Need example on implementing MessageHeaders.WriteHeaderContents

I have a custom header stored in a "string" variable, I need to replace the header of a outgoing SOAP request from my WCF client with the header in the "string" type variable. Based on research I see that implementing the MessageHeaders.开发者_开发问答WriteHeaderContents can work but this method accepts only XmlDictionaryWriter or XmlWriter types as input. I have a string input. How do I code in C# ..

Message headers are a SOAP concept, and SOAP requests are XML documents, so you really need some XML-ness there. But for your scenario, you actually don't need to override MessageHeaders, you can use an inspector and simply replace the header at that point, as shown in the example below (the conversion to XML will be done by the MessageHeader class).

public class StackOverflow_7141998
{
    [MessageContract]
    public class MyMC
    {
        [MessageHeader(Name = "MyHeader", Namespace = "http://my.namespace.com")]
        public string HeaderValue { get; set; }
        [MessageBodyMember(Name = "MyBody", Namespace = "http://my.namespace.com")]
        public string BodyValue { get; set; }
    }
    [ServiceContract]
    public interface ITest
    {
        [OperationContract]
        void Process(MyMC mc);
    }
    public class Service : ITest
    {
        public void Process(MyMC mc)
        {
            Console.WriteLine("Header value: {0}", mc.HeaderValue);
        }
    }
    public class MyInspector : IEndpointBehavior, IClientMessageInspector
    {
        public string NewHeaderValue { get; set; }

        public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
        {
        }

        public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
        {
            clientRuntime.MessageInspectors.Add(this);
        }

        public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
        {
        }

        public void Validate(ServiceEndpoint endpoint)
        {
        }

        public void AfterReceiveReply(ref Message reply, object correlationState)
        {
        }

        public object BeforeSendRequest(ref Message request, IClientChannel channel)
        {
            int originalIndex = request.Headers.FindHeader("MyHeader", "http://my.namespace.com");
            if (originalIndex >= 0)
            {
                request.Headers.Insert(originalIndex, MessageHeader.CreateHeader("MyHeader", "http://my.namespace.com", this.NewHeaderValue));
                request.Headers.RemoveAt(originalIndex + 1);
            }

            return null;
        }
    }
    public static void Test()
    {
        string baseAddress = "http://" + Environment.MachineName + ":8000/Service";
        ServiceHost host = new ServiceHost(typeof(Service), new Uri(baseAddress));
        ServiceEndpoint endpoint = host.AddServiceEndpoint(typeof(ITest), new WSHttpBinding(), "");
        host.Open();
        Console.WriteLine("Host opened");

        ChannelFactory<ITest> factory = new ChannelFactory<ITest>(new WSHttpBinding(), new EndpointAddress(baseAddress));
        MyInspector inspector = new MyInspector { NewHeaderValue = "Modified header value" };
        factory.Endpoint.Behaviors.Add(inspector);
        ITest proxy = factory.CreateChannel();

        proxy.Process(new MyMC { HeaderValue = "Original header value", BodyValue = "The body" });

        ((IClientChannel)proxy).Close();
        factory.Close();

        Console.Write("Press ENTER to close the host");
        Console.ReadLine();
        host.Close();
    }
}