When four-eyes become too much: a survey on the interplay of authorization constraints and workflow resilience

We survey the state of the art on workflow satisfiability and its practical consequences in terms of runtime obstructions and resilience. The satisfiability problem is related to authorization constraints put on the workflows: irrespective of the particular access control model, authorization constraints such as "separation of duties", delegation of rights and the sudden unavailability of subjects assigned to a particular task (e.g. in case of illness) may lead to situations in which workflow instances cannot be run, i.e. they are not satisfiable. In consequence, these obstructed workflows do not generate the expected value to the company. This constitutes a serious threat for the provision of reliable process-aware information systems and a challenge for reliable enterprise engineering. The contribution of this paper is to systematically classifiy the existing approaches to detect and handle workflow unsatisfiability.