As interactions and dependencies within distributed reactive systems increase, the problem of detecting failures which depend on the exact situation and environmental conditions they occur in grows. As a result, not only the detection of failures is increasingly difficult, but also the differentiation between the symptoms of a fault, and the actual fault itself, i. e., the cause of a failure. This thesis proposes an efficient approach for the analysis of distributed reactive systems at runtime. It introduces a framework, referred to as monitoring-based runtime reflection framework, for the detection of failures as well as identification of their causes. As an interface to the framework, this thesis proposes a specification language, Salt, to express desired system properties, which then have to hold at all times while a system executes. Detection of failures in the framework is based upon monitoring systems with respect to their associated properties, defined in the high-level specification language Salt. Salt specifications are translatable into the real-time temporal logic TLTL as well as in the untimed temporal logic LTL, and as such can also be used with other temporal logic verification frameworks, such as model checkers. For both logics, an efficient monitor generation procedure is developed for either monitoring qualitative assertions about a system’s behaviour in the untimed case, or quantitative assertions reflecting dense real-time constraints. In order to reflect the semantics of LTL, respectively TLTL, with respect to a finite observational trace in a suitable and unambiguous manner, a 3-valued interpretation is proposed. The corresponding 3-valued monitoring procedure is shown to be optimal with respect to the space-complexity of the generated monitors, and able to detect all minimal bad prefixes of non-conforming system behaviour. Based on the results of the monitors, a dedicated failure diagnosis is performed to identify possible explanations for an observed deviation. As such, diagnosis can either confirm that a monitor detected the root cause for a failure, or indicate that the fault is located elsewhere, and possibly outside the scope of the monitored system. In the runtime reflection framework, diagnosis is based upon the principles of first-order model-based diagnosis, but developed in the propositional domain. The propositional diagnosis problem is then shown to correspond to a deterministic implementation of a solution to the #SAT problem for which a computationally efficient realisation is introduced. This thesis develops both the theoretical foundations for runtime reflection as well as efficient means for its implementation.     «

As interactions and dependencies within distributed reactive systems increase, the problem of detecting failures which depend on the exact situation and environmental conditions they occur in grows. As a result, not only the detection of failures is increasingly difficult, but also the differentiation between the symptoms of a fault, and the actual fault itself, i. e., the cause of a failure. This thesis proposes an efficient approach for the analysis of distributed reactive systems at run...     »

Zunahme von Abhängigkeiten und daraus resultierende, komplexe Interaktionsmuster in verteilten reaktiven Systemen erschweren die Entdeckung von Fehlern, die in komplizierter Weise von Situations- und Umweltbedingungen der Systeme abhängen. In Folge ist oft nicht nur die Erkennung von Fehlverhalten technisch aufwändig, sondern auch die Unterscheidung zwischen Fehlersymptomen und -ursachen. Im Rahmen dieser Arbeit wird ein Verfahren zur dynamischen Analyse von verteilten reaktiven Systemen vorgestellt, welches auf der Überwachung und Interpretation des beobachtbaren Systemverhaltens, sowie der anschließenden Diagnose registrierter Abweichungen basiert. Als Schnittstelle zum Benutzer wird eine abstrakte Spezifikationssprache vorgestellt, um beobachtbare Eigenschaften zu definieren, die vom System stets erfüllt werden müssen. Die formalen Grundlagen des dynamischen Analyseverfahrens, sowie effiziente Techniken zu deren Umsetzung, bilden den Hauptgegenstand dieser Arbeit.     «

Zunahme von Abhängigkeiten und daraus resultierende, komplexe Interaktionsmuster in verteilten reaktiven Systemen erschweren die Entdeckung von Fehlern, die in komplizierter Weise von Situations- und Umweltbedingungen der Systeme abhängen. In Folge ist oft nicht nur die Erkennung von Fehlverhalten technisch aufwändig, sondern auch die Unterscheidung zwischen Fehlersymptomen und -ursachen. Im Rahmen dieser Arbeit wird ein Verfahren zur dynamischen Analyse von verteilten reaktiven Systemen vorgest...     »