Seam @In EntityManager vs. Extended Persistence context.

[marius.oancea]

I;ve build a tree using richfaces and seam. The tree model is saved into a session stateful component.

@Stateful
@Scope(SESSION)
@Name("leftTreeBean")


I used Extended Persisence Context and all works but it seems that that exteded persistence context does not propagate into DAO objects (Stateless session beans).

If I switch to seam managed persistence tree does not work (i supose because seam managed persistend only work inside conversation - and this cannot be the case because the tree is displayed all the time).

How can I make the dao called from "leftTreeBean" use the same EntityManager?

[matt.drees]

"marius.oancea" wrote:
If I switch to seam managed persistence tree does not work

What, precisely, breaks?

(There should be no problem injecting a SMPC into a session-scoped component)

[matt.drees]

"matt.drees" wrote:
There should be no problem injecting a SMPC into a session-scoped component

That is, if the conversation context is active. (eg, not during RestoreView).

[pmuir]

Matt, the problem is that the SMPC is not session scoped,so therefore stuff loaded by the SMPC becomes unmanaged inside that bean (I guess this is the problem, it normally is).

[pmuir]

There are a number of techniques discussed on the forum a few times for dealing with this.

[thejavafreak]

"marius.oancea" wrote:
I;ve build a tree using richfaces and seam. The tree model is saved into a session stateful component.

@Stateful
@Scope(SESSION)
@Name("leftTreeBean")


I used Extended Persisence Context and all works but it seems that that exteded persistence context does not propagate into DAO objects (Stateless session beans).

If I switch to seam managed persistence tree does not work (i supose because seam managed persistend only work inside conversation - and this cannot be the case because the tree is displayed all the time).

How can I make the dao called from "leftTreeBean" use the same EntityManager?

I made the SMPC into a conversation scoped and it works. But I don't know in your case.

[marius.oancea]

Just for clarification some of my requirements:

- Session scoped "leftTreeBean" (because conversation is too short)
- "leftTreebean" provides a getRoot method that creates a new TreeNodeimpl and makes db query to populate first level of the tree. Tree nodes are a custom class ClazzTreeNode.

ClazzTreeNode is not a seam component. Just a java object. Its "getChildren" makes a database call to a dao to find out the children of a specific node.

I would like to push the code to findChildrens, findFirstLevel and so on into another classes (DAO) to be able to reuse them.

Note:

During working with the application tree can be modified.
Tree is huge (about 2.5 million nodes) so it cannot be loaded in memory.
I expect DAO-s to be stateless session beans

I use richfaces with ajax switch type.

Any critics to this design ?