How to create MQTT Client using .Net Core 

Glad I could help!

Glad it was helpful Garry!

Glad it helped!

Glad it was helpful! 😁

Thanks!

Check if you have a main method which is the entry point for your application, it is the main which creates the instance of other class and calls the methods using those instances like subscribe and receive messages.

The public broker (test.mosquitto.org) is open to entire world so its pretty busy, maybe that is the reason you getting timeout, try to host your own broker locally and connect to it, let me know if you are still facing an issue then in that case there is probably an issue with code.

can you please elaborate, I couldn't understand your query.

I want to show a message in a textbox according to type of topic. How can I know which topic is received?

You should not check for the topic in case of every received message, it is the other way round, you have to subscribe to the topics in which you are interested in, the broker will take the responsibility of sending you all the messages for the topic which you have subscribed to, in case you are subscribing to multiple topics you need to also specify multiple message handlers in case you are planning to execute different functionality per topic.

@@RishabhSharma_95822 Can you give an example how to subscribe to multiple topics and use multiple message handlers? Thanks.

Yes exactly, once the broker is configured with a given username and password, in c# client you need to add .WithCredential(username, password) in your OptionsBuilder

ConnectionTimedOut mostly is due to the client not being able to establishing a connection with broker, the sequence does not matter much either the publisher or subscriber can establish the connection first in an asynchronous manner.

@@RishabhSharma_95822 Ah I see... is there any way/MQTT setting we can implement to ensure the connection can be established properly to the MQTT broker? As some Wi-Fi seems to block the connection (presumably due to Firewall, etc)?

if the connection is not established it'll automatically timeout and the event handler for successful connection will never be triggered, hence you'll get to know at the time of connection itself incase there is some issue.