You can't really push a class back into the app. Instead you must
wait for the app to load (pull) a class and hook the load via the
javaagent.
In a managed (container) environment this works quite well because
the container can guarantee that the JPA provider is full initialized
before any app code is called. In an unmanaged environment life is
much more difficult since it is by definition the application code
that initializes the system. To get around this, you will need the
javaagent to search for persistence units and determine which classes
need to be enhanced. One nice thing, is most people will use the
@Entity annotation instead of XML to declare their persistent beans,
and this entity is easy to detect directly using asm. You should ask
David Blevins about his xbean-finder code which is designed to detect
such annotations.
-dain
On Feb 22, 2007, at 10:21 AM, Andrus Adamchik wrote:
I see how TemporaryClassLoader operates. We haven't been using
'getNewTempClassLoader' in the provider code as of yet. Let me poke
around and see if I am overcomplicating the issue... I still don't
understand how to push an enhanced class back into the app
classloader space, but maybe I am wrong (still thinking in Cayenne
classic terms), and this is not needed.
Andrus
On Feb 22, 2007, at 7:46 PM, Dain Sundstrom wrote:
Sorry, got busy and missed this email.
This is such a common problem, it was addressed directly by the
JPA specs. When loading classes for inspection use the class
loader returned from
javax.persistence.spi.PersistenceUnitInfo.getNewTempClassLoader().
For Cayenne's own PersistenceUnitInfo implementation, I suggest
you copy org.apache.openejb.core.TemporaryClassLoader which I
copied from OpenJPA and cleaned up.
-dain
