We are happy to announce the integration of FedX as federation engine into RDF4J.
FedX provides transparent federation of multiple SPARQL endpoints under a
single virtual endpoint. As an example, a knowledge graph such as Wikidata can
be queried in a federation with endpoints that are linked to Wikidata as an
integration hub. In a federated SPARQL query in FedX, one no longer needs to
explicitly address specific endpoints using SERVICE clauses. Instead, FedX
automatically selects relevant sources, sends statement patterns to these
sources for evaluation, and joins the individual results. FedX seamlessly
integrates into RDF4J using the Repository API and can be used as a drop-in
component in existing applications including the RDF4J Workbench.