Tucupi: a flexible workflow system based on overridable constraints

Abstract

This work presents the idea and a prototype of workflow systems whose definition is based on constraints. The flexibility is reached through the less rigid definition of workflow definitions - the workflow is defined as a set of pre and post conditions of activities, which are selected dynamically as the process instance unfolds. The workflow system besides dispatching activities that have all their preconditions fulfilled to be executed, also helps users to decide which activity to chose through what if scenarios. The system also includes an access control model which not only represents which users have the authority to chose and execute the activities but also the authority to override the constraints. In particular, overriding constraints is itself an activity and thus may have pre and post conditions defined in other constraints. The paper present Tucupi, a prototype of such constraint based WFMS.