Web Service and Policies: Concepts and Solutions

Despite the extensive adoption of Web services by IT system developers, they still lack the capabilities that could enable them to match and eventually surpass the acceptance level of traditional integration middleware (e.g., CORBA, Java RMI). This lack of capabilities is to a certain extent due to the trigger-response interaction pattern that frames the exchanges of Web services with third parties. Adhering to this interaction pattern means that a Web service only performs the requests it receives without considering its internal execution state, or even questioning if it would be rewarded for performing these requests (e.g., to be favored over similar Web services during selection). There exist, however, several situations that insist on Web services self-management so that scalability, flexibility, and stability requirements are satisfied. The objective of this chapter is to discuss the value-added of integrating contextand policiesinto a Web services composition approach.