programming-for-dummies

110
Software Engineering Methods
After the programmers complete the analysis step, they should know exactly
what the program is supposed to do. Then they can start the design phase
and decide how they’ll create this program.
Design
The design phase is when the programmers write a plan for creating a program
that meets all the customer’s requirements. This can involve deciding
how to break the overall program into smaller parts and then assigning each
part to a different programming team.
At the design phase, the programmers also need to decide on
✦ The programming language to use
✦ A specific compiler and other tools to use
✦ Procedures for keeping all programmers in constant contact with each
other so one programmer doesn’t accidentally duplicate the efforts of
another programmer
The biggest problem with the waterfall model is that if one step isn’t completed
correctly, the rest of the steps won’t work correctly either. For example,
if the analysis part of the waterfall model is done poorly, then it will be
impossible for the design part to be accurate.
✦ Many times the design doesn’t accurately reflect what the customer
wants. Because the programmers talk only to the customer during the
analysis phase, they may cheerfully design a program that almost does
what the customer wants, but not quite. That means the programmers
often create a program that the customer can’t even use without moderate-to-extensive
modifications.
✦ During the design phase, every programmer is supposed to know what the
customer wants, but sometimes programmers leave and new programmers
get added. These new programmers may not have participated in the analysis
phase, so now they have to take time to understand what the customer
wants, which delays the design phase for the entire project.
When everyone finishes deciding how to create the project within a specific
deadline, the design phase is considered over. By forcing programmers to
design a program on paper and create a plan for writing that program, the
waterfall method makes sure that nobody starts writing the program until
they first have a clear idea what they’re doing.
Implementation
After the design phase is done, the implementation phase begins with programmers
actually writing their portion of the program. If the programmers