Manual and Automated Functional Size Measurement of an Aerospace Realtime Embedded System

A Case Study Based on SCADE and on COSMIC ISO 19761

Soubra, H., Jacot, L. and Lemaire S.

Software Functional size allows the application of engineering principles to software development, which provides an objective and quantitative base for management decisions. Automating Functional size measurement (FSM) is important for organizations needing to measure a large number of projects in a short time. In this paper, we present related work on FSM in the context of real-time embedded systems (RTES) with particular emphasis on works covering FSM automation and providing case studies. Next, we present a COSMIC based FSM procedure, for RTES designed with SCADE. Finally, we manually apply the FSM procedure to an aerospace system; and we compare the results obtained with those produced automatically by a prototype tool developed at ESTACA. Our experimentation concluded that no difference is detected between the automated and the manual measurements by comparing the results at the detailed level; however, applying FSM procedures manually is tedious, time-consuming and error-prone. The study, on the one hand, addresses the lack of fully detailed illustrations of FSM applied both automatically and manually, on RTES software via a full case study which tackles all the intermediate measurement steps. On the other hand, it demonstrates the time efficiency of FSM automation.