A declarative approach to timed-properties aware Web services composition

In this paper we propose a paradigm shift for the timedproperties representation, computation and verification, introducing a declarative approach. The proposed approach provides a flexible event calculus based composition design, that allows for modeling different aspects such as the local temporal constraints for Web services with different synchronization modes and the global temporal constraints associated with the composition process. Further, given the composition design with timed properties representation, an event calculus reasoner can be used to compute a solution satisfying associated timed-properties. Then, in case of empty solution set the reasoner can provide near-miss models and/or unsatisfied clauses using a SAT solver to handle model verification. In addition, our approach also handles the run-time monitoring of the composition process and as our approach is declarative, it allows for recovery actions such as the re-computation of the composition plan to cater for detected run-time violations to design level service contracts.