Mqtt
From Federal Burro of Information
mqtt server for centos 7 https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-the-mosquitto-mqtt-messaging-broker-on-centos-7
mqtt clent for pi https://www.baldengineer.com/mqtt-tutorial.html
mqtt for arduino https://io.adafruit.com/blog/security/2016/07/05/adafruit-io-security-esp8266/