public function get_value( $option_name, $default_value = false )
    {
	$service_name = substr( $option_name, 0, strpos( $option_name, '.' ) );
	$option_name = str_replace( $service_name . '.', '', $option_name );

	// debug
	// echo $service_name;
	// echo $option_name;

	$value = false;
	if( array_key_exists( $service_name, $this->_configs ) )
	{ 
	    if( array_key_exists( $option_name, $this->_configs[$service_name] ) )
	    {
		$value = $this->_configs[$service_name][$option_name];
	    }
	    else if( $default_value )
	    {
		$value = $default_value;
	    }
	}

	return $value;
    }