Why does my JBoss module throw a ClassCastException? - jboss

Question

Hi StackOverflow Community,
I have a WAR which I have deployed to a JBoss Wildfly 8.2 instance. Also in Wildfly, I have created two modules:
a third party JMS JCA adapter module,
and a model module (model.jar) that contains message classes used to communicate between the JMS broker and the WAR
The WAR has a jboss-deployment-structure.xml that declares a dependency on the JCA module:
<?xml version='1.0' encoding='UTF-8'?>
<jboss-deployment-structure xmlns="urn:jboss:deployment-structure:1.2">
<deployment>
<dependencies>
<module name="com.thirdparty.mq.ra" slot="main"/>
<module name="com.company.model" slot="main">
</dependencies>
</deployment>
</jboss-deployment-structure>
The WAR has the model.jar file packaged in its WEB-INF/lib folder.
The JMS module has a dependency on the model module:
<?xml version="1.0" encoding="UTF-8"?>
<module xmlns="urn:jboss:module:1.3" name="com.thirdparty.mq.ra">
<resources>
<resource-root path="."/>
<resource-root path="thirdparty-jms-provider.jar"/>
...
<resource-root path="thirdparty-lib.jar"/>
</resources>
<dependencies>
<module name="com.company.model"/>
<module name="javax.api"/>
<module name="javax.jms.api"/>
<module name="javax.transaction.api"/>
<module name="javax.management.j2ee.api"/>
<module name="javax.resource.api"/>
<module name="org.jboss.invocation"/>
<module name="org.jboss.remote-naming" optional="true"/>
<module name="org.slf4j"/>
</dependencies>
</module>
When running, I get the following exception:
Caused by: java.lang.ClassCastException: com.company.model.web.dto.WebAuthenticationResponse cannot be cast to com.company.model.web.dto.WebAuthenticationResponse
I suspect it is a classloader issue. Is there some extra information I have to specify in the module.xml or jboss-deployment-structure.xml files?
Thanks for your help!

Answer 1

Assuming that your model.jar corresponds to your com.company.model module, your WAR classloader now sees the model classes twice, both from its own libraries in WEB-INF/lib and via the module dependency.
You should either import or embed a module/library, but not both.
By the way, importing a RAR module looks a bit suspicious. You should never depend on the implementation of a resource adapter. Maybe you can factor out an API module and import that.