Virtuoso Open-Source Edition

VOS.VirtTipsAndTricksFedOptionClauseSupport

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    • VOS.VirtTipsAndTricksFedOptionClauseSupport(Last) -- DAVWikiAdmin? , 2017-06-13 05:45:20 Edit
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    WebDAV System Administrator 2017-06-13 05:45:20

    How to handle SPARQL-FED queries for SPARQL endpoints with no OPTION() clause supported?

    Suppose the following sample scenario:

    1. Assume the following SPARQL-FED query: 

      PREFIX wp:         <http://vocabularies.wikipathways.org/wp#> 
PREFIX atlasterms: <http://rdf.ebi.ac.uk/terms/atlas/> 
PREFIX efo:        <http://www.ebi.ac.uk/efo/> 

SELECT DISTINCT ?wpTitle ?dbXref ?expressionValue 
WHERE 
  {
    { 
      GRAPH <http://wikipathways>
        {
          ?pwElement dcterms:isPartOf ?wpPathway .
          ?wpPathway dc:identifier <http://identifiers.org/wikipathways/WP455> .
          ?wpPathway dc:title ?wpTitle .
          ?pwElement wp:bdbEnsembl ?dbXref .
        } 
      SERVICE <https://www.ebi.ac.uk/fgpt/atlasrdf/sparql> 
       {
        ?value atlasterms:hasFactorValue ?factor . 
        ?value atlasterms:isMeasurementOf ?probe . 
        ?value atlasterms:pValue ?pvalue . 
        ?value rdfs:label ?expressionValue . 
        ?probe atlasterms:dbXref ?dbXref .
        ?disFactor rdfs:subClassOf+ efo:EFO_0000408 .
        ?disease rdf:type ?disFactor .
        ?disFactor rdfs:label ?label .
    }
  }
}

    2. Execute the query from Virtuoso sparql endpoint
    3. As result you should get the following error: 

      Virtuoso 37000 Error SP031: SPARQL compiler: 
SERVICE <https://www.ebi.ac.uk/fgpt/atlasrdf/sparql> at line 18 does not 
support OPTION (...) clause for triples so SPARQL query can not be composed

    The error message means that the https://www.ebi.ac.uk/fgpt/atlasrdf/sparql sparql endpoint does not support OPTION clause.

    Basically, one should be able to use the following command to interrogate a target SPARQL endpoint (if initial SPARQL-FED fails): 

    SPARQL
LOAD SERVICE  <{SPARQL-END-POINT-URL}> DATA

    So in our example it would be: 

    LOAD SERVICE  <https://www.ebi.ac.uk/fgpt/atlasrdf/sparql> DATA ;

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