Memory fault tolerance software mechanisms: design and configuration support through SWN models

We present a case study of a software fault tolerance mechanisms, the distributed memory, designed and implemented within the European projects TIRAN and DEPAUDE, and currently under study within the Italian project ISIDE. The studied mechanisms are part of a complete framework of general purpose software fault tolerance mechanisms. We show a method for the compositional construction of models of the DM and of the environment in which it operates, expressed in the stochastic well formed nets (SWN) formalism. Different versions of submodels, at different detail level are presented and compared using some behaviour inheritance notions taken from the literature.