Class Reuse and Classloader Issue

[cstettler]

Hi there,

I just wrote two small EAs,e ach in its own .ear file as specified. The setup is the following:

EA A:
- a-ejb.jar with BeanA
- CommonClass.class
- descriptors

EA B:
- b-ejb.jar with BeanB
- CommonClass.class
- descriptors

Both x-ejb.jars contain one distinct Session Bean with one method, calling a method of CommonClass.

Deployment works fine, but when calling each Session Bean from a simple client, BeanA gets loaded from Classloader #1, BeanB from Classloader #2, and - suprisingly - CommonClass from Classloader #1, too, no matter which Session Bean called the CommonClass method.

This means, that te two EAR share the same instance of the CommonClass, which may lead to problems if CommonClass exists in two different version or - even worst - one CommonClass has nothing to do with the other CommonClass except of the same name and package.

I would expect all classes from one EAR to be loaded by a single classloader that is not reused for any other EARs. Otherwise, using static fields would be impossible, not only not in EJBs (as specified by J2EE), but also in all helper classes and other third party libraries.

May anyone comment on this?

[raja05]

If you need isolation of ur classes, you have to scope the classloader for each ear. Look at "EAR Scoping" in the getting started documentation.

You have to create a jboss-app.xml and place this tag <loader-repository>jboss.test:loader=urear.ear</loader-repository>
(Take a look at http://jboss.org/j2ee/dtd/jboss-app_3_0.dtd

This would create a classloader that only those classes in the ear use.

-Raj

[cstettler]

Thanks a lot for your fast answer! It works now.

Btw: this is a proprietary feature of JBoss, isn't it? Do you know if there is planned to support this option in upcoming J2EE specs?