Software Engineering for Students A Programming Approach

23.5 Evolutionary prototyping 307
Users should resist the temptation to turn a throwaway prototype into a delivered
system that is put into use. The reasons for this are:
1. important system characteristics, such as performance, security and reliability, will
probably have been ignored during prototype development
2. during the prototype development, the prototype will have been changed to reflect
user needs. It is likely that these changes will have been made in an uncontrolled
way and not properly documented other than in the prototype code
3. the changes made during prototype development will probably have degraded the
architectural structure of the software. Therefore the software may be difficult and
expensive to maintain.
23.5 ● Evolutionary prototyping
This type of prototyping is based on the idea of developing an initial implementation,
exposing it to user comment and refining it through repeated stages until an adequate
system has been developed.
To be effective, evolutionary prototyping is carried out within a systematic framework.
Evolutionary prototype development is shown in Figure 23.2. Note the similarities
and differences between this figure and Figure 23.1.
Draw up initial
specification
[User happy]
Figure 23.2 Evolutionary prototyping
Construct
prototype
Check with
user
Deliver the working
system
[User requires change]
Refine
prototype