Runtime monitoring of web service conversations

For a system of distributed processes, correctness can be ensured by (statically) checking whether their composition satisfies properties of interest. In contrast, Web services are being designed so that each partner discovers properties of others dynamically, through a published interface. Since the overall system may not be available statically and since each business process is supposed to be relatively simple, we propose to use runtime monitoring of conversations between partners as a means of checking behavioural correctness of the entire web service system. Specifically, we identify a subset of UML 2.0 Sequence Diagrams as a property specification language and show that it is sufficiently expressive for capturing safety and liveness properties. By transforming these diagrams to automata, we enable conformance checking of finite execution traces against the specification. We describe an implementation of our approach as part of an industrial system and report on preliminary experience.