Delegation and satisfiability in workflow systems

Supporting delegation mechanisms in workflow systems is receiving increasing interest from the research community. An important requirement of a constrained workflow is to guarantee the satisfiability of the workflow, which requires that some set of authorized users can complete a workflow. Typically, any mechanism that is used to establish the satisfiability of a workflow is based on the workflow specification and the user authorization information. The effect of a successful user delegation request is to change the user authorization information, thereby affecting the satisfiability of the workflow. Existing work on delegation in workflows does not consider the satisfiability of the workflow. In this paper, we address the satisfiability problem of workflows, while supporting user delegation mechanisms, in the context of three different workflow execution models. We consider delegation of concrete tasks, abstract tasks and roles. We present algorithms for evaluating various delegation requests in each workflow execution model.