Specifying and Monitoring Temporal Properties in Web Services Compositions

Current Web service composition approaches and languages such as WS-BPEL do not allow to define temporal constraints in a declarative and separate way. Also it is not possible to verify if there are contradictions between the temporal constraints implemented in the composition. These limitations lead to maintainability and correctness problems. In this paper, we tackle these problems through a novel approach to temporal constraints in Web service compositions, which combines formal methods and aspect-oriented programming. In this approach, we use a powerful and expressive formal language, called XTUS-Automata, for specifying time-related properties and we introduce specification patterns that ease the definition of such constraints. The formal specifications are translated automatically into AO4BPEL aspects, which ensure the runtime monitoring of the temporal constraints. Our approach enables a declarative, separate, and verifiable specification of temporal properties and it generates automatically modular enforcement code for those properties.