1. November 2003J. B. Wordsworth: J3ISDQR41 Information Systems Development Quality and Risk (4)

2. November 2003J. B. Wordsworth: J3ISDQR42 What is a method? Defined way of performing an activity Defined inputs Notation for expressing outputs – syntax and semantics Heuristics – how to proceed Analysis approach Computational model

3. November 2003J. B. Wordsworth: J3ISDQR43 Notation Syntax – how to write it –Java, VDM-SL, UML Semantics – what it means –Operational semantics of programming languages Worldliness –The world consists of objects (?) Relevance to the problem in hand –Java for programming, UML for recording a data structure Formality –Z based on sets and logic; UML based on diagrams and annotations.

4. November 2003J. B. Wordsworth: J3ISDQR44 Heuristics Strength – how much guidance is given? –SSADM has strong heuristics. –VDM has weak heuristics. Correctness potential –Formal methods have high correctness potential. –Object-oriented development has a weaker correctness potential.

5. November 2003J. B. Wordsworth: J3ISDQR45 Analysis approach Strength – degree to which we can check the quality of the outputs V&V potential – the degree to which we can verify or validate our outputs –Verification question – does the product agree with its specification? –Validation question – does the product behave the way its users expect?

6. November 2003J. B. Wordsworth: J3ISDQR46 Computational model Specifies units of description and their relationships. –O-O uses objects with relationships of various sorts. –CSP uses processes that synchronise on events and pass information. There are lots of them – see next.

7. November 2003J. B. Wordsworth: J3ISDQR47 Classification of methods From Ould’s Managing Software Quality … JSP, E-R model, UML class diagram module hierarchy, JSD, UML interaction diagram ELH, VDM, Z, UML state diagram Petri nets, CSP, CCS, UML activity diagram DFD, MASCOT, UML sequence diagram Petri nets, MASCOT, FSM, CCS, CSP, UML state and activity diagram datacontrol static dynamic event/ time place

8. November 2003J. B. Wordsworth: J3ISDQR48 Choice of method Choose the view (dynamic, static, data, control). Choose the methods. –(Be prepared to use several.) Check the appropriateness of the computational model. Check the V&V potential.

9. November 2003J. B. Wordsworth: J3ISDQR49 Quality achievement plan Characterisation of system: –data or control –concurrent operations –criticality Client expectations Chosen development methods Chosen tool support Chosen target environment –Development environment Consequent activities

10. November 2003J. B. Wordsworth: J3ISDQR410 Verification opportunities Specifications –For consistency –Against a standard –Against a higher specification For completenes For behavioural equivalence Code –Against a specification –Against a standard

11. November 2003J. B. Wordsworth: J3ISDQR411 Inspections Discovering defects in work products Roles –Moderator –Reader –Inspector Preparation Meeting Correcting the defects Statistics

12. November 2003J. B. Wordsworth: J3ISDQR412 Process Capability Maturity Model (CMM) Devised the by the SEI at Carnegie-Mellon University. Five maturity levels –Initial –Repeatable –Defined –Managed –Optimising

13. November 2003J. B. Wordsworth: J3ISDQR413 Summary Methods help us perform the activities on the project plan. Methods contribute to product quality in various ways. There are many computational models to choose from. Quality control activities are an essential part of the project plan.