Verification Reuse and Frameworks

Design patterns and frameworks as reuse mechanisms hold much promise in the continuing effort to manage software complexity. They provide a vehicle for experts to convey their experience to other software designers. The formal verification of programs is an aspect of system development which software designers find difficult and cumbersome. This is mainly due to the complexity and amount of work involved in applying formal verification techniques. Software managers in particular are not yet convinced of the cost-effectiveness of program verification. These problems are addressed in this paper. We endeavour to extend reusability into the realm of program verification. Our research is based on a methodology for program specification and verification first proposed by Chandy and Misra. It is called UNITY and applies equally well to sequential and parallel programs. From our perspective the main advantage of their approach is that it simplifies reasoning about the correctness of programs. We have extended their methodology with object-oriented concepts, resulting in frameworks that include verification reuse. The example framework in this paper illustrates the general applicability of our methodology.