Skip to content

iolanta:visualizes property

  • Domain

    np:Assertion
    An assertion graph inside a nanopublication

  • Range

    owl:Ontology
    The ontology this assertion describes how to render

iolanta:visualizes links a nanopublication assertion to the ontology whose visualization metadata it carries. The triple lives in the nanopublication's provenance graph, not its assertion graph: the assertion describes how to group an ontology's terms (using vann:termGroup), while the provenance says which ontology that assertion is about.

Iolanta uses iolanta:visualizes at render time to discover community-published visualization information for any ontology, without that information having to be bundled in the Iolanta repository. See the related ADR: Publish visualization information for ontologies on ….

Discovery flow

When MkDocsOntologyFacet or OntologyFacet is asked to render an ontology <O>, it queries the public Knowledge Pixels nanopub registry for the most recent signed, non-invalidated, non-superseded nanopublication whose provenance asserts ?assertion iolanta:visualizes <O>, and loads that nanopublication's assertion graph into the local dataset. The grouping triples (vann:termGroup, rdfs:label) then become visible to the regular ontology-rendering SPARQL.

SELECT ?nanopub WHERE {
  ?nanopub np:hasAssertion       ?assertion ;
           np:hasProvenance      ?provenance ;
           np:hasPublicationInfo ?pubinfo ;
           npa:hasValidSignatureForPublicKey ?pubkey .

  GRAPH ?provenance { ?assertion iolanta:visualizes <O> }
  GRAPH ?pubinfo    { ?nanopub  dcterms:created     ?created }

  FILTER NOT EXISTS {
    ?invalidator npx:invalidates ?nanopub ;
                 npa:hasValidSignatureForPublicKey ?invalidator_pubkey .
  }
  FILTER NOT EXISTS {
    ?newer npx:supersedes ?nanopub ;
           npa:hasValidSignatureForPublicKey ?newer_pubkey .
  }
}
ORDER BY DESC(?created)
LIMIT 1

ORDER BY DESC(?created) LIMIT 1 is last-writer-wins: only one nanopublication per ontology is loaded so different publishers' grouping schemes never mix. To override what Iolanta picks up for a given ontology, sign and publish a newer nanopublication.

The discovery code lives in iolanta/discovery/visualization_nanopublications.py.

Example

The current grouping for the rdf: namespace is loaded from https://w3id.org/np/RAXhiZMoa3JldEhxcgVyp8UIJL_N0PhEJpCTRXdKl7H_Q. Its provenance graph contains, in essence:

"@context":
  iolanta: https://iolanta.tech/
  rdf: http://www.w3.org/1999/02/22-rdf-syntax-ns#

$id: "_:assertion"
iolanta:visualizes:
  $id: "rdf:"

…and its assertion graph contains the vann:termGroup triples that produce the Datatype / Language / Triples / Compound Literal / Containers / Properties / Value groups visible on the RDF reference page.