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To answer user queries efficiently, a stream management system must handle continuous, high-volume, possibly noisy, and time-varying data streams. One major research area in stream management seeks to allocate resources (such as network bandwidth and memory) to query plans, either to minimize resource usage under a precision requirement, or to maximize(More)
There have been a number of recent proposals for distributed monitoring infrastructures. We argue that a vital missing component from these proposals is a distributed triggering mechanism, by which nodes in the system can proactively work together to maintain invariants and constraints over the system-wide behavior. Without such a triggering component ,(More)
To serve users quickly, Web service providers build infrastructure closer to clients and use multi-stage transport connections. Although these changes reduce client-perceived round-trip times, TCP's current mechanisms fundamentally limit latency improvements. We performed a measurement study of a large Web service provider and found that, while connections(More)
A distributed data-stream architecture finds application in sensor networks for monitoring environment and activities. In such a network, large numbers of sensors deliver continuous data to a central server. The rate at which the data is sampled at each sensor affects the communication resource and the computational load at the central server. In this(More)
Sensor research has been undergoing a quiet revolution , promising to have significant impact on a broad range of applications relating to national security, health care, the environment, etc. In this work, we particularly focus our effort on building large-scale video-sensor networks, addressing several large-scale data-management and data-mining issues.(More)