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IS0514 Lecture - Week 1 (Semester 2)

IS0514 Lecture - Week 1 (Semester 2). Business Systems Development Tools and Techniques. Learning Outcomes. 6. Discuss an object-oriented development lifecycle and the role of UML techniques within it.

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IS0514 Lecture - Week 1 (Semester 2)

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  1. IS0514 Lecture - Week 1(Semester 2) Business Systems Development Tools and Techniques

  2. Learning Outcomes 6. Discuss an object-oriented development lifecycle and the role of UML techniques within it. 7. Explain fundamental principles of object-orientation as applied during analysis and design. 8. Specify system requirements in analysis by means of use cases and use case diagrams. 9. Identify classes in a domain and allocate responsibilities to them. 10. Interpret a realistic domain model in UML class diagram notation. 11. Use UML class diagram notation for simple modelling tasks such as producing a simple class diagram of domain concepts or extending/changing existing models.

  3. Business Systems Development Tools and Techniques • Semester 2 • Unified Modelling Language (UML) • Unified Process • Object Orientation • Use case Diagrams • Class Diagrams • CRC Cards

  4. Assignments • One assignment • Set Week 7 • Due 12/05/2008 • Object Oriented Modelling Exercise

  5. Module Team • Module Tutor • Paula Brumby • Team • Dr Akhtar Ali Room PB101 Ext 3521 • Please contact us at the seminar / lecture in the first instance • Please see module tutor for admin issues

  6. Today's Lecture • What is modelling? • Why model? • Introduction to UML.

  7. What is modelling? • Information System Development is too complex to carry out in your head • Analysis and design produce models • In Information System Development, models are: • Abstract / None physical • Software in non-tangible • Visible • You wish to visualise non-tangible items

  8. What is a model? Some definitions: • A hypothetical description of a complex entity or process • A simplified representation or description of a system under investigation • The act of representing something • A representation of some aspect of external reality in a program

  9. Exercise 1 • In groups of 3-4 spend 5 minutes discussing and identifying • Diagrams you have come across • What purpose they serve • Are they sufficient in themselves? • At the end of that time you will be asked to share your thoughts with the rest of the group.

  10. Exercise 1 – Possible Suggestions

  11. Exercise 1 • Also need • Data • Documentation • Street signs • Material information / craft skill • OK so how do I build this wall here? • Organisation knowledge • What does a managing director do? • Technical information • Is this in Java? • Is the database oracle or access?

  12. Aims of modelling • Aims in modelling : • helps visualise the system as it is, or as we want it to be • permits the specification of the structure and behaviour of the system • provides a template which guides construction of the system • documents the decisions that have been made • provides a common language for all stakeholders • facilitates clarity and understanding

  13. Principles of modelling • What is modelled affects: • How problems are attacked? • How the solution is shaped? • Every model may be expressed at different levels of • Detail – amount modelled • Precision – how much information supplied • The best models are connected to reality • No single model is sufficient. • non-trivial system is best approached through a small set of nearly independent models • we need several model types representing different views • Each model has different diagram(s) – we need several diagrams to model different views

  14. Object Oriented Modelling • In systems, there are two main ways to approach modelling: • Structured – focuses on processing, data and time aspects – separate but related decompositions of these • Object Oriented – based on objects and classes • object – a “thing” of interest, which has uniqueness, state and behaviour (i.e. processing & data) • class – description of a group of objects • We are looking at Object-oriented modelling in this module

  15. Why Model? • A model is a simplification of reality • Choose details to represent • Choose details to ignore • A model can evolve as our understanding does • A model can represent real and abstract things • Creating models allow a system to be better understood • A model can be used to communicate ideas • The larger the system the more important the models • A model can be used to simulate a real system • A model is quicker and easier to build than a real system!

  16. Exercise 2 • In groups of 3-4 spend 5 minutes discussing models you have come across • What is the difference between a diagram and a model • At the end of that time you will be asked to share your thoughts with the rest of the group.

  17. Exercise 2 - Answer

  18. Brief History of Modelling tools • Up to late 1980s • Structured System Analysis and Design (SSADM) / Yourdon / etc • Focus upon processes and data • Late 1980s-1997 • Rise of Object Oriented Technologies • Useful / disparate – need for standardisation • 1995 – now • Unified Modelling Language (UML)

  19. Why UML? • Best practice model • Consolidation of other languages (e.g., OMT, OOSE) • Internationally accepted – ISO standard - ISO/IEC 19501 • UK government mandate • e-Government Interoperability Framework (e-GIF) • Intuitive • Tool support • Widely Used

  20. Use of UML • Surveys of development managers show • 20% of organisations use UML on all development projects • 59% of organisations use UML on some development projects • 18% of organisations never use UML • 3% of organisations have used UML in the past and have no plans to use it again • (Skidmore S (2004))

  21. Introducing the Unified Modelling Language (UML) • UML is a language for • visualising • communication • complexity • specifying • models which are precise, unambiguous and complete • constructing • maps to a programming language like C++, JAVA • documentation

  22. Where UML is used? • banking and financial systems • telecommunications • transportation and distribution • defence and aerospace • retail • medical electronics • scientific systems • distributed web-based services • business modelling • government • computer industry

  23. Diagrams / Models • In UML a model is a collection of diagrams which describe a system from different views • Need to check • Consistency • Completeness – show all that is required • Simplicity of representation • Hierarchical representation • Different diagrams showing different amounts of detail

  24. UML in this module • use case modelling – for requirements • identification/analysis of candidate objects • class diagrams – for specifying classes & relationships • Class, Responsibility, Collaboration (CRC) cards – for responsibilities & interactions

  25. This weeks reading SUPPORTING READING Dennis A, Wixom B, and Tegarden D (2005) System Analysis and Design with UML version 2 second edition, Wiley – Pages 29-35 Bennett S., McRobb, S. and Farmer, R. (2002) Object-Oriented Systems Analysis and Design using UML, 2nd Edition, McGraw-Hill– Chapter 5 CRaG Systems (2004) A UML Introduction Tutorial • Available at: http://www.cragsystems.co.uk/ITMUML/ • Accessed 27/01/2008 Priestley M. (2003) Practical object-oriented design with UML, 2nd Edition, McGraw-Hill– Chapter 1

  26. Summary • What is modelling • Why modelling • Introduction to UML • Next Week • Best Practice Development Methodology

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