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In replication, data is synchronized between two or more servers. This is a method of storing the same data on more than one site or server. This feature allows data to be accessed seamlessly EVEN during server downtimes or heavy traffic. Users gain CONSISTENT access to data while not INTERFERING with or slowing down those of other users.  

Replication of data is more than just a BACKUP. A publisher is considered to be the server that originates the data, and a subscriber is the one where it is replicated. Data replication involves the publisher synchronizing its transaction with the subscriber and UPDATING subscriber data automatically. A change made on the publisher's side is automatically reflected on the subscriber's side as well. 

Sharding is the PROCESS of splitting very large databases into smaller, faster, and EASIER to manage pieces, called data shards. A shard is a small portion or chunk of a large data set. The principle of sharding is to split a logical DATASET into multiple databases in order to store it more EFFICIENTLY. In the case of a dataset that cannot be stored in a SINGLE database, sharding is necessary. 

The FOLLOWING DATABASES are SUITABLE for IOT: 

• InfluxDB
• Apache Cassandra
• RethinkDB
• MongoDB
• Sqlite

Contiki is an operating system DEVELOPED for IOT devices with limited MEMORY, power, bandwidth, and processing power. DESPITE being minimalist, it still contains many of the FEATURES common to modern operating systems. Programs, processes, resources, memory, and communication can be managed with its help. Due to its lightweight (by modern standards), mature, and flexible nature, it has become a go-to operating system by many academics, researchers, and professionals. 

Shodan (Sentient Hyper-Optimized Data ACCESS Network) is a SEARCH engine similar to Google, but it does not search for websites, but rather maps and information about internet-connected devices/systems. Shodan is sometimes referred to as an IOT search engine. To put it simply, Shodan is an IoT TOOL used to identify Internet-connected devices. It keeps track of all the machines with direct Internet access. 

Cybersecurity experts use Shodan as a tool to protect individuals, companies, and even public utilities against cyber-attacks. Shodan lets you search for any internet-connected device, and it will tell you if it is PUBLICLY available or not. 

Have trouble ADJUSTING the brightness of the LEDs in your project? Changing the voltage of the power supply directly in the circuit isn't easy. In that case, you can use Pulse WIDTH Modulation (PWM).  

Pulse Width Modulation (PWM), also referred to as PDM (Pulse Duration Modulation) refers to changing the amount of power that is delivered to a device. PWM is a TECHNIQUE for generating an analog signal from a digital source and is an efficient way to control the amount of energy delivered to a load without wasting any energy. PWM regulates voltage and is therefore used to control brightness in Smart Lighting Systems and also to control motor SPEED. 

IoT technology has been a driving force behind the development of smart cities since their inception. IoT technology will continue to grow as more countries adopt next-generation connectivity, and it will have a GREATER impact on our lives.  Connected sensors, lights, and meters are some of the IoT devices in smart cities that collect and ANALYZE data. As a result, cities use this data to improve INFRASTRUCTURE, utilities, and other city services.

It is possible to create clever energy grids, automated waste management systems, smart homes, advanced SECURITY systems, traffic management mechanisms, water conservation mechanisms, smart lighting, and more with the help of the IoT. IoT has added a new layer of artificial intelligence and innovation to public utilities and urban planning, allowing them to be highly INTUITIVE. These innovations have led to the emergence of smart homes and cities. 

A thermocouple is a sensor that measures temperature by coupling two metal pieces TOGETHER. The temperature is measured at a junction between these two pieces of metal which are joined at one END. A small voltage is generated by the metal conductors, which can be interpreted to calculate the temperature. A thermocouple is a simple, robust, and cost-effective temperature sensor available in multiple types and sizes. ADDITIONALLY, they measure a wide temperature range, making them suitable for a VARIETY of applications, such as scientific research, industrial settings, HOME appliances, and so on. 

Beginners may see BLE (Bluetooth LOW Energy) as a type of Bluetooth that uses less power, uses less energy. BLE, or Bluetooth Smart, is a relatively new form of Bluetooth technology that consumes much less power and costs than classic Bluetooth while offering a similar range of communication. As shown in the following diagram, BLE is not a replacement for Classic Bluetooth and they both serve a specific marketplace. 

The Bluetooth Low Energy technology has been developed with the purpose of facilitating the IoT. Generally, the Internet of Things is about connecting devices with each other, usually VIA a wireless connection, such as Bluetooth low energy to allow them to communicate and share DATA. With its high energy efficiency, BLE has become a PREFERRED and ideal choice for IoT. IoT enthusiasts and application developers have increasingly adopted Bluetooth LE to connect smart devices. 

Artificial Intelligence is at the core of IoT devices. The IoT consists of multiple components: sensors, a cloud component, data processing software, and cutting-edge user INTERFACES.   

IoT SYSTEMS consist of sensors/devices connected to the cloud VIA some form of connectivity. A Raspberry Pi equipped with a quadcore processor can be used as an "Internet gateway" for IoT devices. It is a card-sized COMPUTER using which you can control outputs with GIPO (general purpose input/output) pins as well as collect data about real-world conditions using sensors. A sensor gathers live data from the surrounding environment and sent to a cloud infrastructure. Once the data reaches the cloud, the software can process it and decide what action to take, such as sending an alert or automatically adjusting the sensors/devices without user intervention.

A user interface is used if user input is required or if they want to check in on the system. Adjustments made by the user are then sent inversely through the system - from the user interface to the cloud, and from the cloud BACK to the sensors/devices to make changes. As a result, a highly reactive and intuitive device is created which greatly increases automation. 

Following are some of the most common real-world applications of IoT: 

• Smart Homes: Smart homes are one of the most practical applications of IoT. Though IoT is applied in smart homes at various levels, the best one combines intelligent systems and entertainment. Example: Set-top box that allows you to record shows from REMOTE, an automatic lighting system, a smart lock, etc.
• Connect Health: Connected health systems allow for real-time monitoring and patient CARE. Patient data assists in better medical decisions. Also, IoT improves the power, precision, and availability of current devices.
• Wearables: Wearable devices have emerged as one of the earliest industries to deploy the IoT at scale. Various wearable devices are available today, such as Fit Bits, heart rate monitors, and smartwatches.
• Connected Cars: Connected cars use internet connectivity and onboard sensors to optimize their operation, maintenance, and PASSENGERS' comfort. Some of the LEADING automakers are working on bringing the next revolution to the car industry, including Tesla, BMW, Apple, and Google.
• Hospitality: By applying IoT to the hotel industry, a higher level of service quality is achieved. Various interactions can be automated by using electronic keys that are sent directly to the mobile devices of guests. Therefore, the IoT technology enables integrated applications to manage activities such as tracking guests' locations, sending offers or information about interesting activities, placing orders for room service or room orders, and automatically charging the room account.
• Farming: A variety of tools are being developed to deal with Drip Irrigation, understanding crop patterns, Water Distribution, drones for farm surveillance, etc. Farmers will be able to increase yields and address concerns using these methods.

In general, the Internet of Things is about connecting devices to the Internet, but how they connect is not always obvious. IoT devices connect and communicate through their technical communication models. An effective communication model shows how the process works and helps one understand how communication can be done. The Internet of Things (IoT) enables people and things (devices) to be connected wherever they are, using any network or service they like.  

Types of communication models -

• Request-Response Model: This communication model is based on the CLIENT (IoT DEVICE) making REQUESTS and the server responding to those requests. Upon receiving a request, the server decides what response to provide, fetches the requested data, prepares the response, and then sends it back to the client. This model is stateless because the data between requests is not RETAINED, THEREFORE each request is handled independently.

• Publisher-Subscriber Model: Publishers, brokers, and consumers are all involved in this communication model. Publishes are the sources of data that send data to topics. The broker manages the topics, and consumers (consume data from topics) subscribe to the topics. Publishers and consumers are unaware of each other. Upon receiving data for a topic from the publisher, the broker forwards it to all subscribed consumers. As a result, brokers are responsible for receiving data from publishers and sending it to the appropriate consumers.

• Push-Pull Model: This communication model entails data producers pushing the data into queues, while data consumers pull the data from the queues. Neither producer nor consumer needs to know about each other. The queues help decouple the messages between the consumers and the producers. Also, queues act as a buffer when there is a mismatch between the rate at which producers push data and the rate at which consumers pull it.

• Exclusive-Pair Model: Exclusive pairs are full-duplex, bidirectional communication models developed for constant/continuous connections between a client and server. After a connection is established, clients and servers can exchange messages. As long as a client doesn't send a request to close the connection, the connection remains open. The server is aware of every open connection.

Internet of Things (IoT) PROTOCOLS are ways of protecting data and ensuring it is exchanged securely between devices via the Internet. IoT protocols define how data is transmitted across the internet. By doing so, they ensure that data being exchanged between connected IoT devices is secure.  

Classification of IoT Protocols-

In recent years, Internet-of-Thing sensors have gained importance for enhancing productivity, lowering costs, and improving worker safety. Sensors are DEVICES that detect CHANGES in the environment condition and act accordingly. They detect specific types of CONDITIONS (such as light, heat, sound, distance, pressure, presence or absence of gas/liquid, etc.) in the physical world and then generate a signal (usually an electrical signal) as a measure of their magnitude. Sensors commonly USED in IoT systems include: 

• TEMPERATURE sensors
• Pressure sensor
• Motion detection sensors
• Gas sensor
• Proximity sensor
• IR sensors
• Smoke Sensor, etc.

The following are some security risks associated with IoT:  

• Privacy: Connected IoT devices are vulnerable to hacking. Many IoT devices collect and transmit personal data over an open network without ENCRYPTION, making it easy for hackers to access. Hackers may also use cloud endpoints to attack servers.
• Insufficient testing & Outdated product: In a fast-paced market like IoT, many companies or manufacturers rush to start releasing their products and software without doing enough testing. Many of them don't provide timely updates as well. Unlike other devices such as smartphones, IoT devices are not UPDATED, which can leave them vulnerable to data theft. Thus, IoT devices should be TESTED thoroughly and updated as soon as new vulnerabilities are identified in order to maintain security.
• Lack of KNOWLEDGE and awareness: Despite being a growing technology, people do not know much about IoT. A major security threat associated with IoT is the user's lack of knowledge and awareness of its capabilities. This POSES a threat to all users.
• Network Connectivity: Network connectivity can be challenging for many IoT devices. Particularly if such devices are widely dispersed, in remote locations, or if bandwidth is severely limited.
• Reliability: Given the highly distributed nature of IoT devices, it can be difficult to ensure the reliability of IoT systems. Various conditions can affect the components that make up an IoT system, such as natural disasters, disruptions in cloud services, power outages, and system failures.

An IoT (Internet of Things) system is an advanced automation and analytics system that makes use of networking, big data, sensing, and Artificial Intelligence to provide a complete solution. It provides the following benefits:   

• Improved customer engagement: IoT facilitates a better customer EXPERIENCE by automating tasks. In a car, for instance, any issue will be detected automatically by sensors. It will be notified to both the driver and manufacturer.
• Technical optimization: IoT has improved technology and made it more efficient. It has turned even old "dumb" devices into "smart" ones by making them able to transmit data over the internet, facilitating communication with PEOPLE and other IoT-enabled devices. For example, coffee machines, smart toys, smart microwaves, etc.
• Ease of Access: IoT has now enabled access to real-time information from (almost) any location. All you need is a smart device connected to the internet.
• Improved Insights: Currently we rely on superficial insights to make DECISIONS, but IoT provides real-time insights that lead to more efficient resource management.
• New business opportunities: By collecting and analyzing data from the network, you can uncover new business insights and generate new opportunities while reducing OPERATIONAL costs.
• Effective Time Management: Overall, the Internet of Things can save you a lot of time. While we commute to work, we can read the latest news on our phones, browse a blog about our favourite hobby, or shop online.
• Improved security measures: Using IoT, access control systems can provide ADDITIONAL security to organizations and individuals. As an example, IoT technology in surveillance can assist in improving security standards in an organization, as well as identifying any suspicious activity.

IoT devices usually consist of four main components as follows:   

• SENSORS: A sensor or device is an important component for gathering live data from the surrounding environment. The nature of this data can vary. This could be as simple as your phone having a temperature sensor, GPS, an accelerometer, or as complex as a live video feature on a social media platform. Sensors make it possible for IoT devices to CONNECT to the real world and environment.
• Connectivity: Upon collection, all data is sent to a cloud infrastructure. This could be done by connecting the sensors to the cloud using a variety of communication mediums such as mobile or satellite networks, Bluetooth, WI-FI, WAN, etc. Various IoT devices use different types of connectivity.
• Data Processing: Once the data has been collected, and has reached the cloud, it is the responsibility of the data processors to process it. Data processing software can enhance IoT devices in a wide range of ways, from adjusting the temperature of the air conditioner to recognizing faces on mobile phones.
• User Interface: An IoT device interacts with a user through a User Interface. A user interface is the visible, tangible component of an IoT system that can be accessed by users. It involves presenting the information in a way that is valuable to the end-user. A well-designed user interface will simplify the experience for users and ENCOURAGE them to interact more. Information needs to be made accessible to end-users in some way, like sending them ALERTS via notification, email or text message.

The following are the most important features of IoT on which it OPERATES: 

• Connectivity: Connectivity is the most important aspect of IoT. The IoT ecosystem (i.e. sensors, compute engines, DATA hubs, etc.) cannot operate properly without seamless communication among the interrelated components or objects. There are many ways to connect IoT devices including radio waves, Bluetooth, Wi-Fi, and Li-Fi.
• Analyzing/Sensing: Once all the relevant things are connected, the next step is to analyze data that is being collected and use it to build effective business intelligence. It is very important to extract knowledge from the generated data. A sensor, for example, generates data, but those data won't be of much use unless they are INTERPRETED properly by us.
• Active Engagements: A lot of today's interactions with connected technology occur via passive engagement. Through IoT, multiple products, cross-platform technologies, and services work together on an active engagement basis. The use of cloud computing in blockchain enables active engagements among IoT components in general.
• Scalability: Each DAY, more and more elements are connecting to the IoT zone. IoT setups should therefore be able to handle massive expansion. The data generated as a RESULT is immense, and it should be handled correctly.
• Artificial Intelligence: The IoT essentially makes things such as mobile phones, wearables, vehicles, etc., smart and enhances life by making use of data collection, artificial intelligence algorithms, and networked technologies. For example, if you have a coffee machine whose beans are going to end, it will order coffee beans from the retailer of your choice.