beginner with session.end question

[janetb]

Environment is Server2003,IIS6 ,Asp.net 2,VisualStudio2 005,SQl2005.

1. Event viewer showing lots of session abandon errors.
asp.nt 2.0.50727.0
web event id: 1309
event code 3005 An unhandled exception has occurred
Thread ID: 8
Thread account name: NT AUTHORITY\SYSTE M
Is impersonating: False
Stack trace: at System.Web.Http Application.get _Response()
at ASP.global_asax .Session_End(Ob ject sender, EventArgs e)

Have a very basic intranet beginners site. After a person logs in, they can click a button and logout. Here's the code for that (just in case it's causing the error):

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not Page.IsPostBack Then
            If Request("lo") = "1" Then
                System.Web.Security.FormsAuthentication.SignOut()
                Session.Abandon()
            End If
        End If
    End Sub

Here's the global.asax:

    Sub Session_End(ByVal sender As Object, ByVal e As EventArgs)
        Response.Cookies.Clear()
    End Sub

I'm very new at this and would appreciate some input...Thanks.

[kenobewan]

Thanks for outlining your platform. I don't understand what your problem is - are you getting an error? If so what is it?

[janetb]

See above repeated here - No error to the client during the process, but lots of errors in the event view:

asp.nt 2.0.50727.0
web event id: 1309
event code 3005 An unhandled exception has occurred
Thread ID: 8
Thread account name: NT AUTHORITY\SYSTE M
Is impersonating: False
Stack trace: at System.Web.Http Application.get _Response()
at ASP.global_asax .Session_End(Ob ject sender, EventArgs e)

[kenobewan]

My bad - In ASP.NET 2.0, the Session object is not "Live" until something has been added to it. Is it possible that you are trying to abandon what is not there?
Have you tried abandon and then signout? Is the cookie being removed before the abandon? HTH.

[janetb]

The message seems to imply the end event is causing a problem. Could it be that it's looking for a response.cookie object that isn't there because it's been abandoned through the button onClick event (or timed out because the client just left the machine there and walked away past the set time out)? Would something like this prevent the error?

If IsDBNull(Respon se.Cookies) = False Then
Response.Cookie s.Clear()
End If

Thanks, Janet

[kenobewan]

This is a good idea. Unfortunately, we are left with debugging which like fishing can take time. I still think that session has ended before you abandon and this causes the errors.

I have found some FAQs that may be helpful:

Q: In Proc mode, why do I lose all my session occasionally?
A: InProc - Session state will be lost if the worker process (aspnet_wp.exe) recycles, or if the appdomain restarts. It's because session state is stored in the memory space of an appdomain. The restart can be caused by the modification of certain config files such as web.config and machine.config, or any change in the \bin directory (such as new DLL after you've recompiled the application using VS) For details, see KB324772. In v1, there is also a bug that will cause worker process to restart. It's fixed in SP2 and in v1.1. See KB321792.

If you're using IIS 6.0, you may want to go to IIS Manager, go to Application Pools/DefaultAppPool, and see if any of the parameters on the Recycling and Performance tabs are causing the IIS worker process (w3svc.exe) to shutdown.

For more details about app recycling, see my other FAQ: http://www.asp.net/Forums/ShowPost.aspx?t abindex=1&PostI D=232621

Q: Why isn't Session_End fired?
A: This is one of the most frequently asked question.
1. Remember Session_End event is supported only in InProc mode.
2. Session_End won't be fired if you close your browser. HTTP is a stateless protocol, and the server has no way to know if your browser has closed or not.
3. Session_End will be fired only (i) after n minutes of inactivity (n = timeout value), or (ii) if someone calls Session.Abandon ().
4. For case (i) (pt. 3), Session_End will be run by a background thread, which implies:

a. Your code in Session_End is running using the worker process account. You may have permission problem if you're accessing resource such as database.
b. If an error happens in Session_End, it will fail silently.
5. For case (ii), please note that in order for Session_End to be fired, your session state has to exist first. That means you have to store some data in the session state and has completed at least one request.
6. Again for case (ii), Session_End will be called only if the abandoned session is actually found. As a result, if you create and abandon a session inside the same request, because the session hasn't been saved and thus can't be found, Session_End won't be called. This is a bug in v1 and upcoming v1.1.

Q: Why are my Session variables lost frequently when using InProc mode? A: Probably because of application recycle.
See http://support.microso ft.com/default.aspx?sc id=kb;en-us;Q316148
In v1, there is also a bug that will cause worker process to restart. It's fixed in SP2 and v1.1. See http://support.microso ft.com/default.aspx?sc id=kb;EN-US;321792

For more details about app recycling, see my other FAQ:
http://www.asp.net/Forums/ShowPost.aspx?t abindex=1&PostI D=232621

Q: What is the difference between Session.Abandon () and Session.Clear() ?
A:The major practical difference is that if you call Session.Abandon (), Session_End will be fired (for InProc mode), and in the next request, Session_Start will be fired. Session.Clear( ) just clears the session data without killing it.

Q: How do I use session state with web services?
A: The extra trick needed is on the caller side. You have to save and store the cookies used by the web service. See the MSDN documentation on HttpWebClientPr otocol.CookieCo ntainer property.

However, please note if you're using proxy object to call a web service from your page, the web service and your page cannot share the same session state due to architecture limitation.

This can be done if you call your web service through redirect.

Q: In Session_End, I tried to do some cleanup job using SQL but it failed. Why?
A: First, Session_End is supported only in InProc mode.
Second, Session_End is run using the account which runs the worker process (aspnet_wp.exe) , which can be specified in machine.config. Therefore, in your Session_End, if you connect to SQL using integrated security, it will use that worker process account credential to connect, and may fail depending on your SQL security settings.

Q: In InProc mode, I change the timeout value of a session programmaticall y, and that causes my Session_End to be called. Why?
A:It is a a bug of InProc mode. If you change a session's timeout to a different value, Session_End will be called (but not Session_Start). We will looking into that in v2 and see if we can fix it.

Hope that something here helps :).