IIS 7.0 and IIS 8.0 Have the Same Working Architecture , So let us discuss the Difference Between IIS 6.0 and IIS 7.0 ( IIS 8.0 )
In IIS 6.0 the www service Performs the following Tasks
a) The WWW Service manages application pools and worker processes, such as starting, stopping, and recycling worker processes.
b) The WWW Service reads configuration information from the IIS metabase and uses that information to configure and update the HTTP listener, HTTP.sys
In IIS 7.0 and 8.0 the above tasks which were performed by the www Service alone are Split into two Services www Service and Windows Process Activation Service also called as WAS .
The WWW Service is the listener adapter for the HTTP listener, HTTP.sys. As the listener adapter, the WWW Service is primarily responsible for configuring HTTP.sys, updating HTTP.sys when configuration changes, and notifying WAS when a request enters the request queue.
Windows Process Activation Service (WAS) manages application pool configuration and worker processes instead of the WWW Service. This enables you to use the same configuration and process model for HTTP and non-HTTP sites.
- When a client browser initiates an HTTP request for a resource on the Web server, HTTP.sys intercepts the request.
- HTTP.sys contacts WAS to obtain information from the configuration store.
- WAS requests configuration information from the configuration store, applicationHost.config.
- The WWW Service receives configuration information, such as application pool and site configuration.
- The WWW Service uses the configuration information to configure HTTP.sys.
- WAS starts a worker process for the application pool to which the request was made.
- The worker process processes the request and returns a response to HTTP.sys.
- The client receives a response.