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Some standards, some examples, and a UK

perspectivePaul Miller

Interoperability FocusUK Office for Library & Information Networking (UKOLN)

P.Miller@ukoln.ac.uk http://www.ukoln.ac.uk/

UKOLN is funded by the Library and Information Commission, the Joint Information Systems Committee (JISC) of the Higher Education Funding Councils, as well as by project funding from the JISC and the European Union. UKOLN also receives support from the University of Bath where it is based.

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Outline• Scoping the problem

• Cultural Heritage information• Other ‘memory organizations’• The Internet

• Standard solutions• Catalogues, Metadata, Terminology control…• Localised developments• Dublin Core• XML/RDF• Z39.50

• Examples• AHDS and ADS• CIMI• The Distributed National Electronic Resource.

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Cultural Heritage

• Information traditionally analogue• Tradition of preservation• Complex in nature• Often transcends (current) national

boundaries, raising political issues• Currently ‘cool’

• potentially profitable (Micro$oft)• Important for Lifelong Learning and

other hot phrases (NGfL).

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Other memory organizations• Similar analogue tradition

• Similar focus on preservation

• Greater tendency to single format• Books• Musical scores• Archival manuscripts

• Traditionally complex cataloguing paradigm.

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The Internet

• Traditionally digital• Now adding access to analogue

• Two million web sites

• Half a billion addressable pages

• Everyone’s an author

• Everyone’s a publisher

• Everyone can assert authority

• Sustainable models prove elusive

• Still waiting for the ‘killer app’ ?.

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Standard solutions

The nice thing about standards…

…is that there are so many to choose from!

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Standard solutions

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Standard solutions• Different solutions to information

management have evolved• Detailed catalogues

– Curatorial tradition– Principally for internal management?– MARC/AACR, SPECTRUM…

• ‘Metadata’ catalogues– Access tradition– Principally for external use– Dublin Core…

• etc• Control of semantics and syntax useful.

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Semantics, Structure, Syntax

SemanticInteroperability

StructuralInteroperability

SyntacticInteroperability

“Let’s talk English”Standardisation ofcontent

Standardisation ofform

“Here’s how to make a sentence”

Standardisation ofexpression

“These are the rulesof grammar”

“cat milk sat drank mat ”

“Cat sat on mat. Drankmilk.”

“The cat sat on the mat.It drank some milk.”

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What is a catalogue?• A database of holdings/resources

within defined collection policy, with stated cataloguing procedures, and with some intention towards comprehensiveness?

– A library catalogue– A museum collection management system– A national register of monuments

• Can be a single resource– OPAC97, the British Library catalogue

• A union of other catalogues– COPAC– vCUC (virtual)– ADS (virtual)– AHDS (virtual).

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What is ‘Metadata’?

– meaningless jargon– or

a fashionable term for what we’ve always done– or

“a means of turning data into information”– and

“data about data”– and

the name of a film director (‘Luc Besson’)– and

the title of a book (‘The Lord of the Flies’).

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What is ‘Metadata’?

Metadata exists for almost anything;• People• Places• Objects• Concepts• Web pages• Databases.

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What is ‘Metadata’?

Metadata fulfils three main functions;• Description of resource content

– “What is it?”

• Description of resource form– “How is it constructed?”

• Description of resource use– “Can I afford it?”.

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Introducing the Dublin Core

• An attempt to improve resource discovery on the Web

– now adopted more broadly

• Building an interdisciplinary consensus about a core element set for resource discovery

– simple and intuitive– cross–disciplinary — not just libraries!!– international– flexible.

See http://purl.org/dc/See http://purl.org/dc/

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• 15 elements of descriptive metadata• All elements optional• All elements repeatable• The whole is extensible

– offers a starting point for semantically richer descriptions

• Interdisciplinary– libraries, government, museums,

archives…

• International– available in 20 languages, with more on the

way...

Introducing the Dublin Core

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• Title• Creator• Subject• Description• Publisher• Contributor• Date• Type

• Format• Identifier• Source• Language• Relation• Coverage• Rights

http://purl.org/dc/

Introducing the Dublin Core

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Extending DC (semantic)

• Improve descriptive precision by adding sub–structure (subelements and schemes)

– Greater precision = lesser interoperability

• Should ‘dumb down’ gracefully

Creator

First Name

Surname Contact Info

Affiliation

Based on a slide by Stu Weibel

Element qualifier Value qualifier

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Extending DC (modularity)

• Modular extensibility…• Additional elements to support local needs• Complementary packages of metadata

• …but only if we get the building blocks right!

Description Spatial character

Terms & Conditions

Based on a slide by Stu Weibel

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Extending DC?

• DC offers a semantic framework• Through use of further substructure,

meaning can often be clarified…

<Creator> “John”John Inc. ?John xyz ?xyz John ?

<Creator> <fore name> “John” John Inc.John xyzxyz John.

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Extending DC?

• DC offers a semantic framework• Use of domain–specific schemes

greatly increases precision

<Coverage> “Washington”Washington State ?Washington DC ?Washington monument ?

<Coverage> <TGN> “Washington” Washington StateWashington DCWashington monument

“North and Central America, United States, Washington”

http://gii.getty.edu/tgn_browser/

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Introducing XML

• eXtensible Markup Language• World Wide Web Consortium

recommendation• Simplified subset of SGML for use on the

Web• Addresses HTML’s lack of evolvability• Easily extended• Supported by major vendors• Increasingly used as a transfer syntax, but

capable of far more….

See http://www.w3.org/XML/See http://www.w3.org/XML/

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Introducing RDF

• Resource Description Framework• World Wide Web Consortium

recommendation• Fully compliant application of XML• Improves upon XML, HTML, PICS…• Machine understandable metadata!• Supports structure• Encourages authenticity assertions.

See http://www.w3.org/RDF/See http://www.w3.org/RDF/

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Data Integration• “The author of this document is Paul”• “Paul is the author of this document”• “This document is authored by Paul”• “The author of this document is Paul”

• 3 Representation(s) in XML:

<author> <url> http://doc_url </url> <name> Paul </name></author>

<document> <author> <name> Paul </name> </author> <url> http://doc_url </url></document>

<document href = “http://doc_url”author = “Paul”/>

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Data Integration

• Querying XML documents is hard• N ways of mapping XML to logical structure• Requires the normalization of all possible

representations for effective query

• Mean the same thing to a person• Mean very different things to a machine• RDF much less flexible

• less flexible = more interoperable! • consistent way of representing statements

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RDF Data Model

• Imposes structural constraints on the expression of application models• for consistent encoding, exchange

and processing of metadata

• Enables resource description communities to define their own semantics

• Provides for structural interoperability

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RDF Data Model basics

ResourceProperty

ValueResource

Statement

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A simple example

ResourceAuthor

“Paul”

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RDF Model Example

URI:R“Maastricht Presentation”

title

creatordc:

dc:

“Paul Miller”

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RDF Syntax Example

URI:R“Maastricht Presentation”

title

creatordc:

dc:

“Paul Miller”

<RDF xmlns = “http://www.w3.org/TR/WD-rdf-syntax#” xmlns:dc = “http://purl.org/dc/elements/1.0/”> <rdf:Description rdf:about = “URI:R”> <dc:title> Maastricht Presentation </dc:title> <dc:creator> Paul Miller </dc:creator> </Description></RDF>

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Where do you stop…?

• Model provides enabling technology for almost infinite cross–linking

• How far any one community goes should be governed by• Domain needs, best practice and

experience• Organizational/ institutional policy• Economics

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RDF Schemas

• Declaration of vocabularies• properties defined by a particular community• characteristics of properties and/or constraints on

corresponding values

• Schema Type System - Basic Types• Property, Class, SubClassOf, Domain, Range• Minimal (but extensible) at this time• minimize significant clashes with typing system

designed for XML NG DTDs (1999?)

• Expressible in the RDF model and syntax• Interest in trying this with some of the Getty

thesauri…

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Schema Vocabularies

• Enables communities to share machine readable tokens and locally define human readable labels.

dc:Creator“Nom”rdfs:label

“Author”rdfs:label

“$100 $a”

rdfs:label

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Relationships between elements

URI:R “John Smith”ms:Kgrip

dc:Creatorms:Kgrip

rdfs:subPropertyOf

rdfs:label“Key Grip”

dc:Creator

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Some reading

• eXtensible Markup Language• http://www.w3.org/XML/

• Resource Description Framework• http://www.w3.org/RDF/

• Dublin Core• http://purl.org/dc/

• Expressing Dublin Core in RDF• http://www.ukoln.ac.uk/metadata/

resources/dc/datamodel/WD-dc-rdf/

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Introducing Z39.50

• International Standard (ISO 23950)

• Originally library–centric

• Permits remote searching of databases

• Access via Z client or over web

• Relies upon ‘Profiles’• CIMI profile for cultural heritage

See http://www.ariadne.ac.uk/issue21/See http://www.ariadne.ac.uk/issue21/

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Z39.50 Challenges

• Profiles for each discipline• Defeats interoperability?

• Bib–1 bloat

• Largely invisible

• Seen as complicated

• Seen as expensive

• Seen as old–fashioned

• Surely no match for XML/RDF/whatever.

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Z39.50 Futures

• International Interoperability Profile

• Cross–Domain Attribute Set

• Attribute Architecture

• Bib–2

• XER

• DNER/ RDN/ NGDF/ New Library?.

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Examples: AHDS

• Arts & Humanities Data Service• Funded by JISC to preserve and

provide access to digital arts and humanities resources

• Five ‘service providers’ for archaeology, history, text, visual and performing arts

– Each Service provider offers its own access to holdings

– AHDS–wide access also provided through Z39.50/DC gateway.

See http://ahds.ac.uk/See http://ahds.ac.uk/

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Examples: ADS

• Archaeology Data Service• Service provider of the AHDS• Specialising in archaeological data, as well as advising

on geospatial data issues to the other four services• ArcHSearch catalogue system, making data available

for local government agencies, national agencies, universities, contractual organizations…

– Dublin Core used to extract ‘essence’ of legacy rich data– Perceived as neutral ‘honest broker’

• Holdings also visible through AHDS Gateway• Working with SCRAN and others to link cultural

heritage data of relevance to the UK through Z39.50.

See http://ads.ahds.ac.uk/See http://ads.ahds.ac.uk/

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Examples: CIMI

• Consortium for the Computer Interchange of Museum Information• Membership organization, comprising

museums, cultural heritage agencies and system vendors

• Work through series of test beds– Z39.50– Institutional Information Management– Dublin Core Metadata

– Uses XML transfer syntax

– Investigating RDF

See http://www.cimi.org/See http://www.cimi.org/

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Examples: DNER• Distributed National Electronic Resource

• Vision of the Joint Information Systems Committee (JISC), funders of most home–grown network content in the UK HE sector

• Raise awareness of available resources (SBIGs, Data Centres…)

• Offer distributed cross–searching of diverse resources• Interfaces

– Resource specific (as now)– DNER– Institutional– Personal.

• DC and Z39.50 likely as key enabling technologies– International Interoperability Profile.

See http://www.jisc.ac.uk/See http://www.jisc.ac.uk/