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Frequently Asked Questions
How would you rate WebSocket versus XMPP for Chat Apps?
How do MQTT and WebSockets differ?
Can DDS be used with TCP or UDP?
Which of these is an open standard HTTP COAP MQTT XMPP?
Last Updated: Mar 27, 2024

Comparison of IoT Protocols and which one to choose?

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Ashwin Goyal
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The Internet of Things can transmit and perform actions when connected to the Internet. A safe connection to a communication network is one example of an IoT device. Thousands of devices can communicate with each other over a wide range of connections, so the question arises: how many connections are possible? That whole question can be answered by Protocol. These devices can communicate with each other because of protocols, and a great many protocols have been introduced so far and continue to be introduced continuously. A lot of web protocols are used in the Internet of Things. Here are some of the various protocols we can discuss, including CoAP, MQAP, XMPP, DDS, Websockets, and HTTP.


Constrained Application Protocol(CoAP) is an internet application protocol for constrained devices created by IETF's constrained RESTFUL Environment (CoRE). CoAP is designed for devices connected to the same constrained network and for devices on different constrained networks connected via the Internet. It is designed specifically for IoT systems that use HTTP protocols.

CoAP uses UDP for lightweight implementation. The GET/POST/PUT/DELETE HTTP methods are used to eliminate ambiguity in social networking and mobile applications. CoAP is also used to send secure messages in the transport layer and DTLS (Datagram Transport Layer Security).


  • This allows for more efficient memory use and more rapid communication because the packet size is so small.
  • Due to the UDP protocol, devices can sleep for extended periods before waking up. By doing so, batteries can be conserved, and power consumption is reduced.
  • Asynchronous messages can be exchanged over CoAP.
  • Multicast messages can be forwarded to sensor nodes.


  • There is no broadcasting capability built into the Protocol because it is a one-to-one protocol but other protocols like MQTT, XMPP HTTP, etc.
  • It does not have a publish-subscribe queue but protocols such as MQTT, XMPP, etc.
  • There is no encryption involved in the Protocol.
  • CoAP may encounter problems if Network Address Translation devices are used since a dynamic IP address may be used.
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Messaging protocol MQTT (Message Queuing Telemetry Transport) is designed for devices with low bandwidth and limited hardware. As a result, there is no better way to exchange data between multiple IoT devices. It works by publishing data and receiving it by subscribing to it. A device publishes messages about a specific topic. These messages are distributed to all devices that are subscribed to the topic. Sending messages to control outputs, reading and publishing data from sensor nodes, and other functions make it useful.


  • The device is capable of broadcasting many-to-many.
  • Published-subscribed messaging is supported.
  • It offers lightweight and efficient communication.
  • Communication via MQTT uses less network bandwidth.


  • It is possible to put a device to sleep only a certain number of times. For devices that sleep more, use MQTT-S since it works with UDP instead of TCP.
  • The base protocol does not use encryption.
  • It is challenging to customize security at the application level.


Client-server communication can be done using Websocket because it is a full-duplex two-way communication protocol. A WebSocket API enables a browser to open interactive two-way communication sessions with a server using advanced technology. The API provides event-driven responses so that you don't have to poll the server for responses.

This Protocol supports stateful connections. This means the connection between the client and server stays alive until it is terminated by either the client or the server. After the connection is closed by either of the two, the connection will be closed from both ends. 

Websockets do not follow the HTTP protocol, so they do not use http:// or https://. 


  • The fastest transfer protocol due to its persistent connection. 
  • With a single connection, multiple users can communicate simultaneously, reducing latency. 
  • Data formats include binary and text. 
  • The Protocol can be extended and adapted to connect many types of protocols. 


  • It is a combined security measure.
  • The client does not support messaging or presence and needs to be connected to a separate chat protocol to provide these features.


This Protocol was developed for instant messaging (IM). XMPP stands for extensible messaging and presence. This type of communication is in the form of a text format in XML, a native format for personal communications. The XMPP protocol provides an easy way to address devices. The Protocol is not intended to handle large amounts of data rapidly. Most implementations rely only on periodic polling and checking of data. You can connect your home device to a web server using XMPP, for example, to access it from your home. In consumer-oriented IoT applications, it is not suitable due to its addressing, security, and scalability strengths.


  • A decentralized, open standard that allows extension and flexibility. 
  • A wide range of security features, including encryption, authentication, etc.
  • The product has been used for two decades. 
  • The Protocol can be used alongside others, such as WebSockets.


  • Binary data cannot be sent via this Protocol but MQTT, CoAP, etc can send binary data.
  • The slower transmission speed of centralized architecture is the result of decentralized architecture it can be solved by using the protocols such as MQTT, HTTP, XMPP.


Middleware and API standards for data-centric connectivity make up the data distribution service. The m2m object management group developed it for the m2m machine-to-machine communication protocol. Through its publisher-subscriber architecture, data can be exchanged between machines. As opposed to MQTT and CoAP, DDS has a broker-less architecture. Applications cannot be served in a high-quality manner by multicasting. A low-footprint device can deploy the DDS protocol to the cloud.


  • Due to its publish-subscribe architecture, a DDS-based system can quickly adapt and extend to changing environments and requirements.
  • The QoS mechanism used by the application is powerful.
  • This standard is flexible, extensible, and efficient.
  • A real-time IoT application can be implemented with this technology.
  • Using RTPS (Real Time Publish Subscribe) protocol, DDS allows interoperability for different vendors to communicate on the wire.
  • The DDS communication architecture offers low latency.
  • It uses TLS, DTLS, and DDS security mechanisms to provide a secured connection.


  • Embedded systems cannot use because it is too heavyweight. For this, we can use HTTP, XMPP, or WebSockets protocol. 
  • DDS does not support web services but WebSockets, HTTP, etc support web services.
  • Moreover, DDS uses twice as much bandwidth as MQTT.
  • To apply quality-of-service policies, DDS must be strictly defined.
  • The source of the event must be identified in real-time.


Hypertext transfer protocol is known as HTTP. It is used to send and receive messages between various systems on a network. It is one of the most popular application protocols used today. As an asymmetric client-server protocol, HTTP works by requesting some information from the server and requesting it back if it is available online. The HTTP protocol is stateless, meaning the server does not remember the previous requests sent by the client, so each request is independent. The OSI model requires it to operate over TCP and IP layers.


  • A user-friendly addressing scheme is used by HTTP. Names are assigned to IP addresses. In this way, the Web can easily identify them.
  • It is possible to process extremely large amounts of data using HTTP.
  • HTTP is flexible and can download plugins and extensions, such as Flash players.


  • HTTP does not use encryption methods, so there is no data integrity issue.
  • Data integrity issues result as a result of HTTP being insecure. 
  • A hacker can view all the content on a page if they intercept a request. Plus, they may be able to access confidential information that is sent over HTTP.
  • It consumes a great deal of power because HTTP uses more system resources.

Also see, Difference Between Verilog and Vhdl

Frequently Asked Questions

How would you rate WebSocket versus XMPP for Chat Apps?

Whether to use WebSockets or XMPP depends on the needs of your chat application - if you want high-grade security, presence, and a wide ecosystem of plugins, then XMPP is the better choice. However, if you're going to open multiple connections per user for different types of binary data with faster data transfer, WebSocket could be a better option.

How do MQTT and WebSockets differ?

In WebSockets, the client and the server are connected via a point-to-point connection. A benefit of MQTT is that it adds abstraction to the basic message sending mechanism so multiple interested machines can subscribe to the same topic.

Can DDS be used with TCP or UDP?

The data transfer protocol used by DDS is RTPS. The discovery and data transfer are handled by UDP/IP and comply with the wiring standard.

Which of these is an open standard HTTP COAP MQTT XMPP?

In lightweight M2M communication, MQTT is a public messaging protocol. The Protocol was initially developed by IBM and was made open for the world to use.

Also See - ,Locked based protocol in DBMS


This blog has discussed different protocols with their pros and cons through which you can understand the Protocol you need to use.

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Check out this article - Components Of IOT

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