programming-for-dummies

Software Engineering Methods 109
Figure 5-1:
The
waterfall
method
divides a
project into
four distinct
and
mutually
exclusive
steps.
Analysis
Design
Implementation
Testing
Book I
Chapter 5
Managing Large
Projects with
Software
Engineering
Analysis
The first step is to analyze the project to determine exactly what the program’s
supposed to do. (Surprisingly, many people, companies, and government
agencies skip this first step all the time.)
During this analysis step, the customer (the person or group that wants the
program) defines exactly what they want the program to do, which are the
requirements. The programmers read these requirements and ask the customer
for clarification until they “think” they understand exactly what the
customer wants. At this point, the analysis step is done, and the customer
can no longer ask for any more changes.
When a customer’s requirements are written down, they’re often called the
program specifications or just the specifications.
One common problem is that the customer may ask for a new feature that he
didn’t ask for initially. By shutting down the analysis step, the waterfall method
prevents the customer from coming back two days before the project is done
and asking, “Can’t you add just one more feature? It’ll only set the project back
another 3 months and require rewriting 90 percent of the program from
scratch. And by the way, we aren’t going to pay you for the delay either.”
The most common problem during the analysis phase is that the programmers
never clearly understand what the customer wants:
✦ Sometimes the customer clearly defines what he wants, and the programmers
misinterpret it.
✦ Sometimes the customer doesn’t really know what he wants, so he keeps
changing his mind, making it impossible for the programmers to define
everything the program’s supposed to do.