Copyright, UCL LEADERS: Linking EAD to Electronically Retrievable Sources Interoperability: Where...

Copyright, UCL LEADERS: Linking EAD to Electronically Retrievable Sources

Interoperability:Where the irresistible force of

flexibility meets the immovable object of standardization.

DRH Conference 2003

Chris TurnerLeaders Project UCL SLAIS


Conflicting needs

• Flexibility in encoding – Wide range of source materials – Existing practices

• Standardisation– Reusability– Support– Sustainability


Interoperability

‘to be interoperable, one should actively be engaged in the ongoing process of ensuring that the systems, procedures and culture of an organisation are managed in such a way as to maximise opportunities for exchange and re-use of information, whether internally or externally’

Miller, Paul. ‘Interoperability. What is it and Why should I want it?’, Aridane, Issue 24 (21 June 2000)

http://www.ariadne.ac.uk/issue24/interoperability/intro.html


6 Aspects of Interoperability

• Technical• Semantic• Political/Human• Inter-community• Legal• Informational


Technical Interoperability

• the ‘plumbing’, or what goes on out of sight to make documents accessible. – http– tcp/ip– etc


Semantic Interoperability

• Works on different levels and enables us to understand and transform documents– Syntactic level

• XML rules for well-formedness provide a standardized structure for files

– Semantic level• Common convention for naming parts of a document –

DTD/Schema– Structural level

• Determines how parts of a file relate to each other – the content models described by a DTD/Schema

– Content level• What does the document actually say. E.g. Index terms for

searching, and lists of descriptors


Interoperability of TEI and EAD documents

• they can be moved between computers and accessed between computers

• being XML they have a recognized syntactic structure

• they use common tag libraries, and thus have consistency of naming.

• the content models of the DTDs offer commonly defined structures

• the DTDs offer some pre-defined attribute values.


Flexibility of TEI/EAD

• A goal of EAD is to make archival resources from many institutions accessible to users. To achieve this goal, EAD must accommodate a wide range of internationally divergent descriptive practices (EAD Working Group, 2002).

• It is important to remember...[that] many -- perhaps most -- serious TEI applications have found it necessary to build their own customization of the full scheme in some way (Burnard, 2000).


Consequence

No two documents created in EAD or TEI need have the same structural or content markup.

– Limits possibilities for data exchange and re-usability

– Makes consistent search and retrieval and presentation of results difficult


Solution approach

• Determined by project aims– ‘Document-centric’ – focus is on retrieval and

presentation of TEI encoded transcripts and images

• EAD used for metadata to facilitate search and retrieval

• EAC used for contextual information

– Reusability of files– Hospitality to existing files?


Contextual presentation


Metadata in EAD file

item description in Leaders-EAD

to harvest index terms and description from EAD documents

resulting index document


Controlled terms for searching


TEI - descriptive markup

• Pizza Chef approach helpful

• Wide range of formats of archival documents

• Descriptive/procedural distinction

• But just one DTD.

• Modify stylesheets


Examples

Example EAC document

Example TEI document

Application example


TEI DTD modification

TEI for Archives DTD

Abbreviations entity file


Re-use through Web Services

• Standardisation of encoding makes possible standardised application functions.

• Application functions described by WSDL (Web Services Description Language) file

• Means application developers can incorporate LEADERS functions into their own applications.


Conclusions

• Trade-offs– EAD: stricter control vs loss of hospitality to

legacy data and variation in existing practices.– TEI: a single DTD but hospitality to a

potentially wide range of source materials vs less reusability of stylesheets.

• Paradox– More standardisation of encoding vs more

flexibility in terms of interoperability.

Copyright, UCL LEADERS: Linking EAD to Electronically Retrievable Sources Interoperability: Where...

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