Improving Takuan to Analyze a Meta-Search Engine WS-BPEL Composition

Web Services composition languages, such as the OASIS WS-BPEL 2.0 standard, open a vast new field for programming in the large. But the inclusion of WS-specific instructions presents a challenge for traditional white-box testing techniques. Takuan helps overcome this challenge by implementing an automated workflow which has already generated invariants from the execution logs of simple WS-BPEL compositions, avoiding the usual problems related to modeling impedance that other techniques face. In this work we show how we have extended Takuan with two complementary techniques to analyze more complex compositions with non-scalar variable content despite the limitations of the dynamic invariant generator used, Daikon. We discuss their relative advantages and disadvantages and illustrate them through some of the invariants obtained from a composition which implements a meta-search engine.