What is the difference between classic and integrated pipeline mode in IIS7

Question

I was deploying an ASP NET MVC application last night  and found out that it is less work to deploy with IIS7 set to integrated mode  My question is what is the difference  And what are the implications of using one or the other

User · Answer

IIS 6 0 and previous versions      ASP NET integrated with IIS via an ISAPI extension  a C API   C Programming language based API   and exposed its own application and request processing model      This effectively exposed two separate server  request   response   pipelines  one for native ISAPI filters and extension components  and another for managed application components  ASP NET components would execute entirely inside the ASP NET ISAPI extension bubble AND ONLY  for requests mapped to ASP NET in the IIS script map configuration   Requests to non ASP NET content types -  images  text files  HTML pages  and script-less ASP pages  were processed by IIS or other ISAPI extensions and were NOT visible to ASP NET   The major limitation of this model was that services provided by ASP NET modules and custom ASP NET application code were NOT available to non ASP NET requests  What s a SCRIPT MAP    Script maps are used to associate file extensions with the ISAPI handler that executes when that file type is requested   The script map also has an optional setting that verifies that the physical file associated with the request exists before allowing the request to be processed  A good example can be seen here     IIS 7 and above   IIS 7 0 and above have been re-engineered from the ground up to provide a brand new C   API based ISAPI    IIS 7 0 and above integrates the ASP NET runtime with the core functionality of the Web Server  providing a unified single  request processing pipeline that is exposed to both native and managed components known as modules   IHttpModules    What this means is that  IIS 7 processes requests that arrive for any content type  with both NON ASP NET Modules   native IIS modules and ASP NET modules providing request processing in all stages This is the reason why NON ASP NET content types   html  static files   can be handled by  NET modules    You can build new managed modules  IHttpModule  that have the ability to execute for all application content  and provided an enhanced set of request processing services to your application  Add new managed Handlers   IHttpHandler

User · Answer

Classic mode  the only mode in IIS6 and below  is a mode where IIS only works with ISAPI extensions and ISAPI filters directly  In fact  in this mode  ASP NET is just an ISAPI extension  aspnet isapi dll  and an ISAPI filter  aspnet filter dll   IIS just treats ASP NET as an external plugin implemented in ISAPI and works with it like a black box  and only when it s needs to give out the request to ASP NET   In this mode  ASP NET is not much different from PHP or other technologies for IIS   Integrated mode  on the other hand  is a new mode in IIS7 where IIS pipeline is tightly integrated  i e  is just the same  as ASP NET request pipeline  ASP NET can see every request it wants to and manipulate things along the way  ASP NET is no longer treated as an external plugin  It s completely blended and integrated in IIS  In this mode  ASP NET HttpModules basically have nearly as much power as an ISAPI filter would have had and ASP NET HttpHandlers can have nearly equivalent capability as an ISAPI extension could have  In this mode  ASP NET is basically a part of IIS

User · Answer

Integrated application pool mode      When an application pool is in Integrated mode  you can take advantage   of the integrated request-processing architecture of IIS and ASP NET    When a worker process in an application pool receives a request  the   request passes through an ordered list of events  Each event calls the   necessary native and managed modules to process portions of the   request and to generate the response       There are several benefits to running application pools in Integrated   mode  First the request-processing models of IIS and ASP NET are   integrated into a unified process model  This model eliminates steps   that were previously duplicated in IIS and ASP NET  such as   authentication  Additionally  Integrated mode enables the availability   of managed features to all content types       Classic application pool mode      When an application pool is in Classic mode  IIS 7 0 handles requests   as in IIS 6 0 worker process isolation mode  ASP NET requests first go   through native processing steps in IIS and are then routed to   Aspnet isapi dll for processing of managed code in the managed   runtime  Finally  the request is routed back through IIS to send the   response       This separation of the IIS and ASP NET request-processing models   results in duplication of some processing steps  such as   authentication and authorization  Additionally  managed code features    such as forms authentication  are only available to ASP NET   applications or applications for which you have script mapped all   requests to be handled by aspnet isapi dll       Be sure to test your existing applications for compatibility in   Integrated mode before upgrading a production environment to IIS 7 0   and assigning applications to application pools in Integrated mode    You should only add an application to an application pool in Classic   mode if the application fails to work in Integrated mode  For example    your application might rely on an authentication token passed from IIS   to the managed runtime  and  due to the new architecture in IIS 7 0    the process breaks your application    Taken from  What is the difference between DefaultAppPool and Classic  NET AppPool in IIS7   Original source  Introduction to IIS Architecture

User · Answer

In classic mode IIS works h ISAPI extensions and ISAPI filters directly  And uses two pipe lines   one for native code and other for managed code  You can simply say that in Classic mode IIS 7 x works just as IIS 6 and you dont get extra benefits out of IIS 7 x features   In integrated mode IIS and ASP Net are tightly coupled rather then depending on just two DLLs on Asp net as in case of classic mode

[asp.net] What is the difference between 'classic' and 'integrated' pipeline mode in IIS7?

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