[Feature] Topic browser

[daenney]

Motivation

When connecting to a broker for exploration purposes you don't always know what topics are available. It would be nice if there was a topic browser, that showed all topics on the broker.

Detailed design

MQTT Explorer provides this feature. It seems to do this by subscribing to # and then continuously updating a tree view.

This would relate partially to #533.

More details

I realise it's not really possible to always show all topics. Even by subscribing to # the client would only become aware of topics that have messages published to them but that's already a lot more helpful than nothing at all.

[oceanlvr]

@daenney thanks for your suggestion, it's a great idea that topics show like a tree view when we sub # just in MQTT X. BTW, we developed another product named EMQX dashboard which clearly shows the sub/pub topic in the broker if your MQTT broker is EMQX.

[oceanlvr]

MQTT Explorer sub the # and $SYS/# automatically:

and show as a tree view like (when the # and $SYS topic available )

@ysfscream what's your opinion? Displaying all the topics exist/available in broker when the MQTT broker allows user to sub # topic, or just keep sub list clean, and suggest they use EMQX dashboard?

[daenney]

I had completely forgotten about the dashboard, that’s a great point. It would be nice to have a similar capability even if the broker isn’t emqx.

[ysfscream]

@daenney Hi! Thanks for your great suggestions and @oceanlvr thanks for your reply.

In fact, this functional design is there from the beginning, but I don't think it should be a default main feature, perhaps an extended feature is better and optional. We will consider implementing it later, but there is no actual idea. Maybe we can do more and discuss here.

[distinctdan]

I'll add that this is pretty much a deal breaker feature for me. Right now, there's no way to organize any of the messages, they just get dumped in one big giant list. I'm subscribing to a stream of events across maybe 20 topics, so I really need a way to organize them. I recognize tree views are hard to build - an easier, although not as good feature would be:

• Make clicking the topic toggle showing messages from that topic in the main list, so that you could hide message from certain topics, as a way to filter.
• Include a message count in the topic name instead of QoS. QoS isn't really important to view, and seeing the number of messages for a topic would be more useful.