Systematic derivation of operational requirements using the ECSAM method

ECSAM is a method for modeling and analysis of embedded computer systems and their software and the generation of their requirements. Previous ECSAM papers described its application to the conceptual modeling of systems' internals, providing white box models. The paper extends the use of ECSAM to the systematic derivation of systems' external specifications taking into consideration the behaviour of the environmental systems. The application of the method described in the paper results in a black box external model which provides the operational specifications of the system in terms of system modes and behavioral processes. The resulting external and internal system models are inherently consistent. The external specifications are translatable into operational scenarios, which can successively be transformed into operational and test requirements. The approach is demonstrated by an external analysis of a simplified home alarm system. The approach lends itself to the automatic derivation of operational and test requirements from the black box external model using CAS/sup 2/E tools.