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https://issues.apache.org/jira/browse/ARIES-1346?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14615132#comment-14615132
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Christian Schneider commented on ARIES-1346:
--------------------------------------------
I agree that this is a typical use case and we should support it. I am not sure
though how to implement it in the best way.
About two weeks ago I discussed with Peter Kriens how to handle the
EntityManager lifecycle and transactional contexts. He proposed to use the OSGi
coordination API for this task (See
https://osgi.org/javadoc/r5/enterprise/org/osgi/service/coordinator/Coordination.html).
I think it could indeed help. The concept would be to start a Coordination
where the transaction starts and attach the EntityManager to the Coordination
as a Participant. This would allow to then close the EntityManager when the
Coordination ends without directly tying it to the Transaction.
What do you think?
> EntityManager injection issue
> -----------------------------
>
> Key: ARIES-1346
> URL: https://issues.apache.org/jira/browse/ARIES-1346
> Project: Aries
> Issue Type: Improvement
> Components: JPA
> Affects Versions: jpa-2.0.0
> Environment: karaf-4.0.0, java 8
> Reporter: Michał Woś
> Priority: Critical
>
> Consider scenario:
> - blueprint service A with JPA
> {code}
> A {
> C find() {
> return em.find();
> }
> void delete(C c) {
> em.remove(c)
> }
> }
> {code}
> - blueprint bean B with A injected. B call methods of A within transaction
> {code}
> B {
> @Transaction
> B1() {
> C = A.find(); // Entity returned by find (em.find())
> A.delete(C); // Entity is not attached!!!!!!
> }
> }
> {code}
> Reason:
> Method of bean A are proxied in following way:
> {code}
> emsupplier.precall()
> emsupplier.get()
> find(); //or delete()
> emsupplier.postcall()
> {code}
> Each method call gets its own EM so find has one EM, delete has another one.
> Entity C is managed within first EM but not the second.
> EM should be shared in transaction within single Thread, not by single method
> call.
> Please also note that:
> - transaction could be JTA and use different units in single transaction
> My scenario:
> - bundle A1,A2,A3 with persistence JPA exposing entities through services
> (domain module), Each bundle (A1, A2, A3) uses different schema in database
> (different unit name)
> - bundle B1,B2,B3 with rest services using entity services in a transaction
> (Separation of domain logic from business logic). Each of B1,B2,B3 can use
> any method of A1,A2,A3
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