code: private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException
      {
          // We never write any superflous data to disk so on a read
          // offset is always going to be set to 0.
          _offset = 0;
          _length = in.readInt();
  
          _bytes = new byte[_length];
          in.readFully(_bytes, _offset, _length);
      }
docs: This is a CUSTOM serialisation method for the DataSlice
  object.
  
  As we have only written the data that we care about we can do
  a simple read of the length of data and then directly read the
  byte data into a pre-defined byte array.
  
  @param in
  
  @exception IOException
  @exception ClassNotFoundException