I am facing an issue and was hoping if you could please provide me with some guidance:
I have a Asp.net 4.0 website application that uses spring.net and ext.net libraries. I have deployed it in IIS 7 using classic application pool mode and it works. It doesn't work in integrated mode.
I have another Asp.net 4.0 silverlight website application that is deployed in IIS 7 using integrated application mode and it works. It doesn't work in classic mode.
I have created a new ASP.net web application that combines both of the 1 and 2 web applications above. It uses Ext.Net, Spring.Net and Silverlight 4.0. In Visual Studio's web server, when I run it in debug mode, it works perfectly.
When I deploy it in IIS 7, it doesn't work. How can I make the application run in one mode? Is there a web.config setting that can define the parts of the website to run under a different application pool mode?
I suspect that the problem you're having with the [ext.net] application is due to it being in integrated mode and you not having populated your web.config correctly. Take a look at the Ext.Net wiki page for Web.config. (That said, I didn't realise there was an Ext.Net wiki until I searched to pickup the exact details a moment ago!)
Basically, for "classic" you need to have configuration entries under <system.web><httpModules> and <system.web><httpHandlers> whereas for IIS7/Integrated mode you need to have configuration entries under <system.webServer><modules> and <system.webServer><handlers> respectively.
This MSDN document might help you better understand the differences and then modify the one to use Integrated mode, which is the preferred mode going forward and if you're going to be deploying to IIS 7.
来源：https://stackoverflow.com/questions/5051138/application-pool-mode-problem-classic-or-integrated