WCF webservice fails after "extracting interface" - web-services

Question

I am new to WebServices, and have a simple question.
I wrote a "Hello World" Service with Visual Studio 2017:
ServiceAjax.svc.cs:
namespace WebServiceTest
{
[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class ServiceAjax
{
[OperationContract]
[WebGet]
public string DoWork()
{
return "Hallo World";
}
}
}
the ServiceAjax.svc reads as this:
<%# ServiceHost Language="C#" Debug="true" Service="WebServiceTest.ServiceAjax" CodeBehind="ServiceAjax.svc.cs" %>
Running this works fine.
Now i read it's the way to go to declare an Interface for the Service.
Nearly every example does this ..., so i tried:
ServiceAjax.svc.cs:
namespace WebServiceTest
{
[ServiceContract]
public interface IServiceAjax
{
[OperationContract]
[WebGet]
string DoWork();
}
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class ServiceAjax: IServiceAjax
{
public string DoWork()
{
return "Hallo World";
}
}
}
Running this i get an error:
It's german, so my translation might be not excatly as the english message:
"From http://localhost:58513/ServiceAjax.svc no metadata could be loaded ..."
I Little bit below he tells me:
WebServiceTest.ServiceAjax wos not found in the List of contracts implemented by ServiceAjax
So, it must be a dump foult, cause i cant explain why extracting an Interface blows the Service, i sure missed something simple.
But i cant find a difference to the "simple WCF Web HTTP Service" samples in the net.
Ideas?
Update: I added this to an existing ASPX-Project, not a "clean" wcf Project ....

Answer 1

I found the answer myself (after earning the Tumbleweed badge ...)
There was one line missing in the WebConfig
<endpoint address="mex"
binding="mexHttpBinding"
name="mex"
contract="IMetadataExchange" />
I had tried with different "Factorys" in the SVC-Markup, which did not work.
Perhaps havent found the right one ...
i.e.
<%#ServiceHost language=c# Debug="true" Service="WebServiceTest.ServiceAjax"
Factory=System.ServiceModel.Activation.WebScriptServiceHostFactory%>
Adding the Config manually and adding to it did the trick after all.
I followed the steps in
https://learn.microsoft.com/en-us/dotnet/framework/wcf/feature-details/how-to-use-configuration-to-add-an-aspnet-ajax-endpoint
This lead to the "cant load metadata" Problem which i could fix with the line on Top (mex endpoint).
Why mircosoft [sic] did not point that out, i dont know ...
And why this starts beeing needed when using an interface i dont know neither.
But I stumbled about more occasions, when he needed that, i.e, AJAX Scripting Manger, which needs the Namespace-Argument in the Servicedeclaration too:
[ServiceContract(Namespace = "AJAXService")]
Below what i added to web.config (allready included Lines where dropped 4 shortage
<system.serviceModel>
<behaviors>
<serviceBehaviors>
<behavior name="myServiceTypeBehaviors" >
<serviceMetadata httpGetEnabled="true" />
</behavior>
</serviceBehaviors>
<endpointBehaviors>
<behavior name="myDataAspNetAjaxBehavior">
<enableWebScript />
</behavior>
</endpointBehaviors>
</behaviors>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true"
multipleSiteBindingsEnabled="true" />
<services>
<service behaviorConfiguration="myServiceTypeBehaviors"
name="WebServiceTest.ServiceAjax">
<endpoint address=""
behaviorConfiguration="myDataAspNetAjaxBehavior"
binding="webHttpBinding"
name="ZESData"
contract="WebServiceTest.IZESData" />
<endpoint address="mex"
binding="mexHttpBinding"
name="mex"
contract="IMetadataExchange" />
</service>
</services>
</system.serviceModel>