Specifying and Constructing Schedulers for Workflows with Autonomous Executions

Workflow has become an important paradigm for distributed data and computing systems in a wide range of application areas. In a workflow, tasks executing on autonomous, heterogeneous systems are coordinated through data and control flow constraints. An important challenge in workflow management is the scheduling of actions and operations performed by the concurrently executing tasks. The legal interleavings among the tasks must be specified, and scheduling control mechanisms to ensure correct, efficient executions must be generated. Scheduling workflows is particularly difficult because the dependencies between tasks may be application-specific and task autonomy may place certain actions outside the control or observation of the scheduler. We use techniques from supervisory control theory of discrete event systems for specifying and generating scheduling controllers in workflow environments. We specify the tasks and the intertask dependencies as finite state automata. To model task aut..