@lar3ry, you don't know MQTT? Then for sure my code makes no sense to you.
MQTT = Message Queue Telemetry Transport: MQTT - Wikipedia
Callback is part of Arduino Client for MQTT · knolleary
So "volume-up" runs if my MQTT broker on my server sends: "/mytopic/mytopic/IR-SonyTV/volume-up"
And "test" gets changed if i call/send: "/mytopic/mytopic/IR-SonyTV/volume-stop"