How to read WCF message headers in duplex callback? - wcf

Question

In a normal WCF request/reply contract, you can read the message headers using something like:
OperationContract.Current.IncomingMessageHeaders
What I can't figure out is how to do this on the callback side of a duplex contract. Inside the callback implementation OperationContext.Current is null.
Edit 4/5/2013:
I'm using a custom binding based on net.tcp, but with a lot of customizations. For example, using protocol buffers message encoding rather than Xml. Also there is some custom security.

Answer 1

What binding are you using? In the SSCCE below the context is not null on the callback implementation.
public class StackOverflow_15769719
{
[ServiceContract(CallbackContract = typeof(ICallback))]
public interface ITest
{
[OperationContract]
string Hello(string text);
}
[ServiceContract]
public interface ICallback
{
[OperationContract(IsOneWay = true)]
void OnHello(string text);
}
public class Service : ITest
{
public string Hello(string text)
{
ICallback callback = OperationContext.Current.GetCallbackChannel<ICallback>();
ThreadPool.QueueUserWorkItem(delegate
{
callback.OnHello(text);
});
return text;
}
}
class MyCallback : ICallback
{
AutoResetEvent evt;
public MyCallback(AutoResetEvent evt)
{
this.evt = evt;
}
public void OnHello(string text)
{
Console.WriteLine("[callback] Headers: ");
foreach (var header in OperationContext.Current.IncomingMessageHeaders)
{
Console.WriteLine("[callback] {0}", header);
}
Console.WriteLine("[callback] OnHello({0})", text);
evt.Set();
}
}
public static void Test()
{
bool useTcp = false;
string baseAddress = useTcp ?
"net.tcp://" + Environment.MachineName + ":8000/Service" :
"http://" + Environment.MachineName + ":8000/Service";
ServiceHost host = new ServiceHost(typeof(Service), new Uri(baseAddress));
Binding binding = useTcp ?
(Binding)new NetTcpBinding(SecurityMode.None) :
new WSDualHttpBinding(WSDualHttpSecurityMode.None)
{
ClientBaseAddress = new Uri("http://" + Environment.MachineName + ":8888/Client")
};
host.AddServiceEndpoint(typeof(ITest), binding, "");
host.Open();
Console.WriteLine("Host opened");
AutoResetEvent evt = new AutoResetEvent(false);
MyCallback callback = new MyCallback(evt);
DuplexChannelFactory<ITest> factory = new DuplexChannelFactory<ITest>(
new InstanceContext(callback),
binding,
new EndpointAddress(baseAddress));
ITest proxy = factory.CreateChannel();
Console.WriteLine(proxy.Hello("foo bar"));
evt.WaitOne();
((IClientChannel)proxy).Close();
factory.Close();
Console.Write("Press ENTER to close the host");
Console.ReadLine();
host.Close();
}
}