MDA Distilled: Principles of Model-Driven Architecture

Models, Models, Models

There are at least three meanings of “model,” and each one implies diverse usages and connotes different processes.

One meaning for the word “model” is a sketch. For example, we might sketch out the shape of a wing on the back of a beer mat, show a few lines indicating air flow, and write an equation or two describing how the two interact. The sketch is not precise or complete, nor is it intended to be. The purpose of the sketch is to try out an idea. The sketch is neither maintained nor delivered. Agile exponents are willing to sketch out classes and use cases (the latter are akin to “user stories”) and perhaps even use the UML to do it. There's no fight here: Even the most extreme folk use sketches to outline their ideas ...