@Override
 public SessionID createIdentifier() {
   final UUID uuid = UUID.randomUUID();
   ByteBuffer bb = ByteBuffer.wrap(new byte[16]);
   bb.putLong(uuid.getMostSignificantBits());
   bb.putLong(uuid.getLeastSignificantBits());
   return SessionID.createSessionID(bb.array());
 }
 @Override
 public SessionID readObject(ObjectInput input) throws IOException {
   byte[] encoded = new byte[input.readInt()];
   input.readFully(encoded);
   return SessionID.createSessionID(encoded);
 }