An empirical study of injected versus actual interface errors

The reuse of software components is a common practice in commercial applications and increasingly appearing in safety critical systems as driven also by cost considerations. This practice puts dependability at risk, as differing operating conditions in different reuse scenarios may expose residual software faults in the components. Consequently, software fault injection techniques are used to assess how residual faults of reused software components may affect the system, and to identify appropriate counter-measures. As fault injection in components’ code suffers from a number of practical disadvantages, it is often replaced by error injection at the component interface level. However, it is still an open issue, whether such injected errors are actually representative of the effects of residual faults. To this end, we propose a method for analyzing how software faults turn into interface errors, with the ultimate aim of supporting more representative interface error injection experiments. Our analysis in the context of widely used software libraries reveals that existing interface error models are not suitable for emulating software faults, and provides useful insights for improving the representativeness of interface error injection.