The configuration settings for all application pools running on
the Internet Information Service (IIS) 7 are the main elements of an
application pool. Application pools contain one or more worker process.
Application pool is assigned with the common settings, which are used to serve
for one or more requests. The worker process are then configured and assigned
to the application pool. The isolation from one web application from another
web application is achieved because of the application pool, which allows the
web applications to share one or more similar configured worker process. Any
error in one application pool does not affect websites or applications in
another application pool. This is implemented by the boundaries set for the
process of each worker process.
In
IIS 7 and later, 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.
Integrated
Integrated
mode is the default mode by which all the application pools in the IIS 7 and
later runs. This mode allows all the ASP.NET modules to be a part in IIS
request process without checking the type of resource requested. In this
integrated mode all the features of the ASP.Net 2.0 request pipeline are made
available to the requests for static content, as well as ASP, PHP, and other
content types.
Classic
In Classic mode the
asp.net applications are hosted by the IIS 6.0 processing pipe line. In this
mode, The ASP.NET requests are processed first through the IIS 7 and later
modules. Also ASP.NET requests are then processed by the aspnet_isapi.dll. The
IIS 7, later processing pipe lines, and the ASP.NET pipelines are separate from
each other. The other resource types do not get the features of the ASP.NET
request processing pipelines. This indicates the fact that ASP.NET request
should undergo through authentication and authorization modules in both process
models. However, Classic mode is not as efficient as integrated mode. Classic
mode is not compatible with applications that were developed using ASP.NET
version 1.1 on an IIS 7 and later server. It cannot be ran without modifying
the application in integrated mode.
The
Application Pool Identity type is a feature in new IIS 7.5 and above editions,
which is used for identity attribute of the <processModel> element. This
process identity feature is a default for applications, and allows to secure
the content areas to allow a specific application pool. This security feature
can be enabled using the name of an application pool by using syntax “IIS
AppPool\DefaultAppPool.” The surface attack area of the server is reduced
severely because the identity feature is created dynamically.
