public static function compressString( $content, $type = NULL )
	{
		switch( $type )
		{
			case NULL:
				return $content;
			case 'deflate':
				return gzdeflate( $content );														//  compress Content
			case 'gzip':
				return gzencode( $content, 9 );														//  compress Content
			default:																				//  no valid Compression Method set
				throw new InvalidArgumentException( 'Compression "'.$type.'" is not supported' );
		}
	}