  The RDF data model facilitates integration of diverse data available in
structured and semi-structured formats. To obtain an RDF graph with a low
amount of errors and internal redundancy, the chosen ontology must be
consistently applied. However, with each addition of new diverse data the
ontology must evolve thereby increasing its complexity, which could lead to
accumulation of unintended erroneous composites. Thus, there is a need for a
gatekeeping system that compares the intended content described in the ontology
with the actual content of the resource.
  Here we present Empusa, a tool that has been developed to facilitate the
creation of composite RDF resources from disparate sources. Empusa can be used
to convert a schema into an associated application programming interface (API)
that can be used to perform data consistency checks and generates Markdown
documentation to make persistent URLs resolvable. In this way, the use of
Empusa ensures consistency within and between the ontology (OWL), the Shape
Expressions (ShEx) describing the graph structure, and the content of the
resource.
