The cleanroom software engineering process is a
software development process intended to produce software with a certifiable level of
reliability. The central principles are software development based on formal methods, incremental implementation under statistical quality control, and statistically sound testing.
History
The cleanroom process was originally developed by
Harlan Mills and several of his colleagues including Alan Hevner at
IBM.[1]
The cleanroom process first saw use in the mid to late 1980s. Demonstration projects within the military began in the early 1990s.[2] Recent work on the cleanroom process has examined fusing cleanroom with the automated verification capabilities provided by specifications expressed in
CSP.[3]
Philosophy
The focus of the cleanroom process is on defect prevention rather than defect removal. The name "cleanroom" was chosen to evoke the
cleanrooms used in the
electronics industry to prevent the introduction of defects during the fabrication of
semiconductors.
Software tool support based on some mathematical formalism includes
model checking,
process algebras, and
Petri nets. The
Box Structure Method might be one such means of specifying and designing a software product.[4] Verification that the design correctly implements the specification is performed through team review, often with software tool support.
Cleanroom development uses an
iterative approach, in which the product is developed in increments that gradually increase the implemented functionality. The quality of each increment is measured against pre-established standards to verify that the development process is proceeding acceptably. A failure to meet quality standards results in the cessation of testing for the current increment and a return to the design phase.
Software testing in the cleanroom process is carried out as a statistical experiment. Based on the formal specification, a representative subset of software input/output trajectories is selected and tested. This sample is then statistically analyzed to produce an estimate of the reliability of the software and a level of confidence in that estimate.
^Guy H. Broadfoot and P. J. Hopcroft (2005). "Introducing formal methods into industry using Cleanroom and CSP". Dedicated Systems e-Magazine.
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Stavely, Allan (1999). Toward Zero-Defect Programming. Addison-Wesley.
Stacy J. Prowell and Carmen J. Trammell and Richard C. Linger and Jesse H. Poore (1999). Cleanroom Software Engineering: Technology and Process. Addison-Wesley.
Jesse H. Poore and Carmen J. Trammell (1996). Cleanroom Software Engineering: A Reader. NCC Blackwell.