Effiziente verträglichkeitsprüfung und automatische migration von workflow-instanzen bei der evolution von workflow-schemata

A promising technology to enhance the flexibility of business processes is offered by workflow management systems (WfMS). In principle, changes of the process logic of application systems can be easily accomplished by modifying the (graphical) workflow (WF) schema accordingly. In doing so, it is extremely important that already running WF instances will not be disturbed. In current WfMS, this is achieved by the use of simple versioning concepts. WF schema adaptations, however, get much more difficult if the applied changes are to be propagated to already running WF instances as well. On the one hand such a feature is indispensable for many process-centered applications, on the other hand dynamic changes must not violate WF consistency. This paper presents a comprehensive framework for propagating WF schema changes to in-progress WF instances. In particular, we show how this can be done in an efficient manner and without causing inconsistencies or errors in the sequel. We establish well-defined criteria for checking whether a particular WF instance is compliant with the new WF schema or not, and we indicate which information becomes necessary in this context. Furthermore, we discuss how compliant WF instances can be automatically migrated to the new schema.