GarciaPL

public class UserManager implements IUser {
    private IUserDao userDao;

    @Transactional(propagation = Propagation.REQUIRED, readOnly = true, rollbackFor = Exception.class)
    public UserDTO retrieveUserById(Long userId) {
        return userDao.retrieveUserById(userId);
    }

    @Transactional(propagation = Propagation.REQUIRED, readOnly = false, rollbackFor = Exception.class)
    public UserDTO register(final UserDTO user) throws AVValidationException {

        if (user == null) {
            throw new IllegalArgumentException("Wrong params. user cannot be NULL");
        }

    return userDao.register(user);
    }

    public IUserDao getUserDao() {
        return userDao;
    }

    public void setUserDao(final IUserDao userDao) {
        this.userDao = userDao;
    }
}