How to subscribe the data in azure iot hub to device using Mosquitto broker

Question

How to subscribe the data in azure iot hub to device using Mosquitto broker

A Arockia Jabamalai Eldsin 20

Hi,

This is Arockia, I am working in the MQTT for sending and receiving data from Azure IOT hub to device. I can send a data from Device to Azure IOT hub. User's image

but whatever data's send to Azure IOT hub that all I want to subscribe from another device. That area I can't see the msg. I can't connect with the Azure server.

First we are sending data from IOT device to UI successfully. Then we are sending data from UI to IOT device using Api and receiving data in IOT device. we want to display the received data in console using MQTT broker. But we are not able to display it in console.

Can You say what i need to do for the mosquitto_sub to receive the data from IOT hub to device.

Thanks,

Arockia

AshokPeddakotla-MSFT 35,971 Reputation points Moderator

2023-07-10T04:20:56.2433333+00:00

A Arockia Jabamalai Eldsin Just checking to see if you had a chance to review the below response from Sander.

Do let us know if that helps or have any other queries.

If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.

1 answer

Your answer

AshokPeddakotla-MSFT 35,971 Reputation points Moderator

2023-07-10T04:20:56.2433333+00:00

A Arockia Jabamalai Eldsin Just checking to see if you had a chance to review the below response from Sander.

Do let us know if that helps or have any other queries.

If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.

Answer 1

Sander van de Velde | MVP 36,766 MVP Volunteer Moderator

Hello @A Arockia Jabamalai Eldsin ,

thanks for visiting our moderated community forum.

The Azure IoT Hub is a cloud gateway for ingesting IoT Device telemetry.

The IoT Hub comes with impressive features like device registration (each device has its own identity), tagging of metadata, rule bases message routing, message enrichment, and even cloud-to-device communication using synchronous direct methods or asynchronous desired properties in the device twin.

The IoT Hub supports MQTT as a transport protocol (next to AMQP and HTTP) but it's not an MQTT broker. Topics are hidden from the actual message pass-through.

So, if you want to use the IoT Hub for distributing messages between devices, you need to add custom logic (like an Azure Function) and listen for incoming messages (there is an Azure Function IoT Hub trigger) and in the logic, you send a cloud message, set a desired property or try to call a direct method on the target devices of your choice.

If you are looking for full MQTT Broker functionality in the Azure cloud, check out the Event Grid MQTT support which is now in public preview.

Control your MQTT clients using the request-response (one-to-one) messaging pattern. This pattern enables any client to communicate with any other client without restrictions, regardless of the clients' roles. Broadcast alerts to a fleet of clients using the one-to-many messaging pattern. This pattern enables the application to publish only one message that the service replicates for every interested client.

This new service seems to meet your requirements.

If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. All community members with similar issues will benefit by doing so. Your contribution is highly appreciated.

A Arockia Jabamalai Eldsin 20 Reputation points

2023-07-12T11:44:54.83+00:00

Hi Sander,

The Event Grid MQTT is not related to IOT hub. Our main vision is needed to operate the IOT device from the UI using Azure IOT hub only.

In this concept we completed the publish the data from IOT device to Azure IOT hub but the Subscription part we can't achieve that and for publish method we are using the mosquitto MQTT broker and I add the documentation of the Mosquitto broker also.

https://techcommunity.microsoft.com/t5/internet-of-things-blog/mosquitto-client-tools-and-azure-iot-hub-the-beginning-of/ba-p/2824717

So can you tell me how to achieve the Subscribe the data from cloud to device throe IOT hub. Otherwise, can you say any standard MQTT broker for achieve the Publish/Subscribe both in Azure IOT hub.
Sander van de Velde | MVP 36,766 Reputation points MVP Volunteer Moderator

2023-07-12T16:25:21.9133333+00:00

Hello

Check out this blog post regarding the MQTT interface (and all supported topics) of the IoT Hub.

It's written in C# but will do fine as a reference for the strict interface consumption.

You will see that all c2d communication is supported like direct methods and desired properties.

I am not sure these specific MQTT topics and related flows are supported by Mosquitto.

Please share your findings.
A Arockia Jabamalai Eldsin 20 Reputation points

2023-07-31T07:17:11.6133333+00:00

Hi Sander,

Is there any example document for a direct method of cloud to device.
Sander van de Velde | MVP 36,766 Reputation points MVP Volunteer Moderator

2023-07-31T11:05:46.3233333+00:00

Hello Arockia,

Yes, check the documentation for this topic:

public string subscribe_topic_filter_directmethod => "$iothub/methods/POST/#";

In the C# example, a message handler is listening to this topic for direct methods calls.

Remember giving a direct method response:

internal string send_direct_method_response_topic => "$iothub/methods/res/200/?$rid=";

Share via

How to subscribe the data in azure iot hub to device using Mosquitto broker

1 answer

Your answer