Can't stop firing ASP.NET Module for static content

Question

I have a module in an ASP.NET MVC application. The module is working fine, but it's firing for every type of file including static content even though I have: ``` ``` The module hooks AcquireRequestState and PostRequestHandlerExecute events and both show static content firing (.htm, .css, .png etc.). I was under the impression that runAllManagedModulesForAllRequests="false" should keep modules from firing on non-ASP.NET content. To clarify: I can set preCondition="managedHandler" like this: ``` ``` and get my module to fire only managed requests. However, I'm trying to understand why the IIS pipeline in general is firing managed module hits for every request. I think this used to work just fine in older versions where unless runAllManagedModulesForAllRequests="true" it wasn't firing unmanaged content into ASP.NET modul…

Accepted Answer

In IIS7 Microsoft introduced a new way of developing modules and handlers by using managed (.NET) code, not just native code. Problem is switching a request between managed and native code is very expensive, so Microsoft introduced the `preCondition="managedHandler"`. It flags the module as only available for managed content requests (.aspx, .asmx, ...) so IIS avoids firing it for static content.

Now, you can have a situation where you want to modify an static content request, such as minifying JavaScript on the fly. You can write the module using C# and compile it as a managed module, but you want it to be fired for static content, so you simply do not mark it as `managedHandler`.

Finally, `runAllManagedModulesForAllRequests="true"` is used to override `preCondition="managedHandler"` so all of them get fired.

There is more info available at: http://www.iis.net/learn/get-started/introduction-to-iis/iis-modules-overview#Precondition

Can't stop firing ASP.NET Module for static content

Solution

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