Difference between <system.web> and <system.webServer>?

Question

Every time I have to add a handler or module for ASP.NET with IIS7, the instructions always tell me to incorporate it into two sections: system.web and system.webserver.

<system.web>
    <httpHandlers>
    </httpHandlers>
    <httpModules>
    </httpModules>
</system.web>

And this:

<system.webServer>
    <modules>
    </modules>
    <handlers>
    </handlers>
</system.webServer>

What is the difference between these two sections?

In addition, if I don't add it to the system.web section, my Visual Studio 2008 debugger also doesn't work correctly.

a better current reference for this is: msdn.microsoft.com/en-us/library/46c5ddfy.aspx — Shannon
– Shannon, Commented Jun 6, 2010 at 17:53

Chris · Accepted Answer · 2008-12-10 06:59:25Z

168

The system.web section is for configuring IIS 6.0, while the system.webserver version is used to configure IIS 7.0. IIS 7.0 includes a new ASP.NET pipeline and some configuration differences, hence the extra config sections.

However...

If you're running IIS 7.0 in integrated mode only, you shouldn't need to add the handlers to both sections. Adding it to system.web as well is a fallback for IIS 7.0 operating in classic mode, unless I'm mistaken. I've not done extensive testing on this.

See http://msdn.microsoft.com/en-us/library/bb763179.aspx for more information.

answered Dec 10, 2008 at 6:59

Chris

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4 Comments

sclarson Over a year ago

What about attributs like <httpRuntime> which are placed in system.web but still make a difference on IIS 7 Integrated mode?

Chris Over a year ago

The system.web section isn't superseded by the system.webserver section, just extended.

Eborbob Over a year ago

On IIS 8.5 I've found that the httpCookies setting is not available in system.webServer but works if I create a system.web and put it in there.

Khurshid Alam Over a year ago

@Chris Hello, How do I set these options in linux ? I want to set following options. maxWorkerThreads = 100, maxIoThreads = "100", minWorkerThreads = "50", minIoThreads = "50".

leppie · Accepted Answer · 2008-12-10 06:59:42Z

47

The former is for Classic Mode.

The latter is for Integrated Pipeline Mode (available in IIS7+).

answered Dec 10, 2008 at 6:59

leppie

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1 Comment

Ben Gripka Over a year ago

Given my experience, is this is a better answer in length, clarity and reality. In addition to classic mode on the former, add IIS express and other servers that are not IIS 7.

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