GEOSPARQL IN PARLIAMENT Terra Cognita Dave Kolas November 12, 2012

Parliament  Parliament  In continuous customer use for ~10 years (Originally DAML-DB)  Triple Store with SPARQL support  Implemented as a persistence layer for Jena/Sesame  Includes spatial and temporal indexing/processing  Open source!

3 Design Joseki Spatial Index Processor Spatial Index Processor Parliament Graph Model IndexingGraph Spatial Index (deegree) Spatial Index (deegree) Parliament (C++) Part of Jena Parliament Framework External Storage Temporal Index Processor Temporal Index Processor Temporal Index (BDB) Temporal Index (BDB)

Parliament’s Indexing Strategy  Applications often require efficient statement insertion  Goal: Balanced insertion, query performance, and space required  Parliament stores triples using two components:  Resource dictionary  Statement table  Additional indices can be added for specific purposes and vocabularies  Spatial Index  Temporal Index

Parliament’s Spatial Index  First created before GeoSPARQL, used terms derived from GeoRSS  Now supports most of GeoSPARQL specification  Index is based on R tree in deegree library (deegree.org)  Approach:  Explicit geometries, no qualitative reasoning  Optimization so far on triple patterns, not functions

GeoSPARQL Implementation  Parliament supports:  Both GML and WKT literals, and can interchange between them  All three vocabularies for spatial relations (simple features, rcc8, and Egenhofer)  Triple-pattern spatial relations  Filter functions for spatial relations and spatial combinations  A large number of coordinate reference systems  RDFS Reasoning

GeoSPARQL Missing Pieces  The following features of GeoSPARQL are not currently implemented in Parliement:  Feature-to-feature spatial relations via query rewriting  Optimization on FILTER functions  Qualitative reasoning  Standard properties for Geometry dimension, spatialDimension, isEmpty, isSimple, hasSerialization  Function getSRID

Parliament’s Temporal Index  Parallel to spatial index  Terminology taken from OWL-Time (using Allen relations for overlapping intervals, etc)  Uses Java version of Berkeley DB for persisting index

Build Process Improvements  Until very recently, GeoSPARQL support was on a branch, and required building for your desired platform  GeoSPARQL support has been merged into the trunk and prebuilt binaries are now available for Windows, Mac, and Linux  Parliament build structure has been improved again to require fewer dependencies

Examples  Data on geosparql.bbn.com  Data sets:  USGS data in Atlanta, GA Rails, Rivers  Geonames data Administrative areas Points for buildings, such as schools

Example Query 1  Find All Schools within Georgia SELECT DISTINCT ?school WHERE { GRAPH { # get Georgia geometry gu:_ geo:hasGeometry ?ga_geo. # get schools within Georgia ?school a gn:Feature ; geo:hasGeometry ?school_geo ; gn:featureCode gn:S.SCH. ?school_geo geo:sfWithin ?ga_geo. }

Example Query 2  Find Geonames features within 10k of the Nixon Grove School SELECT ?x WHERE { GRAPH { geo:hasGeometry ?geo1. ?geo1 geo:asWKT ?wkt1. BIND (geof:buffer(?wkt1, 10000, units:metre) as ?buff). ?x geo:hasGeometry ?geo2. ?geo2 geo:asWKT ?wkt2. FILTER (geof:sfContains(?buff, ?wkt2)) }