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It’s Distributed searching, Jim
But not as you know it!
ZIG meeting, LeuvenJuly 12th, 2000
Bert Degenhart DrenthADLIB Information Systems [email protected]://www.nl.adlibsoft.com
A problem to be solved
Multiple database architectures
(ODBC, ADO, other)
Use of standard components
Use of standard protocols
Distributed database
Close to Web development
Use for ‘cross domain’ application: library, museum and archives.
An alternative architecture
3 functions
Query through URL’s (get/post method)
Return results in XML
Use a broker or gateway to combine results
A prototype:
2 databases: an ODBC source (MS-Access)an ADLIB database
ODBC source contains simple ‘library’ records
ADLIB database contains Dublin Core records
System setup:
ODBC sourceADLIB
database
translator translator
ASP broker
Web browser
HTMLurl
urlurlXML
XML
SQLTDS AQLrecords
Technology used
1. Express query in URL (proprietary syntax) 2. Query is handed to translators by a HTTP request
using Microsoft.XMLHTTP3. Translators hand query to database engine using
ODBC (ACCESS) or native calls4. Translators return XML to broker5. Broker uses XMLDOM to integrate results6. Broker runs on ASP written in Jscript
Comparison with Z39.50
Differences:
No BER
No ‘library specific’ technology
Current implementation does not split between search and retrieve
No extended services
Comparison with Z39.50
Similarities
Asynchronous searches possible
For ‘real’ applications standardisation needs to take place on:
Definition of query URL’s
The three S-s : Syntax, Structure and SemanticsSyntax : XML
Structure : return elements (DTD/schema)
Semantics : attribute set and profile
The mechanism for setting up this can be ‘borrowed’ from Z39.50
Decouple transport mechanism from application
Technology changes and is driven by forces outside of the library / museum / archive arena
If you can’t beat them, join them
Inertia (MARC is still there!)
Developments in CIMI : what happened after the Z39.50 testbed
Testbed proved that the technology worked, but no practical implementations are out there!
No support for Z39.50 in commercial products
Developments in CIMI : what happened after the Z39.50 testbed
After the Z39.50 testbed the Dublin Core testbed was conducted.
Proved to be successful, with a central repository.
Support for DC in XML in commercial products.
Developments in CIMI : what happened after the Z39.50 testbed…
CIMI moved from DC to intra community data exchange, based on XML.
MDA and CIMI are producing a DTD for Spectrum, scheduled for november 2000
The CIMI Z39.50 profile could be used as a basis for distributed applications using HTTP technology, notably important:record schema (dtd / XML-schema)access points and semantics
The end for Z39.50?
My personal opinion : NO!
Emphasis has to shift from ‘bits on the wire’ to theThree S-es for a variety of information services
Integration, communication needs to take place with similar fields : TEI, EAD, Spectrum-XML and DC
Of course: existing systems need upgrade / maintenance
