Stateful aspects for conversational messaging with stateful Web services

Web service technology allows for the development of client applications independently of the Web services they use. In this article, we propose a dynamic invocation mechanism for unanticipated Web services that offers support for conversational messaging, based on dynamic aspect oriented programming (AOP) techniques. Aspects are used to store the communication details and the conversational context of the Web service. In case of service failures, the conversation can be replayed on another semantically equivalent Web service, in a transparent way for the client. Code examples are given in the dynamic AOP language JAsCo, and a prototype, called Web services management layer, is discussed as a proof of concept.