A COMPOSITIONAL FRAMEWORK FOR FAULT-TOLERANCE BY SPECIFICATION TRANSFORMATION

The incorporation of a recovery algorithm into a program can be viewed as a program transformation, converting the basic program into a fault-tolerant version. We present a framework in which such program transformations are accompanied by a corresponding specification transformation which obtains properties of the fault tolerant versions of the programs from properties of the basic programs. Compositionality is achieved when every property of the fault tolerant version can be obtained from a transformed property of the basic program. A verification method for proving the correctness of specification transformations is presented. This makes it possible to prove just once that a specification transformation corresponds to a program transformation, removing the need to prove separately the correctness of each transformed program