I am looking into identifying handler that will handle my request.
I would like to know if request is asking for static resource (that is css,js or image files).
Upon inspecting HttpContext.Request on PreRequestHandlerExecute Event i see that handler and currentHandler variables are null for static resources and for any other custom handlers or aspx pages i have handler and currentHandler variables.
My question is: Is the is good place to differ handlers that will handle request or not?
I would like not to identify handler file extension by taking it from system.web/httpHandlers, cause i would like not to use system.web/httpHandlers just system.webServer/handlers. And i don't want to use Microsoft.Web.Administration namespace cause that will make me modify configurations on all servers.
Forgot to make an update on how i resolved it. I actually do deffer native from custom handlers on PostMapRequestHandler event. If your request will be handled by native handler than handler and currentHandler vars of HttpContext.Request will be null. Also by setting runAllManagedModulesForAllRequests to false request that will be handled by native handlers want even raise PostMapRequestHandler event. Hope this helps someone.
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Is there no way to detect if the current request is being mapped via ASP.NET 4.0 URL routing?
I have an HTTP module that handles the application's BeginRequest event. I have found that this handler is called for all file types, including CSS, JS, image files, etc., and I just want to perform an action if the target file is an ASPX page.
In the case of routed pages, all the properties of the HttpRequest object reflect the requested URL, and not the ASPX page that the request is being mapped to. How can I determine if the request will be handled by an ASPX file?
Thanks for any suggestions.
Inside of the Begin Request event a Handler has not been defined for the specific URL.
So there is no way of determining what will actually end up handling that URL because IIS has yet to decide. That happens after Begin Request has been fired, that is why all file types are being called.
That's one of the reasons why Begin Request is not a good event to really execute code on that needs to target specifically .NET files. A good use for the Begin Request method is adding cookies or headers to either a request or response. Those can be tacked on without a problem no matter what ends up handling the request.
As mentioned before I would suggest a Base Class that inherits from System.Web.UI.Page that all your other pages inherit from, or create a Master page.
Now without specifically knowing what you are trying to do it's hard to give a good solution. It may be possible to test a URL to check if it'll be fired by a Route, but I don't know how and it also seems excessive when you can handle it through a base class or master page.
You can create a BasePage as a base class for all pages in the application, and handle the Page_Load event there instead of using an HTTP module.
We have an HTTPModule whose sole purpose is to do "url rewriting". By definition of an HTTPModule, ALL browser requests (html, css, javascript, images, etc) go through the event handlers of this class.
During the signin process, we are catching the moment when the user switches from "anonymous" to "signed-in" user in the Global.asax's Profile_OnMigrateAnonymous event handler. One issue we're finding is that when the user signs in, the Profile_OnMigrateAnonymous event fires, seemingly, for possibly EVERY resource within the request to generate the page to the user - namely, the html, css, javascript, images, etc. It was my understanding that this event will fire only ONCE. Why would it be firing multiple times? Is it a result of our registered "url rewriting" HTTPModule? Is there a way we can configure the application to only fire that event once?
For normal resource reqeusts (css/js/img etc) IIS handles the request directly. It only passes to the asp_net worker requests for specfic filenames (such as .aspx and .asmx).
Your HTTPModule is basically forcing IIS to forward all requests to the worker process, hence each request is firing off the Profile_OnMigrateAnonymous.
I don't think you can bypass the call to Profile_OnMigrateAnonymous, however you could implement a bit of code to check for a an .aspx/.ascx etc file name and only then perform the actual actions specified.
When we write our own custom HTTPHandlers aren't they behave the same way as ICallBackEventHanlder does? we use both to make ajax calls from our web page, isn't this correct? or my understanding wrong, I wont doubt if it is :(
Obviously HTTPHandlers are more broader concept since a web page (.aspx) etc are also http handlers.
A ICallBackEventHandler is for integration with a page -- a handler is for anything. A callback handler is useful when you want to do an ajax request from the client-side of a page, and from that handler you still want access to all of the controls on the page, their re-saturated state that comes from ViewState, etc. An http handler has no access to the page or its state. A callback handler can also push some state changes back to the client. For example, a callback handler might render something which requires the __EVENTVALIDATION field on the client-side to be updated.
I've got an HTTPModule that does some role-based page access security (I'm having to retrofit some security into some code that we've acquired).
I've noticed that in one instance that it doesn't fire on a Server.Transfer.
Here's a snippet of the code:
' move to target page
Select Case eTransferMethod
Case TargetPageTransferMethod.Redirect
Page.Response.Redirect(strPage, False)
Case TargetPageTransferMethod.Transfer
Context.Handler = Me
Page.Server.Transfer(strPage)
Case TargetPageTransferMethod.None
' Do nothing
End Select
The case that I'm talking about here is the TargetPageTransferMethod.Transfer case. The page will be an .aspx page.
Now I know that AcquireRequestState is fired on other Server.Transfer calls in this code. In fact it gets fired on the postback when a button on the page transferred to is clicked. Ironically my security code is bypassed on the transfer to this page but denies access on the postback when this page's cancel button is clicked! :eek:
I'd post further details of the codebase but it's so convoluted and sprawling it'd be a nightmare to explain.
So basically I'm asking 'What might cause the AcquireRequestState event in an HTTPModule to not fire when a Server.Transfer is called?'
The way to get around this is to create a custom HttpHandler that inherits the System.Web.UI.PageHandlerFactory class.
You can then override the GetHandler method which is called whenever a page instance is created, both on Response.Redirect and on Server.Transfer.
Register this new handler to use the "*.aspx" extension and all pages will automatically use the new handler. This allows you to do custom authorisation on Server.Transfer as well as use a dependency injection framework (e.g. MS Unity).
I can understand it being called on a post back, as that is another request from the client, but Server.Transfer doesn't initiate a new request, it transfers execution from one page to another.
As the AcquireRequestState event is fired "when ASP.NET acquires the current state (for example, session state) that is associated with the current request" - this would occur on the initial request from the browser, but not on the server transfer as the server didn't get another request, you're just asking it to process a different page.
A key comment is this one from the HttpServerUtility.Transfer documentation:
ASP.NET does not verify that the current user is authorized to view the resource delivered by the Transfer method. Although the ASP.NET authorization and authentication logic runs before the original resource handler is called, ASP.NET directly calls the handler indicated by the Transfer method and does not rerun authentication and authorization logic for the new resource. If your application's security policy requires clients to have appropriate authorization to access the resource, the application should force reauthorization or provide a custom access-control mechanism.
Server.Transfer doesn't reprocess the entire HTTP pipeline for the destination page. It just calls the destination page's HttpHandler. Because of this, you shouldn't see any of the earlier applicaton events get fired.
In our asp.net 2.0 application we have the an HttpModule and HttpHandler. They are registered in web.config to handle requests for certain file types.
The request is initiated asynchronously from client side using MS AJAX.
I noticed something strange:
HttpHandler:ProcessRequest is not entered on every HttpModule:EndRequest which seems like incorrect behavior since my understanding of the flow of events:
HttpModule:BeginRequest > HttpHandler:ProcessRequest > HttpModule:EndRequest. For some reason, the handler part is sometimes skipped.
What could be causing this?
If I understand correctly, HttpModule would get executed for every request which comes to your application, while the HttpHandler would execute only for the registered extension.
So, there could be other request to the app apart from the ones you make to your handler.
Do you have that file type set up in IIS to be processed by .net?
I believe that calls to Server.Transfer and Response.End can short-circuit the pipeline, is it possible a branch of your logic does this?