VirtSparqlCxmlHead

Draft documentation for CXML generation from /sparql endpoint

Work in progress ...

• VirtSparqlCxml

• VirtSparqlCxmlDzcs

• SparqlCxmlDzcsOld

• VirtSparqlCxmlFacetPivotBridge

-- CarlBlakeley 29 Sep 2010

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• SparqlCxmlQueriesCollection

CXML Generation Routines used by /sparql

The main Virtuoso/PL procedures used are:

• DB.DBA.SPARQL_RESULTS_TO_CXML_WRITE
  • Prepares CXML data for a given SPARQL SELECT result set. metas[1] can be tweaked by caller and contain get_keyword style vector of collection attributes.
• DB.DBA.RDF_TRIPLES_TO_CXML
  • Prepares CXML data for a given SPARQL CONSTRUCT-like dictionary of triples
• DB.DBA.CXML_CONVERT_FACET_VALUES
  • Calls any value conversion callback functions of all facets for all facet values.
• DB.DBA.CXML_MAKE_COLLECTION
  • Serializes facets and items into a complete CXML text.
• DB.DBA.CXML_FACET_OF_COL
  • Returns a facet IRI for the given column name. (Used by DB.DBA.SPARQL_RESULTS_TO_CXML_WRITE)
• DB.DBA.CXML_FACET_OF_P
  • Returns a facet IRI (facet name) for the given item type and predicate. By default, the facet IRI is equal to the predicate IRI.
• DB.DBA.CXML_FACET_ATTRS
  • Given a facet IRI, the function returns a vector of attributes of the facet.
  • Attributes currently recognized by the CXML serializer are:
    • @Name (the fragment from the facet / predicate IRI is used if not specified)
    • @Type (default is 'String', values are standard CXML types or one of 'Item/Description', 'Item/Related', 'Item/@Img', 'Item/@Id', 'Item/@Href', 'Item/@Name' )
    • @Format
    • d1p1:IsFilterVisible
    • d1p1:IsMetaDataVisible
    • d1p1:IsWordWheelVisible

Default CXML Output

The default settings for the CXML generation include the following defaults:

• FacetCategory attributes
  • Name
    • Defaults to a short property name, without a prefix. e.g. Predicate http://www.openlinksw.com/campsites/schema#distance_from_calais_km becomes a FacetCategory with Name="distance_from_calais_km"
  • Type
    • Defaults to CXML type "String"
  • IsFilterVisible, IsMetaDataVisible, IsWordWheelVisible
    • All default to "true"

• Facet attributes
  • Name
    • As with the FacetCategory Name attribute, defaults to a short property name.
  • Type
    • As with the FacetCategory Type attribute, defaults to "String".

• Item attributes
  • Name
    • Defaults to the URI of the entity described by the Item element
  • Href
    • Defaults to the URI of the entity described by the Item element
  • Img
    • Defaults to "#10"

• Items attributes
  • ImgBase
    • Defaults to "/pivot_collections/default_pivot_collection_files/n3ijndyb.ian.xml"

Tailoring the CXML Output

The CXML output can be tailored by settings in graph <http://www.openlinksw.com/schemas/virtcxml#>. The graph can also be referred to by its short name virtcxml: which is declared in table DB.DBA.SYS_XML_PERSISTENT_NS_DECL.