Comunica LeftJoin Query Operation Actor

A Query Operation actor that handles SPARQL OPTIONAL operations by delegating to the RDF Join bus bus.

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-leftjoin

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-leftjoin/^4.0.0/components/context.jsonld"
  ],
  "actors": [
    ...
    {
      "@id": "urn:comunica:default:query-operation/actors#leftjoin",
      "@type": "ActorQueryOperationLeftJoin",
      "mediatorQueryOperation": { "@id": "urn:comunica:default:query-operation/mediators#main" },
      "mediatorJoin": { "@id": "urn:comunica:default:rdf-join/mediators#main" },
      "mediatorMergeBindingsContext": { "@id": "urn:comunica:default:merge-bindings-context/mediators#main" },
      "expressionEvaluatorFactory": { "@id": "urn:comunica:default:expression-evaluator/evaluators#main" }
    }
  ]
}

Config Parameters

• mediatorQueryOperation: A mediator over the Query Operation bus.
• mediatorJoin: A mediator over the RDF Join bus.
• mediatorMergeBindingsContext: A mediator over the Merge Bindings Context bus.
• expressionEvaluatorFactory: A factory to create an Expression Evaluator;