Structured software fault-tolerance with BSM

This paper presents a structured way of inserting software redundancy in programs and to describe the solutions provided for programming software fault-tolerance techniques. It is based on a data-flow like programming paradigm, which is more suitable to implement fault-tolerant systems, with high levels of flexibility and performability, than conventional imperative programming paradigms. The proposed computational model, BSM describes an application in a set of atomic modules, mainly functional, which: (1) maintain the visibility of the semantic of the application, in order to take full advantage of the possibility offered by the use of assertions and predicates for early error detection, and (2) maintain a close correlation between the logical structure of the application and the physical support, to take full advantage of replication as a mechanism of redundancy. The set of modules is executed asynchronously, with a firing rule similar to that of data-flow model; the modules are atomic and do not interact or communicate with other modules during execution, but release data only at their termination. The close correlation between the semantic of the application and the module structuring also allows to scale the needed redundancy since it can be properly driven by the semantic of the application itself