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Towards a repository – independent implementation of D igital O bject Prototypes

10 th European Conference on Research and Advanced Technology for Digital Libraries DORSDL Workshop. Towards a repository – independent implementation of D igital O bject Prototypes. K. Saidis 1 , G. Pyrounakis 2. 1 Department of Informatics And Telecommunications

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Towards a repository – independent implementation of D igital O bject Prototypes

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  1. 10th European Conference on Research and Advanced Technology for Digital Libraries DORSDL Workshop Towards a repository – independentimplementation of Digital Object Prototypes K. Saidis1, G. Pyrounakis2 1Department of Informatics And Telecommunications 2Libraries Computer Center University of Athens

  2. Digital Material • Model • Store • Preserve • Search • Retrieve • Describe • Publish • Share • Relate • Validate

  3. In a … manner • User-friendly • Effective • Inexpensive • Uniform • Flexible • Correct • [Add your own]

  4. Complex, isn’t it? Can we make it any simpler?

  5. A real-life example • Pergamos: University of Athens DL • Demo (in beta phase): http://homer.lib.uoa.gr:8080/dl • Cataloging Demo will be also available • Contact: pergamos@lib.uoa.gr

  6. Requirements • Build an integrated web-based DL • Small development team • Mostly digitized material, requiring detailed cataloging • Catalogers & digitizers without technical background • Simplify and speed up cataloging & object input

  7. Pergamos Material • Handwritten Notebooks • Historical Archive • Theatrical Programmes • Medical Images • Papyri • Byzantine Music Manuscripts • Research Papers and Dissertations • Press Articles

  8. We wanted to… Treat digital material variations in a uniform manner

  9. But… • Current DL systems focus on how DOs are encoded & stored… • Which parts constitute each object and how each part should behave is not effectively handled • In other terms, it is hard to make DOs behave according to the nature imposed by their underlying “real-world” objects

  10. Nature? Essence? Type? “Types arise informally in any domain tocategorize objects according to their usage andbehavior. The classification of objects in terms of the purposes for which they are used eventually results ina more or less well-defined type system… Sets of objects with uniform behavior may be named and are referred to as types.” L. Cardelli, P. Wegner, On Understanding Types,Data AbstractionandPolymorphism Computing Surveys, Vol 17 n. 4, pp 471-522, December 1985

  11. We argue • Lack of DO types leads to manual resolution of DO variations: • Catalogers • Developers • Designers • Users • The DL system should resolve DO typing issues automatically

  12. Digital Object Prototypes • First realization of DO types, introduced in last year’s ECDL • A DOP is a DO Type specification that provides a detailed definition of a DO’s constituent parts: metadata, files, relationships and behaviors • DOs automatically conform to their respective DOP

  13. DOPs Implementation • DOPs draw on the notions of the OO model to implement DO types • All objects have a type • Objects honor encapsulation • Inheritance (under development) • DOs are conceived as instances of their respective prototype • Stored DOs are treated as serializations of DO instances

  14. A DO Instance

  15. Instantiation / Serialization

  16. DOPs Power • Provide the means to generate user-defined types of digital objects • Allow the inexpensive addition of new types of digital material (no custom coding required) • Enable high level services to treat digital material variations in a uniform manner

  17. DOPs 3-tier DL Architecture Composition Semantics Storage

  18. What’s next • dops4j: DOPs Open Source release • Pergamos DOPs implementation is tightly coupled to FEDORA • Re-engineering that focuses on making DOPs operate independently of the underlying repository • Inexpensive DO type conformance for all

  19. The concept • Pluggable, Configurable Approach • Developers use the DOPs API to implement DL services • Repository implementers provide repository-specific implementations of the DOStorage interface

  20. Visualization DL services DOPS API DO Dictionary DOStorage Interface DO Repository

  21. Scenario 1 dops4j

  22. Scenario 2 DO Repository dops4j

  23. Scenario 3 Repository-independent Type-conscious DL Services dops4j

  24. Benefits • The DOPs framework will become a reusable, configurable component • Easier to switch repositories • Easier to add DO type conformance in many DL application contexts: Centralized, P2P, Distributed, Service-based • Advance interoperability capabilities of repositories

  25. Thank you • dops4j release in October (hopefully) • Contact: saiko@di.uoa.gr • Questions?

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