Overview of Application Layer Protocol of Internet of Things

The IoT is enabled by the latest developments in RFID, smart sensors, communication technologies, and Internet protocols. The basic premise is to have smart sensors collaborate directly without human involvement to deliver a new class of applications. Besides, IoT has now a wide range of life applications such as industry, transportation, logistics, healthcare, smart environment, as well as personal, social gaming robot, and city information. The current revolution in Internet, mobile, and machine-to-machine (M2M) technologies can be seen as the first phase of the IoT. In the coming years, the IoT is expected to bridge diverse technologies to enable new applications by connecting physical objects together in support of intelligent decision making. This paper will give an overview of the current popular Internet of Things application layer protocols, including CoAP, MQTT, XMPP, DDS and AMQP. In addition, it will compare between commonly IoT communication protocols, with an emphasis on the main features and behaviors of various metrics of power security coding method transport layer protocol and other features. This comparison aims at presenting guidelines for the researchers to be able to select the right protocol for different applications.