FORMAL METHOD FOR AUTOMATED TRANSFORMATION OF LOTOS SPECIFICATIONS TO ESTELLE SPECIFICATIONS

Abstract

ISO and IEC have jointly developed two Formal Description Techniques (FDTs) for specifying distributed real time systems such as computer/telecommunications protocols. These are Lotos and Estelle. In this paper, a formal method for automated transformation of a Lotos specification to an Estelle specification is presented. The method is applicable to various Lotos specification styles and to various communications protocols of ISO OSI layers. Our method has applications in conformance testing of such systems and building common semantic model for the various FDTs. In this paper, we develop an algorithm for constructing a 'Data Oriented'-Restricted Behavior Tree T that represent both the control flow aspects and the data flow aspects of the system. Then, we develop an algorithm for constructing the Estelle specifications from T. A minimization rule is also developed to optimize the size of the Estelle specification by reducing both the number of states and the number of transitions.