curl - Using Google Url Shortener service from PHP: how to improve performance using gzip? -

i'm using google url shortener service in php code.

it's working i'd improve performances , i've seen documentation (rif. https://developers.google.com/url-shortener/v1/performance) suggests working partial resources , using gzip.

i've adopted partial resources approach , works fine i'd use gzip suggestion too.

by code is

function compacturl($longurl)    {    $apikey = api;     $postdata = array('longurl' => $longurl);    $jsondata = json_encode($postdata);     $curlobj = curl_init();     curl_setopt($curlobj, curlopt_url,  'https://www.googleapis.com/urlshortener/v1/url?key='.$apikey'&fields=id);    curl_setopt($curlobj, curlopt_returntransfer, 1);    curl_setopt($curlobj, curlopt_ssl_verifypeer, 0);    curl_setopt($curlobj, curlopt_header, 0);    curl_setopt($curlobj, curlopt_httpheader, array('content-type:application/json'));    curl_setopt($curlobj, curlopt_post, 1);    curl_setopt($curlobj, curlopt_postfields, $jsondata);     $response = curl_exec($curlobj);    //print 'response = '.$response;     // change response json string object    $json = json_decode($response);     curl_close($curlobj);    $shortlink = get_object_vars($json);     return $shortlink['id'];  } 

the google documentation says use

accept-encoding: gzip user-agent: program (gzip) 

my problem don't know how convert in php code ......

any suggestions?

thank in advance!!!

cesare