Runtime web-service workflow optimization

Increasingly, business models build on mechanisms for online interaction. Web Services, business workflows and service orchestrations provide essential tools for staging successful networked business to business (B2B) or business to customer (B2C) transactions. One of the important online interaction quality metrics is perceived response time. The ability to sustain a high throughput and provide fast service effectively means more business and associated revenue. Downtimes and slow transactions can be a strong deterrent for potential customers. The ability to automatically monitor and optimize response performance becomes more important than ever. In this paper we propose a solution for optimizing web service business workflow response times through dynamic resource allocation. On-the-fly monitoring is combined with a novel workflow modeling algorithm that discovers critical execution paths and builds "dynamic" stochastic models in the associated "critical graph". One novel contribution of this work is the ability to naturally handle parallel workflow execution paths. This is essential in applications where workflows include multiple concurrent service calls/paths that need to be "joined" at a later point in time. We discuss the automatic deployment of on-the-fly monitoring mechanisms within the resource management mechanisms. We implement, deploy and experiment with a proof of concept within a generalized web services business process (BPEL4WS/SOAP) framework. In the experiments we show the natural adaptation to changing workflow conditions and appropriate automatic re-allocation of resources to reduce execution times.