%META:TOPICPARENT{name="VirtFacetBrowserInstallConfig"}%

---+ Virtuoso APIs for FCT REST services

%TOC%

---++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:

   * [[VirtFacetBrowserAPIsFCTEXEC][Typical Usage Example]].


---+++API Definition 
<verbatim>
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;
}
;
</verbatim>

---++Related

   * Facets Web Service:
      * [[VirtuosoFacetsWebService][Virtuoso Facets Web Service]]
   * Linked Data:   
      * [[VirtuosoFacetsViewsLinkedData][Faceted Views over Large-Scale Linked Data]]   
   * Facet Browser Installation and configuration:   
      * [[VirtFacetBrowserInstallConfig][Virtuoso Facet Browser Installation and configuration]]   
   * Facet APIs:
      * [[VirtFacetBrowserAPIsFCTEXEC][<code><nowiki>fct_exec</nowiki></code> API Example]]                   
   * Pivot Viewer and CXML:         
      * [[http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VirtSparqlCxmlFacetPivotBridge#AncSparqlCxmlFacetPivotBridge][Facet Pivot Bridge -  A bridge to PivotViewer from Virtuoso's Faceted query service for RDF]]      
      * [[http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VirtSparqlCxml#AncFacetTypeAutoDetection][Auto-Detection of Facet Type]]
   * Tutorials:
      * [[VirtuosoLODSampleTutorial][Faceted Browsing Sample using LOD Cloud Cache data space]]         
      * [[VirtuosoFacetsWebServiceSOAPExample][SOAP Facets Example]]   
      * [[VirtFacetBrowserInstallConfigQueried][Querying The Facet Browser Web Service endpoint]]  
      * [[VirtFCTFeatureQueries][Virtuoso Facet Browser Featured Queries]]      
      * [[http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VirtVisualizeWithPivotViewer#GenFCT][Visualizing Your Data With PivotViewer Using The Facet Browser]]       
      * [[VirtTipsAndTricksCustomControlLabelsURI][Custom Controlling Virtuoso Labels for URI functionality Example]]
      * [[VirtuosoFacetsWebServiceCustmExamples][Facets Web Service: Examples for customizing different types]]
      * [[VirtuosoFacetsWebServiceChoiceExample][Facets Web Service: Choice of Labels Example]]      
   * Downloads:   
      * [[http://shop.openlinksw.com/license_generator/virtuoso-download/][Latest Virtuoso]]
      * [[https://virtuoso.openlinksw.com/download/][Virtuoso Facet Browser VAD package]]