Triggers and Queries in Distributed Software Systems for Moving Objects

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The project proposes research on distributed systems that monitor the positions of various moving objects and process queries and triggers referring to their positions. Applications of such systems, called Moving Object Information (MOI) applications, typically occur in transportation systems in the civilian sector and in the digital battlefield management in the military. This proposal considers two different architecture models for the MOI systems; in the first one a single central server (CS) monitors the position of the objects and answers queries; the second architecture is fully distributed in which the moving objects communicate with each other to answer the queries and to monitor trigger conditions. The project proposes various location update policies for maintenance of the position information of the objects in the CS model. All these policies maintain the position of an object as a dynamic attribute that changes with time. The project plans to investigate the cost effectiveness of these policies through analytical and experimental studies. A query language based on Future Temporal Logic (FTL) is proposed for specifying spatial and temporal queries and trigger conditions on the moving objects. The language permits specification of the desired levels of uncertainties in the answer. Research towards the development of efficient query/trigger processing mechanisms in the two architectures are proposed. The proposed mechanisms will be evaluated in an experimental testbed.