EAR Classloader not finding PersistenceProvider class inside packaged WAR

[white_crow]

Hello there

I'm currently trying to pack our web application (WAR) inside an EAR - For the moment we only have this one sub-module. Inside the WAR, there is a JAR in the WEB-INF/lib folder which contains a custom implementation of PersistenceProvider. Also we have a persistence.xml file in this JAR's META-INF folder. So it basically looks something as follows:

EAR

---WAR

------WEB-INF

---------lib

------------JAR

---------------META-INF

------------------persistence.xml (listing CustomPersistenceProvider as provider)

---------------CustomPersistenceProvider.class

However, when trying to deploy the EAR, it complains about not finding CustomPersistenceProvider (ClassNotFoundException at org.jboss.modules.ModuleClassLoader.findClass). According to the documentation, JPA 2.0, chapter 8.2, it should be perfectly fine, having the persistence.xml in a JAR inside the WEB-INF/lib folder of a WAR. And it also seems to find the persistence.xml, because he knows which class he has to look for. But it does not seem to see classes inside the WAR. In chapter 8.2.2 it also states, that when a persistence unit is defined at the level of a WAR, it is also scoped like that - but does this count for the EAR itself as well?

I further found something in this docu Class Loading in AS7 - JBoss AS 7.0 - Project Documentation Editor where it says the following "The ear-subdeployments-isolated element value has no effect on the isolated classloader of the .war file(s). i.e. irrespective of whether this flag is set to true or false, the .war within a .ear will have an isolated classloader and other sub-deployments within that .ear will not be able to access classes from that .war. This is as per spec."

So I guess it's a more general question: Can the EAR module classloader not see classes defined in one of its sub-deployments (eg WAR)? I know that communication between sub-deployments has to be explicitly defined or shared classes should be in a lib folder of the EAR.

What would be the best solution, without having to change the WAR (eg moving classes around), because we're still using it as standalone WAR?

Thanks

[white_crow]

Meanwhile i've refactored our structure a little bit, so that now I have several ejb-jars and one war inside a ear. The persistence unit mentioned in my previous post, is now inside of an ejb-jar.

I could finally run it, but only if I use the parameter:

  <ear-subdeployments-isolated>false</ear-subdeployments-isolated>

As soon as i change it to true, I get the ClassNotFoundException again, which in a way also makes sense, but can't I just selectively export some stuff of an ejb-jar without having to set this parameter to false?

Thanks

[smarlow]

The Class Loading in WildFly documentation may be helpful to you.

[white_crow]

Thanks for your reply

If you look at my post, I've already put in the same link (AS7 instead of Wildfly though) and quoted something from there.

To me it's still unclear, what classes inside an EJB-JAR or WAR can be seen by the EAR classloader or where I've even the chance to define so.

[smarlow]

The JPA persistence provider is not part of the persistence unit, so the rules for loading the persistence unit do not apply to loading the persistence provider.  Have you tried moving the persistence provider (CustomPersistenceProvider) to the EAR/lib folder, I would expect that to help with the loading of the custom persistence provider.

Also, it is the JPA container that reads the persistence.xml file, not the persistence provider.

[white_crow]

Thanks for your reply

I haven't tried it to move it to the EAR/lib folder yet, since I was not sure, since that JAR also contains EJBs and I was not sure, if that would work in the EAR/lib.

I finally managed to get it to work, if I put

<ear-subdeployments-isolated>false</ear-subdeployments-isolated>

into the jboss-deployment-structure.xml

What also came to my mind, but haven't tried it yet, maybe the right way would be having a META-INF/services file as follows:

META-INF/services/javax.persistence.spi.PersistenceProvider

with content: foo.bar.YourCustomPersistenceProvider

Maybe that way, it would be found, even if the isolation is switched on.

[smarlow]

If you run into further difficulties, you could upgrade to the latest WildFly version and if that doesn't help, you could then request enhancements to better support your application. 

https://github.com/wildfly/wildfly/blob/master/testsuite/integration/basic/src/test/java/org/jboss/as/test/integration/jpa/mockprovider/classtransformer/ClassFileTransformerTestCase.java is a (minimal) unit test that includes a mock persistence provider (Java proxy based implementation that ignores most methods) that you might find interesting, as it is in a EAR/lib jar with the META-INF/services file included.  This unit test was added to an AS 8.x release and is still present in the latest WildFly release.  The purpose of the unit test isn't really to ensure that your particular applications works, but more for ensuring that entity class transformers work as designed.  However, you may still find it interesting.

Scott