DAO scope in spring-hibernate multi-user web application?

I really saw this question , but could not get much from it, so I will try to be more specific with mine.
I have a BaseDAO class in my multi-user web application that looks like this:

public abstract class BaseDAO<GenType>
{
private HibernateOperations hibernateTemplate;

protected BaseDAO() {}
protected HibernateOperations getHibernateTemplate() {
    return hibernateTemplate;
}
public void setHibernateTemplate(HibernateOperations hibernateTemplate) {
    this.hibernateTemplate = hibernateTemplate;
}
protected void initialize(final Object proxy) throws DataAccessException {
    hibernateTemplate.initialize(proxy);
}
public GenType merge(GenType entity) throws DataAccessException {
    return (GenType)hibernateTemplate.merge(entity);
}
protected void persist(GenType entity) throws DataAccessException {
    hibernateTemplate.persist(entity);
}
public void refresh(GenType entity) throws DataAccessException {
    hibernateTemplate.refresh(entity);
}
public void save(GenType entity) throws DataAccessException {
    hibernateTemplate.save(entity);
}
public void saveOrUpdate(GenType entity) throws DataAccessException {
    hibernateTemplate.saveOrUpdate(entity);
}
public void update(GenType entity) throws DataAccessException {
    hibernateTemplate.update(entity);
}
public void delete(GenType entity) throws DataAccessException {
    hibernateTemplate.delete(entity);
}
protected void deleteAll(Collection<GenType> entities) throws DataAccessException {
    hibernateTemplate.deleteAll(entities);
}
protected GenType get(Class<GenType> entityClass, Serializable id) throws DataAccessException {
    return (GenType)hibernateTemplate.get(entityClass, id);
}
}

HibernateTemplate. DAO , (, getBySomeAttribute()). , DAO . , , DAO. DAO, spring -AOP / ( ). :

public class ModelDAO extends BaseDAO<Model> implements IModelDAO
{
    @Override
    public Model getNew() {
        return new Model();
    }

    @Override
    public List<Model> getBySomeAttr() {
        DetachedCriteria criteria;
        // define some criteria
        return getHibernateTemplate().findByCriteria(criteria);
    }
}

...

public class ModelService
{
    private ModelDAO modelDAO;
    private ElementDAO elementDAO;
    // GET/SET for model and user DAO

    public void doSomethingWithModel() {

        modelDAO.doSomething();
        elementDAO.doSomethingElse();
    }
}

:

<bean id="hibernateTemplate2" class="org.springframework.orm.hibernate3.HibernateTemplate">
    <property name="sessionFactory" ref="sessionFactory2" />
    <property name="maxResults" value="3000" />
</bean>

<!-- DAO -->
<bean id="baseDAO" abstract="true" 
    class="org.irvas.backend.dao_implement.BaseDAO" scope="session">
    <property name="hibernateTemplate" ref="hibernateTemplate2" />
</bean>
<bean id="modelDAO" 
    class="org.irvas.backend.dao_implement.ModelDAOImplement" 
    parent="baseDAO" scope="session">
</bean>
<bean id="elementDAO" 
    class="org.irvas.backend.dao_implement.ElementDAOImplement" 
    parent="baseDAO" scope="session">
</bean>

<!-- Service -->
<bean id="modelService" 
    class="org.irvas.backend.service_implement.ModelServiceImplement" scope="session">
    <property name="modelDAO" ref="modelDAO" />
    <property name="elementDAO" ref="elementDAO" />
</bean>
<bean id="elementService" 
    class="org.irvas.backend.service_implement.ElementServiceImplement" scope="session">
    <property name="elementDAO" ref="elementDAO" />
</bean>

, , DAO/Service beans ? beans controllesrs GUI. ( scope = "session" ), , :

bean 'modelService': java.lang.IllegalArgumentException setAttribute: : modelDAO

, Tomcat StandardSession.setAttribute(). , DAO Serializable, , , Serializable...

- , , DAO , ...