Abstract
Providing time-dependent and accurate answers to queries over continuous data stream is crucially required for peer-to-peer (P2P) networks, in which the global statistical information can be obtained through aggregation queries. We proposed a constraint-based approach on continuous aggregation queries over hierarchical P2P system. Our technique (termed CARE) acquires a user-specified precision tolerance that manipulates the balance between accuracy and communication cost by users’ requests. As shown in the experimental results, it dramatically reduces the communication cost and obtains the specified tolerable answers adaptively and progressively.