"Top-down doesn't work", quoting from Arlen Nipper, President and CTO of Cirrus Link, speaks at Advantech 2016 Industrial IoT World Partner Conference. Youtube Link The following MQTT Broker application structure is from GTWang Blogger . I think this structure delivers a clear spirit of MQTT that is M2M, Device to Device, Tag to Tag communication. It is a flat structure and just like Arlen said, Top-down doesn't work, because there is no master-slave or top-down relation in it. The Origin of MQTT MQTT(Message Queuing Telemetry Transport) was invented by Andy Stanford-Clark (IBM) and Arlen Nipper (Arcom, now Cirrus Link) back in 1999, when they faced AT&T regulation issue and turned to VSAT(satellite communication) solution to get data and control oil pipeline system. However, they could not use the traditional way to poll devices thru satellites due to data cost expensive and propagation delay. MQTT Benefits - Do More With Less MQTT is