Comunica Service Query Operation Actor

A Query Operation actor that handles SPARQL SERVICE clauses of which the target is a variable.

SERVICE clauses with an IRI target are rewritten into source-annotated operations by @comunica/actor-optimize-query-operation-assign-sources-exhaustive.

Variable targets are disabled by default, as the queried data then determines what is dereferenced, which is problematic when queries originate from untrusted parties. They can be enabled via the serviceAllowVariableTargets context entry.

This module is part of the Comunica framework, and should only be used by developers that want to build their own query engine.

Click here if you just want to query with Comunica.

Install

$ yarn add @comunica/actor-query-operation-service

Configure

After installing, this package can be added to your engine's configuration as follows:

{
  "@context": [
    ...
    "https://linkedsoftwaredependencies.org/bundles/npm/@comunica/actor-query-operation-service/^5.0.0/components/context.jsonld"
  ],
  "actors": [
    ...
    {
      "@id": "urn:comunica:default:query-operation/actors#service",
      "@type": "ActorQueryOperationService",
      "mediatorQueryOperation": { "@id": "urn:comunica:default:query-operation/mediators#main" },
      "mediatorQuerySourceIdentify": { "@id": "urn:comunica:default:query-source-identify/mediators#main" },
      "mediatorMergeBindingsContext": { "@id": "urn:comunica:default:merge-bindings-context/mediators#main" }
    }
  ]
}

Config Parameters

• mediatorQueryOperation: A mediator over the Query Operation bus.
• mediatorQuerySourceIdentify: A mediator over the Query Source Identify bus.
• mediatorMergeBindingsContext: A mediator over the Merge Bindings Context bus.
• forceSparqlEndpoint: If the SERVICE target should be assumed to be a SPARQL endpoint, defaults to false.