Study of Internet-of-Things Messaging Protocols Used for Exchanging Data with External Sources

Internet-of-Things (IoT) is emerging as one of the popular technologies influencing every aspect of human life. The IoT devices equipped with sensors are changing every domain of the world to become smarter. In particular, the majorly benifited service sectors are agriculture, industries, healthcare, control & automation, retail & logistics, and power & energy. The data generated in these areas is massive requiring bigger storage and stronger compute. On the other hand, the IoT devices are limited in processing and storage capabilities and can not store and process the sensed data locally. Hence, there is a dire need to integrate these devices with the external data sources for effective utilisation and assessment of the collected data. Several existing well-known message exchange protocols like Message Queuing Telemetry Transport (MQTT), Advanced Message Queuing Protocol (AMQP), and Constrained Application Protocol (CoAP) are applicable in IoT communications. However, a thorough study is required to understand their impact and suitability in IoT scenario for the exchange of information between external data sources and IoT devices. In this paper, we designed and implemented an application layer framework to test and understand the behavior of these protocols and conducted the experiments on a realistic test bed using wired, wifi and 2/3/4G networks. The results revealed that MQTT and AMQP perform well on wired and wireless connections whereas CoAP performs consistently well and is less network dependent. On the lossy networks, CoAP generates low traffic as compared to MQTT and AMQP. The low memory footprint of MQTT and CoAP has made them a better choice over AMQP.