Resource Relocation in Workflow Nets With Time, Resource, and Task Priority Constraints

Complex workflows arising from practical applications usually combine time, resource, and task priority constraints. The goal of this paper is to formulate a suitable WF net model with all these three types of constraints, and to investigate the soundness property of the resulting model. Thus, the concept of a multilevel resource constrained workflow net (mlRCWF net) as being a place composition of resource constrained workflow (RCWF) nets is introduced, and its soundness property is investigated. This model is then enriched with time and task priority constraints. It is shown that the soundness property of timed priority mlRCWF nets can be reduced in linear time to the soundness property of (untimed) priority RCWF nets. A resource relocation policy is a policy by which resources already allocated to some task are then relocated to urgent tasks, the current task being thus delayed. When the current tasks support an indefinite delay, the soundness of timed priority mlRCWF nets with resource relocation can be reduced in quadratic time to the soundness property of (untimed) priority RCWF nets.