Performance Characterization of MQTT Brokers in a Device-Local Edge Deployment.

The Message Queuing Telemetry Transport (MQTT) protocol is prevalent in the IoT landscape, as it can be used to dynamically interconnect the entities that produce and consume data (i.e., sensors and services/actuators) with easy-to-use abstractions and programming paradigms. In addition to its popularity for handling networked communications, MQTT can also be used to disseminate data towards different services located onto the same device, which can provide a significant amount of flexibility due to the malleable nature of the dynamic subscriptions. This paper presents a detailed performance comparison of four popular MQTT brokers over the use case of an autonomous robot that produces and disseminates data at a high volume and with a high frequency towards various locally deployed services. Our methodology considers various combinations of parameters, and we present a detailed characterization of different performance metrics, both under normal broker operation and peak load.