Monitoring and Recovery of Web Service Applications

For a system of distributed processes, correctness can be ensured by (statically) checking whether their composition satisfies properties of interest. However, web services are distributed processes that dynamically discover properties of other web services. Since the overall system may not be available statically and since each business process is supposed to be relatively simple, we propose to use (on-line) runtime monitoring of conversations between partners as a means of checking behavioural correctness of the entire web service system. Our framework allows application developers to specify behavioural correctness properties. By transforming these properties to finite-state automata, we enable conformance checking of finite execution traces of web services described in BPEL against the specification. Moreover, when violations are discovered at runtime, we automatically propose and rank recovery plans which users of the system can then select for execution. For some of the violations, such plans essentially involve “going back” – compensating the occurred actions until an alternative behaviour of the application is possible. For other violations, such plans include both “going back” and “re-planning” – guiding the application towards a desired behaviour. We report on the implementation and experience with our monitoring and recovery system, and discuss the implications that the move to “smart internet” [39] may have on our approach.