NPE (ProtocolDecoderException) in AbstractIoBuffer

[Ulrich Kreher]

Hi,

we have obviously the same issue as some other guy back in November 2010 
(ProtocolDecoderException on android). I stumbled across this when 
switching from Mina 1.1.7 to Mina 2.0.2. Apparently Mina 1.1.7 does not 
have the problem.

Unfortunately there has not been a solution yet, but I can provide some 
more information on the issue:

The problem is the usage of ObjectStreamClass.lookup(Class) at 
AbstractIoBuffer:1964. ObjectStreamClass.lookup(Class) returns null for 
classes that are not serialisable. This leads to the following issue:

public class PDETest
{
  static class Field
  { }

  static class SerialisableField implements Serializable
  { }

  static class Transferred
  {
    Field notWorking;
    SerialisableField working;
  }
}

You can set notWorking to either an instance of SerialisableField or 
even to null. Deserialisation of an instance of Transferred will always 
fail due to ObjectStreamClass.lookup(Class) returning null for the 
Field-class (which does not implement Serializable).

I think this is a bug, since it is completely legal to transfer a field 
of a non-serialisable type as long as the value of the field is 
serialisable. Using a non-serialisable value is not a problem when 
deserialising since this will raise an exception when serialising.
Using ObjectStreamClass.lookup(Class, true) instead of 
ObjectStreamClass.lookup(Class) would solve this issue, but it may have 
some consequences I cannot see yet.


Ulrich