Version 1.0 of WSCI[*] was written by BEA, Intalio , Sun, and SAP in 2002. Its syntax and semantics are strikingly similar to those of BPML, which is not surprising, given Intalio’s participation in both specifications. In turn, BPML’s close resemblance to BPEL seemingly implies that WSCI participates in a technology competition—XML process definition languages—that has already been won by BPEL. The temptation to dismiss WSCI outright is irresistible.
But there are subtle differences. WSCI is a web services technology, not a business process technology: it extends WSDL with a language that builds stateful, conversational processes out of stateless, atomic web services. BPM languages, by contrast, build business processes whose external interactions are web services. If web services did not exist, BPM languages could substitute a different integration technology, but WSCI would have no reason to exist.
The typical WSCI application describes a business process that
spans multiple participants and has both a single global, objective
view and individual subjective views for each participant. In Example 8-1, there are
separate processes for
Warehouse, each of which controls the logic for that participant, and there is also the overall exchange of messages. If we were to model this behavior in UML, each process would be represented as an activity diagram, and the overall message exchange would be modeled as a sequence diagram, as ...