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https://issues.apache.org/jira/browse/ARIES-1346?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14615512#comment-14615512
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Michał Woś commented on ARIES-1346:
-----------------------------------
Exactly, a single EM per persistence unit util transaction (XA transaction)
finishes so we should keep in mind that an XA transaction could have multiple
persistence units (different schemas or databases) meaning different EMs
injected and those should be cached until transaction ends.
In an XA transaction we could have:
@PersistenceContext(unitName="abcd")
and
@PersistenceContext(unitName="xyz")
> 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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