Requirements engineering (RE) is widely recognized as a crucial factor for the success of software projects. Therefore, companies often request assessments of RE processes and resulting artifacts to identify issues and improvement potential. However, industry claims that current assessment approaches do not always fulfill their needs regarding efficiency and effectiveness. Motivated by needs of both, companies asking for an assessment, and a company in the role of an assessor, we have developed a lightweight, tool-supported RE assessment approach. Apart from presenting the approach, we also discuss early experiences we gained from applying our assessment approach in real-world industrial projects.

This paper addresses the issue of characterizing the respective impact of fault injection techniques. Three physical techniques and one software-implemented technique that have been used to assess the fault tolerance features of the MARS fault-tolerant distributed real-time system are compared and analyzed. After a short summary of the fault tolerance features of the MARS architecture and especially of the error detection mechanisms that were used to compare the erroneous behaviors induced by the fault injection techniques considered, we describe the common distributed testbed and test scenario implemented to perform a coherent set of fault injection campaigns. The main features of the four fault injection techniques considered are then briefly described and the results obtained are finally presented and discussed. Emphasis is put on the analysis of the specific impact and merit of each injection technique.

In the design process of distributed real-time systems, a way must be found to cope with the complexity inherent in these systems. An established technique for this purpose is the decomposition of the system into smaller subsystems with well-defined, stable interfaces among them. In this paper, we propose a design method for the development of distributed real-time systems that are intended for safety-critical applications. The method is devised for the Time-Triggered Architecture, which constitutes such a real-time system. For the purpose of decomposition, we introduce a special type of interface, the so-called temporal firewall. In the Time-Triggered Architecture, there are three interfaces of this type-the Communication Network Interface, the Controlled Object Interface and the Gateway Interface-which partition the real-time system into autonomous subsystems. The design method clearly separates system and subsystem issues and focuses on the definition of the three interfaces between the subsystems. The feasibility and relevance of our design method is demonstrated by means of a small example from the automotive industry.