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Object-Oriented Analysis and Design 333

11

In a waterfall development process, the requirements are detailed, and the clients sign off

(“Yes, this is what I want”); the requirements are then passed on to the designer, set in

stone. The designer creates the design (and a wonder to behold it is), and passes it off to

the programmer who implements the design. The programmer, in turn, hands the code to

a QA person who tests the code and then releases it to the customer. Great in theory,

however, this is potentially disastrous in practice.

The Process of Iterative Development ..........................................................

In iterative development, you start with a concept; an idea of what you might want to

build. As the details are examined, the vision might grow and evolve.

When you have a good start on the requirements, you begin the design, knowing full well

that the questions that arise during design might cause modifications back in the require-

ments. As you work on design, you can also begin prototyping and then implementing

the product. The issues that arise in development feed back into design and might even

influence your understanding of the requirements. Most important, you design and

implement only pieces of the full product, iterating over the design and implementation

phases repeatedly.

Although the steps of the process are repeated iteratively, it is nearly impossible to

describe them in such a cyclical manner. Therefore, the following list describes them in

sequence.

The following are the steps of the iterative development process you’ll use for this:

Step 1: Conceptualization

Conceptualizationis the “vision thing.” It is the single sentence that describes the

great idea.

Step 2: Analysis

Analysisis the process of understanding the requirements.

FIGURE11.3
The waterfall method. Analysis

Design

Implementation

Te s t