Conway's Law
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Conway's Law is an adage named after computer programmer Melvin Conway, who introduced the idea in 1968:
...organizations which design systems ... are constrained to produce designs which are copies of the communication structures of these organizations.[1]
Despite jocular usage and jocular derivative "laws," Conway's law was not intended as a joke or a Zen koan, but as a valid sociological observation. It follows from the reasoning that two software modules A and B cannot interface correctly with each other unless the designer and implementer of A communicates with the designer and implementer of B. Thus the interface structure of a software system as a consequence will show a congruence with the social structure of the organization that produced it.
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[edit] Examples of Conway's Law
Consider a large system S that the government wants to build. The government hires company X to build system S. Say company X has three engineering groups, E1, E2, and E3, that participate in the project. Conway's law suggests that it is likely that the resultant system will consist of 3 major subsystems (S1, S2, S3), each built by one of the engineering groups. More importantly, the resultant interfaces between the subsystems (S1-S2, S1-S3, etc) will reflect the quality and nature of the real-world interpersonal communications between the respective engineering groups (E1-E2, E1-E3, etc).
Another example: Consider a two-person team of software engineers, A and B. Say A designs and codes a software class X. Later, the team discovers that class X needs some new features. If A adds the features, A is likely to simply expand X to include the new features. If B adds the new features, B may be afraid of breaking X, and so instead will create a new derived class X2 that inherits X's features, and puts the new features in X2. So, in this example, the final design is a reflection of who implemented the functionality.
A real life example: NASA's Mars Climate Orbiter crashed because one team used United States customary units (e.g., inches, feet and pounds) while the other used metric units for a key spacecraft operation. This information was critical to the maneuvers required to place the spacecraft in the proper Mars orbit. "People sometimes make errors," said Dr. Edward Weiler, NASA's Associate Administrator for Space Science. "The problem here was not the error, it was the failure of NASA's systems engineering, and the checks and balances in our processes to detect the error. That's why we lost the spacecraft."[2]
[edit] Corollary of Conway's Law
Conway's Law can be construed as humorous, to the extent that rigid organizations that are not willing to re-organize to generate an optimal design, can end up producing a sub-standard design that merely reflects the pre-existing organization.
But the essence of Conway's Law also applies to flexible organizations that are willing to re-organize to produce an optimal design.
For example, consider a flexible company that is charged with designing a car, and the company does not yet have a car-design organization. The new car-design organization will probably consist of groups that correspond to the major components of a car: engine, body, transmission, interior, electrical, etc.
The essence of Conway's Law applies even with this reorganisation: the components and interfaces of the resultant car mirror the engineering groups and their interfaces.
And, significantly, any shortcoming with the interpersonal relationships between the engineering groups, may manifest itself in a shortcoming of the resultant design.
[edit] Service industries
Conway's law may extend to the service industries; for example whether train services are run for the convenience of an individual company or for those they connect with (to the benefit of all). A good example is given in Bill Bryson's Notes From a Small Island, where the only train of the day is scheduled to leave exactly two minutes before the bus to the station arrives.
[edit] Supporting evidence
There is supporting evidence of Conway's Law that has been published by a team of Harvard Business School researchers. Their study reveals significant differences in modularity, consistent with a view that distributed teams tend to develop more modular products.
Another case study of Conway's Law can be found on Microsoft Research.
[edit] Notes
- ^ Conway, Melvin E. (April, 1968), "How do Committees Invent?", Datamation 14 (5): 28-31, http://www.melconway.com/research/committees.html, retrieved 2009-04-05 full text
- ^ Mars Climate Orbiter Team Finds Likely Cause of Loss, NASA, 30 September, 1999, http://mars.jpl.nasa.gov/msp98/news/mco990930.html, retrieved 2009-04-05
