Querying Geospatial Data Expressed in RDF

Abstract

In this chapter, we will show how to query geospatial data expressed in RDF using the query languages GeoSPARQL, stSPARQL, GeoSPARQL+, and GeoSPARQL 1.1. The queries will be posed on the datasets of Chapter 6 and can be run on the demo available on the SPARQL endpoint that can be found at the Web site of the book. Since GeoSPARQL, stSPARQL, and GeoSPARQL+ simply add spatial extension functions to SPARQL, all SPARQL queries are expressible in these languages as well. For example, we can write the following query. Query 1: Give me the population of the municipality of Piraeus (“Πειραιάς” in Greek). This query can be expressed as follows: