Hello!
We have a configuration of multiple datasources, where one of them is used for read-only access and has thus no transaction manager configured (the jndi datasource on wls that is involved is non transactional). Now we have a jpa entity with a blob field, that we can't read, because we get a connection reset exception once we try to access the Blob's InputStream. If on the other hand we create the EntityManager ourselves like:
@Autowired
private EntityManagerFactory entityManagerFactory4Geoportal;

....

EntityManager entityManager = entityManagerFactory4Geoportal.createEntityManager ();
entityManager.getTransaction().begin();

....

entityManager.getTransaction().rollback();
then everything is fine.

Now, that's not very pretty, so what am I doing wrong?
(Configuring a xa datasource is not an option)