1. INSE lecture 17  Standards  Quality

2. SE-related Standards Why? Who? What?

3. Why?  “ Things fitting together ”  People “ talking the same language ”  Avoid duplication of requirements statements & the preceding work

4. Joseph Witworth – Babbage’s Engineer

5. Who? – main players  National bodies (BSI, AFNOR, DIN, etc)  International Standards Organization  International Electrotechnology Commission –ISO/IEC JTC1  Military (UK, US, NATO etc)  European Computer Manufacturers Association (ECMA)  IEEE  IETF (for internet)  W 3 C (for web)

6. What? - examples  Character codes  Floating point  Internet & web  Programming languages  Project Management  Quality

7. Quality in SE  What do we mean by “ Quality ” ?  Some aspects of “ Software Quality ”  ISO 9000

8. “ Quality ” – a muddled concept  “ degree of excellence, relative nature ” (Oxford Concise dictionary)  Two conflicting concepts there:  excellence;  relative nature

9. “ Excellence ”  Top of some scale such as:  excellent  very good  good  OK  bad  very bad  awful  But then we have to ask what each one of these means for a given kind of product …  “ Know it when you see it ”

10. “ Relative nature ”  Easier to compare two products, and as which is “ better ”…  except that one might be better than the other in one way, worse in another.

11. Production jargon Two more senses:  Quality Control – finding out what level of defects we are producing  Quality Assurance – keeping the level of defects down to some acceptable level Both are about “ limiting defects ” – I.e. an opposite sense to “ excellence ”

12. In practice, for SE …  We seldom have a directly comparable product, so “ better/worse ” will usually only apply to generalities;  “ Excellence ” will need a new definition for each new software product  But it is sensible to suggest a list of common defects

13. Aspects of SE excellence (1) From the user point of view:  Correctness  Usability  Reliability Also for safety-critical and security-critical use:  safety  integrity

14. Aspects of SE excellence (2) From the managerial point of view:  Extendability  Scaleability  Portability  Conformance to Standards

15. Aspects of SE excellence (3) From the programmers point of view:  Readability / Learnability  Debugability  Testabilty  Conformance to internal guidelines

16. ISO-9000 series of standards  A set of generic standards covering quality of anything – and in particular “ Quality systems ” for producing anything.  Some of them relate specifically to software –  9000-3 Guidelines for the application of ISO-9001 to the Development, Supply, and Maintenance of Software  9004-2 Quality Management and Quality System Elements, part 2  9126 Quality Factors

17. Management issues  Needs managing sensitively, so that staff are enthusiastic about “ quality ”  despite the bureaucratic aspects being a threat to morale …

18. After this lecture  Standards and Quality are tough issues to be passionate about – but professionalism says you need to be.

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