Flexible workflow management in the OPENflow system

Workflow management systems are required to provide flexible ways of managing workflows as the business processes they represent frequently require changes over time. Provision of flexibility features in workflow management systems is very much a research issue as workflow systems in use today have been found lacking in such features. Two approaches to achieving flexibility in workflows have been identified, namely flexibility by selection and flexibility by adaptation. Flexibility by selection is achieved by ensuring that there are a number of execution paths through the workflow process, such that key decision making points are well represented. This allows the appropriate path to be selected on a per-instance basis to take account of the prevailing circumstances. Flexibility by adaptation permits dynamic changes to workflows to include one or more new execution paths. The paper describes how flexibility is supported in the OPENflow distributed workflow system. In particular, it describes high level tool support for performing dynamic changes to a workflow. In OPENflow, dynamic reconfiguration mechanisms have been provided by making use of atomic transactions to add and remove one or more tasks and to allow the addition and removal of dependencies between tasks from a running workflow. Use of transactions ensures that changes are carried out atomically with respect to normal processing. An example application is described to illustrate flexible workflow management