RDF4J

RDF4J is an open-source Java framework for processing and manipulating RDF data. It provides a modular, standards-based platform for storing, querying, and reasoning over RDF graphs, and is designed to be embedded in Java applications or deployed as a server. The project is maintained by the Eclipse RDF4J community.

Origin and history: RDF4J originated as Sesame, a Java framework created by Aduna. It was adopted by the Eclipse Foundation and renamed to RDF4J, becoming the core project for RDF data management within the Eclipse ecosystem.

Architecture and key concepts: The framework provides a layered API: the Model API for RDF data, the Repository API for data stores, and the Sail (Storage And Inference Layer) API for pluggable backends. A Repository combines a Sail with a set of configurations. Built-in Sails include a MemoryStore and a NativeStore, with support for additional third-party and remote backends.

SPARQL support and features: RDF4J implements SPARQL 1.1 for querying and SPARQL Update for data modification, plus optional inference over RDF schemas using RDFS and some OWL rules. It supports transactions, bulk updates, and flexible data retrieval. Backends can provide inference capabilities that augment direct triples with inferred triples.

Usage and ecosystem: It offers a web-based Workbench for repository administration and a robust Java API for embedding in applications. RDF4J integrates with a range of RDF tools and libraries and maintains an active developer community focused on RDF data management, querying, and interoperability.