indeed, hence the “big question”!
MQTT in general doesn’t seem well supported for PHP, IMO MQTT in emoncms is way more trouble than it’s worth. The Python MQTT (paho) will always be bang up to date for Mosquito as they are both by Eclipse, no reliance on 3rd parties. I think either MQTT in emoncms should be dropped and develop emonhub further to be the MQTT front end for emoncms OR just write a Python service to replace the PHP service, but the latter means you have 2 Python services doing the same thing. I have toyed with the idea of a redis interfacer for emonhub so that it can write directly to emoncms input queue’s somehow, using emonhub you could have as many MQTT interfacers set up as you liked, so subscribing to some obscure IoT devices MQTT topics would easy, rather than forcing all devices to publish to emoncms’s chosen base topic.