IIS Architecture Introduction

Components in IIS

IIS contains several components that perform important functions for the application and Web server roles in Windows Server®2008 (IIS 7.0) and Windows Server 2008 R2 (IIS 7.5). Each component has responsibilities, such as listening for requests made to the server, managing processes, and reading configuration files. These components include protocol listeners, such as HTTP.sys, and services, such as World Wide Web Publishing Service (WWW service) and Windows Process Activation Service (WAS).

Protocol Listeners

Protocol listeners receive protocol-specific requests, send them to IIS for processing, and then return responses to requestors. For example, when a client browser requests a Web page from the Internet, the HTTP listener, HTTP.sys, picks up the request and sends it to IIS for processing. Once IIS processes the request, HTTP.sys returns a response to the client browser.

By default, IIS provides HTTP.sys as the protocol listener that listens for HTTP and HTTPS requests. HTTP.sys was introduced in IIS 6.0 as an HTTP-specific protocol listener for HTTP requests. HTTP.sys remains the HTTP listener in IIS 7 and above, but includes support for Secure Sockets Layer (SSL).

To support services and applications that use protocols other than HTTP and HTTPS, you can use technologies such as Windows Communication Foundation (WCF). WCF has listener adapters that provide the functionality of both a protocol listener and a listener adapter.

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