private string GetFactoryDevices(HttpContext context)
        {
            string strJson      = string.Empty;
            string strFactoryId = context.Request.Params["FactoryId"];

            Data.DataHelper           dataHelper = new Data.DataHelper();
            Data.DeviceInfoCollection items      = dataHelper.GetSmallFactoryDevices(strFactoryId);
            strJson = items.ToJsonString();

            return(strJson);
        }