public function addHyperlink($firstRow, $firstColumn, $totalRows, $totalColumns, $url)
    {
        //check whether worksheet name is set or not
        if ($this->worksheetName == '')
            throw new Exception('Worksheet name not specified');
	
        if ($firstRow == '')
            throw new Exception('First Row not specified');
	
        if ($firstColumn == '')
            throw new Exception('First Column not specified');
	
        if ($totalRows == '')
            throw new Exception('Total Rows not specified');
	
        if ($totalColumns == '')
            throw new Exception('Total Columns not specified');
	
        if ($url == '')
            throw new Exception('URL not specified');				
						
        $strURI = Product::$baseProductUri . '/cells/' . $this->getFileName() .
            '/worksheets/' . $this->worksheetName . '/hyperlinks?firstRow=' . $firstRow .
			'&firstColumn=' . $firstColumn . '&totalRows=' . $totalRows . '&totalColumns=' . $totalColumns .
			'&address=' . $url;
        $signedURI = Utils::sign($strURI);
        $response = Utils::processCommand($signedURI, 'PUT', '', '');
        $json = json_decode($response);
        if ($json->Code == 200)
            return true;
        else
            return false;
    }