Programming WCF Services

Client-Side Programming

To invoke operations on the service, the client first needs to import the service contract to the client’s native representation. If the client uses WCF, the common way of invoking operations is to use a proxy. The proxy is a CLR class that exposes a single CLR interface representing the service contract. Note that if the service supports several contracts (over at least as many endpoints), the client needs a proxy per contract type. The proxy provides the same operations as service’s contract, but also has additional methods for managing the proxy life cycle and the connection to the service. The proxy completely encapsulates every aspect of the service: its location, its implementation technology and runtime platform, and the communication transport.

Generating the Proxy

You can use Visual Studio 2005 to import the service metadata and generate a proxy. If the service is self-hosted, first launch the service and then select Add Service Reference... from the client project’s context menu. If the service is hosted in IIS or the WAS, there is no need to pre-launch the service. Interestingly enough, if the service is self-hosted in another project in the same solution as the client project, you can launch the host in Visual Studio 2005 and still add the reference, because unlike most project settings, this option is not disabled during a debug session (see Figure 1-9).

Figure 1-9. Generate a proxy using Visual Studio 2005

This brings up the Add Service Reference ...