public function getFiles($sDirectory, $sExt = '')
	{
	    $aFiles = array();
	    
	    if(!is_dir($sDirectory)){
			return null;
		}
	    
	    foreach(new \DirectoryIterator($sDirectory) as $oFileInfo){
	        if($oFileInfo->isFile()){
	            if(empty($sExt) || $sExt == $oFileInfo->getExtension()){
	                $aFiles[] = $oFileInfo->getPathname();
	            }
	        }	            
	    }
	    
	    return $aFiles;
	}