private function constructUserAgentHeader()
{
$this->userAgent = $this->quoteApplicationName($this->config['application_name']) . '/' . $this->quoteApplicationVersion($this->config['application_version']);
$this->userAgent .= ' (';
$this->userAgent .= 'Language=PHP/' . phpversion();
$this->userAgent .= '; ';
$this->userAgent .= 'Platform=' . php_uname('s') . '/' . php_uname('m') . '/' . php_uname('r');
$this->userAgent .= '; ';
$this->userAgent .= 'MWSClientVersion=' . self::MWS_CLIENT_VERSION;
$this->userAgent .= ')';
}