Towards Understanding the Importance of Variables in Dependable Software

A dependable software system contains two important components, namely, error detection mechanisms and error recovery mechanisms. An error detection mechanism attempts to detect the existence of an erroneous software state. If an erroneous state is detected, an error recovery mechanism will attempt to restore a correct state. This is done so that errors are not allowed to propagate throughout a software system, i.e., errors are contained. The design of these software artefacts is known to be very difficult. To detect and correct an erroneous state, the values held by some important variables must be ensured to be suitable. In this paper we develop an approach to capture the importance of variables in dependable software systems. We introduce a novel metric, called importance, which captures the impact a given variable has on the dependability of a software system. The importance metric enables the identification of critical variables whose values must be ensured to be correct.