Load Balancing Concurrent BPEL Processes by Dynamic Selection of Web Service Endpoints

Business workflows implemented as BPEL processes play an important role for many business applications. BPEL is used to orchestrate a series of Web service calls. Which provider is used for a specific Web service request is statically defined as endpoint of a Web service call within the BPEL code. If a Web service is offered by more than one provider an intelligent choice of a Web service provider can improve the throughput of a BPEL engine. In this article we study how a scheduling mechanism can be injected into a standard BPEL process by an automatic transformation of the BPEL process. The scheduling mechanism helps the BPEL engine to select between different Web service providers, e. g., according to their current workload. Three different strategies for scheduling Web service calls are examined in practical experiments, considering a homogeneous and a heterogeneous collection of Web service providers. We show that in most cases the dynamic scheduling approach leads to a smaller average execution time (makespan) of concurrently executed BPEL processes.