Comunica Query Source Identify Optimize Query Operation Actor

An Optimize Query Operation actor that identifies all query sources in the context using the Query Source Identify bus. It will store all query sources in the context using KeysQueryOperation.querySources, and sources corresponding to the SERVICE clauses within the query will be stored using KeysQueryOperation.serviceSources.

Sources of SERVICE clauses are not allowed to be dereferenced from the local file system, unless the serviceAllowFileTargets context entry is enabled.

This actor also contains a cache so that identical sources will be reused across multiple query executions. This cache can be invalidated via engine.invalidateHttpCache().

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-optimize-query-operation-query-source-identify

Configure

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

{
  "@context": [
    ...
    "https://linkedsoftwaredependencies.org/bundles/npm/@comunica/actor-optimize-query-operation-query-source-identify/^1.0.0/components/context.jsonld"
  ],
  "actors": [
    ...
    {
      "@id": "urn:comunica:default:optimize-query-operation/actors#query-source-identify",
      "@type": "ActorOptimizeQueryOperationQuerySourceIdentify",
      "mediatorQuerySourceIdentify": { "@id": "urn:comunica:default:query-source-identify/mediators#main" },
      "mediatorContextPreprocess": { "@id": "urn:comunica:default:context-preprocess/mediators#main" }
    }
  ]
}

Context Parameters

• serviceAllowFileTargets: Optional flag indicating if SERVICE clauses may target local files, defaults to false. Enabling this allows queries to read arbitrary local files, which should only be done if all queries originate from trusted parties.

Config Parameters

• serviceForceSparqlEndpoint: Optional flag indicating if the SERVICE target should be assumed to be a SPARQL endpoint, defaults to false.
• cacheSize: The maximum number of entries in the LRU cache, set to 0 to disable, defaults to 100.
• httpInvalidator: An optional actor that listens to HTTP invalidation events.
• mediatorQuerySourceIdentify: A mediator over the Query Source Identify bus.
• mediatorContextPreprocess: A mediator over the context preprocess bus.