Hi David,
see http://www.jboss.org/newsite/documentation/J2eeDeployment_howto.html
there is a part called "understanding the shared classloader
architecture in JBoss"
(to make it short, all components use different classloaders, but these
classloaders have the same parent)
Sebastien
Castro, David wrote:
>
> Running the integrated jboss with tomcat, I noticed that I was getting a lot
> of serialization going on, so I started digging through the code to find out
> what was going on. After looking at it for a long time, however, I dont
> understand how (using an ear file) the optimized code could ever run between
> ejb jars and war files. Im hoping that someone can explain this to me.
> line numbers are from most recent snapshot, but the code is essentially the
> same in 2.0 FINAL
>
> In org/jboss/ejb/plugins/jrmp/server/JRMPContainerInvoker.java is the code
> that determines whether or not we will run optimized: (line 419 for the
> invoke function)
>
> if
> (!m.getDeclaringClass().isAssignableFrom(((ContainerInvokerContainer)contain
> er).getRemoteClass()))
>
> (then serialize, otherwise don't serialize)
>
> Or line 382 for the invokeHome function, same thing except with home
> interface.
>
> which makes sense - if the class being returned isnt assignable locally,
> then wed better serialize. Since the class is the same in both cases (ie.
> the ejb home or remote interface), the key is whether they were loaded by
> the same classloader. The local class was loaded by the calling
> ejb/servlet(tomcat), the remote by the ejb being called.
>
> Here's why I dont see how this can ever work. every ejb has its own
> classloader, which is created in org/jboss/ejb/ContainerFactory.java (line
> 331), and which sees only the ejb-jar file for that ejb. and the web
> context has a different classloader, which is created in
> org/jboss/deployment/J2eeDeployer.java (line 589), and which sees all of the
> ejb jars for the entire application. since every component has its own
> classloader it seems as though the serialization would be necessary in all
> calls between components.
>
> Hopefully at this point someone will tell me Im an idiot and explain why the
> optimization works fine. Im assuming this will happen because people have
> said that they have made the optimized code work. If I am right, I dont
> really see any way to fix it, except by passing the j2ee classloader to all
> the ejb containers as well as to tomcat, so that everyone will see the same
> classloader. This would mean that the individual ejb-jars would see each
> others code, instead of each jar just seeing the classes that it contains.
