| Web service workflows allow autonomous web services to be composed to accomplish user-defined, possibly long-running, processes. What has been missing in web service orchestration frameworks is a common solution for transactional support. This thesis introduces an extensible multi-agent based execution mechanism for transactional web service workflows. A hierarchical agent framework, called TRANSAGENT, which utilizes this mechanism for transactional management of web service workflows, is described. TRANSAGENT provides transactional support capabilities including reliable monitoring of process state changes, transactional atomicity and dependency management, reliable failure-handling and compensation, and consistency-checking during workflow execution. In evaluation, this architecture is shown to be more flexible than existing industry web service orchestration models for handling heterogeneous transactional models. The proposed mechanism also supplements current Semantic Web Web Service (SWWS) models due to its ability to support common transaction semantics, context representation, and coordination protocols. This thesis contributes an expressive transactional framework that improves existing web service workflows. |
