MQTT v2 -> subscribe to topic *and* getting topic names

[binderth (Thomas Binder)]

I’d like to use MQTTv2 as a kind of mqtt-eventbus replacement. The docs are a bit low on examples and the forum is a bit confusing.
What I’d like to have:

• subscribing to mqtt topics
• getting the sent values
• getting the topic to update an item

I know, I could use this on an item-based configuration, but I like the idea laid out in:

openhab/openhab-addons/blob/main/bundles/org.openhab.binding.mqtt.generic/xtend_examples.md#synchronize-two-instances

Problem is: it doesn’t work as intended…

my things:

Bridge	mqtt:broker:synology	"MQTT-Synology"	[host="192.168.x.y", port=1883, secure=false, clientID="OH2Utilities", qos=1 ] 
	// subscribing
	Channels:
		Type	publishTrigger : MQTT_TriggerOHMainState	"MQTT-Eventbus OHMain receive"		[ stateTopic="openHAB/OH2Main/#", seperator="#" ]
}

	// publishing
	Thing  mqtt:topic:Comfoair	"die ComfoAir Topics" (mqtt:broker:synology)  @ "Technikraum"  {                         
		Channels:
			Type    number : MQTT_Comfoair_Filterperiod	"MQTT_ComfoAir Filterperiode"	[ stateTopic="openHAB/OH2Utilities/Comfoair_Filterperiod/state", commandTopic="openHAB/OH2Utilities/Comfoair_Control/command"]
			Type    number : MQTT_Comfoair_Fan_Level	"MQTT_ComfoAir Lüfterstufe"		[ stateTopic="openHAB/OH2Utilities/Comfoair_Fan_Level/state", commandTopic="openHAB/OH2Utilities/Comfoair_Fan_Level/command"]
			... 
    }

my rule

rule "Receive all"
when 
	Channel "mqtt:broker:synology:MQTT_TriggerOHMainState" triggered
then 
	//The receivedEvent String contains unneeded elements like the mqtt topic, we only need everything after the "/" as this is were item name and state are
	logInfo("MQTT OHMain", receivedEvent.getEvent())
	//val parts1 = receivedEvent.toString.split("/").get(1)
	//val parts2 = parts1.split("#")
	// sendCommand(parts2.get(0), parts2.get(1))
end

If I send a item-name to openHAB/OH2Main/# with a value, I only get the value:

2020-11-26 14:47:15.418 [vent.ChannelTriggeredEvent] - mqtt:broker:synology:MQTT_TriggerOHMainState triggered test
2020-11-26 14:47:15.428 [INFO ] [e.smarthome.model.script.MQTT OHMain] - test

So I never get the topic of the item, I send…? Is there a something I missed?

[CrazyIvan359 (Michael Murton)]

@rlkoshak has already made this:

https://github.com/rkoshak/openhab-rules-tools/tree/main/mqtt_eb

[binderth (Thomas Binder)]

still, in the docs it says:

MQTT - Bindings

The event payload (in receivedEvent) will be the received MQTT topic and its value, separated by the hash character (#).

so I guess it’s a bug? or did i miss some configuration option?

		Type	publishTrigger : MQTT_TriggerOHMainState	"MQTT-Eventbus OHMain receive"		[ stateTopic="openHAB/OH2Main/#", seperator="#" ]

[binderth (Thomas Binder)]

after reading this:

OH3 - Textual configuration still supported?

Textual config is still supported. However, disc errors do not occur when creating Things and Items through the Ui. That alone degrees a ton of debugging and time specify on support on this forum. All of the options are self evident and reasonably documented in the UI as well. Those who are motivated to do it all through text files can certainly do so. But ultimately it becomes a big time sink for both then and those of us who offer support on the forum. There are some bugs as well that only …

I did configure the Broker via PaperUI for once and now it worked, so I guess, despite me having Latin in school i misspelled separatorand seperator doesn’t work…
Working PaperUI configuration: note the “#” in the “separator character” part

and my .thing file also works with that:

		Type	publishTrigger : MQTT_TriggerOHMainState	"MQTT-Eventbus OHMain receive"		[ stateTopic="openHAB/OH2Main/#", separator="#" ]

[denominator (James Bowler)]

You set it up as a thing channel. In paper ui you set it up as a bridge channel so it should work.