Formal specification of web services composition

In web service oriented architecture, web services are available in specific registers and described using Web Service Description Language (WSDL). Users or application developers ask these registers to discover the needed services. When the existing services don't meet user's requirements, they must be composed to offer new functionalities. In the last decade, many languages have been proposed to perform web services composition. However, these languages don't take into account the specification step which is very important in the early stages of the composition process. In this paper, we address this problem by modeling web services with the G-Net formalism. We provide a transformation method from WSDL descriptions to their equivalent G-Net specifications. These latter makes easy the services composition and the verification of their behavioral correctness.