[ARIES-1346] EntityManager should be reused for series of coordinated calls

• Type: Improvement
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: jpa-2.0.0
• Fix Version/s: jpa-2.1.0
• Component/s: JPA

Environment

karaf-4.0.0, java 8

• Assignee: Christian Schneider
• Reporter: Michał Woś
• Created: 06/Jul/15 10:06
• Updated: 10/Jun/21 10:37
• Resolved: 13/Jul/15 14:27

Description

Consider scenario:

• blueprint service A with JPA

     A {
  
        C find() {
           return em.find();
        }
  
        void delete(C c) {
           em.remove(c)
        }
    }
  

• blueprint bean B with A injected. B call methods of A within transaction

B {

   @Transaction
   B1() {
      C = A.find(); // Entity returned by find (em.find())

      A.delete(C); // Entity is not attached!!!!!!
   }

}

Reason:
Method of bean A are proxied in following way:

emsupplier.precall()
emsupplier.get()
find(); //or delete()
emsupplier.postcall()

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

Issue Links

• breaks: ARIES-2050 Aries JPA 2.7 shouldn't always reuse EM instance from previous coordinations