To get started with MQTT was quite simple.
I installed Mosquitto MQTT broker and its clients on my (Ubuntu) Linux laptop which I will use as my MQTT server for now:
$ sudo apt-get install mosquitto $ sudo apt-get install mosquitto-clients
Mosquitto started automatically after installation. I checked its status to confirm it’s running:
$ sudo service mosquitto status mosquitto start/running, process 808
I left Mosquitto configuration as-is for now. For any future reference, the config is at /etc/mosquitto/mosquitto.conf.
Installed mosquitto-clients provide two binaries that make testing and playing with MQTT really simple.
I ran a test topic subscribe in one terminal window and I published hello world message to the test topic from second terminal window.
In the first terminal, using mosquitto_sub I can subscribe to any topic (note, topics do not need to be pre-defined/configured first):
$ mosquitto_sub -t test
In the second terminal, using mosquitto_pub I can publish a message to any topic:
$ mosquitto_pub -t test -m "hello world"
The published message pops up in the first window:
$ mosquitto_sub -t test hello world
It’s really that simple.
Further notes are at my EtherMega MQTT Node