PHP SDK Demystified – the $DOMAIN_MAP Property

In the PHP SDK code, after the cURL options is the $DROP_QUERY_PARAMS property:

   * Maps aliases to Facebook domains.
  public static $DOMAIN_MAP = array(
    'api'      => '',
    'api_read' => '',
    'graph'    => '',
    'www'      => '',

The $DOMAIN_MAP property contains the key-value mappings of the commonly used domains where HTTP requests are to send to. Among then

  • api
    This is where to send out the Old REST API “write” requests to
  • api_read
    This is where to send out the Old REST API “read” requests to.
  • graph
    This is where to send out the Graph API requests.
  • www
    This is the general facebook domain where login.php, logout.php reside.

Among the above values, the only point that I would like to draw your attention is the “api_read”.  It is pointing to ‘’.  However, there are some servers that get problem in resolving this domain name.  Just in case this happens to you, please modify it so that it point to ‘’. For details, please see my tutorial Learning PHP SDK – Part 7 (Calling old REST API).

The $DOMAIN_MAP is only used in the protected function getUrl(). In short, the getUrl function is for building a URL by using the given domain alias (i.e. the element keys in the $DOMAIN_MAP), path and parameters.  We will have a more detailed discussion on that later.

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