public static function getCoreLibFilePath($className)
    {
        // if class not yet collect on class map, scan core path.                 
        $classFile = $className . '.php';
        // TODO: search the file under bin/, bin/data, bin/ui. bin/service, bin/easy, bin/Easy/element.
        // guess class type and folder
        $lowClassName = strtolower($className);
        if (strrpos($lowClassName, 'service') > 0) {
            $corePaths = array('service/');
        } else if (strrpos($lowClassName, 'form') > 0 || strrpos($lowClassName, 'form') === 0) {
            $corePaths = array('easy/');
        } else if (strrpos($lowClassName, 'view') > 0 || strrpos($lowClassName, 'view') === 0) {
            $corePaths = array('easy/');
        } else if (strrpos($lowClassName, 'dataobj') > 0) {
            $corePaths = array('data/');
        } else {
            $corePaths = array('easy/element/', '', 'data/', 'easy/', 'service/');
        }
        //$corePaths = array('', 'data/', 'easy/', 'easy/element/', 'ui/', 'service/');
        foreach ($corePaths as $path) {
            $_classFile = OPENBIZ_BIN . $path . $classFile;
            //echo "file_exists($_classFile)\n";
            if (file_exists($_classFile)) {
                return $_classFile;
            }
        }
        return null;
    }