State-Based Formal Methods for Distributed Processing: From Z to Object-Z

In this paper, we look at state-based specification notations and how they may be extended with concepts from object orientation. In particular, we focus on the Z specification language and one of its object-oriented extensions Object-Z. The state-based paradigm is introduced by specifying an ODP trader object in Z. The paper provides an overview of other state-based notations and discusses how such notations have been extended to support object orientation. Finally, we present a specification of the ODP trading function in Object-Z

A blocking model for reactive objects

Objects can be viewed as entities reacting concurrently with their environment through the sending and receiving of messages. In this paper a model for such reactive objects is constructed where messages may be blocked either by the object or by the environment. This model differentiates between output messages controlled by the object, and input messages controlled by the environment. The model is applied to define an object compatibility lattice structure enabling the construction of objects satisfying best possible compatibility requirements