I like the services-layer idea, but also have to agree that it leads to
repetitive code.
In our system, we have implemented the service layer as session beans. The
transaction management is taken care of by the container. But we still have
the repititive
try{
opensession();
}catch(Exception e){
rolbackSession();throw e;
}finally{
closession();
}
I have also simply sacrificed session propagation from one session bean to
another.
If someone were to implement the sessionFactory as a JCA connector, all of
this code would become the responsibility of the container. It would also do
the propagation of transaction contexts.
As an interim solution, someone could perhaps implement a "stateless"
version of the session factory that automatically flushes and closes itself
when a transaction commits, and closes when the transaction rolls back.
Am I on the right track here?
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Jozsa
Kristof
Sent: 15 November 2002 01:02
To: Urberg, John
Cc: [EMAIL PROTECTED]
Subject: Re: [Hibernate] Using hibernate - best practices
On Thu, Nov 14, 2002 at 01:36:13PM -0600, Urberg, John wrote:
.
> The InvoiceRepository would be implemented like this:
>
> public class HibernateInvoiceRepository {
> public void setDatabase(Database database) { _database =
> (HibernateDatabase) database; }
> public List getOverdueInvoices() {
> return database.getSession().find("<hibernate query>");
> }
> public void update(Object object) {
> database.getSession().saveOrUpdate(object);
> }
> }
>
And where do you close those opened sessions using this design? Also, where
did you find a place to implement transaction handling, including joining
into existing transactions if possible?
I have my own pieces of ideas how to implement a design for Hibernate, but
I'm fighting with the questions listed above too. Got some workaround, but
kinda far from being perfect.. Mainly I used Ralf's third possible solution
from these:
> > * Put everything into the domain classes.
> > * Implement something like a "Home" interface
> > * Implement some sort of component-like / "Service" interface
.having a layer of 'service-like' components in charge of database-related
operations, which either use Hibernate (98%) or plain JDBC pulling the
connection from a Hibernate session. These components are always pulled by
the upper layer from a plain component pool, which I implemented myself. But
mentioning one returning problem, I have *LOTS* of repeated code parts like
these:
Session session = null;
Transaction tx = null;
try {
session = Hibernator.getSession(); // my custom class which keeps
the sessions and initializes Hibernate
tx = session.beginTransaction();
..
..
tx.commit();
} catch (Exception e) {
logger.error (<blah/>), e);
tx.rollback();
// rethrow business-exception if suitable
} finally {
if (session != null) session.close();
}
These piece of codes are repeating in almost ALL of the Service classes'
business methods, are just flooding all the logic badly :( (ok, tx handling
is missing from this where i'm doing read-only operations, but still..) I
also have some part-solution related to joining to existing transactions,
but I find it snappy too.
So, as I said, I don't feel my design good at all.. just couldn't find out
any better for the moment. Therefore, I'd be very happy and thankful to read
about others experiences and concrete architecture/design plans.
Regards,
dyn
--
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