Distributed processing of continuous spatiotemporal queries over road networks

This paper presents a distributed algorithm for processing continuous spatiotemporal queries. Distributed query processing that involve multiple servers is inspired by (1) the need for scalability in terms of supporting a large number of moving objects and a large number of queries, and (2) the need for providing real-time answers to users' queries. To rapidly answer queries, incoming data streams are processed in-memory. The load is distributed among a set of regional servers that collaborate to continuously answer the spatiotemporal queries. The algorithm assumes that object movement is constrained by a road network and that the continuous queries are stationary, i.e., the queries' focal points do not move. Continuous queries are evaluated incrementally by monitoring network positions that are part of existing queries' search regions. The performance of the proposed algorithm is measured to analyze their behavior under various work loads and distributed system settings.