public AbstractUser login(String username, String password){
	//Configuration cfg = new Configuration().configure("hibernate.cfg.xml");
	//SessionFactory sessionFactory= cfg.buildSessionFactory();
	SessionFactory sessionFactory;
	sessionFactory = new AnnotationConfiguration()
    .addAnnotatedClass(AbstractUser.class)
    .addAnnotatedClass(CourseSession.class)
    .addAnnotatedClass(Course.class)
    .addAnnotatedClass(Message.class)
    .addAnnotatedClass(Material.class)
    .addAnnotatedClass(TopicSession.class)
    .addAnnotatedClass(Step.class)
    .addAnnotatedClass(Section.class)
    .addAnnotatedClass(Topic.class)
    .addAnnotatedClass(Subtopic.class)
    .configure("hibernate.cfg.xml")
    .buildSessionFactory();
	sessionFactory.openSession();

	emf = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT);
	em = emf.createEntityManager();
	logger.debug("** username:"+username);
	logger.debug("** password:"+password);

	Query q = em.createNamedQuery("users.byUnPass");
	q.setParameter("username", username);
	q.setParameter("password", password);
	AbstractUser user;

	try{
		user = (AbstractUser) q.getSingleResult();
	}catch(javax.persistence.NoResultException e){
		user = new AbstractUser();
	}

	return user;
}