JYI: The class path entry is created by Eclipse if an old style EAR project is used. If you don't add it, the app client project cannot resolve e.g. the ejb remote interface. But this is rather old knowledge - I should test whether it is still necessary.
Best regards
Wolfgang
On 5/17/24 10:27 AM, Scott Marlow wrote:
On Fri, May 17, 2024 at 12:57 AM Wolfgang Knauf via wildfly-dev <wildfly-dev@lists.jboss.org> wrote:
Hi all,
this question is about a change in the way that a JakartaEE application
client is launched: https://issues.redhat.com/browse/WFLY-19020
Before the change, an application client might receive a
ClassNotFoundException because of a missing hibernate class. My
workaround for this was to add jboss-deployment-structure.xml and
include the module "org.hibernate".
This behavior was changed in 31.0.1 after my bugreport: it seems the
application client deploys "persistence.xml" from the EJB jar somehow,
and my sample now works.
But this change also causes the application client to create/drop the
tables each time it is launched if persistence.xml defines
"hibernate.hbm2ddl.auto=create-drop". This did not happen with WildFly
31.0.0 and before.
It can be avoided if the data source in "appclient.xml" points to a H2
memory database instead of the real database defined in "standalone.xml".
I did not verify whether old WildFly versions required the datasource to
be defined in "appclient.xml", but I have the feeling that it was necessary.
Currently, this is only an unnecessary step. But if the datasource
defined in "appclient.xml" would point to the "real" datasource defined
in "standalone.xml", the tables would be created each time the client
starts. Fortunately, I could not make it work to define a MariaDB
connection in "appclient.xml" because it could not resolve the driver,
but with some effort this could be possible.
What do you think about this change? To me, it sounds unnecessary to
create/drop tables from EJB "persistence.xml" when an app client is
started. Is it required if the app client itself would use client side JPA?
Thanks for starting this discussion! I appreciate that you are questioning whether the EJB persistence.xml should be visible to the app client deployment. We should consider the rules in https://jakarta.ee/specifications/platform/10/jakarta-platform-spec-10.0#application-client-container-class-loading-requirements and whether any of those are not being followed correctly for your deployment. The question that we need to answer is whether the (EJB) persistence unit should have been ignored.
Pasting from the referencing rules for easy reference:
"
8.3.3. Application Client Container Class Loading Requirements
Components in the application client container must have access to the following classes and resources.
The content of the application client jar file.
The transitive closure of any libraries referenced by the above jar file (as specified in Library Support).
The transitive closure of any libraries specified by or referenced by the containing ear file (as specified in Library Support).
The Jakarta EE API classes specified in Jakarta EE Technologies for the application client container.
All required Java SE API classes.
Components in the application client container may have access to the following classes and resources. Portable applications must not depend on having or not having access to these classes or resources.
The Jakarta EE API classes specified in Jakarta EE Technologies for the containers other than the application client container.
Any installed libraries available in the application server.
Other classes or resources contained in the application package, and specified by an explicit use of an extension not defined by this specification.
Other classes and resources that are part of the implementation of the application server.
Components in the application client container must not have access to the following classes and resources, unless such classes or resources are covered by one of the rules above.
"
Other classes or resources in the application package. For example, the application client should not have access to the classes in other application client jar files in the same ear file, nor should it have access to the classes in web applications or Jakarta Enterprise Beans jar files in the same ear file.
The attached https://issues.redhat.com/secure/attachment/13134094/KuchenZutatInheritance_Simplied.ear archive contains the KuchenZutatInheritanceClient.jar file that has MANIFEST.MF with:
class-Path: KuchenZutatInheritanceEJB.jar
My read is that the appclient container should have access to the EJB persistence unit since the EJB is on the appclient deployment classpath. Still, I think an interesting experiment would be to try removing the KuchenZutatInheritanceEJB.jar from the appclient classpath to see if the persistence unit still deploys (if it does, I think that is a bug worth creating a new WFLY for.
Scott
Regards,Scott
Best regards
Wolfgang
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