I could assure you that in ATM example, if you make a "commit" every time
you create or destroy a row in the database through SQL (ORACLE) the
Automatic Teller MAchine will detect all the changes.
I don't know why but this is the way it is.
More opinions ???
-------------------------------------------------------------
David Sierra Fern ndez
Ingeniero Tecnico de Telecomunicaci¢n
AULA RETECAL (CEDETEL) Universidad de Valladolid
Campus Miguel Delibes E-Mail: [EMAIL PROTECTED]
47011 Valladolid (SPAIN)
--------------------------------------------------------------
-- Sierr@ --
On Fri, 21 Jul 2000, Robert Krueger wrote:
>
> this is incorrect. the container has to ensure that when a transaction is
> started the entity beans involced in that transaction have to be in sync
> with the underlying datastore. depending on your transaction isolation
> level this locks the record associated with your entity in the db during
> the transaction. if you modify the record with another client, the next
> transaction that is started and involves that entity should reload the
> current state, otherwise the container doesn't conform to the spec. so if
> you deleted records, the load operation should throw an exception. however,
> most containers (including orion) allow you to specify a flag that
> indicates that your server is the only thing writing to the database to
> avoid the expensive load operations at the beginning of each transaction.
> if you specify that and still modify the database from outside, you're on
> your own and can no longer rely on the spec. the effect that you cannot
> recreate an entity that you deleted manually looks like it's a caching
> problem (somewhere there's a hashtable of primary keys kept in memory
> that's not updated when the database record is deleted manually). so if you
> use the exclusive-write-access option then you're to blame. if you don't, I
> guess orion shouldn't behave that way and you should probably consider it a
> bug and post it to [EMAIL PROTECTED] but I might be wrong.
>
> regards,
>
> robert
>
>
> At 14:48 20.07.00 , Nick Newman wrote:
> >Hi Rick,
> >
> >The EJB spec says that once the entity bean is loaded from the database,
> >the container (Orion) doesn't have any responsibility to keep track of any
> >possible changes to the database. So what you are doing is basically
> >sneaking behind Orion's back.
> >
> >The consequences of this depend on the circumstances, I believe. Here's my
> >best guess ...
> >
> >Suppose the server had not been busy for quite a while. Under these
> >conditions Orion would have written all its entity beans back to the DB and
> >removed them from memory. If you now empty the DB, then all the entity
> >beans are gone (in the sense that trying to find one from its primary key
> >will fail).
> >
> >If the server is extremely busy when you emtied the DB, then all the entity
> >beans may well have been in memory, and they will get recreated in the DB
> >when Orion writes them out.
> >
> >Hope that helps.
> >
> >Nick Newman, SCIENTECH
>
> (-) Robert Krüger
> (-) SIGNAL 7 Gesellschaft für Informationstechnologie mbH
> (-) Brüder-Knauß-Str. 79 - 64285 Darmstadt,
> (-) Tel: 06151 665401, Fax: 06151 665373
> (-) [EMAIL PROTECTED], www.signal7.de
>
>
>
