Virtuoso Open-Source Edition

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    • VOS.VirtFacetBrowserAPIs(Last) -- Owiki? , 2018-04-13 12:06:23 Edit
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    owiki 2018-04-13 12:06:23

    Virtuoso APIs for FCT REST services

    Why

    Enables the use Virtuoso's VSP/VSPX technology to produce (X)HTML-based Linked Data explorer pages that are endowed with high-performance (in-process) faceted browsing capability.

    What

    A Virtuoso Stored Procedure that enables faceted browsing over Linked Data hosted in the RDF Quad Store. This also includes Linked Data that is progressively added to the Quad Store via URI de-referencing.

    How

    You can use this API with Virtuoso SQL calls that provide data to your VSP/VSPX, ASP.NET, PHP, etc., -based interfaces using ODBC, JDBC, ADO.NET, or XMLA connectivity (SPASQL) to Virtuoso.

    Examples:

    API Definition

    CREATE PROCEDURE
fct_exec 
  ( 
    IN  tree     ANY , 
    IN  timeout  INT
  )
{
  DECLARE  start_time, 
           view3, 
           inx, 
           n_rows      INT     ;
  DECLARE  sqls, 
           msg, 
           qr,
           qr2,
           act,
           query       VARCHAR ;
  DECLARE  md, 
           res, 
           results, 
           more        ANY     ;
  DECLARE  tmp         ANY     ;
  DECLARE  offs, 
           lim         INT     ;

  SET result_timeout = _min 
                         ( 
                           timeout, 
                           ATOI 
                             (
                               registry_get ('fct_timeout_max')
                             )
                         )
  ;

  offs := xpath_eval ('//query/view/@offset', tree);
  lim := xpath_eval ('//query/view/@limit', tree);

  -- db_activity ();

  results := vector (null, null, null);
  more := vector ();

  IF 
    ( 
      xpath_eval 
        (
          '//query[@view3="yes"]//view[@type="text"]', 
          tree
        ) 
      IS NOT NULL
    )
    {
      more := VECTOR ('classes', 'properties');
    }

  sqls := '00000';
  qr := fct_query 
          (
            xpath_eval ('//query', tree, 1)
          )
  ;
  query := qr;
--  dbg_obj_print (qr);
  qr2 := fct_xml_wrap (tree, qr);
  start_time := msec_time ();

  dbg_printf('query: %s', qr2);

  EXEC 
    (
      qr2, 
      sqls, 
      msg,
      vector (),
      0,
      md,
      res
    )
  ;
  n_rows := row_count ();
  act := db_activity ();
  SET result_timeout = 0;
  IF (
       sqls <> '00000'
       AND
       sqls <> 'S1TAT'
     )
    SIGNAL (sqls, msg);
  IF (
       NOT ISARRAY (res) 
       OR 
       0 = length (res) 
       OR 
       NOT ISARRAY (res[0]) 
       OR 
       0 = length (res[0])
     )
    results[0] := xtree_doc ('<result/>');
  ELSE
    results[0] := res[0][0];

  inx := 1;

  FOREACH (VARCHAR tp IN more) DO
    {
      tree := XMLUpdate (
                          tree, 
                          '/query/view/@type', 
                          tp,
                          '/query/view/@limit',
                          '40',
                          '/query/view/@offset',
                          '0'
                        )
      ;
      qr := fct_query (xpath_eval ('//query', tree, 1));
      qr2 := fct_xml_wrap (tree, qr);
      sqls := '00000';
      SET result_timeout = _min (
                                  timeout, 
                                  ATOI 
                                    ( 
                                      registry_get ('fct_timeout_max')
                                    )
                                )
      ;
      EXEC ( 
             qr2, 
             sqls, 
             msg,
             vector (), 
             0,
             md,
             res
           );
      n_rows := row_count ();
      act := db_activity ();
      SET result_timeout = 0;
      IF ( sqls <> '00000' 
           AND 
           sqls <> 'S1TAT'
         )
    SIGNAL (sqls, msg);
      IF ( 
           ISARRAY (res) 
           AND 
           LENGTH (res) 
           AND 
           ISARRAY (res[0]) 
           AND
           LENGTH (res[0])
         )
    {
      tmp := res[0][0];
      tmp := XMLUpdate (tmp, '/result/@type', tp);
      results[inx] := tmp;
    }
      inx := inx + 1;
    }



  res := XMLELEMENT 
           (
             "facets", 
             XMLELEMENT 
               ( "sparql", query ), 
             XMLELEMENT 
               ( "time", msec_time () - start_time ),
             XMLELEMENT 
               ( 
                 "complete", 
                 CASE WHEN sqls = 'S1TAT' 
                      THEN 'no' 
                      ELSE 'yes' 
                  END
                ),
             XMLELEMENT 
               (
                 "timeout",
                 _min 
                   (
                     timeout * 2, 
                     ATOI 
                       (
                         registry_get 
                           ( 'fct_timeout_max' )
                       )
                   )
               ),
             XMLELEMENT 
               ("db-activity", act),
             XMLELEMENT
               ("processed", n_rows), 
             XMLELEMENT
               (
                 "view", 
                 XMLATTRIBUTES 
                   ( 
                     offs AS "offset", 
                     lim AS "limit"
                   )
               ),
             results[0], 
             results[1], 
             results[2]
           );

---- for debugging:
--string_to_file ('ret.xml', serialize_to_UTF8_xml (res), -2);
--  dbg_obj_print (res);

  RETURN res;
}
;

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