A Relationship Service for Digital Libraries

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A Relationship Service for Digital Libraries

• Trond Aalberg

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Digital Libraries

• Systems for managing content (information
  objects)
• creating
• collecting
• organizing
• retrieval and re-use
• dissemination
• archiving
• etc.

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Relationships in Digital Libraries

• Content management
• not only management of atomic information
  objects, but also management of relationship
  information
• Information retrieval
• Navigation as an alternative information
  discovery strategy
• Integration
• Horisontal integration of possibly distributed
  information and information resources

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RelationshipsState of the Art

• Where do relations come from?
• Cognitive science issue.
• What is a relationship?
• Relationships are present in many fields of
  Information Technology
• Information modeling
• Knowledge representation (AI)
• Database systems
• Object oriented systems
• Hypermedia
• Many common aspects, but when it comes to
  implementations they are often ad hoc and diverse

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Problem

• A general need for relationship support in
  digital libraries
• Many relevant technologies arenavigation
  /relationship centric
• Object oriented systems
• Hypermedia
• Semantic web RDF, TopicMaps, etc
• The same basic problem/need but the different
  implementation

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Proposed Solution

• A general and flexible solution for representing
  relationships between information objects
• Includes
• a generic construct for representing a any kind
  of relationship
• basic processing capabilities (navigation)

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Requirements for a generic relationship contruct

• Instance oriented
• Not a class concept, but something that can be
  additionally added to all objects
• Arbitrary degree
• binary, ternary, etc
• Arbitrary types
• relationship semantics by typing
• Constraints
• restrictions on the configuration of a
  relationship type
• Support for distribution of
• service
• relationship endpoints
• participating information objects

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CORBA

• Why
• established middleware environment for
  distributed computing
• easy to integrate with existing solutions
• existing solutions for additionally needed
  services
• The system proposed in this project
• is a redesign of the CORBA Relationship Service,
  but
• combines the best of the CORBA Relationship
  Service with the Hypermedia approach to
  information linking

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The object model
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Service model
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A Prototype Service

• The Digital Library Link Service
• Interfaces defined using IDL
• Prototype implementation in Java
• XML based format for describing types and
  constraints

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A Prototype Application
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Contributions

• Theory
• A cross-domain understanding of relationships
• Implemented system
• A generic link service as a reusable component
• for digital library systems
• and other applications as well