Class and State Machine Refinement in UML-B

UML-B is a ’UML-like’ graphical front end for Event-B. It adds support for object oriented modeling concepts while visually retaining the Event-B modeling concepts. In the continuity of the work on UML-B, we strengthen its refinement concepts. Development in Event-B is done through refinements of an abstract model. Since Event-B is reflected in UML-B, the abstraction-refinement concepts must also be catered for in UML-B. UML-B introduced the new concept of refinement, where model complexity is managed by introducing more detailed versions of a machine. We extend this refinement concept by introducing the notion of refined classes and refined state machines. A refined class is one that refines a more abstract class and a refined state machine is one that refines a more abstract state machine. The UML-B drawing tool and Event-B translator are extended to support the refinement concepts. A case study of an auto teller machinestate machine. The UML-B drawing tool and Event-B translator are extended to support the refinement concepts. A case study of an auto teller machine (ATM) is presented to demonstrate the notion of refined classes and refined state machines.