BPEL Conformance in Open Source Engines: The Case of Static Analysis

In 2007, OASIS finalized their Business Process Execution Language 2.0 (BPEL) specification which defines an XML-based language for building orchestrations of Web Services. As the validation of BPEL processes against the official BPEL XML schema leaves room for a plethora of static errors, the specification contains 94 static analysis rules to cover all static errors. According to the specification, any violations of these rules are to be checked by a standard conformant engine at deployment time. When a violation is not detected in BPEL processes during deployment, such errors remain unnoticed until runtime, making them expensive to find and fix. In this work, we investigate whether mature BPEL engines that claimed standard conformance implement these static rules. To answer this question, we formalize the static rules and derive test cases based on these formalizations to evaluate the degree of support for static analysis of six open source BPEL engines using the BPEL Engine Test System (betsy). In addition, we propose a method to get more accurate static analysis conformance results by taking the feature conformance of engines into account to exclude false positives in contrast to the classic approach. The results reveal that support for static analysis in these engines varies greatly, ranging from nonexistent to full support. Furthermore, our proposed method outperforms the classic one in terms of accuracy.