How to implement session-per-request pattern in asp.net mvc with Nhibernate

Question

I created the nhibernate session in Application_start event of global.asax file,the session is being passed to constructors of service methods.

In the service method I am using the session to do CRUD operations, this works fine.However, When multiple requests or parallel transactions occuring nhibernate is throwing some exceptions.After reading forums i came to know that Nhibernate session is not thread safe.How to make it thread safe and let my application (ASP.NET mvc) work with parallel trandsactions?

Answer 1

Only way to make it thread safe is to create a new session per each request, you could use current_session_context_class property to managed_web in NHibernate config.

In global.asax

    protected void Application_BeginRequest(object sender, EventArgs e)
    {
        var session = SessionFactory.OpenSession();
        CurrentSessionContext.Bind(session);
    }

    protected void Application_EndRequest(object sender, EventArgs e)
    {
        var session = CurrentSessionContext.Unbind(SessionFactory);
        //commit transaction and close the session
    }

now when you want to access the session, you could use,

Global.SessionFactory.GetCurrentSession()

If you are using a DI container, it's usually built into the container,

For example for Autofac (see this question for more information),

containerBuilder.Register(x => {
    return x.Resolve<ISessionFactory>().OpenSession(); 
}).As<ISession>().InstancePerHttpRequest();

Answer 2

Store it in the HttpContext.

Add this to your global.asax

    public static String sessionkey = "current.session";

    public static ISession CurrentSession
    {
        get { return (ISession)HttpContext.Current.Items[sessionkey]; }
        set { HttpContext.Current.Items[sessionkey] = value; }
    }

    protected void Application_BeginRequest()
    {
        CurrentSession = SessionFactory.OpenSession();
    }

    protected void Application_EndRequest()
    {
        if (CurrentSession != null)
            CurrentSession.Dispose();
    }

And here is the component registration

public class SessionInstaller : IWindsorInstaller
{
    public void Install(IWindsorContainer container, IConfigurationStore store)
    {
        container
            .Register(Component.For<ISession>().UsingFactoryMethod(() => MvcApplication.CurrentSession)
            .LifeStyle
            .PerWebRequest);
    }
}