Log- and Model-Based Techniques for Security-Sensitive Tackling of Obstructed Workflow Executions.

Imposing access control onto workflows considerably reduces the set of users authorized to execute the workflow tasks. Further constraints (e.g. Separation of Duties) as well as unexpected unavailability of users may finally obstruct the successful workflow execution. To still complete the execution of an obstructed workflow, we envisage a hybrid approach. We first flatten the workflow and its authorizations into a Petri net and analyse for or encode the obstruction with a corresponding "obstruction marking". If a log is provided, we partition its traces into "successful" or "obstructed" by replaying the log on the flattened net. An obstruction should then be solved by finding its nearest match from the list of successful traces. If no log is provided, the structural theory of Petri nets shall be used to provide a minimized Parikh vector, that may violate given firing rules, but reach a complete marking and by that, complete the workflow.