Formal Service-Oriented Development of Fault Tolerant Communicating Systems

Telecommunication systems should have a high degree of availability, i.e., high probability of correct and timely provision of requested services. To achieve this, correctness of software for such systems and system fault tolerance should be ensured. Application of formal methods helps us to gain confidence in building correct software. However, to be used in practice, formal methods should be well integrated into existing development process. In this paper we propose a formal model-driven approach to development of communicating systems. Essentially our approach formalizes and extends Lyra – a top-down service-oriented method for development of communicating systems. Lyra is based on transformation and decomposition of models expressed in UML2. We formalize Lyra in the B Method by proposing a set of formal specification and refinement patterns reflecting the essential models and transformations of the Lyra service specification, decomposition and distribution phases. Moreover, we extend Lyra to integrate reasoning about fault tolerance in the entire development flow.