Avi Kivity wrote:
>
> >
> > I believe both you and Avi are confusing what ejbPassivate/ejbActivate do on
> > entity beans with what they do on stateful session beans. For stateful session
> > beans, after ejbPassivate is called, the bean is serialized and stored to
> > some persistent storage (typically, to the file system, perhaps via a database).
> > For entity beans, however, after ejbPassivate is called, the entity does not
> > have to be serialized, or stored on disk, or anything else. It simply moves
> > from the "ready" bin to the "pooled" bin, which is probably a fairly trivial
> > operation. There should not be any memory or disk overhead associated with a
> > passivated entity bean, and thus it is certainly not computationally expensive
> > to passivate.
>
> Can you explain why EB passivation is so different? Consider the following:
>
> public class EB implements EntityBean {
>
> public int cmpField;
> private int myStuff;
>
> // ...
>
> public void sneaky() {
> myStuff = 42;
> }
>
> public void doit() {
> cmpField = myStuff;
> }
>
> }
>
> Now suppose a client calls, in a single transaction, sneaky() and then
> doit(). How can the container passivate the instance between those method
> calls without losing data? Or is "private int myStuff" illegal?
>
> As a matter of fact, I have many lazy stores (where doit() is actually
> ejbStore()). Are they all broken?
Avi,
It is legal, in EJB 1.1, for the above two methods to be executed as
follows:
begin transaction
EB[1].ejbActivate()
EB[1].ejbLoad()
EB[1].sneaky();
EB[1].ejbStore();
EB[1].ejbPassivate();
EB[2].ejbActivate();
EB[2].ejbLoad();
EB[2].doit();
EB[2].ejbStore();
EB[2].ejbPassivate();
commit transaction
// nothing to do here since ejbStore was already called...
By this I mean that the method sneaky() is executed on on instance of EB (that
is, EJ[1]) and doit() is executed on another instance (that is, EB[2]). Not
that I am saying that this is a good way to write a container: it is not.
However, if your code cannot run in this mode (where every entity bean method
could potentially be executed on a different instance) then your code is not
compliant with the EJB spec. Sorry, but it appears the your "private int myStuff"
is illegal (or at least will contain undefined values), unless you convert it
to a state-managed field in ejbLoad and ejbStore.
-jkw
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