mosquitto 1.4.15-2ubuntu0.18.04.1 (s390x binary) in ubuntu bionic

 This is a message broker that supports version 3.1 and 3.1.1 of the MQTT
 protocol.
 .
 MQTT provides a method of carrying out messaging using a publish/subscribe
 model. It is lightweight, both in terms of bandwidth usage and ease of
 implementation. This makes it particularly useful at the edge of the network
 where a sensor or other simple device may be implemented using an arduino for
 example.