Using formal methods to develop WS-BPEL applications

In recent years, there has been an ever increasing acceptance of WS-BPEL as a standard language for orchestration of web services. However, there are still some well-known difficulties that make programming in WS-BPEL a tricky task. In this paper, we firstly point out major loose points of the WS-BPEL specification by means of many examples, some of which are also exploited to test and compare the behaviour of three of the most known freely available WS-BPEL engines. We show that, as a matter of fact, these engines implement different semantics, which undermines portability of WS-BPEL programs over different platforms. Then we introduce Blite, a prototypical orchestration language equipped with a formal operational semantics, which is closely inspired to but simpler than WS-BPEL. Indeed, Blite is designed around some of WS-BPEL distinctive features like partner links, process termination, message correlation, long-running business transactions and compensation handlers. Finally, we present BliteC, a software tool we have developed for supporting a rapid and easy development of WS-BPEL applicaThis work is partially based on two preliminary papers appeared in [29, 17] and has been partially supported by the EU project SENSORIA IST-2005-016004. ∗Corresponding author Email addresses: [email protected] (Alessandro Lapadula), [email protected] (Rosario Pugliese), [email protected] (Francesco Tiezzi) Preprint submitted to Elsevier December 18, 2009 tions. BliteC translates service orchestrations written in Blite into executable WS-BPEL programs. We illustrate our approach by means of an example borrowed from the official specification of WS-BPEL.