|dc.description.abstract||The heterogeneity and mobility inherent in large-scale ad-hoc sensor network accounts for the difficulty in developing applications in such environment. The difficulty primarily arises from weak and intermittent disconnection, dynamic reconfiguration, and limited power availability. The challenge in building a distributed service that simplifies adaptation to environmental change therefore lies in the degree to which communication and adaptation of these nodes can be automated or made transparent to applications.
Most applications in sensor networks involve group of sensor nodes coordinating to perform one task. Distributed composition service enables application to compose sensors to form a dynamic task group and maintains the group of sensors to achieve higher task availability. In this document, we describe the composition service and its implementation in detail and show how the process of re-organization can be automated via an adaptation server in collaboration with the composition service. Our testing and simulation validates the framework of the composition service and performance improvement in terms of service availability and energy preserving brought about by our adaptation algorithm, which is implemented with the support of the composition service.||en_US