Azure IoT Edge Queue Depth - azure

We are trying to debug an issue with Azure IoT edge modules deployed in a transient network environment. The problem is our edge module code sends messages using moduleclient and the call returns successfully. However some messages do not make it to the Azure Iot Hub in the cloud. The devices are often in a disconnected state and we are unsure if the messages are timing out on the upload queue or backing up on the edge hub queue because of lack of bandwidth. Is there anyway to check for edge hub queue depth and failed message count on the IoT edge runtime?

edgeHub exposes some metrics that you can collect and send to Log Analytics (or other tools), including messages received and sent. This might help you.
edgeHub metrics usage
List of edgeHub metrics

You may need to debug the communication between the IoT Edge Hub from the IoT Edge Runtime and the IoT Hub or between your module and the IoT Edge Hub. You can find more here:
https://learn.microsoft.com/en-us/azure/iot-edge/troubleshoot
From the cloud side (IoT Hub), you can try:
https://learn.microsoft.com/en-us/azure/iot-hub/iot-hub-troubleshoot-connectivity

Related

Azure IoT Device to Cloud, Metrics graph drops to zero at a particular time stamp

I have an Azure IoT device connected to an Azure IoT Hub. The device sends 6 - 7 messages per minute. By looking at the D2C message metrics, I found an outlier, that states that at a specific time, the count of the D2C message was zero (see picture). As the messages are routed to a storage, I can check the storage to see if there are messages missing at that specific time, but the data saved in the storage shows that every message was received correctly at that time. Does any one know how that comes or if the metrics are not that reliable generally? If that's the case, what is the best practice to monitor the IoT Hub message transfer?
IoT Hub D2C Message Metrics
EnqueuedTimeUtc in the storage
For precisely monitor the flow of each message through IoT Hub you will need to Trace Azure IoT device-to-cloud messages with distributed tracing (currently in preview)
This trace context includes correlation IDs that allow you to correlate events from one component with events from another component
Automatically log the trace context to Azure Monitor Logs.
Measure and understand message flow and latency from devices to IoT Hub and routing endpoints.
Ref: https://learn.microsoft.com/en-us/azure/iot-hub/iot-hub-distributed-tracing

What is practical usage of CorrelationId and MessageId when sending telemetry?

In the Azure IOT Hub Client telemetry sample there are two calls you can make that are commented out:
// Set Message property
/*(void)IoTHubMessage_SetMessageId(message_handle, "MSG_ID");
(void)IoTHubMessage_SetCorrelationId(message_handle, "CORE_ID");
...
*/
https://github.com/Azure/azure-iot-sdk-c/blob/master/iothub_client/samples/iothub_ll_telemetry_sample/iothub_ll_telemetry_sample.c
I understand I can pass strings into these calls in a certain format.
But what is their use case in Azure?
What should go into these fields to best help the user process the telemetry in Azure IoT Hub?
This page tells me the format of message id, not much guidance:
https://learn.microsoft.com/en-us/azure/iot-hub/iot-hub-devguide-messages-construct
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.
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.
here you can find more.

Is it possible to reuse Connections on Azure Functions when sending Device-to-Cloud messages to IoTHub?

I have an Azure IoTHub with thousands of devices registered. These devices communicate through a Telco provider who sends messages through an Azure Storage Queue. This Storage Queue triggers an Azure Function which needs to parse the messages and Send an Event to the IoTHub as below.
Currently, we use the Azure IoTHub SDK to create a DeviceClient for each payload and we send the event. Because the DeviceClient represents a device in the IoTHub and is carrying the context of the source of the events, we are having to recreate a device client for each event. This quickly exceeds the threshold of the number of Connections allowed on Azure Functions.
We have tried using the IoTHub Output bindings for Azure Functions, but could not get to work and I do not think it would work because we need to make sure that the events get to the IoTHub with the right context (messages are sent by the right device).
What's the right way to solve this? Can the connections to the IoTHub be reused? Should we abandon Azure Function in favour of something else?
I assume that Telco is some kind of custom device management solution(vendor lock solution), that can also communicate with the device and receive the device telemetry, and eventually forward it to the specified endpoint, correct?
If I may ask and if my assumption is correct, why do you need to deliver the events to IoT Hub, if you are not managing Telco devices through IoT Hub(the arrows on your diagram are only in one direction)?
Using the IoT Hub just as a message broker for essentially cloud-to-cloud communication is not beneficial if that is the only purpose. Also conceptually what you described is cloud-to-cloud communication, and IoT Hub is intended to be used for devices.
Here is what I would do. Setup the API Management(or http triggered Azure Function) as a front door for Telco and pass the messages to the Event Hub.
You can choose here to pass request body for example where your telemetry data is - I assume again.
Keep the IoT Hub, and setup the routing to previously created Event Hub.
Now, in case you have devices that are not vendor locked and that can talk directly to IoT Hub, messages will be re-routed to Event Hub. Also Telco device messages will be routed to exactly the same Event Hub.
Now you can have for example Azure Stream Analytics that can analyze data stream just from the Event Hub, and for both, Telco devices and potentially non-Telco devices.
After trying a few things, I ended up moving away from using the SDK for pushing messages to IoT Hub. This is because the SDK uses AMQP, and creating a DeviceClient for each payload is not viable.
We switched to using HTTPS instead to push the messages to IoT Hub and using HttpClientFactory, we are able to do connection pooling.
I thought I would put this here in case someone has the same issue.
Here is an example of the Http request to send message to IoT Hub
Host: https://<iothubname>.azure-devices.net/devices/<deviceId>/messages/events?api-version=2018-06-30
Authorization: SharedAccessSignature sr=<iothubname>.azure-devices.net&sig=abc123;12344iweoippweruea=iothubowner&se=1570574220
Body: <normal Interval or alarms payloads> // example {"deviceid": "abc", "hello": "world"}
Lastly, thanks #kgalic for the answer but your suggestion would not work. This is not pure B2B integration. Our implementation have to allow for both devices connecting directly to the IoT Hub and devices connecting through the Telco. This is why every device needs to have its own identity and digital twin.

How to send messages to iot edge hub using REST?

I'm using iot edge modules. I need to send messages to the hub from the edge module.
Per my understanding, I need to send it first to the iot edge hub, the edge hub will take care of transferring it to the cloud iot hub. I can consume it from there.
If that's supported, I'm looking for a REST sample on how to do that (or just REST documentation)
To send data to the IoT Edge hub, a module calls the SendEventAsync method.
ModuleClient client = new ModuleClient.CreateFromEnvironmentAsync(transportSettings);
await client.OpenAsync();
await client.SendEventAsync(“output1”, message);
Checkout the below link for moduleclient class methods and properties.
https://learn.microsoft.com/en-us/dotnet/api/microsoft.azure.devices.client.moduleclient?view=azure-dotnet
You don't necessarily have to use the ModuleClient SDK if you want to sent messages through IoT Edge to the cloud. The alternative would be to use IoT Edge in a transparent gateway mode: https://learn.microsoft.com/en-us/azure/iot-edge/how-to-connect-downstream-device
In this way your (virtual) device could connect to the Edge Hub just as it would connect directly to the IoT Hub - using AMQP, MQTT or - as you want to - HTTP.

Can Azure IOT hub be used to read(Get) data from some devices?

In my case I have 1000+ of devices that stores activity inside. I need to send a http get request to this device to get those data in csv or json format and save it in a storage hosted on azure.
Cab IOT hub require data using get request and can it be scheduled to read daily/weekly?
What other azure services would you suggest to facilitated this scheduled reads?
You have not mentioned which the Azure IoT Hub scale tier is used. Basically there are two price groups such as Basic and Standard with a significant different cost and capabilities. The Basic tier offers only services for one-way communications between the devices and Azure IoT Hub.
Based on that, the following scenarios can be used for your business case:
1. Basic Tier (non event-driven solution)
The device pushs periodicaly a telementry and non-telemetry messages based on the needs to the Azure IoT Hub, where the non-telemetry messages are routed to the Azure Function via the Service Bus Queue/Topic. Responsibility for this non-telemetry pipe is to persist a real device state in the database. Note, that the 6M messages will cost only $50/month. The back-end application can any time to query this database for devices state.
2. Standard Tier (event-driven solution) In this scenario you can use a Device Twin of the Azure IoT Hub to enable storing a real-device state in the cloud-backend (described by #HelenLo). The device can be triggered by C2D message, changing a desired property, invoking a method or based on the device edge trigger to the action for updating a state (reported properties).
The Azure IoT Hub has a capabilities to run your scheduled jobs for multiple devices.
In this solution, the back-end application can call any time a job for ExportDevicesAsync to the blob storage, see more details here. Note, that the 6M messages will cost $250/month.
As you can see the above each scenario needs to build a different device logic model based on the communications capabilities between the devices and Azure IoT Hub and back. Note, there are some limitations for these communications, see more details here.
You can consider using Device Twin of IoT Hub
https://learn.microsoft.com/en-us/azure/iot-hub/iot-hub-devguide-device-twins
Use device twins to:
Store device-specific metadata in the cloud. For example, the deployment location of a vending machine.
Report current state information such as available capabilities and conditions from your device app. For example, a device is connected to your IoT hub over cellular or WiFi.
Synchronize the state of long-running workflows between device app and back-end app. For example, when the solution back end specifies the new firmware version to install, and the device app reports the various stages of the update process.
Query your device metadata, configuration, or state.
IoT Hub provides you with the ability to connect your devices over various protocols. Preferred protocols are messaging protocols, such as MQTT or AMQP, but HTTPS is also supported. Using IoT hub, you do not request data from the device, though. The device will send the data to the IoT Hub. You have to options to implement that with IoT Hub:
The device connects to the IoT Hub whenever it has some data to be sent, and pushes the data up to IoT Hub
The device does not send any data on its own, but stays always or at least regularly connected to IoT Hub. You then can send a cloud to device message over IoT Hub to the device, requesting the data to be sent. The device then sends the data the same way it would in the first option.
When the data then has been sent to IoT Hub, you need to push it somewhere where it is persistently stored - IoT Hub only keeps messages for 1 day by default. Options for this are:
Create a blob storage account and push to that directly from IoT Hub using a custom endpoint This would probably be the easiest and cheapest. Dependening on how you need to access your data, a blob might not be the best option, though
Create a function app, create a function with an EventHubTrigger, connect it to IoT Hub and let the function process incoming data by outputting it into any kind of data sink, such as SQL, CosmosDB, Table Storage...

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