Structure Topic Mqtt Iot Hub

Question

Hello! , I have a question, I know the structure for the topic is "devices/DEVICE_ID/messages/events", without TOPIC, at least it is in the docummention https://learn.microsoft.com/en-us/azure/iot-hub/iot-hub-mqtt-support, but the tests that were done by @Red255 in another question tells us that we can use an extra word in the topic structure, it means the topic structure would be " devices/DEViCE_ID/messages/events/TOPIC".
could you confirm this information? Because if this is correct, the docummentation should be updated.

Answer 1

Hello @Eduardo Guido Flores Pascual ,

you want confirmation about the right topic for non-SDK MQTT communication to the Azure IoT HUb.

I used plain C# to describe the topic interaction workflow.

There I used this solution:

public string send_message_topic => $"devices/{_clientId}/messages/events/";  

var message = new MqttApplicationMessageBuilder()  
               .WithTopic(topics.send_message_topic + "$.ct=application%2Fjson&$.ce=utf-8" + "&a=a1&b=bb2")  
               .WithPayload(payloadString)  
               .WithQualityOfServiceLevel(MQTTnet.Protocol.MqttQualityOfServiceLevel.AtLeastOnce)  
               .Build();  

await mqttClient.PublishAsync(message);  

As you can see, several user properties can be sent along using string concatenation.

I wrote this blog post about the concept a couple of months ago.

See also this GitHub repo.