An embodiment of the invention includes an apparatus, which includes a mediator operable to receive a user request and to transmit a user response; and a dynamic knowledge base including a web service classifier and a domain-relevant ontology. The mediator is operable to transform the user request into a web service request, using said dynamic knowledge base, and to transform a web service response into the user response, using the dynamic knowledge base. Optionally, the dynamic knowledge base includes a web service interface operation index. Optionally, the web service interface operation index includes an autonomous, dynamic web service interface operation index or a static web service interface operation index.