Home > ASP.NET > Internet Information Services (IIS) 7 Application Pools / Types of Application Pools/Difference between Integrated and Classic Application Pool.

Internet Information Services (IIS) 7 Application Pools / Types of Application Pools/Difference between Integrated and Classic Application Pool.

Hi Geeks,

Today , I got a chance to host a ASP.NET application on IIS , and i learnt the advantage of Application pool of IIS in deep.

In this article we will see how application pool works and their types :

Application Pool

The application Pools element contains configuration settings for all application pools running on your Internet Information Services (IIS) 7 server. An application pool defines a group of one or more worker processes, configured with common settings that serve requests to one or more applications that are assigned to that application pool. Because application pools allow a set of Web applications to share one or more similarly configured worker processes, they provide a convenient way to isolate a set of Web applications from other Web applications on the server computer. Process boundaries separate each worker process; therefore, application problems in one application pool do not affect Web sites or applications in other application pools. Application pools significantly increase both the reliability and manageability of your Web infrastructure.

You can choose to use the default application pool provided by IIS on install, or you can create your own application pool. You can run as many application pools on your IIS 7 server as you need, though this can affect server performance. Application pools can contain one or more worker processes. Each worker process represents work being done for a Web site, Web application, or Web service. You can create a Web garden by enabling multiple worker processes to run in a single application pool.

In IIS 7, each application pool uses one of two .NET integration modes for running ASP.NET applications: Integrated or Classic. The .NET integration mode defined for the application pool determines how IIS processes an incoming request to the sites, applications and Web services that run in that application pool.

Types of Application Pools

There are two types of application pools

1) Integrated  (default)

2) Classic


Integrated mode allows IIS to process requests in the application pool by using the IIS 7 integrated pipeline. This allows ASP.NET modules to participate in IIS request processing regardless of the type of resource requested. Using integrated mode makes available features of the ASP.NET 2.0 request pipeline available to requests for static content, as well as ASP, PHP and other content types. By default, IIS 7 application pools run in this mode.

Classic mode uses the IIS 6.0 processing pipeline for hosting ASP.NET applications. In this mode, requests are processed initially through IIS 7 modules, and ASP.NET requests are further processed by the aspnet_isapi.dll. The ASP.NET processing pipeline is separate from the IIS 7 processing pipeline, and the ASP.NET request processing pipeline features are not available to other resource types. This also means that an ASP.NET request must pass through authentication and authorization modules in both process models. While this is not as efficient as Integrated mode, it does allow you to run applications developed using ASP.NET version 1.1 on an IIS 7 server without modifying the application to run in Integrated mode.


Categories: ASP.NET
  1. December 31, 2011 at 5:43 am

    Ganesh S Divekar Thank you for taking the time to inform us. The information in this post I have found to be very useful and will bookmark your site to gather any further relevant content.

  2. January 3, 2012 at 10:59 am

    Ola! Microsoftmentalist,
    I know what you mean, I’ve tried to configure PHP5 to work with Microsoft IIS, but the localstart.asp index page didn’t start anymore.

    Now I can’t run IIS anymore; I cannot change any settings because Internet Information Services doesn’t appear anymore under Services and Application in the Computer Management console.

    If I try to start from IIS shortcut under Administrative Tools throws this error:

    Snap-in failed to initialize.
    Name: <unknown>
    CLSID: {…..}

    Reinstalling IIS from Add/Remove Components has no effect.
    Good Job!

  1. January 5, 2012 at 12:46 pm

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