Chou and Borriello Working paper 1998

[CB98b] Pai Chou and Gaetano Borriello,: "Functional Encapsulation vs. State Encapsulation in the Specification of Reactive Systems," Working paper,; February 1998.

Common approaches to the specification of reactive systems use two different types of encapsulation. Functional encapsulation is used in traditional concurrent processes, such as CSP. State encapsulation has been popularized by synchronous languages such as Esterel and StateCharts. These two styles are often intermixed, as evidenced by CSP extensions to Esterel and ActivityCharts in StateCharts.

This is the case because functional encapsulation facilitates data composition and promotes modularity. On the other hand, state encapsulation is more suitable for control composition. Unfortunately, the dichotomy between data and control often forces the designer to commit to either style of composition, resulting in designs that are either difficult to retarget or reuse.

We examine a detailed example that has been described in both encapsulation styles to illustrate the limitations of these two approaches. From the case study, we discuss properties needed to enhance retargetability and reuse. We are currently developing a specification style with these properties as part of the Chinook Project.

Last modified on Monday, 07-Sep-1998 19:20:38 PDT