MQTT

MQTT is a machine-to-machine (M2M)/"Internet of Things" connectivity protocol. It was designed as an extremely lightweight publish/subscribe messaging transport.

http://mqtt.org/

MQTT Broker

• Mosquitto (Open source & free)

• HiveMQ (Enterprise)

MQTT Client for Android

• https://eclipse.org/paho/clients/android/

References

• https://www.pubnub.com/blog/2014-08-14-what-is-mqtt-use-cases/

• https://code.facebook.com/posts/820258981365363/building-mobile-first-infrastructure-for-messenger/

• https://www.facebook.com/notes/facebook-engineering/building-facebook-messenger/10150259350998920/