A Modal Interface Theory with Data Constraints

For the design of component-based software, the behavioral specification of component interfaces is crucial. We propose an extension of the theory of modal I/O-transition systems by Larsen et al. to cope with both control flow and data states of reactive components at the same time. In our framework, transitions model incoming or outgoing operation calls which are constrained by preand postconditions expressing the mutual assumptions and guarantees of the receiver and the sender of a message. We define a new interface theory by adapting synchronous composition, modal refinement and modal compatibility to the case of modal I/O-transition systems with data constraints. We show that in this formalism modal compatibility is preserved by refinement and modal refinement is preserved by composition which are basic requirements for any interface theory.