Modeling Workflow Systems Constrained by Inputs and Outputs − An Approach Based on Petri Nets

Workflow systems are widely used in our daily life so that the validity, dependability and security with which they need to be assured are important. However, existing researches mainly focus on correctness validation, performance analysis and assignment scheduling, but the testing methods have been seldom suited. In this paper a formalized definition of workflows constrained by an input and output is presented, and based on that, a Petri Net-based model (I/O_WF_Net) is proposed. In I/O_WF_Net, the activities of the workflow can be modeled as transitions of a Petri Net, and the inputs and outputs of an activity can be modeled as places. After the modeling method for I/O constrained workflow net into the I/O_WF_Net model is described, the corresponding transforming algorithm and its simplifying method are given.