WPI - CS - TR - 96 - 2 September 1996 A 3 - level

A work ow management systems (WFMS) employs a work ow manager (WM) to execute and automate the various activities within a work ow. To protect the consistency of data, the WM encapsulates each activity with a transaction; a transaction manager (TM) then guarantees the atomicity of activities. Since work ows often group several activities together, the TM is responsible for guaranteeing the atomicity of these units. There are scalability issues, however, with centralized WFMSs. Decentralized WFMSs provide an architecture for multiple autonomous WFMSs to interoperate, thus accommodating multiple work ows and geographically-dispersed teams. When atomic units are composed of activities spread across multiple WFMSs, however, there is a con ict between global atomicity and local autonomy of each WFMS. This paper describes a decentralized atomicity model that enables work ow administrators to specify the scope of multi-site atomicity based upon the desired semantics of multi-site tasks in the decentralized WFMS. We describe an architecture that realizes our model and execution paradigm.