A Request Oriented Model forWeb Services

The existing service modeling methodologies, such as WSDL and OWL-S, are service-oriented, which mainly focus on providing formalisms for the important features of a web service, including its functionality and QoS parameters. Conforming to these models, users need to first find what the available services are, go through the descriptions, and then shape the request specifications based on the functionality of these services. These modeling methodologies do not cope with the ever-increasing number and variety of web services, which introduces significant difficulties to users when discovering and selecting services in a large scale and heterogeneous environment. To address this issue, we propose a request oriented model, where the formalisms focus on user expectations and experiences on the usage of services, i.e., what a user wants as the result of accessing to services and what the user will experience during the service invocations. The model lays out a foundation for efficient and personalized service selection. It also provides formalisms for describing a service functionality, which supports service reasoning tasks to improve automation of service selection and usage. Based on the model, we propose a Web Service Request Language (WSRL), which allows users to specify their requests in a declarative way. We also present the reasoning procedure that mediates the interactions between users and web services.