9 years, 5 months ago.

MQTT Client reconnection: message Handler being called multiple times

Hi All,

I am using the U-blox C027 kit and programming it to be a MQTT client that publishes to one topic and subscribes to another. It works fine, and messages are sent and received as expected. However, if the client is disconnected unexpectedly, things get a little complicated...

I use the isConnected() function to check if the client has disconnected, reinitialize ipstack and client, and reconnect with the same clientID. Then I re-subscribe to the same topic as before and resume publishing. The publishing part works fine, but for the subscription part: when a new message is received, the messageArrived() function is called twice in succession, and the payload in the second call is only the first character of the actual message (payload in the first call is correct).

If there is another disconnection and reconnection, the same process repeats and the messageArrived() function is now called 3 times. The payload in the last 2 calls now contains only the first character of the actual message.

Please advise if this is a bug in the library, or if I may be doing something wrong.

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