A calculus for the refinement and evolution of multi-user mobile applications

The calculus outlined in this paper provides a formal architectural framework for describing and reasoning about the properties of multi-user and mobile distributed interactive systems. It is based on the Workspace Model, which incorporates both distribution-independent and implementation-specific representations of multi-user and mobile applications. The calculus includes an evolution component, allowing the representation of system change at either level over time. It also includes a refinement component supporting the translation of changes at either level into corresponding changes at the other. The combined calculus has several important properties, including locality and termination of the refinement process and commutativity of evolution and refinement. The calculus may be used to reason about fault tolerance and to define the semantics of programming language constructs.