Design and validate embedded SW with the formal language SDL

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. This calls for the adoption of new design strategies based on formal description of the behaviour and on the use of simulation techniques to check the proposed design solution. Following a preliminary successful experience in the context of an ESTEC R&D study called DDV1 [DDV96], the SDL and MSC languages and the ObjectGeode tool have been evaluated on a real project. This paper describes the process set up for this evaluation, gives a summary of the main conclusions which are much positive and proposes some ideas for future use of such techniques in the development of On-Board software.