/**
* detach persistent objects
*/
public static void detachObject(PersistenceManager pm){
Author author = new Author("Henry Miller");
Address address = new Address("Coronation Street", "811XBA", "Manchester");
Editor editor = new Editor("Grasset", address);
Book book = new Book("Tropic of Capricorn", author, editor, 1939);
//make the book persistent
pm.currentTransaction().begin();