Transactional behavior of a workflow instance

Workflow management systems usually interpret a workflow definition rigidly, allowing no deviations during execution. However, there are real life situations where users should be allowed to deviate from the prescribed static workflow definition for various reasons, including lack of information about parameter values and unavailability of the required resources. To flexibilize workflow execution, this paper proposes an exception handling mechanism that allows the execution to proceed when otherwise it would have been stopped. The proposal is introduced as a set of extensions to OWL-S that capture the information required for the flexibilization mechanism. In particular, this paper focus on the transactional behavior of a workflow instance, in the sense that it guarantees that either all actions executed by the instance terminate correctly or they are all abandoned.