Abstract:The failure of a safety-critical system, though undesirable, is often a source of valuable lessons that can help prevent future failures. Current analysis practices do not always yield as much knowledge as they might about possible flaws in the system safety argument. In this paper, we introduce the lifecycle for safety cases. We use it to develop a framework to guide the analysis process and the development of lessons and recommendations. We illustrate the ideas with an example using the failure history of an air-traffic-control safety system.
Abstract. Software-intensive systems often exhibit dimensions in size and complexity that exceed the scope of comprehension of system designers and analysts. With this complexity comes the potential for undetected errors in the system. While software often causes or exacerbates this problem, its form can be exploited to ameliorate the difficulty in what is referred to as a survivability architecture. In a system with a survivability architecture, under adverse conditions such as system damage or software failures, some desirable function will be eliminated but critical services will be retained. Making a system survivable rather than highly reliable or highly available has many advantages, including overall system simplification and reduced demands on assurance technology. In this paper, we explore the motivation for survivability, how it might be used, what the concept means in a precise and testable sense, and how it is being implemented in two very different application areas. IntroductionSophisticated hardware systems have been providing dependable service in many important application domains for some time. Systems such as electro-mechanical railway signals and aircraft hydro-mechanical controls are safety critical, and many strategies for achieving and analyzing dependability properties in these systems have been developed. Introducing software-intensive components into engineered systems, however, adds extra dimensions in size and complexity. Combining powerful computation facilities with high-speed digital communications can lead to systems that are thousands of times more complex than would normally be considered in a hardware system, such as the electronic funds transfer system within the financial network or the supervisory and control mechanisms within the electric power grid. Such systems are referred to as critical infrastructure systems because of the very high dependence that society now has on them.Software also enables function to be implemented that would be impractical to implement in hardware. In safety-critical embedded systems, important facilitiesincluding many that enhance safety-depend on complex software systems for correct operation. An example of this is stability augmentation in aircraft flight-control, where the digital system calculates a stream of small adjustments that must be made to control surfaces in addition to the pilot's commands. Achieving Critical System Survivability throughSoftware Architectures Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.