Chapter 1 Mathematical Model Transformations

For most computer controlled systems, especially dependable, real–time systems for critical applications , an effective design process requires an early conceptual and architectural validation prior to the implementation in order to avoid costly re–design cycles. In order to have a guaranteed design quality, all relevant system characteristics have to be checked during this system verification phase. These parameters identify critical bottlenecks to which the system is highly sensitive. The increasing need for effective design has necessitated the development of standardized and well-specified design methods and languages, which allow system developers to work on a common platform of design tools. The Unified Modeling Language (UML) is a visual specification language for pure software systems, as well as for embedded real-time systems (systems reactively interacting with their environment). The UML represents a collection of best engineering practises that have proven successful in the modelling of large and complex systems. Recently, UML has been regarded as the standard object–oriented modelling language. Formal methods are mathematics-based techniques offering a rigorous and effective way to model, design and analyze computer systems. They have been a topic of research (in projects like IOSIP [8], SafeRail [5], SpeciMen [7] or HIDE [2]) for many years with valuable academic results. However, their industrial utilization is still limited to specialized development sites, despite their vital necessity originating in the complexity of IT products and the increasing requirements for dependability and Quality of Service (QoS). The use of formal verification tools (like SPIN [11] or PVS [21]) in IT system design is hindered by a gap between practice–oriented CASE tools and sophisticated mathematical tools. On the one hand, system engineers usually show no proper mathematical skills required for applying formal verification techniques in the software design process. On the other hand, even if a formal analysis is carried out, the consistency of the manually created mathematical model and the original system is not assured. Moreover, the interpretation of analysis results, thus the re–projection of the mathematical analysis results to the designated system is problematical. From the engineering point of view, the notion of dependability is a composite one necessitating the analysis of multiple mathematical properties by using different verification tools. The aim of our ongoing research is to provide a provenly correct and complete, automated transformation between UML–based system models and formal mathematical verification tools for an effective software design.[28]