[Springframework-developer] OpenSessionInViewFilter ideas

[Norris, T. <tys...@be...>]

Hi Folks -=20
We have been running into problems with migrating an existing CMT EJB
application to use OpenSessionInViewFilter, and here are a couple
thoughts on the subject.

The basic problem is that when a session is created, then a transaction
is initiated and uses that session, if the transaction rolls back, how
can we still access the initial session created in the filter?

Currently the same session is used after entering the transaction. This
is a problem for us using weblogic, since weblogic datasource become
useless after a transaction rolls back (or commits), but I think this is
also general practice for hibernate users to close the session on
rollback:
"If you rollback the transaction you should immediately close and
discard the current session to ensure that Hibernate's internal state is
consistent."

So, what to do? Would it be desirable to build into SessionFactoryUtils
the ability to generate a new session for each new transaction?=20

I have worked around the problem temporarily by "manually" doing this.
That is, I check for an existing JTA transaction, and if its their,
register a new synchronization that holds a reference to the session
opened with the OpenSessionInViewFilter, and the
TransactionSynchronizationManager's session is unbound. When the
transaction completes, TransactionSynchronizationManager session is
re-bound, and non-transactional data access can proceed after the commit
or rollback.

This of course presents a potential problem of loading the same data in
multiple sessions, but this may be negligible for many cases.

Is this something worth adding as an additional parameter to
SessionFactoryUtils.getSession()? When specified (true), if an existing
SessionHolder is found, if not already synchronized with a transaction,
it would be replaced with a new session, then restored after the
transaction completes.

Let me know what you think. Or if there is a better alternative, I'm all
ears :)

Thanks
tyson =20