Methods And Implement For Exception Handling In Workflow System

With the rapid expansion of Internet and Intranet, some kinds of software systems have been greatly evolved, especially the Workflow Management System. The main intension of WfMS is the automation of procedures where documents, information or tasks are passed between participants according to a predefined set of rules to achieve an overall business goal. There have been a lot of productions of WfMS nowadays. But in most of these productions, it is not well handle the workflow exception and lower the work efficiency of WfMS. However, with the expansion of enterprise and rapid changes of market requirement, workflows model are more and more complexity. It is very necessary to make some good methods to handle all kinds of exception in run time.After a study on exception handling in workflow, based on the conceptual model for transactional workflow, we describe the handling elements that include activities, exception events, strategies, and methods by means of an intuitional formal presentation. And we propose a systematic method to handle expectable and unexpectable exception. On the base of ECA rules, we abstract and present HCA rules for exception handle. HCA rules has the strong flexibility as the ECA rules and they change event test into the judge of condition matching. Then we propose a hierarchical exception recovery algorithm for unexpectable exception. It supports both transactional and non-transactional sub processes, and sub processes of a workflow are nested structure. The algorithm determines the end compensation point dynamically in a hierarchical bottom up manner, so the compensation sphere is confined and compensation costs are reduced.After that, we introduce a WfMS developed with the ability of exception handle and describe the workflow modeling toolkit and the module of exception handle in detail. Finally, the work about this paper is analyzed and evaluated, and the future work is simply discussed.