@SuppressWarnings("unused")
	public String execute() {
		String returnVal = SUCCESS;
		if (getSubmit() != null && SUBMIT.equals(getSubmit())) {
			validate();
			LibraryManagementFacade libraryManagementFacade = new LibraryManagementFacade();
			try {
				UserVO validUserVO = libraryManagementFacade
						.authenticate(getUserVO());
				if (validUserVO != null) {
					Map<String, Object> sessionAttribute = new HashMap<String, Object>();
					getSession().setAttribute("user", validUserVO);
					if ("operator".equals(validUserVO.getUserType())) {
						returnVal = "operatorpanel";
					} else if ("student".equals(validUserVO.getUserType())) {
						returnVal = "studentpanel";
					}
				}
			} catch (LibraryManagementException e) {
				addActionError(e.getExceptionCategory().getMessage());
				returnVal = ERROR;
			}
		} else {
			returnVal = "login"; // when comes first time
		}
		return returnVal;
	}