Componentware for Critical Systems

We give a short overview over the challenges and some solutions for using compo-nentware for building critical systems. The high quality development of critical systems (be it dependable, security-critical, real-time, or performance-critical systems) is difficult. Many critical systems are developed, fielded, and used that do not satisfy their criticality requirements, sometimes with spectacular failures. Systems whose correct functioning human life and substantial commercial assets depend on need to be developed very carefully. Systems that have to operate under the possibility of system failure or external attack need to be scrutinized to exclude possible weaknesses. Part of the difficulty of critical systems development is that correctness is often in conflict with cost. Where thorough methods of system design pose high cost through personnel training and use, they are all too often avoided. On the other hand, there is an increasing interest in the use of componentware due to a possibility for savings from potential reuse. This raises the question whether the component-ware approach can be used fruitfully in the critical systems area. Beyond the general arguments about savings by reuse, the componentware approach offers an interesting opportunity for high-quality critical systems development that is feasible in an industrial context. • If reusable critical components can be identified, they can be developed at a high standard of quality, and possibly even certified by official authorities. • If a suitable methodology for component-based construction of critical system exists, these critical components can be employed safely and securely within the system context. Under these two provisos, the componentware approach has the potential not only to reduce costs, but at the same time to increase the quality of critical systems software. This observation prompts some challenges one has to overcome to exploit this opportunity, which include the following: