@Put("json")
 public Representation putBusDriverJSON(Representation representation) {
   try {
     JsonRepresentation userRepresentation = new JsonRepresentation(representation);
     BusDriver busDriver = JsonHandler.fromJson(userRepresentation.getText(), BusDriver.class);
     // trying to add new user
     int result = busHelper.addBusDriver(busDriver);
     // checking errors
     if (result == BusHelper.EC_INVALID_DNI)
       // an user with that id exists
       getResponse().setStatus(Status.CLIENT_ERROR_CONFLICT);
     else if (result == BusHelper.EC_INVALID_AUTH_CODE)
       // invalid company registry authorization code
       getResponse().setStatus(Status.CLIENT_ERROR_PRECONDITION_FAILED);
     else if (result == BusHelper.EC_BBDD_ERROR)
       // error in DAO
       getResponse().setStatus(Status.CLIENT_ERROR_NOT_ACCEPTABLE);
   } catch (Exception ioe) {
     // an error occurred
     getResponse().setStatus(Status.CLIENT_ERROR_NOT_ACCEPTABLE);
   }
   return null;
 }