INSE lecture 17 Standards Quality
SE-related Standards
Why?Who?What?
Why? “Things fitting together” People “talking the same language” Avoid duplication of requirements
statements & the preceding work
Joseph Witworth – Babbage’s Engineer
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) W3C (for web)
What? - examples Character codes Floating point Internet & web Programming languages Project Management Quality
Quality in SE What do we mean by “Quality”? Some aspects of “Software Quality” ISO 9000
“Quality” – a muddled concept “degree of excellence, relative nature”
(Oxford Concise dictionary) Two conflicting concepts there:
excellence; relative nature
“Excellence” Top of some scale such as:
excellent very good goodOK 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”
“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.
Production jargonTwo 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”
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
Aspects of SE excellence (1)From the user point of view: Correctness Usability ReliabilityAlso for safety-critical and security-critical
use: safety integrity
Aspects of SE excellence (2)From the managerial point of view: Extendability Scaleability Portability Conformance to Standards
Aspects of SE excellence (3)From the programmers point of view:
Readability / LearnabilityDebugabilityTestabiltyConformance to internal guidelines
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
Management issues Needs managing sensitively, so that
staff are enthusiastic about “quality”despite the bureaucratic aspects being a
threat to morale…
After this lecture Standards and Quality are tough issues
to be passionate about – but professionalism says you need to be.
© C Lester 1997-2014