title: apache_request_headers() versus $_SERVER
body: <p>As far as I can tell, <code>apache_request_headers()</code> provides the same information as <code>$_SERVER</code>, but with slightly different keys.  Why should someone ever use <code>apache_request_headers()</code> and not just get this information from <code>$_SERVER</code>?  I am operating PHP 5.3.18 with Apache on Centos.  Thank you</p>
  
  <p>EDIT.  identical data from <code>$_SERVER</code> and <code>apache_request_headers()</code></p>
  
  <pre><code>Jun  2 08:50:53 localhost httpd: HTTP_HOST: www.badobe.com
  Jun  2 08:50:53 localhost httpd: Host: www.badobe.com
  Jun  2 08:50:53 localhost httpd: HTTP_USER_AGENT: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20100101 Firefox/21.0
  Jun  2 08:50:53 localhost httpd: User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20100101 Firefox/21.0
  Jun  2 08:50:53 localhost httpd: HTTP_ACCEPT: */*
  Jun  2 08:50:53 localhost httpd: Accept: */*
  Jun  2 08:50:53 localhost httpd: HTTP_ACCEPT_LANGUAGE: en-US,en;q=0.5
  Jun  2 08:50:53 localhost httpd: Accept-Language: en-US,en;q=0.5
  Jun  2 08:50:53 localhost httpd: HTTP_ACCEPT_ENCODING: gzip, deflate
  Jun  2 08:50:53 localhost httpd: Accept-Encoding: gzip, deflate
  Jun  2 08:50:53 localhost httpd: HTTP_REFERER: http://www.badobe.com/demo/administrator/index.php?cid=3
  Jun  2 08:50:53 localhost httpd: Referer: http://www.badobe.com/demo/administrator/index.php?cid=3
  Jun  2 08:50:53 localhost httpd: HTTP_COOKIE: PHPSESSID=feg3ecd4rsefvd03mgg6qear21
  Jun  2 08:50:53 localhost httpd: Cookie: PHPSESSID=feg3ecd4rsefvd03mgg6qear21
  Jun  2 08:50:53 localhost httpd: HTTP_CONNECTION: keep-alive
  Jun  2 08:50:53 localhost httpd: Connection: keep-alive
  Jun  2 08:50:53 localhost httpd: HTTP_IF_MODIFIED_SINCE: Sun, 02 Jun 2013 15:48:42 GMT
  Jun  2 08:50:53 localhost httpd: If-Modified-Since: Sun, 02 Jun 2013 15:48:42 GMT
  Jun  2 08:50:53 localhost httpd: HTTP_CACHE_CONTROL: max-age=0
  Jun  2 08:50:53 localhost httpd: Cache-Control: max-age=0
  </code></pre>