Hi there,
I am integrating GWT 2.5.1 with Spring 3.0 backend. Run into a problem
that OSIVP should fix but it is not.
A parent object contains a list of children objects, both are EntityProxy.
On client side, I update the child proxy and my Server side API simply
saves the parent. On the server side, my updates to the child object
disappears by the time server business logic is invoked. My transaction
starts and commits in business service layer. I have already used one
single entity manager instance per request by using ThreadLocal.
Without using OSIVP, I did observe if I explicitly start a transaction in
my request factory servlet when request comes in, and then commit the
transaction in the servlet at the end, the problem is fixed. Therefore, I
have to group everything under the same transaction (inside servlet, rather
than in service layer), in addition to use one single entity manager pre
request, is that correct?
Everyone said that the fix is to use OSIVP, however, I do not see it is
fixing the problem afterwards. For whatever reason, using OSIVP does not
have the same effect.
1) In my EntityLocator class, how do I get entityManager? Some has posted
this code, this is what I used. But, does not it start a new entity manager
rather than using what is attached to the thread?
private void init() {
HttpServletRequest request =
RequestFactoryServlet.getThreadLocalRequest();
ApplicationContext context =
WebApplicationContextUtils.getWebApplicationContext(request.getSession().getServletContext());
EntityManagerFactory entityManagerFactory =
context.getBean(EntityManagerFactory.class);
entityManager = entityManagerFactory.createEntityManager();
// then cache this entityManager in locator instance
}
2) In my DAO class, do I need to declare my entity manager as extended like
this? That is what I did.
@PersistenceContext(type=PersistenceContextType.EXTENDED)
private EntityManager em;
3) How does Spring OpenEntityManagerInViewFilter start a transaction? I do
not see it is happening in its source code, other than registering entity
manager to current thread. I think that is my problem. If somehow a
transaction is started before the locator method is called, I would have
been fine.
I wish someone has a sample project illustrates all this.
Thanks,
Yan
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