NPE while calling a simple SLSB

Question

Greetings,
I a SLSB i have the following code:
public String sayHello (String who)
return "Hello " + who;
public void insertArticle (String title, Magazine magazine)
/* Do nothing */
I'm calling from a remote client the sayHello methos and it works. Now, if I modify the code this way:
public String sayHello (String who)
return "Hello " + who;
public void insertArticle (String title, ArrayList<Author> authors, Magazine magazine)
/* Do nothing */
and I call from the same remote client the same sayHello methos, I got:
Exception in thread "Main Thread" java.lang.NullPointerException
     at weblogic.ejb.container.internal.RemoteBusinessIntfProxy.getTargetMethod(RemoteBusinessIntfProxy.java:162)
     at weblogic.ejb.container.internal.RemoteBusinessIntfProxy.invoke(RemoteBusinessIntfProxy.java:53)
     at $Proxy0.sayHello(Unknown Source)
     at fr.simplex_software.jpa.test.LoadDB.main(LoadDB.java:43)
Please notice that I'm never calling the insertArticle methos which modifications obviously raises the exception.
Many thanks in advance for any help,
Nicolas

Answer 1

All right, after having spent two days on this issue, I finally found out that in order to be able to use generics in EJB with WebLogic, one needs to have appc generated stubs on the client side. Doing that is not trivial in Eclipse (OEPE) but adding an ant script like the following
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<project basedir="." default="build-project" name="ww204-ejb">
<property name="jpa.project" value="../ww204-jpa"/>
<target name="build-project">
<echo message="${ant.project.name}: ${ant.file}" />
<taskdef name="wlappc" classname="weblogic.ant.taskdefs.j2ee.Appc"/>
<wlappc source="build/classes" forceGeneration="true" verbose="true" deprecation="true">
<classpath>
<pathelement location="${jpa.project}/build/classes"/>
</classpath>
</wlappc>
</target>
</project>
which generates the appc stubs in the EJB Project's binary output directory and using this directory in the remote client CLASSPATH solves the problem. This is probably not regular as there is no any other application server having such a requirement but, if you want to use EJB with WebLogic and if, as myself, you think it would be too stupide not to use generics, you need to do that. You may continue using the WTP build facilities of Eclipse (OEPE) but you need to add to your EJB Project an ant builder which runs the script above. That's a pain, I know, but it seems to be the only way to decently do EJB/JPA with WebLogic. That's crazy that I needed to spend two days to come to something which is probably already known since longtime. So, I hope that, as oposed to myself, other people will be luckyer and beneficiate of this post.
Kind regards,
Nicolas