class Program
    {
        static void Main(string[] args)
        {
                AuthenticationServiceClient asc = new AuthenticationServiceClient();

                string cookies = "";
                using (OperationContextScope scope = new OperationContextScope(asc.InnerChannel))
                {
                    asc.Login(username, password, null, false);
                    var p = OperationContext.Current.IncomingMessageProperties;
                    var responseProperties = p[HttpResponseMessageProperty.Name] as HttpResponseMessageProperty;
                    cookies = responseProperties.Headers[HttpResponseHeader.SetCookie];
                }

                cookies = ConstructCookies(cookies);

                PrimeServiceClient psc = new PrimeServiceClient();
                using (OperationContextScope scope = new OperationContextScope(psc.InnerChannel))
                {
                    var p = new HttpRequestMessageProperty();
                    OperationContext.Current.OutgoingMessageProperties.Add(HttpRequestMessageProperty.Name, p);
                    p.Headers.Add(HttpRequestHeader.Cookie, cookies);
                    Console.WriteLine(psc.NextPrime(3));
                }

                using (OperationContextScope scope = new OperationContextScope(asc.InnerChannel))
                {
                    var p = new HttpRequestMessageProperty();
                    OperationContext.Current.OutgoingMessageProperties.Add(HttpRequestMessageProperty.Name, p);
                    p.Headers.Add(HttpRequestHeader.Cookie, cookies);
                    asc.Logout();
                }
        }

        private static string ConstructCookies(string cookie)
        {
            // snipped... we will use the extension methods below
        }
    }