I have a question about an Azure IoT project based on Windows Azure. In short; it's an embedded application (ARM based device, running on a custom RTOS) who's sending device information to Windows Azure using the recently announced Serverbus Event Hub. It's using the HTTS endpoint of the Event Hub to send it's information to. So for so good.
But now I want to "talk" to the device from the cloud. Basically, I have a website running on Azure, and I want to send commands to that device (which is not 100% of the time connected, as it's an on-the-field device). What's the best way to do this? What technologies can I use?
Do I need to use Sockets, TCP connections, long-polling HTTP requests, ..? The big 'thing' is that the device is running a custom RTOS, so there are no libraries or whatsoever available..
Thanks! :)
You can think about AMQPS and Azure Service Bus Topics/Subscriptions. Create a subscription with a filter (e.g. by device name or ID) for each device and send annotated messages to the topic.
Count of subscriptions limited by 2000 for 1 topic.
Related
I am designing a solution for connected devices and have a requirement to re-provision a device before sending a message to ensure it is always connected to the nearest IoT Hub (based on latency).
Based on the Microsoft documentation, it is possible to register a device using MQTT by publishing a message to the DPS. However, is it possible to re-provision a device with MQTT?
https://learn.microsoft.com/en-us/azure/iot-dps/iot-dps-mqtt-support
Also, when registering a device for the first time via MQTT, is there a topic to subscribe to obtain the connection of the IoT Hub that DPS assigned the device?
Yes. The same API (Register message) triggers re-provisioning. The device is unaware as to whether it is being provisioned or re-provisioned.
The results of provisioning (or re-provisioning) including the name of the IotHub and the corresponding credential are published in the DeviceRegistrationResult
object. This object is part of the RegistrationOperationStatus object returned in response to the get-operation-status operation.
As per the documentation page you are referring to, you can subscribe to dps/registrations/res/# to be notified of the progress of your (re-)registration request.
I want to implement the following system.
There are users and each user will have an IoT device. The user should be able to do the following:
Login with their email and password.
Control the IoT device in real time (the user will perform some operation on the IoT device and the result will be displayed instantly on the app).
See the state of IoT device in real time. If something changes on the IoT device it should reflect on the app in real time.
I was wondering if this is doable using azure IoT Hub. I came across an architecture where the device is connected to IoT hub and the app is connected to signalR. The messages from IoT device will go to IoT Hub which will update the app using signalR.
But is there any way we can not have additional component like signalR? Can IoT device and mobile app be connected directly to azure IoT hub and exchange data between them without an entity in between other than IoT hub?
Connecting mobile app to IoT hub seems like an option but I did not find any way to implement email and password based authentication to allow users to connect to IoT hub.
Any help in this regard is appreciated.
You could absolutely go without SignalR. You can use the IoT Hub Service SDK to send C2D messages to your device from your phone, and also listen to the device telemetry with the same SDK.
However, it would probably be a better idea to have some restrictions on what you can do with that SDK. If the user first has to log in, I take it that they don't get access to every device in your application? Using some kind of role-based access might be preferable, you would build an API for that, which then uses the Service SDK to give you the data.
Also, even though you could listen to the device data directly from your phone, that means that if you have bad reception/wifi, data might not be received. You might want to consider storing it somewhere? I don't know the details about your application, but if you would then want to listen to events from that storage and send it to your app... SignalR might not be the worst idea.
"See the state of IoT device in real time. If something changes on the IoT device it should reflect on the app in real time."
For this EventGrid integration (https://learn.microsoft.com/en-us/azure/iot-hub/iot-hub-event-grid ) would help. For realtime telemetry as Matthijs said SignalR would be a better choice.If you are fine with some delay (say 10 sec) then Azure Time Series Insights can also be used.
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...
Does someone know the bare minimum required for a device to connect to the Azure IoT Hub and to send and receive messages (in terms of memory usage, processing power etc.). Or is this really case-specific?
I couldn't find a conclusive answer on the web. Does someone have experience with this?
Many thanks!
Does someone know the bare minimum required for a device to connect to
the Azure IoT Hub and to send and receive messages (in terms of memory
usage, processing power etc.).
As #juunas pointed out, it is hard to say precisely.
But you can check from the following two aspects(I assume you mean devices that communicate directly with Azure IoT Hub)：
Using Azure IoT SDKs, the device needs to be capable of establishing an IP connection, support TLS, have at least 64KB of RAM ...
Using REST api, the device can connect to the Azure IoT Hub and to send and receive messages directly over the Internet from any application that can send an HTTPS request and receive an HTTPS response.
There's nothing like system/set-up requirements for Azure IoT Hub so there's no specific document from Microsoft talking about this topic. Depending on your target application you can pick the device, as all descent embedded devices can act as IoT device for Azure.
You can take a look at Azure Certified IoT device catalogue and find out whether particular device is listed under that.
MS has published 2 Whitepapers on this. You may find this useful
Evaluating Your IOT Security
The right secure hardware for your IoT deployment
Consider a device placed in no GSM area, i.e. underground or in a pipe or similar. Those devices needs to be updated, checked, enabled/disabled via smartphones of workers passing by. Does Azure IoT support some kind of solution to this? Meaning a smartphone would store a command to a device or to Azure IoT till it reaches connection to Web.