Mosquitto is an open source implementation of a server for version 3 of the
mqtt protocol. IBM have a closed source version of this server, known as
Really Small Message Broker (rsmb). The plan is to make this a more or less
drop in replacement.

From version 1.4, Python bindings are no longer included, but are available
separately from the Eclipse paho-mqtt project.

Mosquitto was written by Roger Light <roger@atchoo.org>