Supporting fault tolerance in formal service design

This paper considers design environment based on LOTOS formal specification language. Designers need an environment that effectively supports the development of reliable software. As a first step towards this goal, the author introduces an extension of LOTOS that makes it possible to define directly noninterruptible sequences of actions in specifications, that is, atomic actions at any level of abstraction. This allows specifying different software mechanisms for error recovery. The properties of the new language construct are discussed. In addition, how to use the enhanced LOTOS in order to specify a simple reliable protocol is shown.