On Detecting Data Flow Errors in Workflows

When designing a business workflow, it is customary practice to create the control flow structure first and to ensure its correctness. Information about the flow of data is introduced subsequently into the workflow and its correctness is independently verified. Improper specification of data requirements of tasks and XOR splits can cause problems such as wrong branching at XOR splits and the failure of tasks to execute. Here we present a graph traversal algorithm called GTforDF for detecting data flow errors in both nested and unstructured workflows, and illustrate its operation on realistic examples. Two of these have interconnected loops and are free of control flow errors, and the third one is an unstructured loop-free workflow. Our approach extends and generalizes data flow verification methods that have been recently proposed. It also makes use of the concept of corresponding pairs lately introduced in control flow verification. It thus has the potential for development into a unified algorithmic procedure for the concurrent detection of control flow and data flow errors. The correctness of the algorithm has been proved theoretically. It has also been tested experimentally on many examples.