A policy-based approach for resource specification in small devices

A distributed application can be implemented as components, which might be available on a single host or distributed across various hosts. However, in a pervasive environment, such applications cannot be described statically in terms of the required components. This is because in such environments, the device participation is dynamic and the components described in application may not be available at the time of execution of the application. We believe that the description of the application must be generated dynamically at the time of its execution, in terms of the components available at that time. We present an approach in which an application is described in terms of abstract services, which are resolved into concrete components at runtime. When mapping services to components, their resource requirements are matched apart from their functional interfaces. Resources are also specified at both abstract and concrete levels. Only those components are selected whose interfaces and concrete resource requirements match with the abstract service interfaces and abstract resource requirements. The application composition is specified in SCA and CC/PP is used for resource specification using SCA policies.