Re: [Springframework-developer] Hibernate Session Management

[Juergen H. <ju...@in...>]

Hibernate 3.0.1+'s management of Sessions indeed provides a couple of
services: All it does is optionally flush and close each opened =
Hibernate
Session at the end of the transaction (potentially multiple Sessions per
transaction), and optionally manage one single "contextual" Hibernate
Session per transaction (also with flushing at transaction commit). Both =
of
these features are just supported for JTA / EJB CMT transactions.

Spring goes beyond what Hibernate provides:

* Hibernate Sessions can be consistently synchronized with any kind of
Spring-managed transaction, whether a local JDBC transaction or a global =
JTA
transaction. (Furthermore, synchronization will also work with plain JTA
transactions.) Spring's synchronization code will automatically adapt to =
the
environment, without your data access code having to change.

* Spring's snchronization facility can optionally manage one Hibernate
Session per HTTP request, letting transactions participate in it
(OpenSessionInViewFilter / OpenSessionInViewInterceptor in "single =
session"
mode). This does not affect your DAO implementations either, working as
transparently as possible.

* Spring supports finer-grained transaction semantics such as a =
read-only
optimization: Read-only transactions will use a single Session per
transaction, but _not_ attempt to flush it at transaction commit =
(avoiding
the unnecessary effort of looking for changes in persistent objects). =
This
is an important optimization that Spring has been providing for years.

Hence, we will keep our current synchronization mechanism. This is an
internal decision: It simply means that Spring will not use Hibernate3's
built-in mechanism, which should not affect your application code in any
way.

As a side note, Spring does support Hibernate3's
"SessionFactory.getCurrentSession()" method: When you run within a
Spring-managed transaction (any kind: local or global), that method will
return the current Spring-managed transactional Session. This allows for =
DAO
implementations that access Spring-managed Sessions without any Spring =
API
dependencies, coded against Hibernate3's native Session access API.

Juergen


-----Original Message-----
From: spr...@li...
[mailto:spr...@li...] On Behalf =
Of
Raj Patel
Sent: Wednesday, June 29, 2005 7:27 PM
To: spr...@li...
Subject: [Springframework-developer] Hibernate Session Management

Hibernate 3.0 has improved support for session management, including
automatic session management/flushing in transactions:

http://www.hibernate.org/hib_docs/v3/reference/en/html/session-configurat=
ion
.html#configuration-j2ee-currentsession

Have you guys thought about letting hibernate manage this instead of =
having
extra code in Spring to manage this?

Raj


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