public String login(String userId, String password, int department) {
		User user = validateUser(userId);
		if (user == null) {
			m_logger.debug("userId " + userId + " is not valid");
			return ResponseMessages.USER_DOES_NOT_EXIST;
		}
		if (!password.equals(user.getPassword())) {
			m_logger.debug("password for " + userId + " not matched");
			return ResponseMessages.PASSWORD_NOT_MATCHED;
		}
		if (department != user.getDepartment()) {
			m_logger.debug("department for " + userId + " not successful");
			return ResponseMessages.DEPARTMENT_NOT_MATCHED;
		}
		setUser(user);
		return ResponseMessages.LOGIN_SUCCESSFUL;
	}