Combination Of Object-Z Research Articles

Specification and (property) inheritance in CSP-OZ

CSP-OZ [C. Fischer, CSP-OZ: A combination of Object-Z and CSP, in: H. Bowman, J. Derrick (Eds.), Formal Methods for Open Object-Based Distributed Systems, FMOODS’97, vol. 2, Chapman & Hall, 1997, pp. 423–438] is a combination of Communicating Sequential Processes (CSP) and Object-Z (OZ). It enables the specification of systems having both a state-based and a behaviour-oriented view using the object-oriented concepts of classes, instantiation and inheritance. CSP-OZ has a process semantics in the failure divergence model of CSP. In this paper we explain CSP-OZ and investigate the notion of inheritance. Furthermore, we study the issue of property inheritance among classes. We prove in a uniform way that behavioural subtyping relations between classes introduced in [H. Wehrheim, Behavioural subtyping in object-oriented specification formalisms, University of Oldenburg, Habilitation Thesis, 2002] guarantee the inheritance of safety and “liveness” properties.

Structural Refinement of Systems Specified in Object-Z and CSP

Abstract. This paper is concerned with methods for refinement of specifications written using a combination of Object-Z and CSP. Such a combination has proved to be a suitable vehicle for specifying complex systems which involve state and behaviour, and several proposals exist for integrating these two languages. The basis of the integration in this paper is a semantics of Object-Z classes identical to CSP processes. This allows classes specified in Object-Z to be combined using CSP operators. It has been shown that this semantic model allows state-based refinement relations to be used on the Object-Z components in an integrated Object-Z/CSP specification. However, the current refinement methodology does not allow the structure of a specification to be changed in a refinement, whereas a full methodology would, for example, allow concurrency to be introduced during the development life-cycle. In this paper, we tackle these concerns and discuss refinements of specifications written using Object-Z and CSP where we change the structure of the specification when performing the refinement. In particular, we develop a set of structural simulation rules which allow single components to be refined to more complex specifications involving CSP operators. The soundness of these rules is verified against the common semantic model and they are illustrated via a number of examples.