public object BeforeSendRequest(ref Message request, IClientChannel channel)
    {
        HttpRequestMessageProperty httpRequestMessage;
        object httpRequestMessageObject;
        string userName = "";
        string passWord = "";

        if (request.Properties.TryGetValue(HttpRequestMessageProperty.Name, out httpRequestMessageObject))
        {
            httpRequestMessage = httpRequestMessageObject as HttpRequestMessageProperty;

            foreach (var httpHeader in _httpHeaders)
            {
                //httpRequestMessage.Headers[httpHeader.Key] = httpHeader.Value;
                if (httpHeader.Key.CompareTo("Username") == 0)
                {
                    userName = httpHeader.Value;
                }
                else if (httpHeader.Key.CompareTo("Password") == 0)
                {
                    passWord = httpHeader.Value;
                }
            }

            httpRequestMessage.Headers[HttpRequestHeader.Authorization] = "Basic " +
                               Convert.ToBase64String(Encoding.ASCII.GetBytes(userName + ":" + passWord));
        }
        else
        {
            httpRequestMessage = new HttpRequestMessageProperty();

            foreach (var httpHeader in _httpHeaders)
            {
                httpRequestMessage.Headers.Add(httpHeader.Key, httpHeader.Value);
            }
            request.Properties.Add(HttpRequestMessageProperty.Name, httpRequestMessage);
        }
        return null;
    }`