private static void createSubscription(IoTDAClient client)
        {
            CreateSubscriptionRequest req = new CreateSubscriptionRequest
            {
                Body = new CreateSubReq()
                {
                    Callbackurl = "https://10.10.10.10:443/deviceActivate",
                    Channel     = "http",
                    Subject     = new Subject()
                    {
                        Event    = "activate",
                        Resource = "device"
                    }
                }
            };

            try
            {
                var resp = client.CreateSubscription(req);
                Console.WriteLine(resp);
            }
            catch (RequestTimeoutException requestTimeoutException)
            {
                Console.WriteLine(requestTimeoutException.ErrorMessage);
            }
            catch (ServiceResponseException clientRequestException)
            {
                Console.WriteLine(clientRequestException.HttpStatusCode);
                Console.WriteLine(clientRequestException.ErrorCode);
                Console.WriteLine(clientRequestException.ErrorMsg);
            }
            catch (ConnectionException connectionException)
            {
                Console.WriteLine(connectionException.ErrorMessage);
            }
        }