Pass data between events of HttpApplication in .Net

Question

I am looking for a way to pass data between events of HttpApplication. For example, I have the following code in my HTTP module:

public void Init(HttpApplication context)
{
    context.BeginRequest += DoFoo;
    context.EndRequest += DoBar;
}

I want to save some data during BeginRequest event in the DoFoo method and access it later during the EndRequest event in the DoBar method.

As far as I am aware, Session is not available at this point yet. Is there a way to store the data between events so that it is:

1. Available in the current and all subsequent events;
2. Accessible in only in the scope of the current request.

Update:

Is it possible to use HTTP module instance variables to achieve this? Is there any risk that the data stored in these variables would be accessible outside the current request?

Answer 1

As per John Wo's comment under my question, my problem was solved by using HttpContext.Items . This is the link to the article provided by John .

Example of using HttpContext.Items :

public void Init(HttpApplication context)
{
    context.BeginRequest += DoFoo;
    context.EndRequest += DoBar;
}

private void DoFoo(Object sender, EventArgs e)
{
    HttpApplication httpApplication = (HttpApplication)sender;
    httpApplication.Context.Items.Add("MyFlag", true);
}

private void DoBar(Object sender, EventArgs e)
{
    HttpApplication httpApplication = (HttpApplication)sender;
    if(httpApplication.Context.Items.Contains("MyFlag") && (bool)contextItems["MyFlag"] == true)
    {
        //Do stuff...
    }
}

Answer 2

I'm not exactly sure when Session is first available but I'm able to access it with this little-known event in Global.asax, fwiw:

// This event is executed for every page request
// and is run before the PreInit event.
protected void Application_PreRequestHandlerExecute(object sender, EventArgs e)
{
    Session["ok"] = "OK";
}