Mqtt persistency

[Caros2017]

Copied from the discussion section:

I am not sure what I am doing wrong. I am running the latest version (2.7.8). I have multiple(5+) connections to my Mosquitto MQTT broker and they all stay persistent. But I can't get Grott working to be persistent.

In docker-compose I use this:

      - gblockcmd=False    
      - gnomqtt=False
      - gmqttretain=True

when I look at docker logs from Grott I see: Pulled 'gmqttretain=True' from the environment and

_MQTT:
        nomqtt                   False
        mqttip:                  **hidden**
        mqttport:                **hidden**
        mqtttopic:               energy/growatt
        mqttmtopic:              False
        mqttmtopicname:          energy/meter
        mqttinverterintopic:     False
        mqtttretain:             True

and - Grott MQTT message retain enabled But when I look at my Mosquitto logs I still see automatic disconnections from Grott:

1676205753: New connection from 172.21.0.1:54384 on port 1883.
1676205753: New client connected from 172.21.0.1:54384 as automatic (p2, c1, k60, u'grott').
1676205753: Client automatic disconnected.
1676205861: New connection from 172.21.0.1:55590 on port 1883.
1676205861: New client connected from 172.21.0.1:55590 as automatic (p2, c1, k60, u'grott').
1676205861: Client automatic disconnected.
1676205899: New connection from 172.21.0.1:56216 on port 1883.
1676205899: New client connected from 172.21.0.1:56216 as automatic (p2, c1, k60, u'grott').
1676205899: Client automatic disconnected.
1676205957: New connection from 172.21.0.1:56350 on port 1883.
1676205957: New client connected from 172.21.0.1:56350 as automatic (p2, c1, k60, u'grott').
1676205957: Client automatic disconnected.

Am I doing something wrong or is mqtttretain not working properly?

[johanmeijer]

Grott is not designed at this moment to have a persistent mqtt session. It works at fire and forget basis (publish only).

This is easier to program and not really an issue if you send a message once per 5 minutes (original Growatt interval).

Now with grottserver we can achieve a much shorter interval it might be a consideration to implement a persistent mqtt connection. It needs some rethinking while a not working mqqtt connection does not affect the communication flow with growatt (the primary objective).

If we create more and more persistency and statefullness within Grott I need to add all kind of error handling as well. I am not sure if this improve Grott (makes it at least more complex) and going think about it.

Even with a 10 second interval I do not think that not having a persistent mqtt connection is a real issue.

Be aware retain is something different then persistency.

[Caros2017]

Grott is not designed at this moment to have a persistent mqtt session. It works at fire and forget basis (publish only).

This is easier to program and not really an issue if you send a message once per 5 minutes (original Growatt interval).

Now with grottserver we can achieve a much shorter interval it might be a consideration to implement a persistent mqtt connection. It needs some rethinking while a not working mqqtt connection does not affect the communication flow with growatt (the primary objective).

If we create more and more persistency and statefullness within Grott I need to add all kind of error handling as well. I am not sure if this improve Grott (makes it at least more complex) and going think about it.

Even with a 10 second interval I do not think that not having a persistent mqtt connection is a real issue.

Be aware retain is something different then persistency.

Thanks for the comprehensive explanation. My request is for persistency indeed and not for retain. My bad! I confused both terms.