HttpModule.Init - safely add HttpApplication.BeginRequest handler in IIS7 integrated mode
- by Paul Smith
My question is similar but not identical to:
http://stackoverflow.com/questions/1123741/why-cant-my-host-softsyshosting-com-support-beginrequest-and-endrequest-event (I've also read the mvolo blog referenced therein)
The goal is to successfully hook HttpApplication.BeginRequest in the IHttpModule.Init event (or anywhere internal to the module), using a normal HttpModule integrated via the system.webServer config, i.e. one that doesn't:
invade Global.asax or
override the HttpApplication (the module is intended to be self-contained & reusable, so e.g. I have a config like this):
<system.webServer>
<validation validateIntegratedModeConfiguration="false"/>
<modules>
<remove name="TheHttpModule" />
<add name="TheHttpModule" type="Company.HttpModules.TheHttpModule" preCondition="managedHandler" />
So far, any strategy I've tried to attach a listener to HttpApplication.BeginRequest results in one of two things, symptom 1 is that BeginRequest never fires, or symptom 2 is that the following exception gets thrown on all managed requests, and I cannot catch & handle it from user code:
Stack Trace:
[NullReferenceException: Object reference not set to an instance of an object.]
System.Web.PipelineModuleStepContainer.GetEventCount(RequestNotification notification, Boolean isPostEvent) +30
System.Web.PipelineStepManager.ResumeSteps(Exception error) +1112
System.Web.HttpApplication.BeginProcessRequestNotification(HttpContext context, AsyncCallback cb) +113
System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +616
Commenting out app.BeginRequest += new EventHandler(this.OnBeginRequest) in Init stops the exception of course. Init does not reference the Context or Request objects at all.
I have tried:
Removed all references to HttpContext.Current anywhere in the project (still symptom 1)
Tested removing all code from the body of my OnBeginRequest method, to ensure the problem wasn't internal to the method (= exception)
Sniffing the stack trace and only calling app.BeginRequest+=... when if the stack isn't started by InitializeApplication (= BeginRequest not firing)
Only calling app.BeginRequest+= on the second pass through Init (= BeginRequest not firing)
Anyone know of a good approach? Is there some indirect strategy for hooking Application_Start within the module (seems unlikely)? Another event which a) one can hook from a module's constructor or Init method, and b) which is subsequently a safe place to attach BeginRequest event handlers?
Thanks much
