Comunica SPARQL Query Source Identify Hypermedia Actor

A Query Source Identify Hypermedia actor that handles SPARQL endpoints.

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-source-identify-hypermedia-sparql

Configure

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

{
  "@context": [
    ...
    "https://linkedsoftwaredependencies.org/bundles/npm/@comunica/actor-query-source-identify-hypermedia-sparql/^1.0.0/components/context.jsonld"
  ],
  "actors": [
    ...
    {
      "@id": "urn:comunica:default:query-source-identify-hypermedia/actors#sparql",
      "@type": "ActorQuerySourceIdentifyHypermediaSparql",
      "mediatorHttp": { "@id": "urn:comunica:default:http/mediators#main" },
      "mediatorMergeBindingsContext": { "@id": "urn:comunica:default:merge-bindings-context/mediators#main" },
      "mediatorQuerySerialize": { "@id": "urn:comunica:default:query-serialize/mediators#main" },
      "sparqlServerSoftwarePatterns": ["Virtuoso", "Fuseki"]
    }
  ]
}

Config Parameters

• mediatorHttp: A mediator over the HTTP bus.
• mediatorMergeBindingsContext: A mediator over the Merge Bindings Context bus.
• mediatorQuerySerialize: A mediator over the Query Serialize bus.
• checkUrlSuffix: If URLs ending with '/sparql' should also be considered SPARQL endpoints, defaults to true.
• forceHttpGet: If queries should be sent via HTTP GET instead of POST, defaults to false.
• forceSourceType: Forces all sources provided to be interpreted as SPARQL endpoints, defaults to false.
• cacheSize: The cache size for COUNT queries, defaults to 1024.
• bindMethod: The query operation for communicating bindings, defaults to 'values', alt: 'union' or 'filter'.
• countTimeout: Timeout in ms of how long count queries are allowed to take. If the timeout is reached, an infinity cardinality is returned. Defaults to 3000.
• cardinalityCountQueries: If count queries should be sent to obtain the cardinality of (sub)queries. If set to false, resulting cardinalities will always be considered infinity. Defaults to true
• cardinalityEstimateConstruction: If cardinality estimates for larger queries should be constructed locally from (sub)query cardinalities when possible. Defaults to false. If set to false, count queries will be sent for every operation at all levels.
• sparqlServerSoftwarePatterns: An optional list of regular expressions to match against the Server HTTP response header. If a match is found, the source is identified as a SPARQL endpoint.

Endpoint Server Header Report

The following endpoints have been observed to return the following Server headers (at the time of writing):