Ensuring Task Dependencies During Workflow Recovery

Workflow management systems (WFMS) coordinate execution of multiple tasks performed by different entities within an organization. In order to coordinate the execution of the various tasks in a workflow, task dependencies are specified among them. These task dependencies are enforced during the normal execution of the workflow. When a system crash occurs some tasks of the workflow may be committed, some may be partially executed and others unscheduled. In such a situation, the recovery mechanism must take appropriate actions to react to the failure. Although researchers have worked on the problem of workflow recovery, most of these work focus on restoring consistency by removing the effects of partially executed tasks. However, these work fail to address how to ensure task dependencies during workflow recovery. In this paper, we consider the workflow recovery problem and propose a recovery scheme that ensures the satisfaction of dependencies in a workflow and restores consistency as well.