ABSTRACT
Applications related to the Internet-of-Things (IoT) dominate the Internet world. The Internet-of-Things makes computing available everywhere. It enables everyday devices with sensing, processing, and communication capabilities. IoT applications require a specialized protocol other than HTTP to handle the constrained devices involved. One communication protocol popular among IoT applications is Message Queuing Telemetry Transport (MQTT). Features such as its lightweight nature, the small fixed message header, message reliability and features suitable for applications in constrained environments make MQTT suitable for IoT applications. Information from specific sources may be more critical in IoT applications involving multiple input sensors. Such crucial messages should be treated immediately, ahead of other messages. Standard MQTT broker does not prioritize incoming messages. It forwards messages in the order they arrive. This chapter presents the results of analyzing attempts in the literature to assign priority to messages in the MQTT broker. Our study reveals that most of the existing works for prioritizing MQTT messages were proposals only, and it opens up a relevant research area in IoT communications.
