Lessons from an examination of Dublin Core

Paul Miller

UK Interoperability FocusP.Miller@ukoln.ac.uk

<URL: http://www.ukoln.ac.uk/interop–focus/>

1-2/2/1999

<URL: http://www.ukoln.ac.uk/interop-focus/>

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Arts & Humanities Data Service

• AHDS <URL: http://ahds.ac.uk/> funded by the UK Higher Education Funding Councils, and comprises:

Archaeology Data Service (York et al.)History Data Service (Essex Data Archive)Oxford Text Archive (Oxford)Performing Arts Data Service (Glasgow)Visual Arts Data Service (Farnham)an Executive (King’s College, London).

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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Aims of the AHDS• AHDS is

– a distributed collection of discipline–specific services

– each with additional responsibility service–wide for a data ‘type’

– a model for decentralised data archiving and access

• AHDS is building– a single gateway to Arts & Humanities data of

interest to UK academics– data remain distributed in many locations, linked by means

of Z39.50, Dublin Core, etc.

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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Data in the Arts & Humanities (1)

• Arts & Humanities data encompass a wide range of types and formats, includingtext

– raw, SGML marked–up, PDF, etc

databases– flat file, relational, spatial, temporal, GIS, etc

images– manuscripts, works of art, remote sensing, film, video, etc

sound– recordings, MIDI, etc.

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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Data in the Arts & Humanities (2)

• These data not only span diverse technical formats, they are also

– constructed within differing conceptual frameworks

– ‘geographies’, theoretical paradigms, etc– ‘Creator’ may not be quite synonymous with ‘Author’

– recorded following different — and inconsistent — cataloguing practices

– described using many different ‘metadata’ systems, if formally described at all.

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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Data in the Arts & Humanities (3)

These data are too diverse to be effectively retrieved by means of any one search system

…but…

a description of the ‘core metadata’ for each resource may prove comparable within and between disciplines, facilitating effective resource discovery.

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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’)– etc

• Metadata means many things to many people.

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The Dublin Core (1)• probably the best tool for providing core resource

discovery metadata • international, cross–domain effort to achieve definition

of a core element set– defines 15 core elements– allows optional qualification of these through

addition of thesauri and lookup tables (SCHEME), sub–classification of the elements (SUBELEMENT) and metadata language (LANG)

– hopes to capture the essence of any resource…– …but is it too Core?

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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The Dublin Core (2)

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

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

http://purl.org/dc/

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AHDS/UKOLN Workshops (1)

• an attempt to discover what users and depositors require from a Core Element set

– created jointly by AHDS and UKOLN to– resolve AHDS’ immediate problems– explore the wider issues of cross–domain,

interdisciplinary, distributed resource discovery.

– Dublin Core used as reference set, but– participants examined both where it failed to meet

their needs and where it offered more than required– DC was not seen as a replacement for other

standards.

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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AHDS/UKOLN Workshops (2)

• Six workshops held during 1997– two (digital sound and moving images) for Performing

Arts, one for each of the other Service Providers– integrated with ongoing technical deliberations

• Invitees included– experts in holding and describing domain–specific

data– those depositing these data– current and potential users of the data– me.

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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AHDS/UKOLN Workshops (3)

• Draft reports widely circulated for comment• Final reports from each workshop made

available on Service Provider sites• Integrated report published October 1997

– Discovering Online Resources Across the Humanities: a practical implementation of the Dublin Core. Edited by Paul Miller & Daniel Greenstein

– Available on–line from <URL: http://ahds.ac.uk/> or order printed copy from info@ahds.ac.uk.

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Assessing the Dublin Core (1)

• Dublin Core is nota replacement for existing detailed metadata

schemes– they still have an (important) role to play

a means for describing data sets, concepts, or subject issues in great detail

the answer to all our problems (!)– Many of the problems encountered by workshops were not

with Dublin Core itself, but were related to more generic data description and cataloguing issues

– In many cases, workshops began by confusing these external issues with those integral to Dublin Core.

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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Assessing the Dublin Core (2)• Dublin Core is

a useful means by which discrete data types and sets may be described in a comparable fashion

small enough to remain manageable, yet extensible enough to (hopefully) be suitably descriptive

a fascinating example of inter–disciplinary and international co–operation

(if used in conjunction with the concepts of the Warwick Framework) an extremely powerful means of drawing complex metadata and data together, facilitating access and re–use.

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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Assessing the Elements (1)

• Dublin Core found to be fit for purpose• definitions found to be unsatisfactory

– interpreted too differently by the six workshops– AHDS agreed single interpretation– Current review of elements across DC community

• CREATOR and CONTRIBUTORS found to be confusing

– notions of primary intellectual responsibility difficult to assign

– some workshops suggest a single element, NAMES, instead. AHDS agreed to ignore CONTRIBUTORS.

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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Assessing the Elements (2)

• SUBJECT open to abuse– easily overloaded with many terms from many

word lists– potential conflict with COVERAGE and TYPE– what is the subject of ‘Hamlet’, anyway?!

• PUBLISHER means too many different things to different people.

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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Assessing the Elements (3)• DATE not sufficient for requirements

– creation of original work? publication date of version later digitised? release date of electronic version? update cycle dates?

• TYPE represents a confusing collection of concepts.

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Assessing the Elements (4)

• FORMAT concept extended to non–digital– AHDS suggests inclusion of film running times, video

formats, etc where absolutely required

• SOURCE and RELATION need clarified– AHDS Service Providers hold different notions

of ‘source’– both could be misused with over-inclusion of

‘useful’ relationships.

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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Assessing the Elements (5)• COVERAGE is ‘complex’

– is the Deutsche Bibliothek the SUBJECT or COVERAGE of a photograph?

– what are the usefully recorded spatial COVERAGEs for a Frankish bowl made in Aachen, excavated in Trier and on view in London’s British Museum?

– The Holy Roman Empire? Aachen? France? Germany? Trier? British Museum? London? Europe?…

– what is ‘The Holy Roman Empire’?– temporal COVERAGE ?

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Assessing the Elements (6)• RIGHTS essential

– AHDS developed a simple rights management coding scheme to be used in conjunction with a mandatory link to detailed rights management information for each individual resource.

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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Assessing the Qualifiers• ‘optional’ extensibility of SCHEME and SUBELEMENT found to be essential. LANG useful in certain cases

– every use of a SCHEME or SUBELEMENT increases Dublin Core’s value to one discipline, and reduces interoperability with the others

– many SCHEMEs and SUBELEMENTs identified in workshop reports

– integrated report attempts to aggregate these, moving back towards interoperable generalisations

– where is middle ground between value to one discipline and the over–reaching goal of interoperability?

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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Moving Forward (1)• Resources of interest to AHDS are

– diverse– an archaeological excavation database and a recording of the

Berlin Philharmonic playing ‘Ode to Europe’

– distributed– a database physically mounted in York, the Scottish NMR in

Edinburgh, and the Shetland Amenities Trust SMR in Lerwick; all accessible to the user in Pisa or Antwerp

– ‘living’– a Local Authority SMR, updated every day

– rarely in HTML– so ‘Harvesting’ is not the best solution.

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<URL: http://www.ukoln.ac.uk/interop-focus/>

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Moving Forward (2)• Z39.50 seen as the solution

– preserves distributed nature of resources

– capable of expressing many data types

– (relatively) large body of implementation experience

– allows ‘easy’ integration with CIMI, Aquarelle, etc

– having gained sufficient expertise, targets may be implemented at collaborating organisations, extending system functionality.

– probably I–Site (it’s free, and spatially aware).

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A Model

AHDSGateway

AHDSGateway

HDS OTA PADS VADSADS

WWW browser

(Z Target)

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A Model

AHDSGateway

AHDSGateway

HDS OTA PADS VADSADS

WWW browser/Z Target

CIMITest–beds

Aquarelle NMRE NMRS NMRW SMR (c.50)

SCRAN (Scotland)Museums (world–wide)H–SYS (England)ADAP (USA)NGDF (UK)NUTS/ SABE (EU)Thesauri — CoE, GII etc.plus local ADS collections

SCRAN (Scotland)Museums (world–wide)H–SYS (England)ADAP (USA)NGDF (UK)NUTS/ SABE (EU)Thesauri — CoE, GII etc.plus local ADS collections

etc.

… extended for ADS

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The reality

• AHDS Z39.50 Gateway• <http://prospero.ahds.ac.uk:8080/ahds_live/>

• Z39.50 ‘Targets’ at all five Service Providers

• Domain–specific interfaces to collections also available• <http://ads.ahds.ac.uk/catalogue/>

• On–going development of disciplinary Gateways at several Service Providers.