MIS 495 -- Dr. Reithel

Chapter 25

Cleanroom Strategy

The cleanroom approach makes use of a specialized version of the incremental software model. A "pipeline of software increments" is developed by small, independent software engineering teams. As each increment is certified, it is integrated into the whole. Hence, functionality of the systems grows with time.

The initial task in the pipeline of cleanroom increments occurs during Increment Planning, where the functionality of each increment, its projected size, and a cleanroom development schedule are established. Special care mus be taken to ensure that certified increments will be integrated in a timely manner. The remainder of the tasks in the cleanroom process are listed on p. 710 in the Pressman book.

Box Types

Black Box -- This box specifies the behavior of a system or a part of a system. The system responds to specific stimuli by applying a set of transition rules that map the stimulus into a response

State Box -- This box encapsulates state data and services in a manner that is analogous to objects. In this specification view, state box and outputs are represented. The state box also represents the "stimulus history" of the black box, that is, the data ecapsulated in the state box that must be retained between the transitions implied.

Clear Box -- The transition functions that are implied by the state box are defined in the clear box. Stated simply, a clear box contains the procedural design for the state box.

Certification

The verification and testing techniques discussed earlier in this chapter lead to software components that can be certified. Within the context of the cleanroom software engineering approach, certification implies that the reliability can be specified for each component. Because of certification, reusable software components can be stored along with their usage scenarios, program stimuli, and probability distributions.

Certification for cleanroom software engineering requires the creation of three models: sampling model, component model, and certification model.