Chinese Journal of Computers (计算机学报) 2013/36:12 PP.2468-2478
In order to realize automatic composition of semantic Web services, a basic step is to model these services with suitable formal systems; both the accuracy and the efficiency of the composition are determined by the expressive power and the computing property of the formal system adopted. The dynamic description logic DDL(X) is a combination of dynamic logics, description logics and action formalisms constructed over description logics; it provides a new tool for modeling and reasoning about semantic Web services. Based on DDL(X), this paper introduces a method for automatic composition of semantic Web services. Firstly, by translating semantic Web services described by OWL-S into actions, the composition problem is modeled as a planning problem based on DDL(X). Since each solution of the planning problem is formed by actions of DDL(X), any compositions specified by OWL-S, except those with the Split and Split-Join control structures, can be taken into account. Secondly, for any planning problem constructed above, an algorithm for deciding the existence of solutions is developed. The termination, soundness and completeness of this algorithm are proved. Finally, in the case that there exist solutions for the planning problem, it is demonstrated that one of the solutions can be generated from the deciding procedure. This method takes advantages of both the expressive power and the computing property of DDL(X). It provides a suit of effective theoretical tools for automatic composition of semantic Web services.