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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 - PowerPoint PPT Presentation
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Towards a repository – independent
implementation of Digital Object Prototypes
K. Saidis1, G. Pyrounakis2
1Department of Informatics And Telecommunications2Libraries Computer Center
University of Athens
10th European Conference on Research and Advanced Technology for Digital LibrariesDORSDL Workshop
September 21, 2006 - Alicante, Spain 2
Digital Material Model Store Preserve Search Retrieve Describe Publish Share Relate Validate
September 21, 2006 - Alicante, Spain 3
In a … manner User-friendly Effective Inexpensive Uniform Flexible Correct [Add your own]
September 21, 2006 - Alicante, Spain 4
Complex, isn’t it?
Can we make it any simpler?
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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
September 21, 2006 - Alicante, Spain 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
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Pergamos Material Handwritten Notebooks Historical Archive Theatrical Programmes Medical Images Papyri Byzantine Music Manuscripts Research Papers and Dissertations Press Articles
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We wanted to…
Treat digital material variations in a uniform manner
September 21, 2006 - Alicante, Spain 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
September 21, 2006 - Alicante, Spain 10
Nature? Essence? Type?“Types arise informally in any domain to categorize objects according to their usage and behavior. The classification of objects in terms of the purposes for which they are used eventually results in a 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 Abstraction and PolymorphismComputing Surveys, Vol 17 n. 4, pp 471-522, December 1985
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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
September 21, 2006 - Alicante, Spain 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
September 21, 2006 - Alicante, Spain 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
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A DO Instance
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Instantiation / Serialization
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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
September 21, 2006 - Alicante, Spain 17
DOPs 3-tier DL ArchitectureComposition
Semantics
Storage
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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
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The concept Pluggable, Configurable Approach Developers use the DOPs API to
implement DL services Repository implementers provide
repository-specific implementations of the DOStorage interface
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Visualization
DO Repository
DOStorage Interface
DO Dictionary
DL services
DOPS API
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Scenario 1
dops4j
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Scenario 2
dops4j
DO Repository
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Scenario 3
dops4j
Repository-independentType-conscious
DL Services
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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
September 21, 2006 - Alicante, Spain 25
Thank you dops4j release in October (hopefully) Contact: saiko@di.uoa.gr Questions?
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