NHibernate Sessions in ASP.NET

urig · **Joined:** Mon Jun 06, 2005 10:33 am **Posts:** 6

Hi,

In my ASP.net website, I have a static class that is responsible for handling my NHibernate ISession(s). The heart of it is:

Code:

   public abstract class Helper
   {
      private static ISession _current;

      public static ISession GetSession()
      {
         if (_current == null)
            _current = GetNewSession();

         return _current;
      }

      public static ISession GetNewSession()
      {
         NHibernate.Cfg.Configuration cfg = new NHibernate.Cfg.Configuration();
         cfg.AddAssembly("DAL");

         ISessionFactory factory = cfg.BuildSessionFactory();

         _current = factory.OpenSession();

         return _current;
      }

   }
}

If I understand what I did correctly, then my code attempts to maintain a single ISession across the entire application lifespan.

I am concerned - Is this a good strategy for an ASP.net website? If not - what other strategy would you recommened? One Session per one Request?

Thanks!
urig

Guest · **Posted:** Wed Jun 08, 2005 12:07 pm

Thats the same way I'm doing it, I don't use lazy loading so I don't need a session per http request or http session so that solution works fine for me.

martijnb · **Joined:** Sat May 14, 2005 8:40 am **Posts:** 130

Using one single session per application doesn't make a difference for lazy loading.

The problem though is that a Session is not designed to be used like this. It's not threadsafe and there is a high risk that the session will become unusable after a while because of stale data (objects with a state that doesn't correspond anymore with the database).

Just use one session-per request. It's recommended to make your SessionFactory static because configuring takes some time and is the SessionFactory is supposed to be thread safe.

urig · **Joined:** Mon Jun 06, 2005 10:33 am **Posts:** 6

Funny how all my threads seem to converge to one single subject - How to manage NHibernate Sessions in ASP.net :)

I now understand that it would be better for me to use a Session-per-Request approach. I am having difficulties in finding an elegant implementation.

In my project I have a Data Access Layer that manages the NHibernate Session(s). A Business Logic layer that consumes uses the Session(s) and a User Interface layer that is in ASP.net.

How do I make my DAL generate a new session for each new UI request?
Shouldn't non-adjacent layers be completely blind to each other?

martijnb · **Joined:** Sat May 14, 2005 8:40 am **Posts:** 130

Your business logic layer should not be aware of the DAL or any NHibernate sessions but purely focus on business aspects.
I've experienced that a facade layer (service) is the easiest to work with: The UI calls that facade to retrieve or store objects. The facade can do the NHibernate persisting itself or hand it over to a separate Repository (DAL). Besides that, the facade is also responsible for managing sessions and transactions.

szoke · **Joined:** Thu May 12, 2005 3:53 am **Posts:** 4

You should read this: http://www.hibernate.org/168.html - this applies to NHibernate too.

simon7 · **Joined:** Mon May 16, 2005 6:48 pm **Posts:** 9

here is a link to a blog entry regarding this subject, with a link to a sample nHibernate app that uses Session-Per-Request using an Http module.

http://blog.benday.com/archive/2005/03/16/198.aspx

SOL-Invictus · **Joined:** Wed Dec 21, 2005 6:17 am **Posts:** 10

szoke wrote:

You should read this: http://www.hibernate.org/168.html - this applies to NHibernate too.

Not found. [Status 404]