Linked Data view

**Tommy31** · 13/07/2011, 10h35

Bonjour,

Petite question sur le mécanisme de publication Linked Data. Naïvement, je pensais que lors d'une recherche, la présentation des résultats à l'utilisateur se fait en 2 étapes :
1) requête sparql SELECT qui va bien,
2) transformation du résultat

Visiblement, tout du moins dans l'implémentation puelia, à l'issue de la requête sparql SELECT, il y a une requête CONSTRUCT qui est faite sur la base de l'ensemble des éléments trouvés.

J'ai du mal à voir la pertinence, car je pense qu'il est possible de remonter dans un result-set autant d'information qu'un ensemble d'éléments dans un modèle, mais peut-être que je me trompe.

En outre, qu'en est-il de la performance ?

Merci

**Tommy31** · 13/07/2011, 10h38

Exemple de puelia:

requête select qui ne remonte que les URI des ressources recherchées :

Code :

Sélectionner tout - Visualiser dans une fenêtre à part

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PREFIX school: <http://education.data.gov.uk/def/school/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT DISTINCT ?item
WHERE {
  ?item ?p ?o
}
 
LIMIT 3 
OFFSET 0

La requête CONSTRUCT bâtie sur les 3 termes trouvés :

Code :

Sélectionner tout - Visualiser dans une fenêtre à part

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PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX school: <http://education.data.gov.uk/def/school/>
CONSTRUCT { 
    # constructing properties of <a href="http://education.data.gov.uk/id/school/100844" target="_blank">http://education.data.gov.uk/id/school/100844</a> 
    <http://education.data.gov.uk/id/school/100844> rdfs:label ?var_1_0 .
    <http://education.data.gov.uk/id/school/100844> school:uniqueReferenceNumber ?var_2_0 .
    <http://education.data.gov.uk/id/school/100844> school:establishmentNumber ?var_3_0 .
    <http://education.data.gov.uk/id/school/100844> school:typeOfEstablishment ?var_4_0 .
    ?var_4_0 rdfs:label ?var_4_1_0 .
    <http://education.data.gov.uk/id/school/100844> school:phaseOfEducation ?var_5_0 .
    ?var_5_0 rdfs:label ?var_5_1_0 .
    <http://education.data.gov.uk/id/school/100844> school:gender ?var_6_0 .
    ?var_6_0 rdfs:label ?var_6_1_0 .
    <http://education.data.gov.uk/id/school/100844> school:religiousCharacter ?var_7_0 .
    ?var_7_0 rdfs:label ?var_7_1_0 .
 
    # constructing properties of <a href="http://education.data.gov.uk/id/school/101149" target="_blank">http://education.data.gov.uk/id/school/101149</a> 
    <http://education.data.gov.uk/id/school/101149> rdfs:label ?var_1_1 .
    <http://education.data.gov.uk/id/school/101149> school:uniqueReferenceNumber ?var_2_1 .
    <http://education.data.gov.uk/id/school/101149> school:establishmentNumber ?var_3_1 .
    <http://education.data.gov.uk/id/school/101149> school:typeOfEstablishment ?var_4_1 .
    ?var_4_1 rdfs:label ?var_4_1_1 .
    <http://education.data.gov.uk/id/school/101149> school:phaseOfEducation ?var_5_1 .
    ?var_5_1 rdfs:label ?var_5_1_1 .
    <http://education.data.gov.uk/id/school/101149> school:gender ?var_6_1 .
    ?var_6_1 rdfs:label ?var_6_1_1 .
    <http://education.data.gov.uk/id/school/101149> school:religiousCharacter ?var_7_1 .
    ?var_7_1 rdfs:label ?var_7_1_1 .
 
    # constructing properties of <a href="http://education.data.gov.uk/id/school/101240" target="_blank">http://education.data.gov.uk/id/school/101240</a> 
    <http://education.data.gov.uk/id/school/101240> rdfs:label ?var_1_2 .
    <http://education.data.gov.uk/id/school/101240> school:uniqueReferenceNumber ?var_2_2 .
    <http://education.data.gov.uk/id/school/101240> school:establishmentNumber ?var_3_2 .
    <http://education.data.gov.uk/id/school/101240> school:typeOfEstablishment ?var_4_2 .
    ?var_4_2 rdfs:label ?var_4_1_2 .
    <http://education.data.gov.uk/id/school/101240> school:phaseOfEducation ?var_5_2 .
    ?var_5_2 rdfs:label ?var_5_1_2 .
    <http://education.data.gov.uk/id/school/101240> school:gender ?var_6_2 .
    ?var_6_2 rdfs:label ?var_6_1_2 .
    <http://education.data.gov.uk/id/school/101240> school:religiousCharacter ?var_7_2 .
    ?var_7_2 rdfs:label ?var_7_1_2 .
} WHERE { 
  # identifying properties of <a href="http://education.data.gov.uk/id/school/100844" target="_blank">http://education.data.gov.uk/id/school/100844</a> 
  {
    <http://education.data.gov.uk/id/school/100844> rdfs:label ?var_1_0 .
  } UNION {
    <http://education.data.gov.uk/id/school/100844> school:uniqueReferenceNumber ?var_2_0 .
  } UNION {
    <http://education.data.gov.uk/id/school/100844> school:establishmentNumber ?var_3_0 .
  } UNION {
    <http://education.data.gov.uk/id/school/100844> school:typeOfEstablishment ?var_4_0 .
    OPTIONAL { ?var_4_0 rdfs:label ?var_4_1_0 . }
  } UNION {
    <http://education.data.gov.uk/id/school/100844> school:phaseOfEducation ?var_5_0 .
    OPTIONAL { ?var_5_0 rdfs:label ?var_5_1_0 . }
  } UNION {
    <http://education.data.gov.uk/id/school/100844> school:gender ?var_6_0 .
    OPTIONAL { ?var_6_0 rdfs:label ?var_6_1_0 . }
  } UNION {
    <http://education.data.gov.uk/id/school/100844> school:religiousCharacter ?var_7_0 .
    OPTIONAL { ?var_7_0 rdfs:label ?var_7_1_0 . }
  }  UNION
 
  # identifying properties of <a href="http://education.data.gov.uk/id/school/101149" target="_blank">http://education.data.gov.uk/id/school/101149</a> 
  {
    <http://education.data.gov.uk/id/school/101149> rdfs:label ?var_1_1 .
  } UNION {
    <http://education.data.gov.uk/id/school/101149> school:uniqueReferenceNumber ?var_2_1 .
  } UNION {
    <http://education.data.gov.uk/id/school/101149> school:establishmentNumber ?var_3_1 .
  } UNION {
    <http://education.data.gov.uk/id/school/101149> school:typeOfEstablishment ?var_4_1 .
    OPTIONAL { ?var_4_1 rdfs:label ?var_4_1_1 . }
  } UNION {
    <http://education.data.gov.uk/id/school/101149> school:phaseOfEducation ?var_5_1 .
    OPTIONAL { ?var_5_1 rdfs:label ?var_5_1_1 . }
  } UNION {
    <http://education.data.gov.uk/id/school/101149> school:gender ?var_6_1 .
    OPTIONAL { ?var_6_1 rdfs:label ?var_6_1_1 . }
  } UNION {
    <http://education.data.gov.uk/id/school/101149> school:religiousCharacter ?var_7_1 .
    OPTIONAL { ?var_7_1 rdfs:label ?var_7_1_1 . }
  }  UNION
 
  # identifying properties of <a href="http://education.data.gov.uk/id/school/101240" target="_blank">http://education.data.gov.uk/id/school/101240</a> 
  {
    <http://education.data.gov.uk/id/school/101240> rdfs:label ?var_1_2 .
  } UNION {
    <http://education.data.gov.uk/id/school/101240> school:uniqueReferenceNumber ?var_2_2 .
  } UNION {
    <http://education.data.gov.uk/id/school/101240> school:establishmentNumber ?var_3_2 .
  } UNION {
    <http://education.data.gov.uk/id/school/101240> school:typeOfEstablishment ?var_4_2 .
    OPTIONAL { ?var_4_2 rdfs:label ?var_4_1_2 . }
  } UNION {
    <http://education.data.gov.uk/id/school/101240> school:phaseOfEducation ?var_5_2 .
    OPTIONAL { ?var_5_2 rdfs:label ?var_5_1_2 . }
  } UNION {
    <http://education.data.gov.uk/id/school/101240> school:gender ?var_6_2 .
    OPTIONAL { ?var_6_2 rdfs:label ?var_6_1_2 . }
  } UNION {
    <http://education.data.gov.uk/id/school/101240> school:religiousCharacter ?var_7_2 .
    OPTIONAL { ?var_7_2 rdfs:label ?var_7_1_2 . }
  } 
}

N'aurait-on pas obtenu l'équivalence chose dans un unique result-set en réponse d'une unique requête SELECT ?

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