Formalizing the Design of Digital Libraries Based on UML

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Formalizing the Design of Digital Libraries Based
on UML
Delos NoE, Preservation Cluster Workshop
Persistency in Digital Libraries 13. February
2006, Oxford Internet Institute
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Talking about
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• Theoretical stage Transforming conceptual models
  into an UML representation (class diagram)
• Pragmatic model by Endres and Fellner
• Formally defined model 5S Framework for Digital
  Libraries by Fox, Goncalves et al.

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The Endres/Fellner Model (EF-Model)
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• Goals
• Modelling an architecture of a digital library on
  a very high level (Conceptual model)
• Modelling just those elements of a DL which are
  absolutely fundamental and do not change

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Starting point Use cases
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• The EF-Model is based on an essential model,
  regarding
• first of all fundamental scenarios of the system
  (business processes, use cases)

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• How can the digital library system fulfill the
  requirements of the essential model?
• Therefore we need to know With which elements
  and concepts the digital library has to deal in
  order to handle the Use Cases?

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• The fundamental unit of a digital library is
  data.
• All systems data has to be saved.

DigitalLibraryData
saveData()
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• According to the essential model, there are 8
  kind of data within a digital library.
• All of these data is a specialisation of the
  global concept of data.
• So these data can be modelled as super-class -
  sub-class relationships, i.e. as
  generalisations.

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• 1. Users
• Data about people who are users of the digital
  library are one fundamental kind of data within a
  digital library system.
• This data represents the user. Therefore, the
  class to be modelled is termed User.
• Basic attributes are address and profile of the
  user Additionally, users can be identified
  through an identification number operations
  enable to modify or create these data.
• Users are specified through sub-classes.

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Class EFUser
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• 2. Supplier
• Suppliers are the second group of entities which
  interact with the system. They can be real
  persons as well as corporations. Suppliers data
  is encapsulated within the class Supplier.
• According to E/F, basic attributes are address
  and (sales) conditions. They are considered to be
  common to all suppliers.

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Class EFSupplier
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EFSupplier can be specialised through
subclasses. Which particular specialisations
are chosen is up to the designer and

depends on the
requirements of the DL.


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• 3. Documents
• Documents are the core products of a digital
  library.
• All data about digital documents which are
  deliverable (asked for by any user) are subsumed
  within a class EFDocument.
• EFDocument serves as a super-class for a number
  of sub-classes. Again, the question which
  sub-classes can be derived is a matter of the
  needs of every distinct digital library.

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Class EFDocument
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• 4. Finding Aids
• Finding aids cover all of the descriptive
  metadata of a digital library E/F are focussing
  especially on those metadata which you can
  retrieve via e.g. OPACs or search engines.
• We therefore call this class EFRetrieval. The
  tools for retrieval are modelled as sub-classes
  as well.
• According to E/F, basic attributes are
  designation, type and (network) address basic
  operations are inserting new finding aids or
  modifying the existing.

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Class EFRetrieval
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• 5. Services
• Services are defined as all services which are
  supported by the digital library except the
  delivery of documents.
• E/F do not give more detailed statements on
  services.

EFService
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• 6. Orders
• The E/F model also comprises business data, just
  as we can find them in almost every commercial
  company.
• Within the EF-Model, one important task of a
  digital library is its ability to cope with
  orders of users for documents or services.
• The class EFOrder represents this task.

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Class EFOrder
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• 7. Deliveries
• Suppliers provide users with the services or
  documents they have ordered.
• These data concerning deliveries are therefore
  encapsulated within the class EFDelivery.

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Class EFDelivery
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• 8. Accountings
• All deliveries are accounted. The related data is
  encapsulated in the EFAccounting class. The
  particular units of the accounting (items) are
  modelled as a class that is associated to
  EFAccounting.
• Order, Delivery and Accounting are business
  related data.

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Class EFAccounting
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EF-Model Summary
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• The EF-Model is a high-level architecture. It
  provides a conceptual model of a digital library
  system.
• The EF-Model is also a taxonomy of data.
• It focuses on some aspects of digital libraries.
  Not all aspects are equally considered. The
  system is to a certain extent understood as an
  economical one.
• The model is also on an analytical stage of
  system design.

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Complete model (red core classes)
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5S Model of a Digital Library
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• 1. What is 5S?
• 5S stands for Streams, Structures, Spaces,
  Scenarios and Societies
• These five dimensions are considered to be
  crucial for every digital library
• As the main components they constitute a
  framework for a digital library. All of the
  elements in the 5S framework are formally
  described.

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• Streams are defined as a sequence of elements of
  an arbitrary type. This could be e.g. bitstreams,
  stream of characters.
• Structures reflect the organisation of
  information. This can be on quite diffrent
  levels, e.g. structure of streams, structure of a
  hypertext, relationships among actors, system
  connections.

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• Spaces present the content of digital libraries
  in a usable and retrievable way. This could be
  the interface to a bibliographic database or a
  browser for accessing objects.
• Scenarios detail the behaviour of digital library
  services and explain the functionality of
  structures and spaces. An example is the act of
  searching for objects.
• Societies focus on the actors involved in the
  functionality of a digital library, e.g. users,
  suppliers, service staff.

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Formal Definition of a DL
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Formal Definition of a DL
28.1

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Formal Definition of Repository
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5S Repository
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Formal Definition of a Digital Object
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Formal Definition of a Digital Object
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Enlarged Repository Structure
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Formal Definition of a DL
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Formal Definition of Catalogue
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5S Catalogue
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Formal Definition of a DL
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Formal Definition of Service
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5S Service
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Formal Definition of a DL
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Formal Definition of Society
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5S Society
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What about the Spaces?
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UML model of the 5S DL
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References
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• Endres, A. Fellner, D.W. Digitale Bibliotheken.
  Heidelberg d-punkt, 2000.
• Goncalves, M.A. Fox, E.A. Watson, L.T. Kipp,
  N. Streams, Structures , Spaces, Scenarios,
  Societies (5S) A formal model for digital
  libraries. Technical report 03-04, Virginia
  Tech., 2004.
• Link http//portal.acm.org/citation.cfm?id98432
  1.984325