USING FRAGMENTATION TO INCREASE RELIABILITYFOR WORKFLOW SYSTEMS

摘要

In a large organization, at any moment there may exist a large number of process instances. Ifrna failure occurs a considerable number of them may be affected. Thus enhancing reliability isrnan important issue in workflow applications. Traditionally, reliability is enhanced by replication.rnIn the context of business processes with a client-server architecture, this can be done byrnreplicating process instances at multiple servers. However, because of the large number ofrnprocess instances and the potentially large amount of information pertaining to each instance,rnmaintaining consistency among replicas is more complex and hence causes in a businessrnenvironment a higher overhead than do traditional data-intensive applications. Thus the usernof replication for business processes should be limited.rnIn this paper, we propose a scheme to enhance reliability of business process without replication.rnThe scheme incurs lower overhead than any replication scheme, yet can improve the reliabilityrnover the normal non-replication case. Our scheme can be used as a complement to replication.rnFor example, it can be adopted in a case where the degree of criticality of a process instancerndoes not warrant its replication, yet improving its reliability is desirable. Another merit of thernscheme is that recovery can start even before the failed server is repaired.