CODEWITHSUNDEEP
.netwcfinterface
Andrew Wu
Andrew Wu

Reputation: 3

Multiple WCF Services implementing same Service Contract interface

Is it possible for multiple wcf services to implement the same service contract interface?

What I want to do is allow for a test service to be interchangeable for the real service, and to specify which service to be used in the configuration file.

For example:

[ServiceContract]
public interface IUselessService  
{  
  [OperationContract]   
  string GetData(int value);   
}

Test implementation 

public class TestService : IUselessService  
{  
  public string GetData(int value)  
  {  
    return "This is a test";   
  }  
}

Real class 

public class RealService : IUselessService  
{  
  public string GetData(int value)  
  {  
    return string.Format("You entered: {0}", value);  
  }  
}

Upvotes: 5

Views: 5794

Answers (4)

user19026443
user19026443

Reputation: 1

I was just experimenting with this issue trying to get the 2 code behind cs files to implement the same contract interface and then trying to switch the concrete classes employed by the .svc file that is exposed. This HAS TO BE possible, as if it is not, it defeats the purpose of a class implementing an interface when it cannot facilitate the polymorphic behavior on it.

I found this line of the .svc file:

<%@ ServiceHost Language="C#" Debug="true" Service="Service2" CodeBehind="~/App_Code/Service2.cs" %>

Basically this line switches the concrete classes which implements the same contract interface.

You will have to reference the class name of the concrete class in the Service attribute. You will also have to change the class file name in the CodeBehind attribute as well, but it is really the class in the Service attribute that will make the switch.

Upvotes: 0

Andrew Wu
Andrew Wu

Reputation: 3

Thanks guys for your answers. I have a solution now that works for me, without putting the interface in a separate assembly and in the GAC. I'm not looking at using the interface for other projects, just using the same interface for multiple services in the same project.

What I was trying to do was make the change between RealService and TestService in the configuration file of the WCF service, so the client would not know the difference (the client would not have to change its configuration to point to a different .svc file). I'm not sure this is possible, or it least if it is, it is definitely not straightfoward.

What I am doing now is just specifying both services in the configuration file of the WCF service, and then I point the client to one or the other based on which service I want. Since this WCF service is for internal use only and we have control of both the client and the service, it is not a bad tradeoff. This solution is probably more explicit in its intentions anyways.

Here is the snippet of the configuration file:

<services>
      <service behaviorConfiguration="WcfService1.Service1Behavior"
               name="WcfService1.TestService">
        <endpoint address="" binding="basicHttpBinding" bindingConfiguration="testBasicHttpBinding" 
          contract="WcfService1.IUselessService">              
        </endpoint>
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
      </service>
      <service behaviorConfiguration="WcfService1.Service1Behavior"
               name="WcfService1.RealService">
        <endpoint address="" binding="basicHttpBinding" bindingConfiguration="testBasicHttpBinding"
         contract="WcfService1.IUselessService">             
        </endpoint>
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
      </service>
    </services>

Upvotes: 5

Oleg
Oleg

Reputation: 222007

If you define IUselessService interface inside a separate assembly and place this in GAC. This assembly should don't implement anything only define IUselessService interface and some other types which use needs as a parameters of IUselessService.

Both TestService and RealService should implement the same IUselessService interface. I mean you should create two additional project for each service, then TestService and RealService will have no type conflicts.

Upvotes: 2

John Weldon
John Weldon

Reputation: 40789

Yes, it's not only possible, it is explicitly within the design intentions of service contract interfaces.

Upvotes: 5

Related Questions