IMS5024 Information Systems Modelling

1. IMS5024 Information Systems Modelling Blum’s Taxonomy

2. Content • re-visit the taxonomy • application to the methods

3. Why create models? • to communicate • to represent • to explain • to clarify • to simplify • to contextualise • to record

4. Software development • analysis • design • implementation

5. Taxonomy of methods • “…there will be few invariants in the domain of design methods.”

6. Domains of modelling • business occurs in the application domain • what people do • what management wants • how results are interpreted • models of the application domain • correspond to the described need • are valid solutions to a problem

7. Domains of modelling • software development occurs in the implementation domain • demonstrably correct • logically precise • technologically operable • models in the implementation domain • correct in terms of instrumental technology • verifiable against formal criteria

8. The software process Application domain Formal model Conceptual model Implementation domain

9. Correspondence • for any identified business need there may be many conceptual models • for each conceptual model, many formal models are possible • for each formal model there may be many correct implementations • There is no formal way of defining the “best” response

10. Openness • business problems are Open • some requirements are considered implicit • software products are Closed • the delivered functionality is explicit • scope for mismatch

11. A framework of methods • problem oriented or product oriented • conceptual or formal • (this is Blum’s framework – there are sure to be other, different views)

12. Blum’s framework after Blum, p86

13. Blum’s classification of design methods after Blum, p92

14. Reference Blum, B.I. (1994) A taxonomy of software development methods. Communications of the ACM, 37, 11, pp 82-94.