Beginning Software Engineering, 2nd Edition

PART IIProcess Models

• Chapter 17: Predictive Models
• Chapter 18: Iterative Models
• Chapter 19: RAD

According to Darwin’s Origin of Species, it is not the most intellectual of the species that survives; it is not the strongest that survives; but the species that survives is the one that is able best to adapt and adjust to the changing environment in which it finds itself.

—Leon C. Megginson

That’s the basic philosophy behind many modern software process models. They start with an incomplete or imperfect version of an application and then gradually improve it over time. That approach allows the development to change as needed in the face of changing requirements or shifts in the business environment.

In contrast, predictive models define a vision of the completed application at the outset and then work tirelessly toward that vision. Some of those models may allow some limited change, but in general they are much less adaptable than iterative and rapid application development models.

The chapters in this part of the book describe a variety of process models ranging from the relatively inflexible waterfall model to more recent rapid development and iterative models. Each has its strengths and weaknesses, and with some study and experience, you can combine at least some of the strengths with those of another.