Question

I am receiving the following error when trying to create an endpoint with the System.Data.Services.IRequestHandler contract

The operation ‘ProcessRequestForMessage’ could not be loaded because it has a parameter or return type of type System.ServiceModel.Channels.Message or a type that has MessageContractAttribute and other parameters of different types. When using System.ServiceModel.Channels.Message or types with MessageContractAttribute, the method must not use any other types of parameters.

I found two other questions with this error (here and here), but neither of them had satisfactory solutions. I pulled the Northwind example and was able to reproduce the problem.

The simplified web.config file:

<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.0">
      <assemblies>
        <add assembly="System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
      </assemblies>
    </compilation>
  </system.web>
  <system.webServer>
    <modules runAllManagedModulesForAllRequests="true" />
  </system.webServer>
  <system.serviceModel>
    <services>
      <service  name="NorthwindService.Northwind">
        <endpoint address="http://localhost:12345/Northwind.svc" binding="basicHttpBinding" contract="System.Data.Services.IRequestHandler" />
      </service>
    </services>
  </system.serviceModel>
</configuration>

.svc file:

<%@ ServiceHost Language="C#" Factory="System.Data.Services.DataServiceHostFactory, Microsoft.Data.Services, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" Service="NorthwindService.Northwind" %>

I can get rid of the error by replacing the System.Data.Services.IRequestHandler contract with my own and removing the parameter that the error message is complaining about.

The built-in ServiceContract, which throws the error:

namespace System.Data.Services
{
  [ServiceContract]
  public interface IRequestHandler
  {
    [OperationContract]
    [WebInvoke(UriTemplate = "*", Method = "*")]
    Message ProcessRequestForMessage(Stream messageBody);
  }
}

My ServiceContract, which doesn’t throw the error (but also doesn’t really work since I didn’t replicate all of the DataService<T> functionality):

namespace NorthwindService
{
  [ServiceContract]
  interface Interface1
  {
    [OperationContract]
    [WebInvoke(UriTemplate = "*", Method = "*")]
    Message ProcessRequestForMessage();
  }
}

I’m confused about why the built-in ServiceContract is throwing this error when I try to use it in an endpoint. I’m fairly new to Data Services, so I’m sure I am missing something that seems obvious to everyone else.

Thanks

Edit:
At the end of the day my goal is to use Certificate Authentication, so if there is a way to do that while working around this problem I’m open to it. I’ve been using this example.

Answer 1

You are using basicHttpBinding. Change it to webHttpBinding.