A workflow is a series of work processes performed under rules that reflect the formal structure of the organization in which they are carried out and the relationships between their various parts. Workflow applications are software applications used to automate part of workflow processes. They run under the control of a workflow management system (WfMS). The WfMS usually comprises an organizational model, describing the process structure, and a process model, describing the process logic. The Workflow Management Coalition (WfMC, 2004) publishes a set of workflow definitions and related material, including a reference model.