Editing Software prototyping (section)

===Operational prototyping===
Operational prototyping was proposed by Alan Davis as a way to integrate throwaway and evolutionary prototyping with conventional system development. "It offers the best of both the quick-and-dirty and conventional-development worlds in a sensible manner. Designers develop only well-understood features in building the evolutionary baseline, while using throwaway prototyping to experiment with the poorly understood features."<ref name=Davis1992p71/>

Davis' belief is that to try to "retrofit quality onto a rapid prototype" is not the correct method when trying to combine the two approaches. His idea is to engage in an evolutionary prototyping methodology and rapidly prototype the features of the system after each evolution.

The specific methodology follows these steps:<ref name=Davis1992p71/>

*An evolutionary prototype is constructed and made into a baseline using conventional development strategies, specifying and implementing only the requirements that are well understood.
*Copies of the baseline are sent to multiple customer sites along with a trained prototyper.
*At each site, the prototyper watches the user at the system.
*Whenever the user encounters a problem or thinks of a new feature or requirement, the prototyper logs it. This frees the user from having to record the problem, and allows him to continue working.
*After the user session is over, the prototyper constructs a throwaway prototype on top of the baseline system.
*The user now uses the new system and evaluates. If the new changes aren't effective, the prototyper removes them.
*If the user likes the changes, the prototyper writes feature-enhancement requests and forwards them to the development team.
*The development team, with the change requests in hand from all the sites, then produce a new evolutionary prototype using conventional methods.

Obviously, a key to this method is to have well trained prototypers available to go to the user sites. The operational prototyping methodology has many benefits in systems that are complex and have few known requirements in advance.