Data flow testing of service-oriented workflow applications

WS-BPEL applications are a kind of service-oriented application. They use XPath extensively to integrate loosely-coupled workflow steps. However, XPath may extract wrong data from the XML messages received, resulting in erroneous results in the integrated process. Surprisingly, although XPath plays a key role in workflow integration, inadequate researches have been conducted to address the important issues in software testing. This paper tackles the problem. It also demonstrates a novel transformation strategy to construct artifacts. We use the mathematical definitions of XPath constructs as rewriting rules, and propose a data structure called XPath rewriting graph (XRG), which not only models how an XPath is conceptually rewritten but also tracks individual rewritings progressively. We treat the mathematical variables in the applied rewriting rules as if they were program variables, and use them to analyze how information may be rewritten in an XPath conceptually. We thus develop an algorithm to construct XRGs and a novel family of data flow testing criteria to test WS-BPEL applications. Experiment results show that our testing approach is promising.