4. Implement new interfaces, inherit from new classes

7. Under the Looking Glass (EclipseLink example )

8. Java Byte Code as a Second Language cv = cw.visitMethod(ACC_PUBLIC, "setId", "(Ljava/lang/Integer;)V", null, null); cv.visitVarInsn(ALOAD, 0); cv.visitVarInsn(ALOAD, 1); cv.visitFieldInsn(PUTFIELD, "org/eclipse/persistence/testing/models/jpa/advanced/PhoneNumber", "id", "Ljava/lang/Integer;"); cv.visitInsn(RETURN); cv.visitMaxs(2, 2); public void setId(Integer id) { this . id = id; } Java Code ASM Code

11. Static weaver

13. Behaviour varies among versions

14. Need to get predictable version

15. Repackaged version available as bundle and in eclipselink.jar Bundle-Vendor : Eclipse.org - EclipseLink Project Bundle-SymbolicName : org.eclipse.persistence.asm Bundle-Name : EclipseLink ASM Export-Package : org.eclipse.persistence.internal.libraries.asm;... ...

17. Other libraries may weave in incompatible ways

19. eclipselink.weaving.changetracking = true/false

20. eclipselink.weaving.internal = true/false

21. eclipselink.weaving.lazy = true/false

22. eclipselink.weaving.eager = false/true public class PhoneNumber implements Serializable, Cloneable, PersistenceWeaved , PersistenceEntity , PersistenceObject , FetchGroupTracker, PersistenceWeavedFetchGroups , PersistenceWeavedLazy , ChangeTracker, PersistenceWeavedChangeTracking

26. Down the Rabbit Hole (Equinox Example)