Dr. rer. nat.

Weiß, Gereon

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  • Publication
    Resumption of runtime verification monitors: Method, approach and application
    ( 2018)
    Drabek, Christian
    ;
    Weiß, Gereon
    ;
    Bauer, Bernhard
    Runtime verification checks if the behavior of a system under observation in a certain run satisfies a given correctness property. While a positive description of the system's behavior is often available from specification, it contains no information for the monitor how it should continue in case the system deviates from this behavior. If the monitor does not resume its operation in the right way, test coverage will be unnecessarily low or further observations are misclassified. To close this gap, we present a new method for extending state-based runtime monitors in an automated way, called resumption. Therefore, this paper examines how runtime verification monitors based on a positive behavior description can be resumed to find all detectable deviations instead of reporting only invalid traces. Moreover, we examine when resumption can be applied successfully and we present alternative resumption algorithms. Using an evaluation framework, their precision and recall for detecting different kinds of deviations are compared. While the algorithm seeking expected behavior for resumption works very well in all evaluated cases, the framework can also be used to find the best suited resumption extension for a specific application scenario. Further, two real world application scenarios are introduced where resumption has been successfully applied.
  • Publication
    Method for automatic resumption of runtime verification monitors
    ( 2017)
    Drabek, Christian
    ;
    Weiß, Gereon
    ;
    Bauer, Bernhard
    In networked embedded systems created with parts from different suppliers, deviations from the expected communication behavior often cause integration problems. Therefore, runtime verification monitors are used to detect if observed communication behavior fulfills defined correctness properties. However, in order to resume verification if unspecified behavior is observed, the runtime monitor needs a definition of the resumption. Otherwise, further deviations may be overlooked. We present a method for extending state-based runtime monitors with resumption in an automated way. This enables continuous monitoring without interruption. The method may exploit diverse resumption algorithms. In an evaluation, we show how to find the best suited resumption extension for a specific application scenario and compare the algorithms.
  • Publication
    Generic management of availability in fail-operational automotive systems
    ( 2017)
    Schleiß, Philipp
    ;
    Drabek, Christian
    ;
    Weiß, Gereon
    ;
    Bauer, Bernhard
    The availability of functionality is a crucial aspect of mission- and safety-critical systems. This is for instance demonstrated by the pursuit to automate road transportation. Here, the driver is not obligated to be part of the control loop, thereby requiring the underlying system to remain operational even after a critical component failure. Advances in the field of mixed-criticality research have allowed to address this topic of fail-operational system behaviour more efficiently. For instance, general purpose computing platforms may relinquish the need for dedicated backup units, as their purpose can be redefined at runtime. Based on this, a deterministic and resource-efficient reconfiguration mechanism is developed, in order to address safety concerns with respect to availability in a generic manner. To find a configuration for this mechanism that can ensure all availability-related safety properties, a design-time method to automatically generate schedules for different modes of operations from declaratively defined requirements is established. To cope with the inherent computational complexity, heuristics are developed to effectively narrow the problem space. Subsequently, this method's applicability and scalability are respectively evaluated qualitatively within an automotive case study and quantitatively by means of a tool performance analysis.