@comunica/actor-rdf-join-optional-bind

Comunica Optional Bind RDF Join Actor

An RDF Join actor that left-joins (optional) 2 streams using the bind join algorithm. It binds each item of the first stream with the second operation, and recursively resolving that operation by delegating to the Query Operation bus.

By default, it will bind in a depth-first manner, but this can be changed to breadth-first iteration if needed.

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-rdf-join-optional-bind

Configure

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

{
  "@context": [
    ...
    "https://linkedsoftwaredependencies.org/bundles/npm/@comunica/actor-rdf-join-optional-bind/^3.0.0/components/context.jsonld"
  ],
  "actors": [
    ...
    {
      "@id": "urn:comunica:default:rdf-join/actors#optional-bind",
      "@type": "ActorRdfJoinOptionalBind",
      "mediatorJoinSelectivity": { "@id": "urn:comunica:default:rdf-join-selectivity/mediators#main" },
      "mediatorQueryOperation": { "@id": "urn:comunica:default:query-operation/mediators#main" },
      "mediatorMergeBindingsContext": { "@id": "urn:comunica:default:merge-bindings-context/mediators#main" }
    }
  ]
}

Config Parameters

• mediatorJoinSelectivity: A mediator over the RDF Join Selectivity bus.
• bindOrder: The order in which elements should be bound. (defaults to depth-first, but can also be breadth-first)
• mediatorQueryOperation: A mediator over the Query Operation bus.
• mediatorMergeBindingsContext: A mediator over the Merge Bindings Context bus.