A Major Misconception

Although the four phases of a RUP project (Inception, Elaboration, Construction, and Transition) are run sequentially, remember at all times that the RUP lifecycle is fundamentally iterative and risk-driven . There is a big misconception that we would like to push aside very early in our discussion: The various phases are not simply a renaming (to sound fancy or different) of the classical phases of a waterfall process. From practitioners making their first acquaintance with the RUP, we have frequently heard , "Oh, I get it! In Inception you do all the requirements, in Elaboration you do the high-level design, in Construction you write the code, and you finish the testing in Transition."

In trying to match the RUP to their current practice, they completely miss the point of iterative development. Yes, in the early weeks or months of a project the emphasis is very likely to be more on requirements and during the final weeks or months to be more on testing and polishing. This change in focus across the lifecycle is precisely what is hinted at by the "humps" on the lifecycle iteration graph (see Figure 1.3); the height of the humps varies across the cycle. But inside each phase, you plan iterations (see how in Chapter 12), and each of these iterations includes many of the software development activities to produce tested code as an internal ”and later external ”release.