SPARQL Endpoints

What is a SPARQL Endpoint?

A SPARQL endpoint is a web service that accepts SPARQL queries and returns results. Each endpoint provides access to a specific knowledge base or dataset. You can query these endpoints directly or federate from Wikidata using the SERVICE keyword.

Popular Public Endpoints

Querying DBpedia

DBpedia extracts structured information from Wikipedia. It's one of the most commonly used endpoints for federation because it has rich links to Wikidata via owl:sameAs.

PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX dbo: <http://dbpedia.org/ontology/>

SELECT ?person ?personLabel ?abstract
WHERE {
  # Nobel Prize winners in Physics
  ?person wdt:P166 wd:Q38104 .

  # Get English abstract from DBpedia
  SERVICE <http://dbpedia.org/sparql> {
    ?dbPerson owl:sameAs ?person ;
               dbo:abstract ?abstract .
    FILTER(LANG(?abstract) = "en")
  }

  SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . }
}
LIMIT 5

Querying Getty Vocabularies

The Getty Research Institute provides vocabularies for art, architecture, and cultural heritage. Useful for enriching Wikidata's art-related entities.

PREFIX gvp: <http://vocab.getty.edu/ontology#>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>

SELECT ?painting ?paintingLabel ?gettyTerm
WHERE {
  # Famous paintings
  ?painting wdt:P31 wd:Q3305213 ;
            wdt:P1014 ?aatID .

  # Get preferred label from Getty AAT
  SERVICE <http://vocab.getty.edu/sparql> {
    ?gettyUri skos:prefLabel ?gettyTerm .
    FILTER(LANG(?gettyTerm) = "en")
  }

  SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . }
}
LIMIT 10

Querying UniProt

UniProt is the most comprehensive protein database. Use it to enrich biological entities in Wikidata with protein sequences and functional annotations.

PREFIX up: <http://purl.uniprot.org/core/>

SELECT ?protein ?proteinLabel ?sequence
WHERE {
  # Proteins with UniProt IDs
  ?protein wdt:P31 wd:Q8054 ;
           wdt:P352 ?uniprotID .

  # Get sequence from UniProt
  SERVICE <https://sparql.uniprot.org/sparql> {
    ?uniprotEntry up:mnemonic ?uniprotID ;
                  up:sequence ?seqObj .
    ?seqObj up:value ?sequence .
  }

  SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . }
}
LIMIT 5

Finding More Endpoints

The Linked Data ecosystem is constantly growing. Here are resources for discovering new SPARQL endpoints:

• Datahub.io — Catalog of open datasets with SPARQL access
• LOD Cloud — Visualization of linked open data sources
• SPARQL Endpoint Status — Monitor endpoint availability
• VoID descriptions — Metadata about RDF datasets

Endpoint Considerations

• Availability — Public endpoints may have downtime; use SERVICE SILENT
• Rate limits — Many endpoints limit queries per minute
• Timeout — Complex federated queries may time out
• Data freshness — Some endpoints update less frequently than Wikidata
• Schema differences — Each endpoint uses different ontologies

Key Properties