Based on your own knowledge of some of the application types discussed in section 1.1.2, explain, with examples, why different application types require specialized software engineering techniques to support their design and development.

Question

What will be an ideal response?

Answer 1

Different application types require the use of different development techniques for
a number of reasons:
1. Costs and frequency of change. Some systems (such as embedded systems
in consumer devices) are extremely expensive to change; others, must
change frequently in response to changing requirements (e.g. business

systems). Systems which are very expensive to change need extensive up-
front analysis to ensure that the requirements are consistent and extensive

validation to ensure that the system meets its specification. This is not cost-
effective for systems that change very rapidly.

2. The most important ‘non-functional’ requirements. Different systems have
different priorities for non-functional requirements. For example, a real-time control system in an aircraft has safety as its principal priority; an interactive
game has responsiveness and usability as its priority. The techniques used to
achieve safety are not required for interactive gaming; the extensive UI
design required for games is not needed in safety-critical control systems.
3. The software lifetime and delivery schedule. Some software systems have a
relatively short lifetime (many web-based systems), others have a lifetime of
tens of years (large command and control systems). Some systems have to
be delivered quickly if they are to be useful. The techniques used to develop
short-lifetime, rapid delivery systems (e.g. use of scripting languages,
prototyping, etc.) are inappropriate for long-lifetime systems which require
techniques that allow for long-term support such as design modelling.