BIS2311Topic2

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  • As described in chapter1, ideally IS Linear and from scratch. No we do mistakes & requirements of client change
  • Implementation has coding & testing
  • BIS2311Topic2

    1. 1. Development of UML, Programming and SA/SD <ul><li>At the end of this session you should be able to: </li></ul><ul><li>Describe how information systems are developed </li></ul><ul><li>Explain the importance of not making changes late in the life cycle </li></ul><ul><li>Distinguish clearly between iteration and incrementation </li></ul><ul><li>Explain the terms iterative and incremental life-cycle model </li></ul><ul><li>Explain in up-to-date terms what ‘maintenance’ means </li></ul><ul><li>Explain what UML is and give reasons for using UML </li></ul>
    2. 2. Idealised Information System Development Does this life cycle apply in the real world? Design Implement Requirements Analysis
    3. 3. The System was finished and the tests were concluded, The users’ last changes were even included, and the user exclaimed with a snarl and a taunt, “ It’s just what I asked for, but not what I want” User Satisfaction
    4. 4. Requirements Classic Life Cycle or Traditional Life Cycle (TLC) or “ Waterfall Model” Also see last week’s slides Analysis Design Implement Towards completion? Nothing gained if the project is discontinued Late discovery of problems lead to cost escalation Clients see nothing until implementation Shifting requirements - not reflected in the implementation Development Maintenance
    5. 5. Iteration <ul><li>The basic information system development process is iterative </li></ul><ul><ul><li>Iterate means to repeat </li></ul></ul><ul><li>Each successive version is intended to be closer to its target than its predecessor </li></ul>Source: ch2, An Introduction to Object-Oriented Systems Analysis and Design with UML and the Unified Process, 2004, Schach, S
    6. 6. Incrementation <ul><li>At any one time, we can concentrate on only approximately seven chunks (units of information) </li></ul><ul><li>To handle larger amounts of information, use stepwise refinement </li></ul><ul><ul><ul><li>Concentrate on the aspects that are currently the most important </li></ul></ul></ul><ul><ul><ul><li>Postpone aspects that are currently less critical </li></ul></ul></ul><ul><ul><ul><li>Every aspect is eventually handled, but in order of current importance </li></ul></ul></ul><ul><li>This is an incremental process </li></ul><ul><ul><ul><li>To “increment” means to increase </li></ul></ul></ul>Source: ch2, An Introduction to Object-Oriented Systems Analysis and Design with UML and the Unified Process, 2004, Schach, S
    7. 7. Iteration, Incrementation <ul><li>Iteration and incrementation are used in conjunction with one another </li></ul><ul><li>There is no single “requirements phase” or “design phase” </li></ul><ul><li>Instead, there are multiple instances of each phase </li></ul>Source: ch2, An Introduction to Object-Oriented Systems Analysis and Design with UML and the Unified Process, 2004, Schach, S
    8. 8. Iteration, Incrementation (1) Source: ch2, An Introduction to Object-Oriented Systems Analysis and Design with UML and the Unified Process, 2004, Schach, S
    9. 9. Iteration, Incrementation (2) Source: ch2, An Introduction to Object-Oriented Systems Analysis and Design with UML and the Unified Process, 2004, Schach, S
    10. 10. Structured Analysis V OOAD <ul><li>Structured Programming/Analysis based around </li></ul><ul><ul><ul><ul><ul><li>Sequence </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Iteration </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Decision </li></ul></ul></ul></ul></ul><ul><li>OO Programming/Analysis based around </li></ul><ul><ul><ul><ul><li>Objects/Classes </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Progression/development from the above! </li></ul></ul></ul></ul>
    11. 11. Origins of UML (Textbook P 5) <ul><li>UML was developed to bring together ‘best features’… </li></ul><ul><li>OO Programming Languages </li></ul><ul><li>Analysis and Design </li></ul><ul><li>Emergence of UML … Rambaugh/Booch/Jacobson </li></ul><ul><li>UML today – Version 2 </li></ul>
    12. 12. What UML is not… (Textbook P 10) <ul><li>Not a Method </li></ul><ul><li>Not a Methodology (What is a Methodology ** ?) </li></ul><ul><li>Not a Software Development Process) </li></ul>** In a lab exercise later, we investigate this further
    13. 13. Why Use UML? (Textbook P 12) <ul><li>Analysis and Design Diagrams </li></ul><ul><ul><ul><ul><li>Abstract features of the design </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Show relationships between elements of the design </li></ul></ul></ul></ul><ul><li>UML is used specifically </li></ul><ul><ul><li>It has become a de facto standard for OOAD </li></ul></ul>
    14. 14. Questions to consider <ul><li>What is a life cycle model? </li></ul><ul><li>Give four advantages of the iterative and the incremental life cycle model. </li></ul><ul><li>Does stepwise refinement correspond to iteration or incrementation? </li></ul><ul><li>What is the connection between the waterfall life-cycle model and the iterative lifecycle model? </li></ul><ul><li>Is there a way of reconciling the traditional definition of maintenance with it’s more recent interpretation? </li></ul><ul><li>What is UML and Why Use UML? </li></ul>

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