Azure Device Provisioning Service(DPS) when transient isn’t

After some updates to my Device Provisioning Service(DPS) code the RegisterAsync method was exploding with an odd exception.

TTI Webhook Integration running in desktop emulator

In the Visual Studio 2019 Debugger the exception text was “IsTransient = true” so I went and made a coffee and tried again.

Visual Studio 2019 Quickwatch displaying short from error message

The call was still failing so I dumped out the exception text so I had some key words to search for

Microsoft.Azure.Devices.Provisioning.Client.ProvisioningTransportException: AMQP transport exception
 ---> System.UnauthorizedAccessException: Sys
   at Microsoft.Azure.Amqp.ExceptionDispatcher.Throw(Exception exception)
   at Microsoft.Azure.Amqp.AsyncResult.End[TAsyncResult](IAsyncResult result)
   at Microsoft.Azure.Amqp.AmqpObject.OpenAsyncResult.End(IAsyncResult result)
   at Microsoft.Azure.Amqp.AmqpObject.EndOpen(IAsyncResult result)
   at Microsoft.Azure.Amqp.Transport.AmqpTransportInitiator.HandleTransportOpened(IAsyncResult result)
   at Microsoft.Azure.Amqp.Transport.AmqpTransportInitiator.OnTransportOpenCompete(IAsyncResult result)
--- End of stack trace from previous location ---
   at Microsoft.Azure.Devices.Provisioning.Client.Transport.AmqpClientConnection.OpenAsync(TimeSpan timeout, Boolean useWebSocket, X509Certificate2 clientCert, IWebProxy proxy, RemoteCertificateValidationCallback remoteCerificateValidationCallback)
   at Microsoft.Azure.Devices.Provisioning.Client.Transport.ProvisioningTransportHandlerAmqp.RegisterAsync(ProvisioningTransportRegisterMessage message, TimeSpan timeout, CancellationToken cancellationToken)
   --- End of inner exception stack trace ---
   at Microsoft.Azure.Devices.Provisioning.Client.Transport.ProvisioningTransportHandlerAmqp.RegisterAsync(ProvisioningTransportRegisterMessage message, TimeSpan timeout, CancellationToken cancellationToken)
   at Microsoft.Azure.Devices.Provisioning.Client.Transport.ProvisioningTransportHandlerAmqp.RegisterAsync(ProvisioningTransportRegisterMessage message, CancellationToken cancellationToken)
   at devMobile.IoT.TheThingsIndustries.AzureIoTHub.Integration.Uplink(HttpRequestData req, FunctionContext executionContext) in C:\Users\BrynLewis\source\repos\TTIV3AzureIoTConnector\TTIV3WebHookAzureIoTHubIntegration\TTIUplinkHandler.cs:line 245

I tried a lot of keywords and went and looked at the source code on github

One of the many keyword searches

Another of the many keyword searches

I then tried another program which did used the Device provisioning Service and it worked first time so it was something wrong with the code.

using (var securityProvider = new SecurityProviderSymmetricKey(deviceId, deviceKey, null))
	using (var transport = new ProvisioningTransportHandlerAmqp(TransportFallbackType.TcpOnly))
		DeviceRegistrationResult result;

		ProvisioningDeviceClient provClient = ProvisioningDeviceClient.Create(
			 dpsApplicationSetting.GroupEnrollmentKey, <<= Should be _azureIoTSettings.DeviceProvisioningService.IdScope,

				result = await provClient.RegisterAsync();
		catch (ProvisioningTransportException ex)
			logger.LogInformation(ex, "Uplink-DeviceID:{0} RegisterAsync failed IDScope and/or GroupEnrollmentKey invalid", deviceId);

			return req.CreateResponse(HttpStatusCode.Unauthorized);

		if (result.Status != ProvisioningRegistrationStatusType.Assigned)
			_logger.LogError("Uplink-DeviceID:{0} Status:{1} RegisterAsync failed ", deviceId, result.Status);

			return req.CreateResponse(HttpStatusCode.FailedDependency);

		IAuthenticationMethod authentication = new DeviceAuthenticationWithRegistrySymmetricKey(result.DeviceId, (securityProvider as SecurityProviderSymmetricKey).GetPrimaryKey());

		deviceClient = DeviceClient.Create(result.AssignedHub, authentication, TransportSettings);

		await deviceClient.OpenAsync();

		logger.LogInformation("Uplink-DeviceID:{0} Azure IoT Hub connected (Device Provisioning Service)", deviceId);

I then carefully inspected my source code and worked back through the file history and realised I had accidentally replaced the IDScope with the GroupEnrollment setting so it was never going to work i.e. IsTransient != true. So, for the one or two other people who get this error message check your IDScope and GroupEnrollment key make sure they are the right variables and that values they contain are correct.

Microsoft Sync Framework timezones

Over the last few months I have been working with the Microsoft Sync Framework and the time zone issues have been a problem.

New Zealand has a 12hr standard time or 13 hr daylight savings time offset from Coordinated Universal Time (UTC) and at a glance our customer data could look ok if treated as either local or UTC.

After some experimentation I found that it was due to Windows Communication Foundation(WCF) serialisation issues (The proposed solutions looks like it might have some limitations, especially across daylight savings time transitions).

For the initial synchronisation DateTime values in the database were unchanged, but for any later incremental synchronisations the DateTime values were adjusted to the timezone of the server (Our Azure Cloud Services are UTC timezone, though I don’t understand why Microsoft by default has them set to US locale with MM/DD/YY date formats)

In our scenario having all of the DateTime values in the cloud local looked like a reasonable option and this article provided some useful insights.

In the end I found that setting the DateSetDateTime  for every DateTime column in each DataTable in the synchronisation DataSet to unspecified in the ProcessChangeBatch (our code was based on the samples) method meant that no adjustment was applied to the incremental updates

public override void ProcessChangeBatch(ConflictResolutionPolicy resolutionPolicy, ChangeBatch sourceChanges, object changeDataRetriever, SyncCallbacks syncCallbacks, SyncSessionStatistics sessionStatistics)
DbSyncContext context = changeDataRetriever as DbSyncContext;

if (context != null)
foreach (DataTable table in context.DataSet.Tables)
foreach (DataColumn column in table.Columns)
// Switching from UnspecifiedLocal to Unspecified is allowed even after the DataSet has rows.
if ((column.DataType == typeof(DateTime)) && (column.DateTimeMode == DataSetDateTime.UnspecifiedLocal))
column.DateTimeMode = DataSetDateTime.Unspecified;

Hope this helps someone else