ADEPTflex - Supporting Dynamic Changes of Workflows Without Losing Control

Current process-oriented workflow technology is only applicable in a secure and reliable manner if the business process (BP) to be supported is well-structured and there is no need for dynamic extensions or ad hoc deviations at runtime. As only few BPs are statically in this sense, this limits the applicability of today's workflow management systems (WFMSs) significantly. On the other hand, to support deviations from the premodelled task sequences at runtime should not mean that the responsibility for the avoidance of consistency problems (e.g., unintended lost updates) or even runtime errors (e.g., program crashes due to the invocation of task modules with invalid or missing parameters) is now completely shifted to the (naive) end user. Instead, a formal foundation must be established that allows the runtime system to decide whether an intended deviation can be handled in a proper and secure manner.
In this paper we present a conceptual and operational framework for the support of dynamic structural changes of workflows (WFs) in WFMSs. Based upon a simple WF model (ADEPT) we define a complete and minimal set of change operations (ADEPTflex) that support users in modifying the structure of WFs at runtime, while maintaining their correctness and consistency. Correctness properties defined by the ADEPT model are used to determine whether a specific change can be applied to a given WF or not. If these properties are violated the change is either rejected or the correctness must be restored by handling the exceptions resulting from the change. Further, we discuss basic issues with respect to the management of changes and the undoing of temporary changes when backward operations are applied. The change facilities presented in this paper will form a key part of process flexibility in future WFMSs.