Hibernate and DAO Pattern

flam70 · **Joined:** Thu Oct 02, 2003 8:02 am **Posts:** 45

Fisrt, I wonder if it is possible to use hibernate with the DAO Pattern.
Second, I use servlets as client. Does servlets must directly use DAO objects that encapsulate RDB's access or must i use a layer between servlet and DAO that will act as Business layer.

I notice that i don't want to use EJB.

Thanks

christian · **Posted:** Thu Oct 23, 2003 4:13 am

Hibernate is not restricted to a particular architecture. Use it in whatever way you like, but understand SessionFactory, Session and Transaction first.[/quote]

steve · **Posted:** Thu Oct 23, 2003 11:59 pm

Quote:

must i use a layer between servlet and DAO that will act as Business layer

Not really related to Hibernate, but unless the requirements for your app have extremely modest and straight-forward logic I would highly recommend a business-logic abstraction. There are many ways to implement such a beast such as the Command, Transaction Script, and Service Layer patterns to name a few.

Hibernate would tie pretty nicely with all of those approaches.

le_sharingan · **Joined:** Fri Oct 03, 2003 6:53 am **Posts:** 7

We have been using Hibernate in all of our application DAOs.

A SessionFactory instance for the whole application is created when Hibernate configuration is loaded.

Then, every DAO method that needs to perform a database operation opens a Session from that SessionFactory and closes it when finished.

This is how we have done it, although I'm not sure if this is the best and/or right way to do it.

micho2001 · **Posted:** Wed Oct 29, 2003 10:31 pm

check out this discussion:http://forum.hibernate.org/viewtopic.php?t=925108

jelmer · **Joined:** Thu Sep 25, 2003 7:21 pm **Posts:** 17

le_sharingan wrote:

Then, every DAO method that needs to perform a database operation opens a Session from that SessionFactory and closes it when finished.
This is how we have done it.

bt do your dao's contain business logic

ko5tik · **Posted:** Thu Jun 03, 2004 9:37 am

le_sharingan wrote:

Then, every DAO method that needs to perform a database operation opens a Session from that SessionFactory and closes it when finished.

If you do this, you will get OSUser hibernate provider, which
scales ( or at least used to scale ) really poor...

"open session in view" gives you more performance
- in web application you can outsource session management into
request filter.

And another problem with is is lazy loading of collections....

However, if your session lives longer ( and used by several DAOs )
you will have to ensure that stale session ( every session where error happened ) is discarded safely.

Anyway it's kind of tricky...

At the moment I prefer "lifecycle" session from nanocontainer
( well, I use nanocontainer in my app ) , and struggle to make
hibernate session/transaction constructor-injectable.