Providing High Availability in Very Large Workflow Management Systems

Title Providing High Availability in Very Large Workflow Management Systems
Author(s) M. Kamath, G. Alonso, R. Günthör, C. Mohan
Type inproceedings
Booktitle Proceedings of the Fifth International Conference on Extending Database Technology (EDBT'96)
Avignon, France
Organization Institute for Information Systems, ETH Zürich
Month March
Year 1996


Workflow management systems (WFMSs) support the modeling, coordinated execution and monitoring of business processes within an organization. In particular, very large workflow management systems are used in organizations where the number of users may be in the tens of thousands, the number of process instances in the hundreds of thousands, and the number of sites in the thousands, all distributed over wide geographic areas. In these environments, failure of the WFMS or the underlying workflow database which stores the meta-information about the processes is not tolerable and hence continuous availability is a key aspect of the system. This paper addresses the problem of providing high availability in workflow management systems by proposing a backup technique which ensures that execution of a process instance can be resumed at any point in time in the event of failures. An essential characteristic of our backup scheme is that it allows the user to define different availability levels in order to avoid high costs for maintaining backups for all process instances. The backup scheme to support the different availability levels is implemented using the workflow semantics, which we believe will --- (i) make it independent of the underlying workflow database, thus permitting the use of heterogeneous databases as primary and backup, (ii) reduce overheads, especially when compared to backup schemes provided by database systems.

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