ClassCastException really means "not Serializable" in Weblogic

Question

I'm writing this more as a public service announcement than anything else. We spent a whole day trying to diagnose a strange ClassCastException in Weblogic 8.1 SP2.
Basically, a local EJB 2.0 call was working fine for our test page, but the remote call from another server was failing. We would see a ClassCastException on a call to writeObject(). We assumed the RMI stubs and skeletons were out of synch or had a classloader issue. Nope. The complex return type did not implement Serializable. Rather than indicate this in the logs, WL threw a cryptic CCE.
When decompiling their generated classes, we did in fact see that they were attempting to cast to Serializable without first checking via instanceof.
So, please spare yourself the pain we went through. If you get a CCE in WL 8.1, first check all your arguments and return types (and any exceptions) are Serializable.
- Saish

Answer 1

I'm writing this more as a public service announcement than anything else. We spent a whole day trying to diagnose a strange ClassCastException in Weblogic 8.1 SP2.
Basically, a local EJB 2.0 call was working fine for our test page, but the remote call from another server was failing. We would see a ClassCastException on a call to writeObject(). We assumed the RMI stubs and skeletons were out of synch or had a classloader issue. Nope. The complex return type did not implement Serializable. Rather than indicate this in the logs, WL threw a cryptic CCE.
When decompiling their generated classes, we did in fact see that they were attempting to cast to Serializable without first checking via instanceof.
So, please spare yourself the pain we went through. If you get a CCE in WL 8.1, first check all your arguments and return types (and any exceptions) are Serializable.
- Saish