Software Engineering

• intro, life-cycle, prototyping, XP
• HCI
• Open source
• Prog languages, errors, scripting

What is S.E?

• design & construction of software to a required standard
• not just 'writing a program'

Software characteristics

• like hardware?
• spares? wearing out?
• no 'production line'
• logical, not physical

'Software crisis'

• coined in 60's, when huge problems existed
• now there are more systematic approaches

Some myths

• from management:
  'our people have the latest PC's, so they will develop good software.

  'if we fall behind, we can add more people'

• from a customer:
  'a general plan is sufficient for you to start from - we will add more details later.'

  'software is 'soft' - easy to change.'

• developer:
  'methods don't work - I just begin coding.'

  'once it is written, the job is done.'

Some data

• Typical stages in a project: req's analysis, specification, design, coding, testing.
• testing consumes approx 45% of cost.
• maintenance can cost as much as all the previous stages
• it costs 100 times as much to fix an error in the maintenance stage relative to the spec. stage

Software Quality

This is too vague. Which qualities - and how much?

Answer: it depends!

Example - Some qualities:

• easy to maintain
• cheap to produce
• on time
• performance: fast? - small?
• reliable
• portable (can it run on other platforms (e.g Mac?)
• ...etc