AZ-220 Microsoft Azure IoT Developer Questions and Answers

https://docs.microsoft.com/en-us/azure/iot-edge/deploy-modbus-gateway

In your Azure IoT Central application, add a real device to the device template

1. On the Devices page, select the Environmental sensor device template.

2. Select + New.

3. Make sure that Simulated is Off. Then select Create.

Click on the device name, and then select Connect. Make a note of the device connection information on the Device Connection page - ID scope, Device ID, and Primary key. You need these values when you create your device code:

Step 1: Provision Time Series Insights

Select Provision new IoT Hub to create a new IoT hub.

Step 2: Route telemetry from IoT Hub to a custom event.

Step 3: Add a data access policy to Time Series Insights for the dashboard web app

Scenario: Requirements. Pilot Requirements

During the pilot phase, devices will be deployed to 10 offices. Each office will have up to 1,000 devices.

During this phase, you will add Azure Time Series Insights in parallel to Stream Analytics to support real-time graphs and queries in a dashboard web app.

The pilot deployment must minimize operating costs.

When you create a Time Series Insights Preview pay-as-you-go (PAYG) SKU environment, you create two Azure resources:

An Azure Storage general-purpose V1 blob account for cold data storage.

An Azure Time Series Insights Preview environment that can be configured for warm data storage.

Scenario: POV Requirements

Ensure that all message content during this phase is human readable to simplify debugging.

Avro uses a binary format, so it is not human readable.

The more lightweight JSON (Javascript object notation) has become a popular alternative to XML for various reasons. A couple obvious ones are:

Less verbose- XML uses more words than necessary

JSON is faster- Parsing XML software is slow and cumbersome.

IoT Hub is one of the first Azure services to support distributed tracing. As more Azure services support distributed tracing, you'll be able trace IoT messages throughout the Azure services involved in your solution.

Note:

Enabling distributed tracing for IoT Hub gives you the ability to:

Precisely monitor the flow of each message through IoT Hub using trace context. This trace context includes correlation IDs that allow you to correlate events from one component with events from another component. It can be applied for a subset or all IoT device messages using device twin.

Automatically log the trace context to Azure Monitor diagnostic logs.

Measure and understand message flow and latency from devices to IoT Hub and routing endpoints. Start considering how you want to implement distributed tracing for the non-Azure services in your IoT solution.

Box 1: iothub1

The Azure IoT hub is named iothub1.

Box 2: azure-devices.net

The format of the device connection string looks like:

HostName={YourIoTHubName}.azure-devices.net;DeviceId=MyNodeDevice;SharedAccessKey={YourSharedAccessKey}

Box 1: device1

Device1 has a primary key of Uihuih76hbHb.

Box 1: ID Scope

In the Azure portal, select the Overview blade for your Device Provisioning service and copy the ID Scope value. The ID Scope is generated by the service and guarantees uniqueness. It is immutable and used to uniquely identify the registration IDs.

Box 2: Global device endpoint

The global_prov_uri variable, which allows the IoT Hub client registration API IoTHubClient_LL_CreateFromDeviceAuth to connect with the designated Device Provisioning Service instance.

Example code:

static const char* global_prov_uri = "global.azure-devices-provisioning.net";

static const char* id_scope = "[ID Scope]";

Scenario: You discover connectivity issues between the IoT gateway devices and iothub1, which cause IoT devices to lose connectivity and messages.

To log device connection events and errors, turn on diagnostics for IoT Hub. We recommend turning on these logs as early as possible, because if diagnostic logs aren't enabled, when device disconnects occur, you won't have any information to troubleshoot the problem with.

Step 1:

1.Sign in to the Azure portal.

2.Browse to your IoT hub.

3.Select Diagnostics settings.

4.Select Turn on diagnostics.

5.Enable Connections logs to be collected.

6.For easier analysis, turn on Send to Log Analytics (see pricing).

Step 2:

Set up alerts for device disconnect at scale

To get alerts when devices disconnect, configure alerts on the Connected devices (preview) metric.

Create a dedicated consumer group in the IoT hub for the Time Series Insights environment to consume from. Each Time Series Insights event source must have its own dedicated consumer group that isn't shared with any other consumer. If multiple readers consume events from the same consumer group, all readers are likely to exhibit failures.

Scenario: You plan to use a 30-second period to calculate the average temperature reading of the sensors.

Tumbling window functions are used to segment a data stream into distinct time segments and perform a function against them, such as the example below. The key differentiators of a Tumbling window are that they repeat, do not overlap, and an event cannot belong to more than one tumbling window.

InAnswers:

A: Hopping window functions hop forward in time by a fixed period. It may be easy to think of them as Tumbling windows that can overlap, so events can belong to more than one Hopping window result set.

Scenario: You discover connectivity issues between the IoT gateway devices and iothub1, which cause IoT devices to lose connectivity and messages.

To synchronize state information between a device and an IoT hub, you use device twins. A device twin is a JSON document, associated with a specific device, and stored by IoT Hub in the cloud where you can query them. A device twin contains desired properties, reported properties, and tags.

The Device Provisioning Service is included in the Basic Tiers (such as B1).

Instead update the twin desired property and check the corresponding reported property.

Note: IoT Hub provides three options for device apps to expose functionality to a back-end app:

• Twin's desired properties for long-running commands intended to put the device into a certain desired state. For example, set the telemetry send interval to 30 minutes.
• Direct methods for communications that require immediate confirmation of the result. Direct methods are often used for interactive control of devices such as turning on a fan.
• Cloud-to-device messages for one-way notifications to the device app.

Step 1: Run the following commands

Install the container runtime.

Azure IoT Edge relies on an OCI-compatible container runtime. For production scenarios, we recommended that you use the Moby-based engine provided below. The Moby engine is the only container engine officially supported with Azure IoT Edge. Docker CE/EE container images are compatible with the Moby runtime.

Install the Moby engine.

sudo apt-get install moby-engine

Install the Moby command-line interface (CLI). The CLI is useful for development but optional for production deployments.

sudo apt-get install moby-cli

Install the security daemon. The package is installed at /etc/iotedge/.

sudo apt-get install iotedge

Step 2: From Iot Hub,create an IoT Edge device registry entry.

Note: In your IoT Hub in the Azure portal, IoT Edge devices are created and managed separately from IOT devices that are not edge enabled.

• Sign in to the Azure portal and navigate to your IoT hub.
• In the left pane, select IoT Edge from the menu.
• Select Add an IoT Edge device.
• Provide a descriptive device ID. Use the default settings to auto-generate authentication keys and connect the new device to your hub.
• Select Save.

Retrieve the connection string in the Azure portal

1. When you're ready to set up your device, you need the connection string that links your physical device with its identity in the IoT hub.

2. From the IoT Edge page in the portal, click on the device ID from the list of IoT Edge devices.

3. Copy the value of either Primary Connection String or Secondary Connection String.

Step 3: Add the connection string to..

To manually provision a device, you need to provide it with a device connection string that you can create by registering a new device in your IoT hub.

Open the configuration file.

sudo nano /etc/iotedge/config.yaml

Find the provisioning configurations of the file and uncomment the Manual provisioning configuration section. Update the value of device_connection_string with the connection string from your IoT Edge device.

Save and close the file.

After entering the provisioning information in the configuration file, restart the daemon:

sudo systemctl restart iotedge

Box 1: Cert2 only

Cert2: The leaf certificate, or end-entity certificate, identifies the certificate holder. It has the root certificate in its certificate chain as well as zero or more intermediate certificates. The leaf certificate is not used to sign any other certificates. It uniquely identifies the device to the provisioning service and is sometimes referred to as the device certificate.

Box 2: Cert1 only

Cert1: A root certificate is a self-signed X.509 certificate representing a certificate authority (CA). It is the terminus, or trust anchor, of the certificate chain. Root certificates can be self-issued by an organization or purchased from a root certificate authority.