/// <summary>
        /// private: convert response to dto object
        /// </summary>
        /// <param name="response"></param>
        /// <param name="session"></param>
        internal static PwgImageRate ConvertProxyResponseToDTO(PwgImageRateProxyResponse response)
        {
            PwgImageRate returnValue = new PwgImageRate();
            Double aDouble = 0;
            NumberStyles style = NumberStyles.AllowDecimalPoint;
            CultureInfo en_us = CultureInfo.CreateSpecificCulture("en-US");

            returnValue.Count = response.Count;

            returnValue.Stdev = 0.0 ;
            if (Double.TryParse(response.Stdev, style, en_us, out aDouble))
            {
                returnValue.Stdev = aDouble;
            }

            returnValue.Average = 0.0;
            if (Double.TryParse(response.Average, style, en_us, out aDouble))
            {
                returnValue.Average = aDouble;
            }

            return returnValue;
        }
        public PwgImageRate RateImage(Int32 imageId, Int32 imageRate)
        {
            PwgImageRate returnValue = new PwgImageRate();

            try
            {
                PwgImageRateProxyResponse response = PwgImagesProxy.pwg_images_rate(imageId, imageRate);

                if (response.Retour != PwgBaseProxyReponseRetourEnum.Ok)
                {
                    if (response.Erreur != null)
                    {
                        throw new PwgServiceException("RateImage, the server has return the error.",
                            response.Erreur.Code,
                            response.Erreur.Message);
                    }
                    else
                    {
                        throw new PwgServiceException("RateImage : a error occurs during server process.");
                    }
                }
                else
                {
                    returnValue = ConvertProxyResponseToDTO(response);
                }
            }
            catch (PwgProxyException ex)
            {
                throw new PwgServiceException("RateImage : a error is raised by proxy.", ex);
            }
            return returnValue;
        }