public class NHibernateSessionModule : IHttpModule
    {
        public void Init(HttpApplication context)
        {
            context.BeginRequest += new EventHandler(BeginTransaction);
            context.EndRequest += new EventHandler(EndTransaction);
        }

private void BeginTransaction(object sender, EventArgs e)
        {

        }
private void EndTransaction(object sender, EventArgs e)
        {
        }
}

<system.web>
<httpModules>
         <add name="NHibernateSessionModule" type="NHibernateSessionModule, <Assembly>"/>
</httpModules>
</system.web>

//Binding the current Session
ManagedSessionContext.bind(currentSession);

public class HibernateSessionConversationFilter : OpenSessionInViewModule, IHttpModule
{
    /// <summary>
    /// Initializes a new instance of the <see cref="T:HibernateSessionConversationFilter"/> class.
    /// </summary>
    public HibernateSessionConversationFilter() : base("appSettings", false)
    {
    }

    ///<summary>
    ///Initializes a module and prepares it to handle requests.
    ///</summary>
    ///
    ///<param name="context">An <see cref="T:System.Web.HttpApplication"></see> that provides access to the methods, properties, and events common to all application objects within an ASP.NET application </param>
    public void Init(HttpApplication context)
    {
        context.PreRequestHandlerExecute += new EventHandler(context_PreRequestHandlerExecute);
        context.PostRequestHandlerExecute += new EventHandler(context_PostRequestHandlerExecute);
    }

    void context_PreRequestHandlerExecute(object sender, EventArgs e)
    {
        // Try to get a Hibernate Session from the HttpSession
        ISession disconnectedSession = HttpContext.Current.Session["HIBERNATE_SESSION_KEY"] as ISession;

        try
        {
            // Start a new conversation or in the middle?
            if (disconnectedSession == null)
            {
                Log.Write(">>> New conversation");
                base.Open();
                currentSession = base.SessionFactory.OpenSession();
            }
            else
            {
                Log.Write("< Continuing conversation");
                currentSession = disconnectedSession;
            }

            //HOW TO BIND THE SESSION
            //ManagedSessionContext.bind(currentSession);

            CacheHibernateSession("HIBERNATE_SESSION_KEY", currentSession);
        }
        catch (StaleObjectStateException staleEx)
        {
            throw staleEx;
        }
        catch (Exception ex)
        {
           throw ex;
        }
    }

    void context_PostRequestHandlerExecute(object sender, EventArgs e)
    {
        // Try to get a Hibernate Session from the HttpSession
        ISession currentSession = HttpContext.Current.Session["HIBERNATE_SESSION_KEY"] as ISession;

        try
        {
            // End or continue the long-running conversation?
            if (null != HttpContext.Current.Session["END_OF_CONVERSATION_FLAG"] &&
                true != Convert.ToBoolean(HttpContext.Current.Session["END_OF_CONVERSATION_FLAG"]))
            {
                base.Close();

                Log.Write("Cleaning Session from HttpSession");
                RemoveHibernateSessionFromCache("HIBERNATE_SESSION_KEY");
                Log.Write("<<< End of conversation");
            }
            else
            {
                Log.Write("Committing database transaction");

                if (currentSession.Transaction.IsActive)
                {
                    currentSession.Transaction.Commit();
                }

                Log.Write("Storing Session in the HttpSession");
                CacheHibernateSession("HIBERNATE_SESSION_KEY", currentSession);
                Log.Write("> Returning to user in conversation");
            }
        }
        catch (StaleObjectStateException staleEx)
        {
            throw staleEx;
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

    private void CacheHibernateSession(string key, object value)
    {
        if (null != HttpContext.Current.Session[key])
        {
            HttpContext.Current.Session[key] = value;
        }
        else
        {
            HttpContext.Current.Session.Add(key, value);
        }
    }

    private void RemoveHibernateSessionFromCache(string key)
    {
        if (null != HttpContext.Current.Session[key])
        {
            HttpContext.Current.Session.Remove(key);
        }
    }
}