A formal framework for workflow type and instance changes under correctness constraints

Abstract

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 long-running 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.