A Flexible Policy Framework for the QoS Differentiated Provisioning of Services
Ranking of Semantic Web Services is usually performed based on user preferences descriptions. These descriptions are expressed in terms of an underlying logical formalism, which limits their expressiveness. Thus, there are some kind of descriptions, such as utility functions, that cannot be handled by reasoners currently being used to perform Semantic Web Services tasks, though utility functions provide a higher level of expressiveness. In this work, we present a hybrid solution to allow the introduction of utility functions in user preferences descriptions, using both Logic Programming rules evaluation and Constraint Programming to perform the ranking process. This proposal is based on the Web Service Modeling Ontology, extending it with a highly expressive framework to specify user preferences, and enabling the integration of different engines to perform the ranking process.