Metrics for Object-Oriented Software Reliability Assessment - Application to a Flight Manager

In avionics domain, the software applications grew to millions of source lines of code representing important development expenditures. To cut the costs, the avionics suppliers are studying the potential use of new software approaches such as object-oriented technologies. These technologies reduce the development and maintenance costs, in particular, thanks to the use of the inheritance mechanism. However, these technologies also create a new structural complexity of the programs which is at the origin of new risks of faults. To be embedded in aircraft systems, the avionics certification authorities require the assurance of the control of these faults. This paper proposes a new metrics which quantifies the intrinsic risk level of an object-oriented program. This metrics takes into account the influence of the object structure on the difficulty in identifying an element among the numerous others. It is based on the information theory and the entropy principle applied to structured sets. To highlight its benefits, the metrics is applied to a Java program of a flight manager prototype developed by Thales Avionics.