Combining the Strengths of BPEL and Mule ESB

Abstract

Service Oriented Architecture (SOA) provides an application framework which integrates variety of technology services in a loosely coupled way. Mule Enterprise Service Bus (ESB) is a widely-used ESB product that provides important functions such as message routing, message transformation, protocol-mediation, and event handling. These functions enable Mule ESB to integrate services implemented on various platforms and technologies. However, Mule ESB does not support business logic at all. Another approach to integrate services is to use a business process language such as BPEL (Business Process Execution Language). BPEL is used to define activities along with control flow. It is limited to Web service connections. One major difference is that BPEL is capable of orchestrating a business process with programming constructs, whereas Mule ESB is capable of processing messages in many protocal connections. Both BPEL and Mule ESB have different advantages. Unfortunately, neither one is powerful enough to solve some classes of business problems. In this paper we present the COMBO framework, which merges the strengths of Mule ESB and BPEL. We develop a tool to translate an extended BPEL file to a Mule ESB configuration file. The configuration file is used within a Mule ESB to execute the process that has been described within the BPEL document. We add extension modules to the standard Mule ESB for supporting BPEL functions that Mule ESB does not provide. The extended ESB has capabilities for supporting variable assignment and conditional branches in complex business processes. Our translation can cover frequently used activities in business processes. We also present case studies that use many business activities to show how the COMBO framework supports various activity translation.