The cleanroom software engineering process is a
software development process
In software engineering, a software development process or software development life cycle (SDLC) is a process of planning and managing software development. It typically involves dividing software development work into smaller, parallel, or s ...
intended to produce software with a certifiable level of
reliability
Reliability, reliable, or unreliable may refer to:
Science, technology, and mathematics Computing
* Data reliability (disambiguation), a property of some disk arrays in computer storage
* Reliability (computer networking), a category used to des ...
. 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
Harlan D. Mills (May 14, 1919 – January 8, 1996) was professor of computer science at the Florida Institute of Technology and founder of Software Engineering Technology, Inc. of Vero Beach, Florida (since acquired by Q-Labs). Mills' cont ...
and several of his colleagues including Alan Hevner at
IBM
International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
.
The cleanroom process first saw use in the mid to late 1980s. Demonstration projects within the military began in the early 1990s. Recent work on the cleanroom process has examined fusing cleanroom with the automated verification capabilities provided by specifications expressed in
CSP.
Philosophy
The focus of the cleanroom process is on defect prevention rather than defect removal. The name "cleanroom" was chosen to evoke the
cleanroom
A cleanroom or clean room is an engineered space that maintains a very low concentration of airborne particulates. It is well-isolated, well-controlled from contamination, and actively cleansed. Such rooms are commonly needed for scientifi ...
s used in the
electronics industry
The electronics industry is the industry (economics), industry that produces electronic devices. It emerged in the 20th century and is today one of the largest global industries. Contemporary society uses a vast array of electronic devices that ar ...
to prevent the introduction of defects during the fabrication of
semiconductor
A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...
s.
Central principles
The basic principles of the cleanroom process are
;Software development based on
formal methods
In computer science, formal methods are mathematics, mathematically rigorous techniques for the formal specification, specification, development, Program analysis, analysis, and formal verification, verification of software and computer hardware, ...
: Software tool support based on some mathematical formalism includes
model checking
In computer science, model checking or property checking is a method for checking whether a finite-state model of a system meets a given specification (also known as correctness). This is typically associated with hardware or software syst ...
,
process algebras, and
Petri nets
A Petri net, also known as a place/transition net (PT net), is one of several mathematical modeling languages for the description of distributed systems. It is a class of discrete event dynamic system. A Petri net is a directed bipartite grap ...
. The
Box Structure Method might be one such means of specifying and designing a software product.
Verification that the design correctly implements the specification is performed through team review, often with software tool support.
;Incremental implementation under
statistical quality control
Statistical process control (SPC) or statistical quality control (SQC) is the application of statistical methods to monitor and control the quality of a production process. This helps to ensure that the process operates efficiently, producing mo ...
: Cleanroom development uses an
iterative
Iteration is the repetition of a process in order to generate a (possibly unbounded) sequence of outcomes. Each repetition of the process is a single iteration, and the outcome of each iteration is then the starting point of the next iteration.
...
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.
;Statistically sound
testing: 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.
References
Further reading
*
*
*
External links
An introduction
{{Software engineering
Software quality