Semantic repository, in general, is a database management system. It allows storing, querying, and managing structured data. Semantic repository is still not a largely adopted term and is often referred to by synonyms such as semantic graph database, reasoner, ontology server, semantic store, metadata store, RDF database, RDF triplestore, and more. Different wording often emphasizes the particular features and usages, rather than the difference in the implementation and performance.
The major benefit of semantic repositories, compared to traditional DBMSs such as relational databases (RDBMSs), is the usage of semantic data schema paradigm, called ontology, which is stored and managed independently from the data. It allows you to:
- change the data schema “on the fly” without interfering with the data;
- automatically discover new facts and build new data based on semantic rules (data inference or reasoning);
- seamlessly integrate data from distributed data sets and data sources (data federation);
- see your data as flexible, interconnected, interlinked graph data models.
As a result, semantic repositories offer easier data integration of diverse sources as well as more analytical power.
Over the last decade, the Semantic Web emerged as an area where the semantic repository systems became as important as the HTTP servers. This tendency led to very high interest and activity in the field and resulted in a number of robust metadata, ontology and query language standards, delivered by the W3C-driven community processes, most notable among which are RDF(S), OWL and SPARQL.
The W3C standard for query language – SPARQL – have a role similar to the role SQL played for the development and spread of RDBMSs.
Although primarily designed for use in the Semantic Web, these standards were widely accepted in areas such as Enterprise Data Integration, Linked Open Data, Semantic Search, Knowledge Discovery, etc.
GraphDB™ is one of the most popular semantic repositories that supports W3C standards and all major syntaxes and query languages related to it. It implements and extends the open source engine rdf4j, adding efficient operational features such as inferencing, visual data exploration and database management, as well as enterprise features such as high availability, distribution, consistency checks, etc.
GraphDB™ is implemented on top of the TRREE engine (TRREE stands for ‘Triple Reasoning and Rule Entailment Engine’) to combine RDFS, OWL DLP, and OWL Horst support with high-performance reasoning and reliable persistence strategy. This engine performs reasoning based on forward-chaining of entailment rules over RDF triple patterns with variables and as such is optimized for very fast and computationally efficient querying. As the engine’s reasoning strategy is total materialization, various optimizations are used to ensure not only faster repository setup but also lower resource requirements.
Download GraphDB™ to get started with setting up your first semantic repository and automatically discovering new facts derived from your data.