R – Why migrate from IIS6 to IIS7

iis-6iis-7windows-server-2003windows-server-2008

I have a number of web apps running on several IIS6/Server 2003 boxes. They run well and are happy. They are all asp.net web apps and use .NET 3.5.

What, if any, would be valid reasons for contemplating moving the web apps to IIS7/Server 2008?

Best Answer

IIS7 is rewritten from the ground up with a concept of being "pluggable". IIS7 is more extensible than it ever has been before. The entire request pipeline has be reworked to allow you to more easily work with requests, as well.

From a performance aspect, these changes are immediately recognizable. You can run sites developed for IIS6 in a "Classic" application pool that will preserve compatibility, but provide a noticeable performance boost. In the non-scientific evaluation that we have done so far, our legacy application has seen about a 20% reduction of load times on our IIS7 test machine.

Of course, the reason we have to run in "classic" mode is an interesting side note. Inside the global.asax, there is some pre-fetching on application start which touches the HttpContext. Specifically, there is pre-caching done, which IIS7 does not allow. So, before we can switch from "classic" mode, there are some changes that we will have to make.

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