A Logical Basis for Component-Oriented Software and Systems Engineering

A theory for the systematic development of distributed interactive software systems constructed in terms of components requires a basic system model and description techniques supporting specific views and abstractions of systems. Typical system views are the interface, the distribution, or the state transition view. We show how to represent these views by mathematics and logics. The development of systems consists in working out these views leading step by step to implementations in terms of sets of distributed, concurrent, interacting state machines. For large systems, the development is carried out by refinement through several levels of abstraction. We formalize the typical steps of the development process and express and justify them directly in logic. In particular, we treat three types of refinement steps: horizontal refinement which stays within one level of abstraction, vertical refinement addressing the transition from one level of abstraction to another, and implementation by glass box refinement. We introduce refinement relations to capture these three dimensions of the development space. We derive verification rules for the refinement steps and show the modularity of the approach.