MODELING AND ANALYSIS OF WORKFLOWS USING PETRI NETS

A workflow system, in its general form, is basically a heterogeneous a nd distributed information system where the tasks are performed using autonomous systems. Resources, such as databases, labor, etc. are typi cally required to process these tasks. Prerequisite to the execution o f a task is a set of constraints that reflect the applicable business rules and user requirements. In this paper we present a Petri Net (PN) based framework that (1) facilitates specification of workflow applic ations, (2) serves as a powerful tool for modeling the system under st udy at a conceptual level, (3) allows for a smooth transition from the conceptual level to a testbed implementation and (4) enables the anal ysis, simulation and validation of the system under study before proce eding to implementation. Specifically, we consider three categories of task dependencies: control flow, value and external (temporal). We id entify several structural properties of PN and demonstrate their use f or conducting the following type of analyses: (1) identify inconsisten t dependency specifications among tasks; (2) test for workflow safety, i.e. test whether the workflow terminates in an acceptable state; (3) for a given starting time, test whether it is feasible to execute a w orkflow with the specified temporal constraints. We also provide an im plementation for conducting the above analyses.