The application protocols of IoT enable network entities to identify and interact with each other. The application protocols form the functional blocks of IoT. It determines the application's complexity. the logical design of IoT system is the actual design of the configuration and assembly of its components (computers, sensors, and actuators).

1. What is the application protocol for IoT?
The application protocols of IoT enable network entities to identify and interact with each other. The application protocols
form the functional blocks of IoT. It determines the application's complexity. the logical design of IoT system is the actual
design of the configuration and assembly of its components (computers, sensors, and actuators).
Some of the IoT application protocols are
• MQTT (Message Queueing Telemetry Transport)
It is designed for IoT and M2M applications. It’s excellent for applications with limited bandwidth. Its architecture
is connection-oriented publish or subscribe. Here its applications can either publish (transmit) or subscribe to
(receive) topics which is done by the MQTT broker.
• HTTP (HyperText Transfer Protocol)
It is the most widely used protocol for navigating the Internet and making data available over REST APIs. it is
supported by IoT cloud services such as AWS IoT and Azure IoT.
Its main advantage is that web application developers use this mechanism to send data to a Webserver through
an HTTP POST request. Its disadvantages are that HTTP uses a connectionless request-respond communication.
This means that every message needs to include authentication information. Authentication information requires
data and energy consumption.
HTTP is ideal for cases that have fewer data and battery constraints as here the devices already need to call
existing REST APIs.

2. • WebSocket
It is a bi-directional communication protocol designed to quickly send large quantities of data in web applications.
It establishes a connection between the client and server after the initial connection establishment. Devices and
servers can simultaneously transmit and receive data in real-time. This makes WebSocket the best protocol for
IoT applications as low latency is critical and communication happens frequently. Due to this data consumption is
less important here.
• AMQP (Advanced Message Queuing Protocol)
It is an open-source protocol for Message-Oriented Middleware (MOM). It facilitates communications between
systems, devices, and applications from multiple vendors. It supports more routing options than just publishing
and subscribing to topics, unlike MQTT. it is supported by Azure IoT for device communication.
• CoAP (Constrained Application Protocol)
It is designed for low-power, lossy networks or “constrained” networks. It is highly efficient as it is paired with
User Datagram Protocol which makes it highly efficient. This makes it suitable for IoT applications where battery
conservation is important. It can use TCP or SMS as the transport mechanism.
• LwM2M (Lightweight Machine-to-Machine)
This protocol builds on CoAP for highly efficient low-power communication. It specifies device management and
provisioning functionality. It has a standardized procedure to clarify which security mechanism is used and how
the device firmware is updated. it can be used with UDP, TCP, and SMS for data transport since it is built with
CoAP.
• DDS (Data Distribution Service )
It is a communication protocol designed for solutions that require significant coordination, reliable transmissions,
and distributed processing between the devices themselves. the data can be directly been exchanged between
peers instead of sending data to a central hub or broker. This makes the system more robust and efficient. It uses
a publish/subscribe mechanism in which the devices subscribe to a topic and devices. It can also use TCP and
UDP as transmission protocols.
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