/**
  * This constructor for the RepositoryConnection.
  *
  * @param string $url
  *   The URL to Fedora.
  * @param string $username
  *   The username to connect with.
  * @param string $password
  *   The password to connect with.
  */
 function __construct($url = self::FEDORA_URL, $username = NULL, $password = NULL)
 {
     // Make sure the url doesn't have a trailing slash.
     $this->url = rtrim($url, "/");
     $this->username = $username;
     $this->password = $password;
     try {
         parent::__construct();
     } catch (HttpConnectionException $e) {
         throw new RepositoryException($e->getMessage(), $e->getCode(), $e);
     }
 }