The structure of a workflow process is determined by the activities in the process and the transitions between them. Hence a workflow forms a Graph in which the activities are vertices and the transitions are arcs (the graph formed by a workflow can be viewed using the Visualize Workflow Process feature in the Process Definition Tool).
In order for the workflow engine to successfully interpret and execute a process, the graph formed by that process must meet certain criteria. This chapter presents those criteria under two main headings: Graph Structure and Block Structure.