source: Dev/trunk/rdfapi/sparql/SparqlClient.php @ 12

<?php

// ----------------------------------------------------------------------------------
// Class: SparqlEngine
// ----------------------------------------------------------------------------------

/**
* Client for querying a sparql server.
*
* @version  $Id: SparqlClient.php 573 2008-05-26 09:04:29Z cyganiak $
* @author   Tobias Gauß <tobias.gauss@web.de>
* @license http://www.gnu.org/licenses/lgpl.html LGPL
*
* @package sparql
*/

class SparqlClient extends Object {

        var $server;
        var $output;    

        /**
        * Constructor of SparlClient.
        *
        * @param String  $server   server address.
        */
        function SparqlClient($server){
                $this->server = $server;
                $this->output = "array";
        }


        /**
        * Sets the output format for a SELECT or ASK query. Possible formats are "xml" for
        * Sparql Query Results XML Format (http://www.w3.org/TR/rdf-sparql-XMLres/) or array
        * for the format described in our SparqlEngine.
        *
        * @param String  $format   the format.
        */
        function setOutputFormat($format){
                if(strtolower($format)=="xml")
                $this->output = "xml";
                if(strtolower($format)=="array")
                $this->output = "array";

        }

        /**
        * Main function of SparqlClient.
        *
        * @param ClientQuery  $query   the ClientQuery object.
        * @return mixed returns an array that contains the variables an their bindings or a MemModel
        *
        */
        function query($query){
                if(!is_a($query,"ClientQuery"))
                die;//ErrorHandling

                $url    = $this->_buildurl($query);
                $result = $this->_http_get($url);
                return $this->returnResult($result);

        }


        /**
        * Helper function that builds the url.
        *
        * @param ClientQuery  $query   the ClientQuery Object.
        */

        function _buildurl($query){
                $url = "";
                $url = $this->server."?query=".urlencode($query->query);
                foreach($query->default as $defaultg){
                        $url = $url."&default-graph-uri=".$defaultg;
                }
                foreach($query->named as $namedg){
                        $url = $url."&named-graph-uri=".$namedg;
                }

                return $url;

        }

        /**
        * Returns the query result.
        *
        * @param String  $result  the result.
        * @return mixed
        */
        function returnResult($result){

                if(strpos($result,"<rdf:RDF")){
                        include_once(RDFAPI_INCLUDE_DIR.PACKAGE_SYNTAX_RDF);
                        $parser = new RdfParser();
                        return $parser->generateModel(substr($result,strpos($result,"<rdf:RDF")));
                }

                if($this->output == "xml"){
                        $pos = strpos($result,"<?xml");
                        return substr($result,$pos);
                }
                if($this->output == "array"){
                        //      $pos = strpos($buffer,"<?xml");
                        return $this->parseResult($result);
                }
                return $result;
        }


        function parseResult($buffer){
                include_once(RDFAPI_INCLUDE_DIR.PACKAGE_SYNTAX_SPARQLRES);
                $parser = new SparqlResultParser();
                return $parser->parse($buffer);
        }


        /**
        * Executes the GET Request.
        *
        * @param String  $url  the url.
        * @return String result.
        */
        function _http_get($url)
        {
                $url = parse_url($url);
                $port = isset($url['port']) ? $url['port'] : 80;

                $fp = fsockopen($url['host'], $port);

                $replace = $url['path'];

                fputs($fp, "GET ".$replace."?".$url['query']." HTTP/1.0\r\n");
                fputs($fp, "Host: ". $url['host']."\r\n");
                fputs($fp, "Accept: application/sparql-results+xml, application/rdf+xml\r\n");
                fputs($fp, "Connection: close\r\n\r\n");

                $buffer = "";
                while ($tmp = fread($fp, 1024))
                {
                        $buffer .= $tmp;
                }

                return preg_replace("/^.*?(\r\n\r\n|\n\n)/s", "", $buffer);
        }
}



?>