On-the-fly Construction of Web Services Compositions from Natural Language Requests

The introduction of Semantic Web techniques in Service-oriented Architectures enables explicit representation and reasoning about semantically rich descriptions of service operations. Those techniques hold promise for the automated discovery, selection, composition and binding of services. This paper describes an approach to derive formal specifications of Web Service compositions on the basis of the interpretation of informal user requests expressed in restricted Natural Language. Our approach leverages the semantic and ontological description of a portfolio of known service operations (called the Semantic Service Catalog). Each user request is processed against a Natural Language vocabulary that includes lexical constructs designed to convey the operations' semantics, in order to recognize and extract fundamental functional requirements implied by the request, and associate them to entries in the Catalog. In addition, the request interpreter extracts from the request the overall service logic, expressed in terms of a set of modular templates describing control and data flow among the selected operations. The result is a composition specification that associates on demand each user request to a new composed service. That specification is formal and can thus be transformed in an executable flow document for a target service composition engine.