Adopting Cleanroom software engineering with a phased approach

Cleanroom software engineering is a theory-based, team-oriented engineering process for developing very high quality software under statistical quality control. The Cleanroom process combines formal methods of object-based box structure specification and design, function-theoretic correctness verification, and statistical usage testing for reliability certification to produce software approaching zero defects. Management of the Cleanroom process is based on a life cycle of development and certification of a pipeline of user-function increments that accumulate into the final product. Teams in IBM and other organizations that use the process are achieving remarkable quality results with high productivity. A phased implementation of the Cleanroom process enables quality and productivity improvements with an increased control of change. An introductory implementation involves the application of Cleanroom principles without the full formality of the process; full implementation involves the comprehensive use of formal Cleanroom methods; and advanced implementation optimizes the process through additional formal methods, reuse, and continual improvement. The AOEXPERT/MVS™ project, the largest IBM Cleanroom effort to date, successfully applied an introductory level of implementation. This paper presents both the implementation strategy and the project results.