what happens in the background of hosting a rest webservice using wcf

Question

I was trying to understand what goes on in the background when I write the following piece of code to host a REST webservice in WCF:

RouteTable.Routes.Add(new ServiceRoute("", new WebServiceHostFactory(),
                                       typeof(MyConcreteService)));

Also, the class definition is something like this:

public class MyConcreteService : IService

where IService defines the ServiceContract and OperationContract with WebGET etc

In setting up the routes, I never mention IService anywhere. How does the server find out what contracts to use ? Can someone spell out the secret that goes on in the background which makes the webservice work ?

Answer 1

The WebServiceHostFactory returns an instance of WebServiceHost . That class will see if the service class itself is decorated with [ServiceContract] - if so, it will use it as the contract type. Otherwise it will look for the interfaces implemented by the service class to see which ones are decorated with [ServiceContract] . If it finds only one (which is the case in your example), then it will be the one used as the contract type. If it finds 0 or more than 1, it should throw an exception.

Having the contract type, WebServiceHost will add an endpoint with that contract type, the appropriate binding ( WebHttpBinding ) and an empty relative address. It will also add the appropriate behavior for web endpoints ( WebHttpBehavior ). That's essentially it; it may do other things such as setting up a content type mapper if needed, etc, but the beauty of the WebServiceHost (and WebServiceHostFactory) class is that you don't need to know about it (in most of the cases).