WCF Test Client error: Failed to Invoke the service

Question

I'm getting an error when trying to use the WCF Test Client with my WCF service. Here is the service code:

[ServiceContract]
public interface IEmployeeService
{
    [OperationContract(Name = "GetEmployee")]
    [WebGet(RequestFormat = WebMessageFormat.Xml,
     UriTemplate = "/Employees/{employeeNumber}")]
    Employee GetEmployee(string employeeNumber);
}

public Employee GetEmployee(string employeeNumber)
{
    var employeeNumberValue = Convert.ToInt32(employeeNumber);
    var employee = DataProvider.GetEmployee(employeeNumberValue);
    return employee;
}

<system.serviceModel>
    <services>
     <service name="Employees.Services.EmployeeService"
        behaviorConfiguration="metaBehavior">
      <endpoint address=""
          behaviorConfiguration="webHttp"
          binding="webHttpBinding"
          contract="Employees.Services.IEmployeeService">
      </endpoint>
      <endpoint address="mex"
          binding="mexHttpBinding"
          contract="IMetadataExchange">
      </endpoint>
     </service>
    </services>
    <behaviors>
     <endpointBehaviors>
      <behavior name="webHttp">
       <webHttp/>
      </behavior>
     </endpointBehaviors>
     <serviceBehaviors>
      <behavior name="metaBehavior">
       <serviceMetadata httpGetEnabled="true" />
      </behavior>
     </serviceBehaviors>
    </behaviors>
</system.serviceModel>

I am able to connect to the service using the WCF Test Client, but when I try to invoke GetEmployee(employeeNumber) I get the following error:

Failed to invoke the service. Possible causes: The service is offline or inaccessible; the client-side configuration does not match the proxy; the existing proxy is invalid. Refer to the stack trace for more detail. You can try to recover by starting a new proxy, restoring to default configuration, or refreshing the service.

I was able to successfully call this service by sending a request from the browser.

Any idea why I can't use the WCF Test Client?

Answer 1

Please ignore my earlier answer. I don't think the problem is at the client-side config.

See WCF Test Client and WebHttpBinding.

This is a limitation of the web programming model itself. Unlike SOAP endpoints (i.e., those with BasicHttpBinding, WSHttpBinding, etc) which have a way to expose metadata about itself (WSDL or Mex) with information about all the operations / parameters in the endpoint, there's currently no standard way to expose metadata for a non-SOAP endpoint - and that's exactly what the webHttpBinding-based endpoints are. In short, the WCF Test Client won't be useful for web-based endpoints. If some standard for representing web-style endpoints emerges when WCF ships its next version, we'll likely update the test client to support it, but for now there's none widely adopted.