Streams of Steam – The Steam Boiler Specification Case Study

FOCUS is a mathematics-based methodology for the development of distributed reactive systems. This paper sketches the expressiveness and the usefulness of the well-tuned concepts of FOCUS by its application of the requirements specification of a steam boiler, see [Abr96]. We demonstrate the support for non-specialists in formal methods by using userfriendly description techniques, here the state-oriented specification with table notation techniques, and a broad range of refinement techniques, here the concept of data and state refinement, which eases the explicit modeling of fault-tolerant behavior. Additionally we prove its adaptability in different domains by handling an example of the “control theory” application field. Because of complexity of the above mentioned aspects we do not give a complete and detailed specification, but rather concentrate on the control task starting from classical control theory, the conceptual formal model of FOCUS and its possibilities for formal modeling and system development.