in Ed Romans Mastering EJB2 book (downloadable from theserverside.com
for free )
in p121 figure 5.6 he shows entity beans lifecycle
and says "in creation of entity bean : The bean (means the bean's
implementation class) returns a primary key to the home Object so
that the container can identify the bean" p120
but in contrast, in EJB2 Spec, they stated that creation methods
should return null , and the reason is ,"The above requirement is to
allow the creation of an entity bean with bean-managed persistence by
subclassing an entity bean with container managed persistence."
p171 - (footnote)

now How is the lifecycle of entity beans ?
note :in wrox's j2ee server side programming's 1ed ,in samples of
chapter 20 they
obey specification's contract.