Replacing Seam with jee6 in conversation

Question

A project I'm working on is going to upgrade from jee5/seam to jee6, where "those who descide" think it is a good idea to drop seam since most of its features have been incorporated into jee6. But I have a case that I doesn't seem to be able to solve in jee6.

We have several wizards using ConversationScope. We use Seams FlushModeType.Manual in order to avoid getting "dirty" data commited until we want we actually wants to commit it (each page-load basically gets it own transaction but since nothing is written to the database until we flush, most commits doesn't change the state of the database).

I have made a few attempts using PersistenceContextType.EXTENDED in jee6 but it seems like I can't find a way to defer the flush to the database like seam does and the only workarounds seems to be to use detached objects or a separate view-model.

We really like how working with attached objects make (for our cases) things really simple to understand and fast to develop.

Is there a solution where we can keep working with attached objects in conversations?

Answer 1

As a big fan of Seam2 I wrote great apps using conversations, conversation scoped entity manager with flush mode set to manual and detached objects.

However, we must now admit that this pattern, despite being strongly pushed in the Seam manual and working great as far as Hibernate is the JPA implementation, is fundamentally broken. The reason is explained in this post from Mark Struberg: Is There A Way To Fix the JPA EntityManager?

So, the answer is no, there is no practical solution to keep working with attached objects in conversations. You should work with detached objects.

There is another another great CDI blogger who experimented with conversation scoped entity manager: Conversational CRUD. It might be worth reading if you keep on trying to work with attached objects.