/**
  * Returns a certificate from a given serial number
  *
  * @param serialNo serial number of certificate
  * @return certificate
  * @throws AxisFault
  */
 public CertificateDTO getCertificateBySerialNo(String serialNo) throws AxisFault {
   try {
     return stub.getCertificate(serialNo);
   } catch (Exception e) {
     String message = e.getMessage();
     handleException(e.getMessage(), e);
   }
   return null;
 }