Does bridging support subscription propagation?

[afshin-pir-GGL]

Hi

I wonder if the broker supports subscription propagation (topic routing) or not. Any idea?

[fabracht]

Hi. Thanks for the question. I'm not sure I understand what you mean.
Do you mean "propagation" as in:
Client A1 publishes to topic topic/A1 on broker B1
Broker B1 bridges topic/A1 to broker B2
Client A2 subscribes to topic/A1 on broker B2 and receives Client's A1 message?

Then yes. And you can actually simulate that with real MQTT on https://laboverwire.com/en
The simulation runs a full MQTT broker/client within the browser. No mocks, no pretending that we're running MQTT. It runs exactly the same protocol as the full version.

If that's not what you meant, can you please elaborate?

[fabracht]

If you are looking for a "replica" style propagation. Then you should use https://laboverwire.com/en/mqdb

MQDB runs the same broker, but adds a persistent layer within the machinery (not on top, not under, embedded in the MQTT path).
You can use it just as a pure MQTT broker, or use the full database functionality.
MQDB can be run with replicas, and each replica has a full list of what topics are subscribed and where. So the flow above changes to:
Client A1 publishes to topic topic/A1 on replica B1
---- nothing here, no bridging required ----
Client A2 subscribes to topic/A1 on replica B2 and receives Client's A1 message