FULL PRODUCT VERSION :
java version "1.6.0_21"
Java(TM) SE Runtime Environment (build 1.6.0_21-b06)
Java HotSpot(TM) 64-Bit Server VM (build 17.0-b16, mixed mode)

A DESCRIPTION OF THE PROBLEM :
Serialization of enums using RMI-IIOP is impossible

This worked in 1.6.0_18 at least.


ERROR MESSAGES/STACK TRACES THAT OCCUR :
Sep 29, 2010 6:15:39 PM com.sun.corba.se.impl.encoding.CDRInputStream_1_0 read_value
WARNING: "IOP00810211: (MARSHAL) Exception from readValue on ValueHandler in CDRInputStream"
org.omg.CORBA.MARSHAL:   vmcid: SUN  minor code: 211 completed: Maybe
        at com.sun.corba.se.impl.logging.ORBUtilSystemException.valuehandlerReadException(ORBUtilSystemException.java:7004)
        at com.sun.corba.se.impl.encoding.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1045)
        at com.sun.corba.se.impl.encoding.CDRInputStream.read_value(CDRInputStream.java:253)
        at _RServer_Stub.get(Unknown Source)
        at EnumIIOPBreakage.main(EnumIIOPBreakage.java:25)
Caused by: java.lang.IllegalArgumentException
        at java.nio.Buffer.position(Buffer.java:218)
        at com.sun.corba.se.impl.encoding.ByteBufferWithInfo.position(ByteBufferWithInfo.java:158)
        at com.sun.corba.se.impl.encoding.CDRInputStream_1_2.alignAndCheck(CDRInputStream_1_2.java:77)
        at com.sun.corba.se.impl.encoding.CDRInputStream_1_0.read_long(CDRInputStream_1_0.java:478)
        at com.sun.corba.se.impl.encoding.CDRInputStream.read_long(CDRInputStream.java:133)
        at com.sun.corba.se.impl.io.IIOPInputStream.inputObject(IIOPInputStream.java:1002)
        at com.sun.corba.se.impl.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:400)
        at com.sun.corba.se.impl.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:327)
        at com.sun.corba.se.impl.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:293)
        at com.sun.corba.se.impl.encoding.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1034)
        ... 3 more
Exception in thread "main" java.rmi.MarshalException: CORBA MARSHAL 1398079699 Maybe; nested exception is:
        org.omg.CORBA.MARSHAL:   vmcid: SUN  minor code: 211 completed: Maybe
        at com.sun.corba.se.impl.javax.rmi.CORBA.Util.mapSystemException(Util.java:197)
        at javax.rmi.CORBA.Util.mapSystemException(Util.java:67)
        at _RServer_Stub.get(Unknown Source)
        at EnumIIOPBreakage.main(EnumIIOPBreakage.java:25)
Caused by: org.omg.CORBA.MARSHAL:   vmcid: SUN  minor code: 211 completed: Maybe
        at com.sun.corba.se.impl.logging.ORBUtilSystemException.valuehandlerReadException(ORBUtilSystemException.java:7004)
        at com.sun.corba.se.impl.encoding.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1045)
        at com.sun.corba.se.impl.encoding.CDRInputStream.read_value(CDRInputStream.java:253)
        ... 2 more
Caused by: java.lang.IllegalArgumentException
        at java.nio.Buffer.position(Buffer.java:218)
        at com.sun.corba.se.impl.encoding.ByteBufferWithInfo.position(ByteBufferWithInfo.java:158)
        at com.sun.corba.se.impl.encoding.CDRInputStream_1_2.alignAndCheck(CDRInputStream_1_2.java:77)
        at com.sun.corba.se.impl.encoding.CDRInputStream_1_0.read_long(CDRInputStream_1_0.java:478)
        at com.sun.corba.se.impl.encoding.CDRInputStream.read_long(CDRInputStream.java:133)
        at com.sun.corba.se.impl.io.IIOPInputStream.inputObject(IIOPInputStream.java:1002)
        at com.sun.corba.se.impl.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:400)
        at com.sun.corba.se.impl.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:327)
        at com.sun.corba.se.impl.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:293)
        at com.sun.corba.se.impl.encoding.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1034)
        ... 3 more


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.rmi.*;
import java.util.*;

import javax.rmi.*;
import javax.naming.*;

enum MyEnum { ONE, TWO, THREE };

public class EnumIIOPBreakage
{
  public static void main(String[] args)
    throws Throwable
  {
    Hashtable properties = new Hashtable();
    properties.put("java.naming.factory.initial",
                   "com.sun.jndi.cosnaming.CNCtxFactory");
    properties.put("java.naming.provider.url", "iiop://localhost:1099");

    new Server(properties);

    Context context = new InitialContext(properties);
    Object ref = context.lookup("server");
    RServer server = (RServer) PortableRemoteObject.narrow(ref, RServer.class);

    System.out.println("equal?         " +
                       MyEnum.ONE.equals(server.get(MyEnum.ONE.name())));
    System.out.println("classes equal? " +
                       MyEnum.ONE.getClass().equals(
                           server.get(MyEnum.ONE.name()).getClass()));
    System.out.println("names equal?   " +
                       MyEnum.ONE.name().equals(
                           server.get(MyEnum.ONE.name()).name()));
  }
}

class Server
  implements RServer
{
  public Server(Hashtable properties)
    throws Throwable
  {
    PortableRemoteObject.exportObject(this);

    Context context = new InitialContext(properties);
    context.rebind("server", this);
  }

  public MyEnum get(String name)
  {
    return MyEnum.valueOf(name);
  }
}


interface RServer
  extends Remote
{
  MyEnum get(String name)
    throws RemoteException;
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
A)  Don't use Enum types.  This is a bad workaround

B) Change Remote interfaces to use Strings instead of proper enum types.  This is a horrible workaround.