Selection and Ranking of Propositional Formulas for Large-Scale Service Directories

Book One

Volume

Proceedings of the AAAI Conference on Artificial Intelligence, 20

Semantic Web, Information Retrieval, and Extraction

In this paper we consider scenarios, such as web service composition, where a planner needs to discover its operators by querying a potentially very large and dynamically changing directory. Our contribution is a directory system that represents service advertisements and requests as propositional formulas and provides a flexible query language allowing complex selection and ranking expressions. The internal structure of the directory enables efficient selection and ranking in the presence of a large number of services thanks to its organization as a balanced tree with an extra "intersection predicate". In order to optimally exploit the index structure of the directory, a transformation scheme is applied to the original query. Experimental results on randomly generated service composition problems illustrate the benefits of our approach.