Formalizing the Design of Digital Libraries Based on UML Delos NoE, Preservation Cluster: Workshop: Persistency in Digital Libraries 13. February 2006, Oxford Internet Institute

0 Talking about … 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.

1 The Endres/Fellner Model (EF-Model) 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

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

3 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?

4 The fundamental unit of a digital library is data. All systems data has to be saved. DigitalLibraryData saveData()

5 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.

7 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.

8 Class „EFUser“

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9 2.Supplier Suppliers are the second group of entities which interact with the system. They can be real persons as well as corporations. Supplier‘s 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.

10 Class „EFSupplier“ „EFSupplier“ can be specialised through subclasses. Which particular specialisations are chosen is up to the designer and depends on the requirements of the DL.

11 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.

12 Class „EFDocument“

13 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.

Class „EFRetrieval“ 14

15 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

16 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.

17 Class „EFOrder“

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

19 Class „EFDelivery“

20 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.

21 Class „EFAccounting“

22 EF-Model: Summary 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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24 Complete model (red= core classes)

25 5S Model of a Digital Library 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.

26 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.

27 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.

28 Formal Definition of a DL

28.1 Formal Definition of a DL

29 Formal Definition of Repository

30 5S Repository

31 Formal Definition of a Digital Object

32 Formal Definition of a Digital Object

33 Enlarged Repository Structure

34A Formal Definition of a DL

34 Formal Definition of Catalogue

35 5S Catalogue

36A Formal Definition of a DL

36 Formal Definition of Service

37 5S Service

38A Formal Definition of a DL

38 Formal Definition of Society

39 5S Society

40 What about the Spaces?

41 UML model of the 5S DL

42 References Endres, A.; Fellner, D.W.: Digitale Bibliotheken. Heidelberg: d-punkt, 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., Link: