Gaining Control over Time in Workflow Management Applications

Abstract

The need for explicit time management in workflow environments has been recently identified. Although the concept of time is inherent in workflow applications, time management until now has been treated by the same general-purpose structures of the workflow system. This traditional approach does not allow for explicitly specifying timing correctness requirements, temporal consistency checking, immediate control over the diverse set of time constraints that workflow applications exhibit and timely monitoring of the environment. In this paper, we extend the existing workflow specification based on the requirements posed by real-life applications such as health systems. We argue that time management should be an integral part of the workflow management system and not performed by a general-purpose temporal reasoner. We incorporate a subset of interval algebra that allows for efficient consistency checking, while providing expressiveness of temporal constraints. We show that static scheduling for meeting temporal constraints is inadequate for a large class of workflow applications. We show how global scheduling based on temporal constraints can be combined with agent scheduling policies. We demonstrate through examples the working of the scheduling algorithms.