question: public void readUpdate ( InputStream in ) throws Exception { ObjectInputStream s = new ObjectInputStream ( in ) ; applyUpdate ( s . readObject ( ) ) ; }
target:  Reads a stably logged update (a serializable object) from a stream.  This callback is invoked during recovery, once for every record in the log.  After reading the update, this method invokes the applyUpdate (abstract) method in order to execute the update.