Concurrency: State Models and Java Programs

Chapter 8. Model-Based Design

Modeling is widely used in engineering design. Models are simplified representations of the real world, designed to include only those aspects relevant to the problem at hand. The reduction in scale and complexity achieved by modeling enables design engineers to analyze their designs to check the properties of interest.

For instance, a structural engineer may build a mathematical model of a particular bridge design to investigate its strength. Using different model parameters to represent differing situations and materials, the engineer analyzes the stresses and strains on the structural components of the proposed bridge, thereby assessing its strength. The engineer uses data from past experience and knowledge and skill to design and tailor the model such that it accurately reflects the behavior of a real bridge. This is essential if the faults found in the model are to be true indications of faults that could occur in the real bridge, and conversely that the lack of faults indicates a sound design for a fault-free bridge. Thus the engineer interprets the model behavior in order to infer behavior of the real bridge. Of course, the engineer may need to modify the design and corresponding model until, satisfied with the results, he or she can continue with confidence on the path to bridge construction.

As illustrated in the preceding chapters, this book takes a modeling approach to the design of concurrent programs. Our models represent the concurrent behavior ...