Overview of GeoSPARQL Implementation in Parliament

Explore the GeoSPARQL implementation in Parliament, a triple store with SPARQL support used for over a decade. Learn about its design, indexing strategy, spatial features, and missing components compared to GeoSPARQL standards. Discover how Parliament supports GML and WKT literals, various spatial relations, and the challenges it faces in fully implementing GeoSPARQL specifications.

• GeoSPARQL
• Parliament
• Implementation
• Spatial Indexing
• Triple Store

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1. GEOSPARQL IN PARLIAMENT Terra Cognita Dave Kolas November 12, 2012

2. 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! http://parliament.semwebcentral.org/

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

4. Parliaments 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

5. Parliaments 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

6. 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

7. 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

8. Parliaments 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

9. 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

10. 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

11. Example Query 1 Find All Schools within Georgia SELECT DISTINCT ?school WHERE { GRAPH <http://example.org/data> { # get Georgia geometry gu:_1705317 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 . } }

12. Example Query 2 Find Geonames features within 10k of the Nixon Grove School SELECT ?x WHERE { GRAPH <http://www.geonames.org> { <http://sws.geonames.org/4212826/> 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)) } }