Raise Session_OnStart event from custom ASP.NET SessionStateProvider class

Question

I'm working on an asp.net project that uses an in-house developed custom SessionStateProvider class.

Evidently, the Session_OnStart event is not firing. I have code in Global.asax to handle the event. I can only get this code to execute by changing the Web.config to use the default SessionStateProvider.

What must I do to make my Session_OnStart code execute when I'm using a custom SessionStateProvider class? I have access to the source code.

Update: It clearly says on MSDN that ordinarily, Session_OnStart only fires when the Session mode is InProc, so I'm going to have to do something special to get this wired up the way I want it.

My session state configuration in web.config looks like this:

< sessionState cookieless="false" regenerateExpiredSessionId="true" mode="Custom"  
 customProvider="ProgramSessionStateProvider"  
 sessionIDManagerType="SessionIDManager.ProgramSessionIDManager"  
sqlConnectionString="SqlSessionServices" cookieName="smartSessionID" >
< providers >
            < add name="ProgramSessionStateProvider"   
type="SessionStateProvider.ProgramSessionStateProvider"   
connectionStringName="SqlSessionServices" writeExceptionsToEventLog="false" / >  
        < /providers >
    < /sessionState >

Update again: I found something interesting this morning. After reading Chris's answer, I tried using just the customer SessionStateProvider and removed the code for the custom SessionIDManager. Once I did that, I was immediately able to see the Session_OnStart method execute. The problem is, my custom SessionStateProvider requires a custom SessionIDManager. Where exactly is the Session_OnStart event fired from? It looks like it has to do with the SessionIDManager, not the SessionStateProvider.

Answer 1

A second answer dealing with custom SessionStateStores. On looking at the code I could see no reason why it wouldn't call session start so I tried to create my own compliant but non-functional session state provider to see what was going on. With my session state provider it called the Session_start in global.asax fine. I include my code as a demo proof of concept:

Session State Provider:

namespace WebApplication1
{
    public class SessionStateProvider : System.Web.SessionState.SessionStateStoreProviderBase
    {
        public override SessionStateStoreData CreateNewStoreData(HttpContext context, int timeout)
        {
            ISessionStateItemCollection foo = new SessionStateItemCollection();
            HttpStaticObjectsCollection bar = new HttpStaticObjectsCollection();
            return new SessionStateStoreData(foo, bar, 300);
        }
        public override void CreateUninitializedItem(HttpContext context, string id, int timeout){}
        public override void Dispose() { }
        public override void EndRequest(HttpContext context) { }
        public override SessionStateStoreData GetItem(HttpContext context, string id, out bool locked, out TimeSpan lockAge, out object lockId, out SessionStateActions actions)
        {
            locked = false;
            lockAge = TimeSpan.FromSeconds(10);
            lockId = new object();
            actions = SessionStateActions.None;
            ISessionStateItemCollection foo = new SessionStateItemCollection();
            HttpStaticObjectsCollection bar = new HttpStaticObjectsCollection();
            return new SessionStateStoreData(foo, bar, 300);
        }
        public override SessionStateStoreData GetItemExclusive(HttpContext context, string id, out bool locked, out TimeSpan lockAge, out object lockId, out SessionStateActions actions)
        {
            locked = false;
            lockAge = TimeSpan.FromSeconds(10);
            lockId = new object();
            actions = SessionStateActions.None;
            ISessionStateItemCollection foo = new SessionStateItemCollection();
            HttpStaticObjectsCollection bar = new HttpStaticObjectsCollection();
            return new SessionStateStoreData(foo, bar, 300);
        }
        internal virtual void Initialize(string name, NameValueCollection config, IPartitionResolver partitionResolver) { }
        public override void InitializeRequest(HttpContext context) { }
        public override void ReleaseItemExclusive(HttpContext context, string id, object lockId) { }
        public override void RemoveItem(HttpContext context, string id, object lockId, SessionStateStoreData item) { }
        public override void ResetItemTimeout(HttpContext context, string id) { }
        public override void SetAndReleaseItemExclusive(HttpContext context, string id, SessionStateStoreData item, object lockId, bool newItem) { }
        public override bool SetItemExpireCallback(SessionStateItemExpireCallback expireCallback){return true;}
    }
}

Global.asax:

    protected void Session_Start(object sender, EventArgs e)
    {
        throw new Exception("It worked!");
    }

web.config:

    <sessionState mode="Custom" customProvider="MySessionProvider">
        <providers>
            <add name="MySessionProvider" type="WebApplication1.SessionStateProvider"/>
        </providers>
    </sessionState>

The point of this post is mainly to say that if you are using the provided session management module, even with a custom provider it should still fire off the session_start event. Perhaps you can try with my dummy state provider and see if that fires off your event. Also I assume that the signature of your session_onstart is actually correct? (ie no paramaters or (object,eventargs) ).

Currently we are at a duff position because all the information we have so far is along the wrong lines. We are now left with either something about your sessionstateprovider is causing the session_start not to fire or something about the rest of your code is. Using my dummy should help us answer that question (I hope).

For what its worth the session_start event should get fired just after the CreateNewStoreData method has run in your provider class so you can try putting in a breakpoint there and just seeing where it does head to after that method.

Answer 2

Edit: Looks like I did miss the point on the question slightly. I'm going to leave this answer here though just because it may be of interest to some. Feel free to comment if you think it should be deleted though.

Sorry this is an answer since I'm not 100% sure of what I'm saying but it got too long to be a comment...

I wasn't sure if you had created a custom session module or jsut a session state store provider. I'm assuming the module but I wasn't sure from just "SessionStateProvider"...

From what I can tell any httpmodule added in the web.config will go through a process of trying to hook up to events in the global.asax. The way it does this seems to be by looking for methods of the form "{name}_{event}" or "{name}_on{event}" and wiring them up where I think that {name} is the name you gave the module in your web.config and {event} of course is the name of the event in the class (ie start).

So in essence if your new module is included like this:

<add name="MySession" type="MySessionStateModule" />

then you would want in your global.asax MySession_Start

I hope this helps. Sorry if it doesn't and its all stuff you've tried before. I'd suggest giving a bit of code and some ideas of what you have already tried and that fails though. Code that might be interesting is where you add your custom code into the site (ie the appropriate part of web.config) and maybe some code in your session class if it can be easily cut down to a trivial form (eg a session provider that just returns a constant could be short and demonstrate your error). Also some indication of whether it is keeping session state or not (ie does it work apart form not calling onstart) would be good. :)

Edit to add: I thought I'd link one of the useful web pages I came across. http://aspnetresources.com/articles/event_handlers_in_global_asax talks about how standard error handlers are wired up in the global.asax and pointed me at the interesting method HookupEventHandlersForAppplicationAndModules that gave me a clue as to how some of this might be working.

Answer 3

I'm going to guess the operational goal is to do something like, say, initialize the session rather than needing to specifically do something in the Session_OnStart method. Presuming this is the case, I think you can do the following:

1) Handle the Appication.PostAcquireRequestState event.
2) In handler, check if the session is initialized--poor man's way is to set a variable in the session--then act appropriately.