Temporal conceptual modelling of workflows

Business processes require the coordinated execution of simple activities (tasks) by human or automatic executors (agents). Business processes are described in terms of a workflow and their execution is supported by suitable software systems named workflow management systems (WfMS). Several conceptual models for the formal definition of workflows have been defined in the literature. However, a detailed conceptual model enabling the process designer to specify temporal constraints for the activities in a workflow is still lacking. By this paper we enrich a previously published conceptual model of workflows by adding the definition of three kinds of constraints: task constraints, related to the starting timestamp, and to the duration of one single task; schedule-task constraints, related to the time elapsed between the completion of a task and the start of the subsequent task by the entitled agent; inter-task constraints, related to the time elapsed between the execution of a task and of one subsequent task of its. The enriched model enables a WfMS to manage soft real-time processes.