Question

I’ve written a C# Windows Service that provides a REST api through WCF. This Service needs to call another web service which also uses a REST api. My service can communicate perfectly with the other service unless someone has made a call my service and it is currently responding. I wrote up a simple test:

public void TestConnection()
{
    WebChannelFactory<IOtherService> wf = new WebChannelFactory<IOtherService>(otherURI);
    IOtherService service = wf.CreateChannel();
    service.Test();
}

[ServiceContract]
public interface IOtherService
{
    [WebGet(UriTemplate = "services/account?username=testuser&password=d625a4de623dce36af2b75102eaf0ce7&locale=en-US", ResponseFormat = WebMessageFormat.Json, RequestFormat = WebMessageFormat.Json)]
    [OperationContract]
    AccountServiceInfo Test();
}

Normally when I call TestConnection it works perfectly, but when someone makes a call to my service that requires me to call TestConnection the other service sees a POST rather than a GET and returns 400. Does anyone have any idea why this might be the case or how I can fix it? Thanks.

Answer 1

When using a WebChannelFactory inside a WCF service that already has an OperationContext, you may need to create a new context before being able to successfully callout using a channel created by the WebChannelFactory.

public void TestConnection()
{
    var wf = new WebChannelFactory<IOtherService>(otherURI);
    var service = wf.CreateChannel();
    using ((IDisposable)service)
    using (new OperationContextScope((IContextChannel)service))
    {
      service.Test();
    }
}

http://blogs.msdn.com/b/pedram/archive/2008/07/19/webchannelfactory-inside-a-wcf-service.aspx