Why do I get a ClassCastException using JNDI between ears?

Question

This is an issue that has bothered me for almost a year. It comes up every once in a while and usually I can find a workaround, but I need to understand what is causing the failure.
Here is the problem description as an abstract example:
I have two WAR files deployed on WL (8.1 sp3), WarA and WarB.
In a servlet in WarA, I execute the following:
  Context context = new InitialContext();
  MyObject myObj = new MyObject();
  context.bind("myObject", myObj);Then, in a servlet in WarB, I execute the following, receiving a ClassCaseException on the last line of code:
  Context context = new InitialContext();
  Object obj = context.lookup("myObject");
  MyObject myObj = (MyObject)obj;  //ClassCastException!!Of course I have deployed MyObject.class in a jar file inside the WEB-INF/lib of each WAR.
I understand that each WAR file uses a seperate ClassLoader, but I do not understand why the object's class is not recognized when it is retrieved. I have tried several debugging methods (obj.getClass().getName() or halting execution using a debugger and looking at the object's class signature). In every instance the classname looks correct, exactly as I would expect it to, but the ClassCastException is thrown anyways.
In the past I have "copped out" by creating an EAR, putting both WARs in the EAR, and adding the jar containing MyObject to the APP-INF/lib.
Unfortunately the most recent occurrence of this problem is more complex and I do not have the luxury of my standard workaround. Can someone please fill in the blanks of what elementary concept I am overlooking?
Thanks
JB

Answer 1

I don't think the classloader-structure tag is exactly what I am looking for. Based on the documentation I reviewed on the edocs site, that solution appears to make sense if you are manipulating numerous classloaders within a specific ear.
I suppose you could try to use the classloader-structure to reference a classloader from a seperate application, but the docs do not indicate that this is a possibility. Moreover, it seems dangerous and potentially very confusing.
Ultimately, I think this boils down to a lesson for me about classloaders. Unless someone can tell me otherwise, I am ready to concede that you cannot access/cast an object that you have bound to the JNDI tree in one application from within any other application. The notable exception to this rule is the scenario where the class type to which you are casting is a class that is loaded by the system classloader.
This makes some sense to me - each standalone war or ear is independent of other wars/ears deployed on the app server. But, it is also somewhat frustrating because you cannot share global services across a suite of applications via JNDI unless you bundle them all as a single ear.