The Importance of Models

A large part of the Rational Unified Process focuses on modeling. Models help us understand and shape both the problem and the solution. A model is a simplification of reality that helps us master a large, complex system that cannot be comprehended easily in its entirety. The choice of models and the choice of techniques used to express them have a profound effect on the way we think about the problem and shape the solution. The model is not the reality ("the map is not the territory" ^[1] ), but the best models are the ones that stick very close to reality. ^[2]

^[1] "The map is not the territory" is fundamental to the book, Language in Thought and Action by S. I. Hayakawa. New York: Harcourt-Brace, 1939.

^[2] Grady Booch, James Rumbaugh, and Iver Jacobson, The Unified Modeling Language Users Guide . Reading, MA: Addison-Wesley, 1999.

No single model is sufficient to cover all aspects of software development. We need multiple models to address different concerns. These models must be coordinated carefully to ensure that they are consistent and not too redundant.