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APPLICATION LAYER IoT NETWORK TECHNOLOGIES

 

APPLICATION LAYER IOT NETWORK TECHNOLOGIES

The application layer is the interface between the IoT device and the network with which it will communicate. It handles data formatting and presentation and serves as the bridge between what the IoT device is doing and the network handoff of the data it produces

HTTP and HTTPS are ubiquitous across internet applications, which is true also within IoT, with RESTful HTTP and HTTPS interfaces widely deployed. CoAP (Constrained Application Protocol) is like a lightweight HTTP that is often used in combination with 6LoWPAN over UDP. Messaging protocols like MQTT, AMQP, and XMPP are also frequently used within IoT applications:

MQTT

Message Queue Telemetry Transport (MQTT) is a publish/subscribe-based messaging protocol that was designed for use in low bandwidth situations, particularly for sensors and mobile devices on unreliable networks.

AMQP

Advanced Message Queuing Protocol (AMQP) is an open standard messaging protocol that is used for message-oriented middleware. Most notably, AMQP is implemented by RabbitMQ. 

XMPP

The Extensible Messaging and Presence Protocol (XMPP) was originally designed for real-time human-to-human communication including instant messaging. This protocol has been adapted for machine-to-machine (M2M) communication to implement lightweight middleware and for routing XML data. XMPP is primarily used with smart appliances.

 Your choice of technologies at this layer will depend on the specific application requirements of your IoT project. For example, for a budget home automation system that involves several sensors, MQTT would be a good choice as it is great for implementing messaging on devices without much storage or processing power because the protocol is simple and lightweight to implement.

The application layer refers to OSI Levels 5, 6, and 7. It is the application layer in the TCP-IP model. In IoT architecture, this layer lies above the service discovery layer. It is the highest layer in the architecture extending from the client ends. It is the interface between the end devices and the network. This layer is implemented through a dedicated application at the device end. As for a computer, the application layer is implemented by the browser. It is the browser that implements application layer protocols like HTTP, HTTPS, SMTP, and FTP. Same way, there are application layer protocols specified in the context of IoT as well.

This layer is responsible for data formatting and presentation. The application layer on the Internet is typically based on HTTP protocol. However, HTTP is not suitable in a resource-constrained environment because it is extremely heavyweight and thus incurs a large parsing overhead. So, there are many alternate protocols that have been developed for IoT environments. Some of the popular IoT application layer protocols are as follow –

• MQTT

• SMQTT

• CoAP

• DDS

• XMPP

• AMQP

• RESTful HTTP

• MQTT-SN

• STOMP

• SMCP

• LLAP

• SSI

• LWM2M

• M3DA

• XMPP-IOT

• ONS 2.0

• SOAP

• Websocket

• Reactive Streams

• HTTP/2

• JavaScript IOT

MQTT – Message Queuing Telemetry Transport is a lightweight messaging protocol. It uses publish-subscribe communication way and that’s why it is used for M2M (machine-to-machine) communication.  It is based on TCP-IP protocol and is designed to operate in a limited bandwidth. In the protocol terminology, the limited network bandwidth is referred as a ‘small code footprint’. However, the exact meaning of limited network bandwidth is not clear in the specification.

This protocol has been specially designed for sensor networks and wireless sensor networks. MQTT allows devices to send or publish data information on a given topic to a server. There is an MQTT broker (Broker- Mosquitto) in between the publisher and subscriber. The broker then transfers the information to the clients that are previously subscribed.

The sensors are interfaced with a broker which is an IOT device or server that reads and publish sensor data. The other devices that subscribe for and request sensor data are called clients. The sensors themselves are referred as publishers in the network.  The client can be a laptop, smartphone, tablet or another mobile device. The client devices need to subscribe to the broker in the network to receive sensor data. For receiving data, the subscribed client devices have to establish a connection with the broker and request data. The broker takes data from the publisher (wireless sensors) and sends it to the client requesting for it. Even if the connection with the client device is broken after the request has been made, the broker saves the data in a cache so that when the client device reconnects with the broker, it could receive the requested sensor data. Similarly, if the connection between the publisher and the broker is broken after the request has been made, the broker forwards appropriate instructions sent by the publisher, so that the client device can reconnect and receive the requested data.

So, MQTT fares well even when the connection between the broker and the publisher or broker and the client is broken due to limited network bandwidth. This ability to deal with delay or latency in network makes this protocol quite suitable for wireless networks.

'Acharya Ramchandra Shukla' was born in 1884 in a village named Agona in Basti district, Uttar Pradesh, India. His father Pt. Chandrawali Shukla was a Sarayuparin Brahmin. He was a supervisor Kanungo and biased of Urdu. Shuklji had studied till the Intermediate. After this, he did the job. Then he left the job and became a teacher. He started writing in Hindi from his student life. Impressed by Shuklaji's ability, Nagari Pracharini Sabha, Kashi called him to work in the Hindi literature. Shuklaji was appointed Hindi teacher in Hindu University and later became the Head of Hindi Department. He died in 1941 AD. Following are the major compositions of Acharya Ramchandra Shukla- 'Charan Vinod', 'Radhakrishna Das', 'Chintamani Triveni', 'Surdas', 'Ras Mimamsa', 'History of Hindi literature' etc. He edited 'Bhramar Geetasar', 'Bharatendu Sahitya', 'Tulsi Granthavali' and 'Jayasi Granthavali'. The talent of Acharya Ramchandra Shukla Ji was multi-faceted. He was a great essayist, critic and thinker. He is considered the first basic critic of Hindi. His history of Hindi literature is considered to be superior in history. Acharya Ramchandra Shukla was the pride of Hindi. Full name of 'Dr. A.P.J. Abdul Kalam' was 'Dr. Avul Pakir Jainulabdeen Abdul Kalam'. He was born on October 15, 1931 at Dhanushkothi in the temple town Rameshwaram in Tamil Nadu. He was born in a poor family, but he was an exceptionally brilliant child. Kalam passed the B.Sc. examination from Saint Joseph College, Thiruchirapalli. He joined Madras Institute of Technology (MIT). His further knowledge in the field got upgraded when he joined Defense Research and Development Organization (DRDO) in 1958 and Indian Space Research Organization (ISRO) in 1963. He is known as the Missile Man of India. The various Indian Missiles of world order like Prithvi, Trishul, Akash, Agni, etc. are mainly the result of his efforts and caliber. Dr. A.P.J. Abdul Kalam became the 11th President of India. He served the country from 2002 to 2007. For his excellence and brilliance, he was awarded the prestigious Bharat Ratna in 1998; Padma Vibhushan in 1990; and Padma Bhushan in 1981. Dr Kalam expired on Monday 27 July 2015. He suddenly fell unconscious when he was delivering a lecture at the Indian Institute of Management at Shillong. On 30 July 2015, the former President was laid to rest at Rameswaram's Pei Karumbu Ground with full state honours. Over 350,000 people attended the last rites, including the Prime Minister, the governor of Tamil Nadu and the chief ministers of Karnataka, Kerala and Andhra Pradesh. Dr. A.P.J. Abdul Kalam was mainly interested in work. He was a bachelor. He was not interested in going abroad. He wanted to serve his motherland first. He said that he thinks his first and foremost duty is to serve his motherland. He was fond of music and the Koran and the Gita. Ever since becoming the head of the Indian State, he had been having interaction with children all over the country. He was by no means a miracle man. His advice to the youngster of the nation was to "dream dream and convert these into thoughts and later into actions".
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