Smartish Edge Camera – Azure IoT Readonly Properties

This post builds on my Smartish Edge Camera – Azure IoT Direct Methods post adding a number of read only properties. In this version the application reports the OSVersion, MachineName, ApplicationVersion, ImageTimerDue, ImageTimerPeriod, YoloV5ModelPath, PredictionScoreThreshold, PredictionLabelsOfInterest, and PredictionLabelsMinimum.

Azure IoT Explorer displaying the reported “readonly” property values

The AzureMLMetSmartEdgeCamera application supports both Azure IoT Hub and Azure IoT Central connectivity so I have have covered inspecting the properties with Azure IoT Explorer and adding them to an Azure IoT Central Template.

Azure IoT Central Template Readonly properties

The code populates a TwinCollection then calls UpdateReportedPropertiesAsync to push the properties upto my Azure IoT Hub. (This functionality is not available on all Azure IoT hub Tiers)

protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
	_logger.LogInformation("Azure IoT Smart Edge Camera Service starting");

	try
	{
#if AZURE_IOT_HUB_CONNECTION
		_deviceClient = await AzureIoTHubConnection();
#endif
#if AZURE_IOT_HUB_DPS_CONNECTION
		_deviceClient = await AzureIoTHubDpsConnection();
#endif

#if AZURE_DEVICE_PROPERTIES
		_logger.LogTrace("ReportedPropeties upload start");

		TwinCollection reportedProperties = new TwinCollection();

		reportedProperties["OSVersion"] = Environment.OSVersion.VersionString;
		reportedProperties["MachineName"] = Environment.MachineName;
		reportedProperties["ApplicationVersion"] = Assembly.GetAssembly(typeof(Program)).GetName().Version;
		reportedProperties["ImageTimerDue"] = _applicationSettings.ImageTimerDue;
		reportedProperties["ImageTimerPeriod"] = _applicationSettings.ImageTimerPeriod;
		reportedProperties["YoloV5ModelPath"] = _applicationSettings.YoloV5ModelPath;

		reportedProperties["PredictionScoreThreshold"] = _applicationSettings.PredictionScoreThreshold;
		reportedProperties["PredictionLabelsOfInterest"] = _applicationSettings.PredictionLabelsOfInterest;
		reportedProperties["PredictionLabelsMinimum"] = _applicationSettings.PredictionLabelsMinimum;

		await _deviceClient.UpdateReportedPropertiesAsync(reportedProperties, stoppingToken);

		_logger.LogTrace("ReportedPropeties upload done");
#endif

		_logger.LogTrace("YoloV5 model setup start");
		_scorer = new YoloScorer<YoloCocoP5Model>(_applicationSettings.YoloV5ModelPath);
		_logger.LogTrace("YoloV5 model setup done");
...

Azure IoT Central Dashboard with readonly properties before UpdateReportedPropertiesAsync called
Azure IoT Central Telemetry displaying property update payloads
Azure IoT Central Dashboard displaying readonly properties

While testing the application I noticed the reported property version was increasing every time I deployed the application. I was retrieving the version information as the application started with AssemblyName.Version

reportedProperties["ApplicationVersion"] = Assembly.GetAssembly(typeof(Program)).GetName().Version;
Visual Studio 2019 Application Package information

I had also configured the Assembly Version in the SmartEdgeCameraAzureIoTService project Package tab to update the assembly build number each time the application was compiled. This was forcing an update of the reported properties version every time the application started

Smartish Edge Camera – Azure IoT Direct Methods

This post builds on my Smartish Edge Camera – Azure IoT Image-Upload post adding two Direct Methods for Starting and Stopping the image capture and processing timer. The AzureMLMetSmartEdgeCamera supports both Azure IoT Hub and Azure IoT Central connectivity.

Azure IoT Explorer invoking a Direct Method

BEWARE – The Direct Method names are case sensitive which regularly trips me up when I use Azure IoT Explorer. If the Direct Method name is unknown a default handler is called, the issue logged and a Hyper Text Transfer Protocol(HTTP) Not Implemented(501) error returned

protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
	_logger.LogInformation("Azure IoT Smart Edge Camera Service starting");

	try
	{
#if AZURE_IOT_HUB_CONNECTION
		_deviceClient = await AzureIoTHubConnection();
#endif
#if AZURE_IOT_HUB_DPS_CONNECTION
		_deviceClient = await AzureIoTHubDpsConnection();
#endif

...
		_logger.LogTrace("YoloV5 model setup start");
		_scorer = new YoloScorer<YoloCocoP5Model>(_applicationSettings.YoloV5ModelPath);
		_logger.LogTrace("YoloV5 model setup done");

		_ImageUpdatetimer = new Timer(ImageUpdateTimerCallback, null, _applicationSettings.ImageTimerDue, _applicationSettings.ImageTimerPeriod);

		await _deviceClient.SetMethodHandlerAsync("ImageTimerStart", ImageTimerStartHandler, null);
		await _deviceClient.SetMethodHandlerAsync("ImageTimerStop", ImageTimerStopHandler, null);
		await _deviceClient.SetMethodDefaultHandlerAsync(DefaultHandler, null);
...
		try
		{
			await Task.Delay(Timeout.Infinite, stoppingToken);
		}
		catch (TaskCanceledException)
		{
			_logger.LogInformation("Application shutown requested");
		}
	}
	catch (Exception ex)
	{
		_logger.LogError(ex, "Application startup failure");
	}
	finally
	{
		_deviceClient?.Dispose();
	}

	_logger.LogInformation("Azure IoT Smart Edge Camera Service shutdown");
}

private async Task<MethodResponse> ImageTimerStartHandler(MethodRequest methodRequest, object userContext)
{
	_logger.LogInformation("ImageUpdatetimer Start Due:{0} Period:{1}", _applicationSettings.ImageTimerDue, _applicationSettings.ImageTimerPeriod);

	_ImageUpdatetimer.Change(_applicationSettings.ImageTimerDue, _applicationSettings.ImageTimerPeriod);

	return new MethodResponse((short)HttpStatusCode.OK);
}

private async Task<MethodResponse> ImageTimerStopHandler(MethodRequest methodRequest, object userContext)
{
	_logger.LogInformation("ImageUpdatetimer Stop");

	_ImageUpdatetimer.Change(Timeout.Infinite, Timeout.Infinite);

	return new MethodResponse((short)HttpStatusCode.OK);
}

private async Task<MethodResponse> DefaultHandler(MethodRequest methodRequest, object userContext)
{
	_logger.LogInformation("Direct Method default handler Name:{0}", methodRequest.Name);

	return new MethodResponse((short)HttpStatusCode.NotFound);
}

I created an Azure IoT Central Template with two command capabilities. (For more detail see my post TTI V3 Connector Azure IoT Central Cloud to Device(C2D)).

Azure IoT Central Template Direct Method configuration
Azure IoT Central Template Direct Method invocation
Azure Smart Edge Camera console application Start Direct Method call

Initially, I had one long post which covered Direct Methods, Readonly Properties and Updateable Properties but it got too long so I split it into three.