A Formal Framework For Workflow Type And Instance Changes Under Correctness Constraints∗

The capability to rapidly adapt in-progress workflows (WF) is an essential requirement for any workflow system. Adaptations may concern single WF instances or a WF type as a whole. While changes of single instances often have to be applied in an ad-hoc manner, type changes become necessary to adapt to evolving business processes. Especially for longrunning processes it is indispensable to propagate type changes to running instances as well. Very challenging in this context is to correctly adapt a (potentially large) collection of WF instances, which may be in different states and to which various ad-hoc changes may have been previously applied. This paper presents a comprehensive framework for the support of both, WF type and WF instance changes. We establish general correctness principles and show how WF instances can be automatically and efficiently migrated to a modified WF schema. We point out that our approach exceeds existing adaptation models in formal foundation, completeness, and usability.