Pattern-driven Reuse of Behavioral Specifications in Embedded Control System Design

Methods and approaches in systems engineering are often based on the results of empirical observations or on individual success stories. Every real-world embedded system design stems from decisions based on an application domain knowledge that includes facts about some previous design practice. Evidently, such decisions relate to system architecture components, called in this paper as application patterns, which determine not only a required system behavior but also some presupposed implementation principles. Application patterns should respect those particular solutions that were successful in previous relevant design cases. While focused on the system architecture range that covers more than software components, the application patterns look in many features like wellknown software object-oriented design concepts such as reusable patterns (Coad and Yourdon, 1990), design patterns (Gamma et al., 1995), and frameworks (Johnson, 1997). By the way, there are also other related concepts such as use cases (Jacobson, 1992), architectural styles (Shaw and Garlan, 1996), or templates (Turner, 1997), which could be utilized for the purpose of this paper instead of introducing a novel notion. Nevertheless, application patterns can structure behavioral specifications and, concurrently, they can support architectural components specification reuse. Nowadays, industrial scale reusability frequently requires a knowledge-based support. Case-based reasoning (see e.g. Kolodner, 1993) can provide such a support. The method differs from other rather traditional procedures of Artificial Intelligence relying on case history: for a new problem, it strives for a similar old solution saved in a case library. Any case library serves as a knowledge base of a case-based reasoning system. The system acquires knowledge from old cases while learning can be achieved accumulating new cases. Solving a new case, the most similar old case is retrieved from the case library. The suggested solution of a new case is generated in conformity with the retrieved old case. This book chapter proposes not only how to represent a system’s formal specification as an application pattern structure of specification fragments, but also how to measure similarity of formal specifications for retrieval. In this chapter, case-based reasoning support to reuse is focused on specifications by finite-state and timed automata, or by state and timed-state