Extending Policy Languages for Expressing the Self-Adaptation of Web Services

With the growing demand on Web Services, self-adaptation in the highly-dynamic environment is becoming a key capability of service-based systems. As a solution for Web services to provide added value and high QoS, combining self-* and policies allows reducing management complexity and effectively drives adaptation. Also, providers must participate in the self-adaptation process as they are aware of the capabilities of their offered services and exceptions that may occur. Despite the important role of service providers, existing approaches did not address this major issue. Thus, the description of self-adaptive Web services must not be limited to functional and QoS data. To address these issues, we extend the WS-Policy framework to represent capabilities and requirements of self-* Web services. We also extend UDDI in order to store and manage service policies, as the current UDDI model does not offer these capabilities. Finally, we propose an ECA-based planning mechanism to specify decision making in the self-adaptation process.