The WebChannelFactory class WebChannelFactory does not accept HTTP headers, but you can add them to the current WebOperationContext if you create a new scope for it to work - see below.
WebChannelFactory<ICalculator> factory = new WebChannelFactory<ICalculator>(new Uri(baseAddress)); ICalculator proxy = factory.CreateChannel(); using (new OperationContextScope((IContextChannel)proxy)) { WebOperationContext.Current.OutgoingRequest.Headers.Add("referer", "http://stackoverflow.com"); WebOperationContext.Current.OutgoingRequest.Headers.Add("user-agent", "Mozilla/5.0"); Console.WriteLine("Add: {0}", proxy.Add(33, 55)); Console.WriteLine(); } using (new OperationContextScope((IContextChannel)proxy)) { WebOperationContext.Current.OutgoingRequest.Headers.Add("referer", "http://stackoverflow.com"); WebOperationContext.Current.OutgoingRequest.Headers.Add("user-agent", "Mozilla/5.0"); Console.WriteLine("Subtract: {0}", proxy.Subtract(44, 33)); Console.WriteLine(); }
This works, but it is pretty verbose - you need to create a new area for each call if you want to add outgoing headers to it.
Another option is to wrap the client in a client class to make a scope and title for you. Using a class derived from ClientBase<T> is an easy way to do this. The code below is a complete sample for this question with both options (using the scope directly, using a client-based class) to add HTTP headers to requests from proxies created using WebChannelFactory .
public class StackOverflow_10388746 { [ServiceContract] public interface ICalculator { [WebGet] int Add(int x, int y); [WebInvoke(BodyStyle = WebMessageBodyStyle.WrappedRequest)] int Subtract(int x, int y); } public class Service : ICalculator { public int Add(int x, int y) { PrintHeaders("Add"); return x + y; } public int Subtract(int x, int y) { PrintHeaders("Subtract"); return x - y; } void PrintHeaders(string operation) { Console.WriteLine("Incoming HTTP headers for operation '{0}'", operation); foreach (var header in WebOperationContext.Current.IncomingRequest.Headers.AllKeys) { Console.WriteLine(" {0}: {1}", header, WebOperationContext.Current.IncomingRequest.Headers[header]); } } } public class MyWebClient : ClientBase<ICalculator>, ICalculator { Dictionary<string, string> outgoingHeaders = new Dictionary<string, string>(); public MyWebClient(Uri baseAddress) : base(new WebHttpBinding(), new EndpointAddress(baseAddress)) { this.Endpoint.Behaviors.Add(new WebHttpBehavior()); } #region ICalculator Members public int Add(int x, int y) { using (new OperationContextScope(this.InnerChannel)) { foreach (var headerName in this.outgoingHeaders.Keys) { WebOperationContext.Current.OutgoingRequest.Headers.Add(headerName, this.outgoingHeaders[headerName]); } this.outgoingHeaders.Clear(); return this.Channel.Add(x, y); } } public int Subtract(int x, int y) { using (new OperationContextScope(this.InnerChannel)) { foreach (var headerName in this.outgoingHeaders.Keys) { WebOperationContext.Current.OutgoingRequest.Headers.Add(headerName, this.outgoingHeaders[headerName]); } this.outgoingHeaders.Clear(); return this.Channel.Subtract(x, y); } } #endregion public void AddOutgoingHeader(string name, string value) { this.outgoingHeaders.Add(name, value); } } public static void Test() { string baseAddress = "http://" + Environment.MachineName + ":8000/Service"; WebServiceHost host = new WebServiceHost(typeof(Service), new Uri(baseAddress)); host.Open(); Console.WriteLine("Host opened"); WebChannelFactory<ICalculator> factory = new WebChannelFactory<ICalculator>(new Uri(baseAddress)); ICalculator proxy = factory.CreateChannel(); using (new OperationContextScope((IContextChannel)proxy)) { WebOperationContext.Current.OutgoingRequest.Headers.Add("referer", "http://stackoverflow.com"); WebOperationContext.Current.OutgoingRequest.Headers.Add("user-agent", "Mozilla/5.0"); Console.WriteLine("Add: {0}", proxy.Add(33, 55)); Console.WriteLine(); } using (new OperationContextScope((IContextChannel)proxy)) { WebOperationContext.Current.OutgoingRequest.Headers.Add("referer", "http://stackoverflow.com"); WebOperationContext.Current.OutgoingRequest.Headers.Add("user-agent", "Mozilla/5.0"); Console.WriteLine("Subtract: {0}", proxy.Subtract(44, 33)); Console.WriteLine(); } MyWebClient client = new MyWebClient(new Uri(baseAddress)); client.AddOutgoingHeader("referer", "http://stackoverflow.com"); client.AddOutgoingHeader("user-agent", "Mozilla/5.0"); Console.WriteLine("Add (via client): {0}", client.Add(44, 77)); Console.WriteLine(); client.AddOutgoingHeader("referer", "http://stackoverflow.com/another"); client.AddOutgoingHeader("user-agent", "Mozilla/5.0-b"); Console.WriteLine("Add (via client): {0}", client.Subtract(44, 77)); Console.WriteLine(); Console.Write("Press ENTER to close the host"); Console.ReadLine(); host.Close(); } }