Publish/Subscribe (pub/sub) semantics are critical for IoT applications due to their loosely coupled nature. Although OMG DDS, MQTT, and ZeroMQ are mature pub/sub solutions used for IoT, prior studies show that their performance varies significantly under different load conditions and QoS configurations, which makes middleware selection and configuration decisions hard. Moreover, the load conditions and role of QoS settings in prior comparison studies are not comprehensive and well- documented.
