Host environments of different IIS versions of WCF

WCF has the lowest version requirement for the hosted IIS environment. The lowest version of IIS is 5.1, but compared with the later version of IIS environment, iis5.1 only supports binding one application pool (only one site bound to one application pool) to one site ).

The above is the IIS 5.1 architecture. The entire architecture is divided into two parts. W3csvc.exe on the left side host an HTTP listener (HTTP listener), loading processes, and managing configurations. The working process on the right enables IIS 5.1 to manage. Net managed application domains (managed. NET application domains ).

In the IIS 6.0 environment, HTTP. sys is introduced, which is the kernel mode HTTP stack. HTTP. sys is connected to the existing process and Configuration Manager in IIS 5.1 through w3csvc.exe.

The biggest difference between IIS 7.0 and earlier versions is that it not only supports HTTP Communication. It supports all four transmission methods of WCF. At the same time, an operating system service named was added to svchost.exe. Was allows you to host any WCF Service under the IIS model and supports all transmission modes.

When the listener adapter is started, it registers with was and obtains the configuration of the specified communication protocol in was/IIS. At this point, the listening adapter clearly knows that its site supports those application requests.
When the first request arrives, the listener adapter will call was to activate the workflow and load the. NET managed application domain to which the request finally points. The request is then passed to the working process responsible for processing the request. The working process does not care about the specific request type, WCF request, ASP. NET Request, or other requests supported by IIS 7.0. When the request arrives, the activation process is created and valid for the working thread.
When the servicehost in the application domain is started, the application domain protocol handler calls an ensureserviceavailable static method. This method is protocol-independent and activates the entire service, including endpoints and transmission methods (not only the protocol handler that calls it ).