Usual testing is not sufficient because fault events are rare, but may result in an extremely high number of errors, which affect a system in an unexpected way at an arbitrary location. Many fault tolerance techniques have been implemented for distributed systems whose complexity adds to the difficulties of validating dependable behavior. The proposed seminar focuses on validation methods to prove formally or show by heuristics or experiments that a system behaves dependably. Since error detection and processing must be considered from the beginning of the system design phase, the seminar is mainly on model-based validation methods. Other topics like fault injection into implemented systems will also be included to trigger a comparative discussion on the applicability and usefulness of the validation methods for dependability.
Known models are able to express large state spaces in different ways.
Some are exact and complete, others approximative. Some are qualitative and express all possible transitions, others underlay a stochastic model to quantify transition possibilities. All these models benefit from adequate modeling of faults, errors and fault-tolerance properties to obtain a tractable yet sufficiently accurate degree of abstraction. Fault modeling and the validation of fault models will be central themes of the seminar. Currently, a variety of models and fault assumptions, each tailored to special analysis procedures, co-exist.