The Art of Lean Software Development

The Fallacy of Iterative Development

Iterative development is an effective approach for creating software products. However, the desire to create deterministic plans and schedules sometimes leads to an implementation that marginalizes the benefits of iterative development. The fallacy of iterative development is the following pair of false assumptions about iterative development:

• Iterative development is a series of short Waterfalls.

• The content of all iterations should be defined at the outset by divvying up the requirements.

These assumptions lead to a process, shown in Figure 7-4, in which all requirements are gathered at the beginning of the development cycle and an upfront planning activity determines the content of all iterations by divvying up the requirements into iteration-sized pieces, typically with each iteration focused on a different area of the product. The product is then developed via a series of iterations, each of which has the typical Waterfall phases of design, implementation, and test (remember, we eliminated the integration phase with continuous integration). Although this approach is incremental (new features are added each iteration), it doesn’t incorporate customer feedback by reevaluating requirements after each iteration. Features implemented during the iteration are considered complete, and the iteration that follows simply moves on to the next feature.