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amrameshreddy.blog.com166 CHAPTER 5 ■ HOSTING AND CONSUMING WCF SERVICESramrameshreddy.blog.comWindows XP and IIS 5.1IIS 5.0, which came as part of Windows 2000, split the process model of IIS and introducedworker processes. The primary reason for this change was to isolate applications so that IIScould host different applications that were less dependent on each other. IIS 5.0 was releasedwith Windows 2000, and IIS 5.1 was released with Windows XP. WCF doesn’t support hostingservices on Windows 2000 with IIS 5.0; because of that, we will take a closer look at IIS 5.1 only.IIS 5.1 is supported but has a limitation of only one site, and each application runs in oneworker process called aspnet_wp.exe. IIS 5.1 is a great version for developing ASP.NET websitesand WCF services. It is not ready for enterprise use because it has connection limits and runsonly on a client version of earlier Windows versions or Windows XP. In this chapter, we will talkabout IIS 5.1In Figure 5-11 you can see the process model of IIS 5.1. The architecture is split into twopieces. W3svc.exe on the left side hosts an HTTP listener, launches worker processes, andmanages the configuration. The worker processes on the other side enable IIS 5.1 to hostmanaged .NET applications, where ASPNET_ISAPI.dll is responsible for creating managed.NET application domains. Please note that on Windows XP the W3svc.exe Windows service ishosted in the SvcHost.exe process, together with the SMTP and FTP services.Inetinfo.exeW3svc.exeProcess andConfigurationManagerHTTP ListenerAspnet_wp.exeASPNET_ISAPI.dllApplicationDomainsFigure 5-11. IIS 5.1 process model architecture■Note You aren’t required to have IIS to run ASP.NET and WCF services. For example, you can use theASP.NET development web server that is provided with Visual Studio 2005. When Windows XP was released,Visual Studio didn’t have this feature. You were required to work with IIS 5.1 to be able to develop web applicationson Windows XP.ramrameshreddyramrameshreddy