IoT Protocols

Because IoT connects physical objects, the following special requirements come into play:
  • More compact communication packet protocols
  • Real-time communication
  • Low power consumption

The following are three major IoT protocols designed with the above requirements in mind:


  • Stands for Message Queue Telemetry Transport
  • Is a publish-subscribe messaging protocol
  • Has small packet structure
  • Device subscribes to a topic on an MQTT broker
  • Uses an always-on TCP connection
  • MQTT-S (UDP based) can put device to sleep
  • Device publishes to a topic, other subscribed devices get update
  • Advantages: publish-subscribe message queue and many-to-many broadcast​
  • Disadvantage: no encryption in the base protocol


  • Stands for Constrained Application Protocol
  • Uses the UDP protocol
  • Can be interacted using REST-like API
  • Is suitable for low power sensors and devices
  • Is a request/response protocol
  • Has extremely small packet size and is designed to work on microcontrollers
  • Disadvantages: a one-to-one protocol; lack of a publish-subscribe message queue


  • Stands for eXtensible Messaging and Presence Protocol
  • Is a TCP communications protocol based on XML
  • Has been extended for use in publish-subscribe systems
  • Advantage: no single central server or broker
  • Disadvantages: no end-to-end encryption; no Quality of Service (QoS)