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IMS5024 Lecture 1

IMS5024 Lecture 1. Modeling and ISD. Contents. Welcome, Introductions and housekeeping Approach What is Modelling?. Lecturer. Dr Helana Scheepers Building S, 4-14 Phone: 99031066 E-mail: helana.scheepers@sims.monash.edu.au or Helana.scheepers@infotech.monash.edu.au. Assessment.

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IMS5024 Lecture 1

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  1. IMS5024 Lecture 1 Modeling and ISD

  2. Contents • Welcome, Introductions and housekeeping • Approach • What is Modelling? IMS5024 - Lecture 1

  3. Lecturer • Dr Helana Scheepers • Building S, 4-14 • Phone: 99031066 • E-mail: helana.scheepers@sims.monash.edu.au or Helana.scheepers@infotech.monash.edu.au IMS5024 - Lecture 1

  4. Assessment • Individual assignment • Synopsis for evaluation in week 3 • Due Week 6 • Group assignment • Groups of 4 to 6 • List of names, student numbers, telephone numbers, e-mail addresses, signatures • Presentation • Exam IMS5024 - Lecture 1

  5. Pitfalls • Read website regularly for updates on reading, class assignments and announcements • Plagiarism • Group work IMS5024 - Lecture 1

  6. Reading • Lecture 1: • Chapter 2 of Veryard, R (1992). Information Modelling: Practical Guidance, Prentice Hall International, UK. • Lecture 2: • Chapter 2 and 3 of Mathiassen, L and Dahlbom, B. (1993). Computers in Context: The philosophy and practice of systems design, Blackwell Publishers, UK. • Chapter 2 of Hirschheim, R., Klein, H. and Lyytinen, K. (1995) Information Systems Development and Data Modelling: Conceptual and Philosophical Foundations, Cambridge University Press IMS5024 - Lecture 1

  7. WHAT IS A MODEL? Mathematical • an equation; (eg. E=mc2) Symbolic/Visual • a theory; (eg. the theory of relativity) • a hypothesis; (eg. the speed of light is not a limiting velocity) • an analogy; (eg. a map) Physical/Iconic • an artefact; (eg. a model car) IMS5024 - Lecture 1

  8. THE NATURE OF MODELS 1. Scaling Down; both in terms of size and complexity 2. Transfer Across; representation in relative position 3. Workability; in principle the model operates like the original as a consequence of 1&2 4. Appropriateness; to the aspect of reality under investigation IMS5024 - Lecture 1

  9. THE PATHOLOGY OF MODELLING The model is the reality The model represents all of reality IMS5024 - Lecture 1

  10. WHY MODELS ARE USED Models are an agreed “language” by which a diverse group can communicate about an essential aspect of the “Universe of Discourse” (UoD) It facilitates communication, and shared understanding, between people who have a different perspective about an aspect of reality in which they have mutual interest. IMS5024 - Lecture 1

  11. MODELS AS A MEANS OF COMMUNICATION • A descriptive, narrative model - the big picture • An aesthetic model - what will it look like • An environmental model - where does it fit into the world • A designers model - how does it fit together • A fabricators model - what components are needed • A builder’s model - what do we have to build it on • A constructor’s model - how do we put it together IMS5024 - Lecture 1

  12. The problem of communication:views from the coalface Specs Analyst Client/user Programmer IMS5024 - Lecture 1

  13. What is systems development? Systems development is the process of modelling those aspects of the user’s physical requirements which can take advantage of the things a computer can do. The art of the analyst/designer is to convert what the users needs to support their work into the form of instructions which a computer can follow IMS5024 - Lecture 1

  14. Task Design Objects Process Data Events Organisational Design The Discourse of ISD IMS5024 - Lecture 1

  15. Strengths & weaknesses of ALL forms of modelling • StrengthsWeaknesses • Simplify Omit detail • Relate to a particular purposes Inaccurate (for some things) • Relate to a specific audiences Incomprehensible (to some audiences) No single model can accurately communicate information about ALL aspects of an information system. IMS5024 - Lecture 1

  16. The concept of the logical equivalence The analyst is interested in the “essential” model that depicts the essence of the system; what it must do independent of the technology or the actual system. To achieve this the analyst engages in a process of abstraction, which also includes generalisation, to identify the logical equivalent of the physical world. When modelled, such logical equivalents are called logical or conceptual models. The significance of conceptual models is that software can only represents such models and not the physical world. IMS5024 - Lecture 1

  17. Implications of systems modeling • engineering systems are much easier to model than information systems • what gets modelled is what gets built (and remember all models omit some detail!) • some things are easier to model than others • some things are un-modellable • some models are un-buildable • systems development requires a large variety of models to meet the needs of different audiences IMS5024 - Lecture 1

  18. Using Models The analyst needs to; • beware of simple modeling solutions (real organisations are not simple) • think about the things which are too complex and/or can't be modelled • beware of 'engineering' approaches to non-engineering systems IMS5024 - Lecture 1

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