REFINEMENT AND VALIDATION OF SOFTWARE REQUIREMENTS USING INCREMENTAL SIMULATION

Requirements engineering refers to activities of gathering and organiz ing customer requirements and system specifications, making explicit r epresentations of them, and making sure that they are valid and accoun ted for during the course of the design lifecycle of software. One ver y popular software development practice is the incremental development practice. The incremental development refers to practices that allow a program, or similarly specifications, to be developed, validated, an d delivered in stages. The incremental practice is characterized by it s depth-first process where focuses are given to small parts of the sy stem in sequence to fair amounts of detail. In this paper, we present a development and validation of specifications in such an incremental style using a tool called ASADAL, a comprehensive CASE tool for real-t ime systems. ASADAL supports incremental and hierarchical refinements of specifications using multiple representational constructs and the e volving incomplete specifications can be formally tested with respect to critical real time properties or be simulated to determine whether the specifications capture the intended system behavior. In particular , we highlight features of ASADAL's specification simulator, called AS ADAL/SIM, that plays a critical role in the incremental validation and helps users gain insights into the validity of evolving specification s. Such features include the multiple and mixed level simulation, real -value simulation, presentation and analysis of simulation data, and v ariety of flexible simulation control schemes. We illustrate the overa ll process using an example of an incremental specification developmen t of an elevator control system.