XQuery-Based Query Processing in Open Street Map

Volunteered geographic information (VGI) makes available a very large resource of geographic data. The exploitation of data coming from such resources requires an additional effort in the form of tools and effective processing techniques. One of the most established VGI is Open Street Map (OSM) offering data of urban and rural maps from the earth. In this paper we present a library for querying OSM with XQuery. This library is based on the well-known spatial operators defined by Clementini and Egenhofer, providing a repertoire of XQuery functions which encapsulate the search on the XML document representing a layer of OSM, and make the definition of queries on top of OSM layers easy. In essence, the library is equipped with a set of OSM Operators for OSM elements which, in combination with Higher Order facilities of XQuery, facilitates the composition of queries and the definition of keyword based search geo-localized queries. OSM data are indexed by an R-tree structure, in which OSM elements are enclosed by Minimum Bounding Rectangles (MBRs), in order to get shorter answer time.