GraphDB-SE is the commercial edition of GraphDB – a high-performance semantic repository created by Ontotext. It is implemented in Java and packaged as a Storage and Inference Layer (SAIL) for the Sesame RDF framework. GraphDB-SE is a native RDF rule-entailment and storage engine. The supported semantics can be configured through rule-set definition and selection. Included are rule-sets for OWL-Horst [25], unconstrained RDFS [11] with OWL Lite [14] and the OWL2 profiles RL and QL [30][31]. Custom rule-sets allow tuning for optimal performance and expressivity.
Reasoning and query evaluation are performed over a persistent storage layer. Loading, reasoning and query evaluation proceed extremely quickly even against huge ontologies and knowledge bases.
GraphDB-SE can manage billions of explicit statements on desktop hardware and can handle tens of billions of statements on commodity server hardware. According to public evaluation data, GraphDB-SE is the most scalable OWL repository currently available.
GraphDB's web site, http://www.ontotext.com/owlim, provides extensive information and references regarding support contacts and mailing lists, documentation and latest performance benchmarks.

Features

The key features of the current release of GraphDB-SE can be summarised as follows:

• The most scalable semantic repository in the World, both in terms of the volume of RDF data it can store and the speed with which it can load and do inferencing;
• Pure Java implementation, ensuring ease of deployment and portability;
• Compatible with Sesame 2, which brings interoperability benefits and support for all major RDF syntaxes and query languages;
• Compatible with Jena with a built-in adapter layer;
• Customisable reasoning, in addition to RDFS, OWL-Horst, and OWL 2 RL support;
• Optimised owl:sameAs handling, which delivers dramatic improvements in performance and usability when huge volumes of data from multiple sources are integrated.
• Clustering support brings resilience, fail-over and scalable parallel query processing;
• Geo-spatial extensions for special handling of 2-dimensional spherical data allowing data using the WGS84 RDF vocabulary to be indexed and processed quickly using a variety of special geometrical query constructions and SPARQL extensions functions;
• Full-text search support, based on either Lucene or proprietary search techniques;
• High performance retraction of statements and their inferences – so inference materialisation speeds up retrieval, but without delete performance degradation;
• Powerful and expressive consistency/integrity constraint checking mechanisms;
• RDF rank, similar to Google's PageRank, can be calculated for the nodes in an RDF graph and used for ordering query results by relevance, visualisation and any other purposes;
• RDF Priming, based upon activation spreading, allows efficient data selection and context-aware query answering for handling huge datasets;
• Notification mechanism, to allow clients to react to statements in the update stream.

Interfaces, Standards, Requirements

GraphDB-SE is a Java library without user interface. Sesame's Web UI applications can be used.
Interfaces (API, Web Services): GraphDB implements the SAIL interfaces of Sesame, so it can be used locally (embedded) or remotely via the Sesame HTTP server. Additionally, GraphDB-SE can be used with the Jena framework using the built-in adapter.
Platform: Java JRE version 1.6 or later (both 32-bit and 64-bit versions). If custom rule-sets are used then a Java JDK version 1.6 or later is required.
Supported standards: GraphDB is bound to the data and query standards supported by Sesame. RDF is the basic data standard; the supported query languages are: SeRQL and SPARQL 1.1.
Syntaxes: The import and export of all major RDF syntaxes (XML, N3, N-Triples, N-Quads, Turtle, TriG, TriX) is supported through Sesame.
Semantics: GraphDB supports RDFS, OWL Horst, OWL Max (RDFS with that part of OWL Lite that can be captured in rules), OWL2 QL and OWL2 RL, along with the ability to create customised rule-sets.
Required Libraries: Sesame (http://www.openrdf.org) is an open-source RDF database with support for RDF inference and querying. GraphDB-SE has been tested with Sesame release 2.7.

Licensing

GraphDB-SE is available under an RDBMS-like commercial license on a per-server-CPU basis; it is neither free nor open-source. To purchase a license or obtain a copy for evaluation, please, contact GraphDB-info@ontotext.com.

Installation and Usage

GraphDB-SE is distributed as a ZIP archive that contains GraphDB-SE's compiled jar's, all required libraries, configuration files, documentation, sample code and data. GraphDB-SE is designed to be used as a Storage and Inference Layer (SAIL) for the Sesame openRDF framework – no GraphDB specific interfaces are intended for external use. A repackaged Sesame 2 SDK is included as part of the GraphDB distribution. Use of the rule-compiler (i.e. custom rule-sets) requires the Java Development Kit (JDK) version 1.6 or later, otherwise a Java Runtime Environment (JRE) version 1.6 or later is required.
The easiest way to get to know GraphDB-SE is to explore the Getting Started application that is included in the release package and documented in the configuration section – it allows one to load data, evaluate queries, and experiment with the configuration parameters, without the need to understand and compile Java code.
The installation section provides all the information necessary to setup GraphDB-SE with Sesame.

Credits

GraphDB uses Sesame as a library, taking advantage of its APIs for storage and querying, as well as the support for a wide variety of query languages (e.g. SPARQL and SeRQL) and RDF syntaxes (e.g. RDF/XML, N3, Turtle).

The development of GraphDB is partly supported by SEKT, TAO, TripCom, LarKC, and other FP6 and FP7 European research projects.