Programming WCF Services

Hosting

The WCF service class cannot exist in a void. Every WCF service must be hosted in a Windows process called the host process. A single host process can host multiple services, and the same service type can be hosted in multiple host processes. WCF makes no demand on whether or not the host process is also the client process. Obviously, having a separate process advocates fault and security isolation. It is also immaterial who provides the process or what kind of a process is involved. The host can be provided by IIS, by the Widows Activation Service (WAS) on Windows Vista, or by the developer as part of the application.

Tip

A special case of hosting is in-process hosting, or in-proc for short, where the service resides in the same process as the client. The host for the in-proc case is, by definition, provided by the developer.

IIS Hosting

The main advantage of hosting a service in the Microsoft Internet Information Server (IIS) web server is that the host process is launched automatically upon the first client request, and you rely on IIS to manage the life cycle of the host process. The main disadvantage of IIS hosting is that you can only use HTTP. With IIS5, you are further restricted to having all services use the same port number.

Hosting in IIS is very similar to hosting a classic ASMX web service. You need to create a virtual directory under IIS and supply a .svc file. The .svc file functions similar to an .asmx file, and is used to identify the service code behind ...