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CHAPTER 2 THE PROCESS 37

FIGURE 2.8 Planning
A typical spiral Risk analysis
Customer
model
communication
Project entry
point axis

Engineering

Customer
evaluation Construction & release

Product maintenance projects
Product enhancement projects
New product development projects
Concept development projects

• Customer evaluation—tasks required to obtain customer feedback based
on evaluation of the software representations created during the engineering
stage and implemented during the installation stage.
Each of the regions is populated by a set of work tasks, called a task set, that are
adapted to the characteristics of the project to be undertaken. For small projects, the
number of work tasks and their formality is low. For larger, more critical projects,
? What is a each task region contains more work tasks that are defined to achieve a higher level
“task set”?
of formality. In all cases, the umbrella activities (e.g., software configuration man-
agement and software quality assurance) noted in Section 2.2 are applied.
As this evolutionary process begins, the software engineering team moves around
the spiral in a clockwise direction, beginning at the center. The first circuit around
the spiral might result in the development of a product specification; subsequent
passes around the spiral might be used to develop a prototype and then progressively
more sophisticated versions of the software. Each pass through the planning region
results in adjustments to the project plan. Cost and schedule are adjusted based on
feedback derived from customer evaluation. In addition, the project manager adjusts
the planned number of iterations required to complete the software.
Adaptable process model
Unlike classical process models that end when software is delivered, the spiral
model can be adapted to apply throughout the life of the computer software. An alter-
native view of the spiral model can be considered by examining the project entry point
axis, also shown in Figure 2.8. Each cube placed along the axis can be used to rep-
resent the starting point for different types of projects. A “concept development