Strabon

Strabon is a semantic spatiotemporal RDF store. You can use it to store linked geospatial data that changes over time and pose stSPARQL and GeoSPARQL queries. Strabon supports spatial datatypes enabling the serialization of geometric objects in OGC standards WKT and GML. It also offers spatial and temporal selections, spatial and temporal joins, a rich set of spatial functions similar to those offered by geospatial relational database systems and support for multiple Coordinate Reference Systems. Strabon can be used to model temporal domains and concepts such as events, facts that change over time etc. through its support for valid time of triples, and a rich set of temporal functions.

Strabon is built by extending the well-known RDF store Sesame and extends Sesame’s components to manage thematic, spatial and temporal data that is stored in the backend RDBMS. The following figure shows the architecture of Strabon.

 

We chose Sesame because of its open-source nature, layered architecture, wide range of functionalities and the ability to have, a “spatially enabled” or/and “temporally-enabled” DBMS, as a backend to exploit its variety of spatial functions and operators. Strabon is implemented by creating a layer that is included in Sesame's software stack in a transparent way so that it does not affect its range of functionalities, while benefitting from new versions of Sesame. Strabon uses Sesame and comprises three modules: the storage manager, the query engine and the DBMS. Currently, in Strabon both PostGIS and MonetDB can be used as back-end databases. In order to exploit the temporal features of Strabon, the back-end should also be “temporally-enabled” as well, so PostgreSQL temporal is used in addition to PostGIS.

In the research papers

K. Kyzirakos, M. Karpathiotakis and M. Koubarakis. Strabon: A Semantic Geospatial DBMS. In the 11th International Semantic Web Conference (ISWC 2012), Boston, USA, 11-15 November 2012

G. Garbis, K. Kyzirakos and M. Koubarakis. Geographica: A Benchmark for Geospatial RDF Stores. In the 12th International Semantic Web Conference (ISWC 2013), Sydney, Australia, October 21-25, 2013

we describe the system Strabon in detail. In this paper we have also evaluated Strabon against competitor systems and showed that, in terms of geospatial features, it is the richest RDF store available today. In addition, it can scale to very large datasets and it is typically more efficient than competitor systems.

In the research paper

K. Bereta, P. Smeros and M. Koubarakis. Representing and Querying the Valid Time of Triples for Linked Geospatial Data. In the 10th Extended Semantic Web Conference (ESWC 2013). Montpellier, France. May 26-30, 2013

we describe the temporal dimension of stSPARQL and its implementation in Strabon. In the same paper we also present an experimental evaluation of the performance of Strabon in comparison with implementations offering similar temporal functionalities. Our experiments show that Strabon outperforms all systems it has been compared with.

Strabon is released under the Mozilla Public License and is available at http://strabon.di.uoa.gr.