A Case Study in Formal Methods: Specification and Validation of the OM/RR Protocol

This paper reports on the results of the application of formal methods in the development of an industrial, mission-critical system, called the Operator Support System. A critical communication protocol of this system, the OM/RR Protocol, and its corresponding service were formalised using the formal specification language Lotos. The resulting specifications have been validated using the tool set Lite and models of the specifications, obtained by making abstractions, have been verified using the tool Eucalyptus. Whereas the use of formal methods is usually motivated by their ability to allow for unambiguous and precise system descriptions amenable to mathematical reasoning, it turned out that in this project most benefits were obtained by the sheer process of formalising the informal protocol description, revealing many omissions and ambiguities. The results and experiences obtained during formalisation, validation, abstraction and verification are discussed on a non-formal basis in this paper