Implementing BPEL4WS: The architecture of a BPEL4WS implementation

BPEL4WS (BPEL in short) is a business process definition language built natively on top of the Web services application model. BPEL provides a workflow-oriented composition model for Web services applications, and is thus a central piece in the heavily componentized service-oriented computing model. BPEL results from the merger of two distinct process metamodels (the process algebra model of XLANG and the graph-oriented model of WSFL) into a coherent and powerful framework. Implementing BPEL thus presents significant challenges to middleware developers. This paper discusses those challenges and describes the design and architecture of the BPWS4J runtime, and a full implementation of the BPELWS 1.1 specification. Copyright © 2005 John Wiley & Sons, Ltd.