This paper discusses a novel implementation of a workflow engine that supports service-based applications. The applications are defined according to the GAT model, which is an event-based programming model using conditional guards to determine when both normal and exception-handling activities are to be executed. We propose implementation techniques for key features of GAT. These include implementing control flow based on the evaluation of guards, the management and distribution of events, and enforcing atomicity across the evaluation of guards and the execution of the corresponding activities. We have built an engine following this approach which uses available technologies to support translating GAT models into executable applications.
['Julian Jang', 'Alan Fekete', 'Paul Greenfield', 'Surya Nepal']
An Event-Driven Workflow Engine for Service-based Business Systems