public function getAnnotation($pageNumber, $annotationIndex)
    {

        $strURI = Product::$baseProductUri . '/pdf/' . $this->getFileName() . '/pages/' . $pageNumber . '/annotations/' . $annotationIndex;
        $signedURI = Utils::sign($strURI);
        $responseStream = Utils::processCommand($signedURI, 'GET', '', '');
        $json = json_decode($responseStream);
        return $json->Annotation;
    }