/1999/X
  MLSchema"
• SOAPencodingStyle"http//schemas.
  xmlsoap.org/soap/encoding/"gt
• ltSOAPBodygt
• ltezInit xmlnsez"urnez3950api"
  version"1.0"gt
• ltezprotocolVersion xsitype"xsdstring"gt
• version-1 version-2lt/ezprotocolVersio
  ngt
• ltezoptions xsitype"xsdstring"gtsearch
  present scanlt/ezoptionsgt
• ltezpreferredMessageSize
• xsitype"xsdint"gt16384lt/ezpreferred
  MessageSizegt
• ltezexceptionalRecordSize
  xsitype"xsdint"gt500000lt/ezexceptionalRecordSiz
  egt
• ltezimplementationId xsitype"xsdstring"gt1
  995lt/ezimplementationIdgt
• ltezimplementationName xsitype"xsdstring"
  gt
• OCLC z39.50 APIlt/ezimplementationNamegt
  
• ltezimplementationVersion
• xsitype"xsdstring"gt3.0lt/ezimplement
  ationVersiongt
• lt/ezInitgt
• lt/SOAPBodygt

10
Interface Specs. in WSDL

• WSDL is a formal top-down method to specify
  interfaces to Web (SOAP) Services
• http//www.w3.org/Submission/2001/07/
• General interfaces to eZ3950, NCIP and related
  protocols can be specified with XML Schemas and
  WSDL
• http//www.portia.dk/pubs/NCIP/NCIP_v0_1a.xsd
• http//www.portia.dk/pubs/NCIP/PortTypes.wsdl

11
NCIP WSDL Example

• lt!-- Authenticate User porttype   --gt
• ltmessage name"AuthenticateUserRequest"gt
• ltpart name"body" element"xsd1AuthenticateUser"
  /gt
• lt/messagegt
• ltmessage name"AuthenticateUserResponse"gt
• ltpart name"body" element"xsd1AuthenticateUserR
  esponse"/gt
• lt/messagegt
• ltportType name"AuthenticateUserPortType"gt
• ltoperation name"AuthenticateUser"gt
• ltinput message"tnsAuthenticateUserRequest" /gt
• ltoutput message"tnsAuthenticateUserResponse"/gt
  
• lt/operationgt
• lt/portTypegt

12
ZML Development

• ZML Profile of Z39.50 over SOAP
• Optional Init Close
• Search Scan based on Bath Profile
• ISO2709/XML Present format
• by Ray Denenberg P.H. Jørgensen
• ZML Server Client prototypes
• Common Z39.50 Testbed

13
Conclusions

• XML is already implemented within several Z39.50
  functions
• XML is easier and more flexible than ASN.1/BER in
  practice
• Most of Z39.50 can be migráted to XML/SOAP
  (eZ3950)
• Interoperability with related SOAP based
  protocols can be facilitated via comon WSDL
  interface specifications