Formal Design for Automatic Coding and Testing: The ESSI/SPACES Project

Abstract

Embedded software in the space domain must satisfy a set of strong constraints related to behaviour and performance, to fulfil user requirements. Moreover, due to the cost reduction trend in the domain and to the global necessity of increasing the quality of complex software systems, early design validation has become a real challenge for software designers. Currently used methods such as HOOD lacks support for behaviour description. Moreover, design validation is not feasible with such methods and first validation has to be made when the coding phase has sufficiently advanced. This occurs too late in the development phase especially when coding is essentially manual. This calls for the adoption of new development strategies based on formal description of the behaviour, on the use of simulation techniques to check the proposed design solution and on automatic code and tests generation techniques to increase productivity. Following a preliminary successful experience in the context of an ESTEC R&D study called DDV(Dms Design Validation) [1] , the SDL and MSC languages and the ObjectGeode tool have been successfully applied on real projects. To complete those first applications of the technique, a PIE project (Process Improvement Experiment) in the ESSI program [2] has been proposed and accepted by the European Community. That project, called SPACES [3], aims at measuring improvement of development processes through the use of automatic coding and testing from a SDL model. This paper tells the complete story of SDL in our on-board division and focuses on the SPACES project and its current achieved results.