A security patch for ASP.NET v4.0 was released recently. The details of the patch can be found at http://www.microsoft.com/technet/security/bulletin/ms10-070.mspx . I really only have one thing to say in this blog post: If you use an ISAPI Rewrite...

You can disable the v4.0 ASP.NET extensionless URL feature on IIS6 by setting a DWORD at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ASP.NET\4.0.30319.0\EnableExtensionlessUrls = 0. After changing the value, you will need to restart IIS in order for us to pick...

ASP.NET v4.0 has a new feature, when hosted on IIS 7, that enables the execution of extensionless URLs. This feature has a dependency on a QFE from IIS that enables extensionless handler mappings. See KB 980368 for more information and a link to download...

In this post I hope to clear up some misconceptions about the use of threads in ASP.NET applications so that you know the best way to perform asynchronous work in your ASP.NET applications. If you’re in a hurry and don’t want to read the rest...

Recently a number of people have asked how MVC and ASP.NET routing impacts the performance of static requests (HTML, JPG, GIF, CSS, JS, etc). I'll answer that question below while explaining how routing is implemented in the ASP.NET pipeline on IIS 6...

Try very, very hard to avoid using Response.Redirect(url), instead, use Response.Redirect(url, false ). Response.Redirect(url), after writing a 302 redirect response to the response buffers, calls Response.End. This is very expensive. The alternative...

ASP.NET throws HttpException for numerous types of errors, making it difficult to determine exactly what went wrong programmatically. You can parse the error message, but the message can be localized, and therefore parsing it can be non-trivial. There...

This post discusses an efficient way to compress content served by the ASP.NET output cache. In .NET Framework v2.0 SP1, included with Windows Server 2008, the ASP.NET Output Cache includes a new feature that allows cached responses to vary by the response...

.NET Framework v2.0 SP2, which will be included with .NET Framework v3.5 SP1, is scheduled to release this summer. This release contains a long awaited ASP.NET Cache feature, which will notify you when an entry becomes invalid and leave the stale entry...

I've been giving this advice for years internally, and the problem pops up way too often. I'm sure it will be addressed eventually, in a future version of the CLR, but for now, every released version of the CLR has this problem. If you allocate objects...

Perhaps one of the most loved and hated features of ASP.NET is the ability to detect file changes and automatically recompile or reconfigure the application. In development scenarios it’s very nice because you can access the application in a browser...

I've uploaded a brief summary on the extensibility of ASP.NET Session State (see link to AspNetSessionState.pdf below). Many people aren't aware of how easy it is to implement a custom session state provider. Having your very own disk based (file based...

Server.TransferRequest is a new API in the IIS 7.0 release of ASP.NET. It is essentially a server-side redirect. When invoked, a new request context is created, called the child request, and it goes through the entire IIS 7.0/ASP.NET integrated pipeline...

1.0 What is the IIS Pipeline Conceptually, the IIS pipeline is a state machine with the following states: BEGIN_REQUEST AUTHENTICATE_REQUEST AUTHORIZE_REQUEST RESOLVE_REQUEST_CACHE MAP_REQUEST_HANDLER ACQUIRE_REQUEST_STATE PRE_EXECUTE_REQUEST_HANDLER...

This appears to be undocumented. By default, IIS7 uses kernel-mode authentication, which happens to have a large performance benefit. There is a bug in kernel-mode authentication where requests that send credentials will fail unless an anonymous request...

Using a timer in an ASP.NET application is not as simple as it seems. There are three problems that commonly occur: ASP.NET applications shutdown for a number of reasons, and if the timer is not disposed before the AppDomain is unloaded, the timer...

I'd like to briefly explain how ASP.NET uses threads when hosted on IIS 7.5, IIS 7.0 and IIS 6.0, as well as the configuration changes that you can make to alter the defaults. Please take a quick look at the “Threading Explained” section in...

When v1.0 released, the only OS that ASP.NET supported was Win2k, the only process model was aspnet_wp, and the only architecture we supported was x86. The aspnet_wp process model had a memory limit that was calculated at runtime during startup. The limit...

In Visual Studio Orcas Beta 1, the AJAX ScriptModule is listed in the web.config template used for version 3.5 web projects. There is a known bug (DevDivBugs 78367) that prevents Visual Studio F5 debugging from working on IIS7 / Windows Vista when a module...

The ClrProfiler 1.0 Where can I get it? http://www.microsoft.com/downloads/details.aspx?FamilyId=A362781C-3870-43BE-8926-862B40AA0CD0&displaylang=en 2.0 Should I use it? When running performance tests, if the CPU is maximized...

Good afternoon! My name is Thomas Marquardt. I am a developer at Microsoft on the ASP.NET team. I implemented/designed the ASP.NET/IIS7 integrated pipeline. I own the core of ASP.NET, the pipeline, the hosting interfaces, and application services including...