Relevance, Integration and Classification of Specification Formalisms and Formal Specification Techniques

The purpose of this paper is to discuss the relevance of formal specification techniques versus informal and semi-formal techniques and to propose classification aspects for the great variety of specification formalisms. A formal specification technique is considered to be a specification formalism together with a possibly domain specific methodology for the software development process. For this purpose we first study basic formalisms for different views of systems, in a second step the integration of different basic formalisms and finally we propose a list of relevant classification aspects for specification formalisms. These classification aspects are intended to be a basis for the evaluation of the adequacy of formal specification techniques within specific application domains. 1 . Introduction Formal specification techniques for all kinds of software, communication-based and embedded systems have been developed during the last two decades and applied successfully in several projects. Although informal and semi-formal specification techniques are still dominant in industrial software development the relevance of formal techniques is certainly increasing (see [FM 99]). The relevance of formal methods in the application domain of train-control-systems has been discussed within the workshop FORMS’98 at TU Braunschweig (see [FORMS’98]). In a resolution it was proposed to build up a working group in order to achieve a consensus between developers (industry), users (German Railway, Deutsche Bahn AG) and the federal railway control agency (Eisenbahnbundesamt) concerning the use of formal specification techniques in this application domain. The main purpose of this paper is to give a general introduction to the area of formal specification techniques, to discuss the relevance of formal versus informal and semi-formal techniques, and to propose classification aspects for specification formalisms which later can be used to evaluate the adequacy of different formal specification techniques for the application domain of train-controlsystems.