OWLIM-Lite is a high-performance semantic repository created by Ontotext including a native RDF rule entailment engine. It is implemented in Java and packaged as a Storage and Inference Layer (SAIL) for the Sesame openRDF framework. The supported semantics can be configured through rule-set definition and selection. Rule-sets for OWL-Horst, unconstrained RDFS with OWL-Lite and the OWL2 RL profile are included. Custom rule-sets allow tuning for optimal performance and expressivity.
Reasoning and query evaluation are performed in-memory. A reliable persistence strategy ensures data preservation, consistency, and integrity. OWLIM-Lite can manage millions of explicit statements on desktop hardware. A principle limitation of OWLIM-Lite is the relatively slow delete operation, whereas loading, reasoning, and query evaluation proceed extremely quickly even against huge ontologies and knowledge bases. According to the limited evaluation data available, OWLIM-Lite is the fastest OWL repository available.
OWLIM's web site, http://www.ontotext.com/owlim, provides extensive information and references regarding support contacts and mailing lists, documentation, download details and latest performance benchmarks.

Features

The key features of the current release of OWLIM-Lite can be summarised as follows:

• The fastest semantic repository in the World, it can perform non-trivial inference on millions of RDF data statements;
• 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;
• Customisable reasoning, in addition to RDFS, OWL Horst, and OWL 2 RL support.

Interfaces, Standards, Requirements

OWLIM-Lite is a Java library without user interface. Sesame's Web UI applications can be used.
Interfaces (API, Web Services): OWLIM implements the SAIL interfaces of Sesame, so it can be used locally (embedded) or remotely via the Sesame HTTP server.
Platform: Java JRE version 1.6 or later (both 32-bit and 64-bit versions). If using custom rule-sets are used then a Java JDK version 1.6 or later is required.
Supported standards: OWLIM is bound to the data and query standards supported by Sesame. RDF is the basic data standard; the supported query languages are: SeRQL, SPARQL, RQL, RDQL.
Syntaxes: The import and export of all major RDF syntaxes (XML, N3, N-Triples, N-Quads, Turtle, TriG, TriX) is supported through Sesame.
Semantics: OWLIM 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 framework with support for RDF inference and querying. OWLIM-Lite has been tested with Sesame release 2.6.

Licensing

OWLIM-Lite – (c) Copyright Ontotext AD. OWLIM-Lite is not open-source software. OWLIM-Lite is licensed for use free of charge. Re-distribution of OWLIM-Lite in any form other than the original distribution package is strictly forbidden. Any form of modification or reverse-engineering of OWLIM-Lite is forbidden. OWLIM-Lite is distributed without any warranty. Full licensing information is available in the licence file in the 'doc' folder of the distribution package.
Sesame - (c) Copyright Aduna b.v. Sesame is an open-source library, available under LGPL.

Installation and Usage

OWLIM-Lite is distributed as a ZIP archive that contains the OWLIM-Lite jar, all required libraries, configuration files, documentation, sample code and data. OWLIM-Lite is designed to be used as a Storage and Inference Layer (SAIL) for the Sesame openRDF framework – no OWLIM specific interfaces are intended for external use. Sesame 2 libraries are included as part of the OWLIM distribution; the complete Sesame distribution can be downloaded from http://www.openrdf.org. 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 OWLIM-Lite 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 OWLIM-Lite with Sesame.

Credits

OWLIM 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 1.1 and SeRQL) and RDF syntaxes (e.g. RDF/XML, N3, Turtle).

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