Policy-Aware Service Composition in Sensor Networks

Sensor applications are typically composed of a number of functional components that run distributedly on the nodes of a sensor network, communicating and interacting with one another. Service composition is emerging as a viable approach towards the automatic synthesis of such sensor applications. However, for service composition to be practical, it has to comply with policies that define security and management constraints on the use of these service components and the interconnections amongst them. Prior research efforts have primarily focused on efficient evaluation of security policies during the composition process, which is not sufficient when generic network management constraints need to be expressed and evaluated. In this work, we propose a policy model and evaluation approach that enables us to define and check attribute-based policies, for controlling the sensor service composition process. Attribute-based policies are generic and allows us to express a wider spectrum of constraints than currently possible. Using this model and based on a previously-proposed sensor service composition algorithm, we introduce a policy evaluation method that allows for efficient checking of policy constraints. We further present a novel implementation of the proposed approach in the IBM Sensor Fabric, a middleware framework that simplifies the development of distributed, sensor network services. We also present preliminary performance evaluation results using our prototype.