OWLIM Editions

OWLIM comes in two editions: SwiftOWLIM and BigOWLIM that are identical in terms of usage and integration. The editions differ in the respective version of the Triple Reasoning and Rule Entailment Engine (TRREE) they are based upon, but share the same inference mechanisms and semantics (rule-compiler, etc). The different versions of the TRREE engine use different indexing, inference, and query evaluation implementations, which results in different performance, memory requirements, and scalability.

SwiftOWLIM is designed for medium data volumes (below 100 million statements) and for prototyping. Its key characteristics are as follows:

reasoning and query evaluation are performed in main memory;
it employs a persistence strategy that ensures data preservation and consistency;
the loading of data, including reasoning, is extremely fast;
easy configuration.

BigOWLIM is suitable for handling massive volumes of data and very intensive querying activities. It is designed as an enterprise-grade database management system. This has been made possible through:

file-based indices, which enable it to scale to billions of statements even on desktop machines;
special-purpose index and query optimization techniques, ensuring fast query evaluation against very large volumes of data;
optimized handling of owl:sameAs (identifier equality) to boost efficiency for data integration tasks;
efficient retraction of explicit statements and their inferences, which allows for efficient delete operations.

OWLIM is available in several versions, designed and tailored to efficiently meet the wide range of requirements towards RDF databases and reasoning engines.

OWLIM Versions

The following table summarises the differences between the versions that are currently supported.

	Sesame version	SPARQL	Instant initialisation	owl:sameAs optimisation	Full Text Search	RDF rank	RDF priming	Notifications	Comment
SwiftOWLIM 2.9.x	1.2.x								The fastest OWL database. Multi-threaded inference, with transitive inference optimiz.
BigOWLIM 2.x	1.2.x		√	√					Optimal performance and scalability. The fastest query evaluation. Successor of 0.9.x
SwiftOWLIM 3.x	2.x	√	√						The fastest RDF machine with NG and SPARQL support
BigOWLIM 3.x	2.x	√	√	√	√	√	√	√	Ultimate scalability and fast SPARQL evaluation

Supported Features

Named graphs (NG) represent an extension of the RDF data-model, where quadruples <s,p,o,ng> are used to define RDF multi-graphs. This mechanism allows for (among other things) handling provenance when multiple RDF graphs are integrated into a single repository.

Sesame 2.x is the latest generation of the most efficient RDF framework that supports named graphs (under the name contexts) and SPARQL. The versions of OWLIM that support SPARQL are compliant with Sesame version 2.1 or later.

SPARQL is the most popular RDF query language (W3C recommendation). Comprehensive support for SPARQL requires named graph support.

The owl:sameAs optimisation delivers dramatic improvements in performance and usability when huge volumes of data from multiple sources are integrated.

Full Text Search is a powerful technique that allows 'string-ised' resources and literals to be searched using either a proprietary term search technique or using the integrated Lucene text indexing and search engine. Full Text Search is integrated with SPARQL to allow powerful hybrid queries.

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 many other purposes.

RDF priming is a technique based on activation spreading that allows efficient data selection and context-aware query answering when handling huge datasets.

Notifications provide a mechanism for clients to react to statements in the update stream, i.e. to be notified when statements are inserted in to the repository that match previously requested statement patterns.