A Comprehensive Survey on Application Layer Protocols in the Internet of Things

The number of connected IoT devices deployed globally is increasing at a tremendous rate. The IoT has a wide range of application domains providing extensive IoT-based services. The basic idea is to deliver a new set of applications where smart devices collaborate without any human interference. The variability and visibility of IoT based services lead to the development of the full spectrum of protocols. With the exponential growth of applications, it is essential to analyze the existing application layer protocols being used to exchange information among devices. In this paper, a detailed analysis of existing popular application layer protocols like Constrained Application Protocol (CoAP), Message Queue Telemetry Transport (MQTT), Advance Message Queuing Protocol (AMQP), Extensible Messaging and Presence Protocol (XMPP), etc. has been done to categorize them based on well-known properties such as architecture, energy consumption, reliability, QoS, and security aspects.