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Unit 11: Coding Process

what is recommended by the monolithic waterfall model, the developers may feel culpable that Notes
they are not following the model correctly; better results will be obtained from following the
incremental build and test approach intentionally rather than accidentally. (See Figure : 11.1)

Figure 11.1: Incremental Build and Test

Evolutionary Delivery
Evolutionary delivery is shown in Figure: 11.2, and is the most extreme incremental approach,
defining the increments from the top of the life cycle. Gilb’s method includes incremental delivery
as well as incremental development, and therefore has helpful working facilities available to the
customers much earlier than other life cycle models.
The diagram shown actually does not do justice to the evolutionary delivery method, however,
since there is a higher level procedure which precedes the incremental steps, consisting of setting
system and business objectives, open architecture design, planning and quality assurance.
The evolutionary deliveries are made at frequent intervals (possibly as small as a week), and
consist of some function, facility, or organizational modify which is useful to the customer and
relatively easy to produce. In fact that ratio is used to determine the order of the increments.
A major effect of evolutionary delivery is to elicit requests for change, mainly from users.
However, these change requests may be ‘folded back’ into the development process at significantly
less cost than for monolithic models, for two reasons. First, change is expected and planned for,
so it does not come as an unwelcome surprise. Second, when requirements have been completely
detailed and designed (in the monolithic approach), changes which are requested will affect the
work already invested in the frozen specification.

Figure 11.2: Evolutionary Deliveries

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