Towards A Streams-Based Framework for Defining Location-Based Queries

An infrastructure is emerging that supports the delivery of on-line, location-enabled services to mobile users. Such services involve novel database queries, and the database research community is quite active in proposing techniques for the efficient processing of such queries. In parallel to this, the management of data streams has become an active area of research. While most research in mobile services concerns performance issues, this paper aims to establish a formal framework for defining the semantics of queries encountered in mobile services, most notably the so-called continuous queries that are particularly relevant in this context. Rather than inventing an entirely new framework, the paper proposes a framework that builds on concepts from data streams and temporal databases. Definitions of example queries demonstrates how the framework enables clear formulation of query semantics and the comparison of queries. The paper also proposes a categorization of location-based queries.