Sparql request with CURL

public function executeGetLocation(sfWebRequest $request)
	{
		$ressource = $request->getParameter('ressource');
		if(!empty($ressource))
		{
			$query = "SELECT ?location WHERE {{ <"
			. $ressource
			. "> <http://dbpedia.org/ontology/locationCity> ?location }}";
 
			$searchUrl = 'http://dbpedia.org/sparql?'
			. 'query='.urlencode($query)
			. '&format=json';
 
			if (!function_exists('curl_init')){
				die('CURL is not installed!');
			}
 
			$ch= curl_init();
			curl_setopt($ch, CURLOPT_URL, $searchUrl);
			curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
			$response = curl_exec($ch);
			curl_close($ch);
 
			return $this->renderText( json_encode($response));
		}