On the synthesis of protocol state machines from contracts

Abstract

Contractual specifications and UML state machines belong to the basic means for the specification and modelling of object-oriented system behaviour and are the subject of active research. However, the problem of state machines synthesis from contracts has not been researched. In this paper, this problem is investigated and a suitable procedure for protocol state machine generation is presented. This procedure is based on a method used in specification-based testing; it is formally defined, stepwise and based on a well-defined mathematical model. Its applicability is demonstrated on a bank account example often used in the literature. It is shown that resulting protocol state machines help to grasp the meaning of specifications and, as a side effect, to identify flaws in the specification such as unreachable states.