Introduction to Microservice Architecture Using SpringBoot - Part 1

1] Data communications: components

Data communications involves the transmission of digital data between two or more devices, such as computers or smartphones. There are several components that make up a typical data communications system, including:

Sender: The device or computer that initiates the transmission of data.

Receiver: The device or computer that receives the transmitted data.

Transmission medium: The physical channel through which the data is transmitted, such as wires, cables, optical fibers, or wireless frequencies.

Modem: Short for modulator-demodulator, a device that converts the digital signals into analog signals suitable for transmission over the transmission medium, and converts the analog signals back into digital signals at the receiving end.

Protocols: A set of rules and procedures that govern the transmission of data over the network, ensuring reliable and efficient communication. Examples of protocols include TCP/IP, HTTP, FTP, and SMTP.

Network interface card (NIC): A hardware component that allows a computer to connect to a network and exchange data with other devices.

Switches and routers: Devices that manage and direct the flow of data between devices on a network.

Firewalls: Hardware or software devices that protect a network from unauthorized access and malicious attacks.

2] direction of data flow (simplex, half duplex, full duplex)

Simplex, half duplex, and full duplex are terms used to describe the direction of data flow in communication systems:

Simplex: In simplex communication, data flows in only one direction. For example, a radio station broadcasts a signal to all its listeners, but the listeners cannot send any data back to the station.

Half duplex: In half duplex communication, data flows in both directions, but only one direction at a time. For example, when two people are talking on a walkie-talkie, only one person can talk at a time, while the other person listens.

Full duplex: In full duplex communication, data flows in both directions simultaneously. For example, when two people are talking on a telephone, both can talk and listen at the same time.

The choice of communication mode depends on the requirements of the application and the available resources. Simplex is often used for one-way communication, while half duplex and full duplex are used for two-way communication.

3] physical structure (type of connection, topology) in computer network

Computer networks can be classified based on their physical structures, which refers to the way devices are connected and arranged in the network. Here are some common types of physical structures:

Bus network: In a bus network, all devices are connected to a single cable (known as a "bus"). Data is transmitted from one end of the cable to the other, and all devices receive the data. This type of network is simple to set up, but it can be slow and is not as reliable as other types.

Ring network: In a ring network, devices are connected in a circular loop. Data travels around the ring in one direction, and each device receives and forwards the data to the next device in the ring. This type of network is more reliable than a bus network, as if one device fails, the data can still travel around the ring in the opposite direction.

Star network: In a star network, each device is connected to a central hub or switch. All data transmissions must pass through the central hub, which manages the traffic between devices. This type of network is more reliable than a bus or ring network, as a failure of one device does not affect the entire network.

Mesh network: In a mesh network, each device is connected to multiple other devices, forming a network of overlapping connections. This type of network is highly reliable, as data can travel along multiple paths between devices, and a failure of one device does not necessarily disrupt the entire network.

Hybrid network: A hybrid network combines two or more of the above physical structures. For example, a network might use a star topology for local connections between devices, but also include a bus network for connecting remote locations. This type of network can be more complex to manage, but can offer greater flexibility and scalability.

There are also other types of physical structures, such as tree networks and fully connected networks, but these are less common in practice.

4] Categories of network (LAN, MAN,WAN)

There are three main categories of computer networks:

Local Area Network (LAN): A LAN is a network that connects computers and devices within a limited geographical area, such as a home, school, or office building. The devices are typically connected using Ethernet cables or Wi-Fi, and the network is typically owned and managed by a single organization.

Metropolitan Area Network (MAN): A MAN is a network that spans a larger geographical area than a LAN but is still confined to a single city or metropolitan area. MANs are typically used to connect multiple LANs or to provide high-speed connectivity between different locations of an organization.

Wide Area Network (WAN): A WAN is a network that covers a large geographical area, such as a country or even the world. WANs are typically used to connect multiple LANs and MANs together, and they use various technologies such as leased lines, satellite links, and the Internet to provide connectivity. The Internet is the largest WAN in the world.

5] Protocols and standards

Protocols and standards are both important concepts in the field of computer networking and communication.

A protocol is a set of rules and procedures that govern the communication between two or more devices in a network. It defines how data is transmitted, received, and interpreted by the devices involved in the communication process. Protocols can be implemented in hardware, software, or a combination of both, and they help ensure that devices can communicate with each other even if they are manufactured by different companies or use different technologies.

Some common protocols used in networking include TCP/IP (Transmission Control Protocol/Internet Protocol), HTTP (Hypertext Transfer Protocol), and SMTP (Simple Mail Transfer Protocol).

Standards, on the other hand, are guidelines or specifications that are developed by industry organizations or government agencies to ensure that products and services are interoperable and compatible with each other. Standards define the technical requirements for a product or service, including its design, performance, and interoperability with other products or services.

Standards help to promote innovation, ensure interoperability, and improve the reliability and quality of products and services. Examples of standards organizations include the International Organization for Standardization (ISO), the Institute of Electrical and Electronics Engineers (IEEE), and the Internet Engineering Task Force (IETF).

6] OSI reference model

The OSI (Open Systems Interconnection) reference model is a conceptual framework that describes the functions of a communication system. It consists of seven layers, each of which represents a different aspect of communication. The layers are:

Physical Layer: This layer deals with the physical aspects of communication, such as the transmission of raw data over a communication channel.

Data Link Layer: This layer is responsible for the reliable transmission of data over a physical link. It provides error detection and correction and manages the flow of data.

Network Layer: This layer deals with the routing of data across different networks. It determines the optimal path for data transmission and manages congestion control.

Transport Layer: This layer provides end-to-end communication between applications. It ensures that data is delivered reliably and in the correct order.

Session Layer: This layer establishes, manages, and terminates sessions between applications. It provides services such as authentication and encryption.

Presentation Layer: This layer is responsible for the representation of data in a form that can be understood by the receiving application. It deals with issues such as data compression and encryption.

Application Layer: This layer provides services to the user, such as email and file transfer. It is the layer that interacts with the user and the user's applications.

7] TCP/IP reference model

communication protocols used on the Internet. It is composed of four layers:

Application layer: This layer provides services for end users, such as email, file transfer, and web browsing. Application layer protocols include HTTP, SMTP, FTP, and DNS.

Transport layer: This layer provides end-to-end data transport services between applications. It includes two protocols, Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).

Internet layer: This layer provides routing and addressing functions for the transmission of data packets across networks. The Internet Protocol (IP) is the primary protocol used at this layer.

Network Access layer: This layer provides the interface between the network and the physical transmission medium, such as Ethernet or Wi-Fi.

Each layer of the TCP/IP model performs specific functions that are necessary for communication over the Internet. The model is often compared to the OSI reference model, which has seven layers, but TCP/IP is the de facto standard for Internet communication.

8] OSI vs TCP - IP MODEL

OSI	TCP/IP
Developed by ISO.	Developed by ARPANET.
It is only a reference model and no actual implementation is done on this model.	This model is used for the development of the internet.
Stands for: Open System Interconnection.	Stands for: Transmission Control Protocol/Internet Protocol.
The transport layer confirms the delivery of the packets.	The transport layer does not confirm the delivery of the packets.
A vertical approach followed.	A horizontal approach followed.
Presentation and Session layers are different.	Both are the same and are included under the application layer.
It can be used to build models like TCP/IP.	It cannot be used for model building.
The network layer can provide connectionless service as well along with connection service.	The network layer can only provide connectionless service.
There exist 7 layers.	There exist 5 layers.
Used very less compared to TCP/IP.	Highly used.

Physical Level:

9] Overview of data(analog & digital)

Data can exist in two main forms: analog and digital.

Analog data is continuous and can take on any value within a given range. Examples of analog data include the sound waves produced by a musical instrument, the temperature of a room, and the voltage in an electrical circuit.

Digital data, on the other hand, is discrete and represented by binary code, which is a series of ones and zeros. Digital data is created through a process called digitization, which involves converting analog data into digital form. Examples of digital data include text, images, and videos.

However, some types of data are more suitable for analog representation. For example, music enthusiasts often argue that analog recordings have a warmer, more natural sound compared to digital recordings.

10] signal(analog & digital)

A signal is a physical phenomenon that conveys information. Signals can be either analog or digital.

Analog signals are continuous and vary in amplitude and frequency over time. Examples of analog signals include sound waves, radio waves, and electrical signals in a circuit. Analog signals can take on any value within a given range, and their quality can be affected by noise and distortion.

Digital signals, on the other hand, are discrete and represented by a series of ones and zeros. Digital signals are used to represent data in computers, telecommunications, and other digital devices. They are less prone to noise and distortion compared to analog signals, and can be easily transmitted and stored.

To convert an analog signal to a digital signal, the signal is first sampled at regular intervals, and the amplitude of each sample is quantized into a binary code. The number of bits used to represent each sample determines the resolution of the digital signal, and a higher resolution generally results in better quality.

However, digital signals have some limitations. They require more bandwidth than analog signals to transmit the same amount of information, and they can be affected by jitter and other timing errors. In some cases, analog signals may be preferred over digital signals for their higher fidelity and more natural sound or image quality.

11] Transmission media (guided & unguided)

Transmission media are the physical channels that carry signals from one device to another in a communication system. There are two types of transmission media: guided and unguided.

Guided Transmission Media: Guided transmission media are those in which the signals are guided along a physical path. The guided transmission media can be further classified into two types:

Twisted Pair Cable: Twisted pair cable consists of two copper wires that are twisted together. It is commonly used in telephone lines and LANs (Local Area Networks) for data communication. Twisted pair cables are low cost and easy to install, but they are prone to interference and have limited bandwidth.

Coaxial Cable: Coaxial cable consists of a copper wire that is surrounded by insulation and a second conductor that is a cylindrical shield. It is commonly used for cable TV and broadband internet connections. Coaxial cables have higher bandwidth than twisted pair cables, but they are more expensive and difficult to install.

Fiber Optic Cable: Fiber optic cable consists of a thin glass or plastic fiber that carries signals in the form of light. It is commonly used for long distance communication and high-speed data transmission. Fiber optic cables have the highest bandwidth and are immune to interference, but they are expensive and require special equipment to install and maintain.

Unguided Transmission Media:

Unguided transmission media are those in which the signals are not guided along a physical path, but are instead radiated through the air or space. The unguided transmission media can be further classified into two types:

Radio Waves: Radio waves are used for wireless communication, such as cell phones, radios, and Wi-Fi networks. They have a limited range and are susceptible to interference, but they are easy to use and do not require physical infrastructure.

Microwaves: Microwaves are used for point-to-point communication, such as satellite communication and microwave ovens. They have a higher bandwidth than radio waves, but they require a clear line of sight and are affected by weather conditions.

In summary, guided transmission media use physical channels to carry signals, while unguided transmission media use the air or space to transmit signals. Guided transmission media include twisted pair cables, coaxial cables, and fiber optic cables, while unguided transmission media include radio waves and microwaves.

12] Circuit switching: time division & space division switch

Circuit switching is a method of establishing a dedicated communication path between two devices in a network. In circuit switching, a physical path is established between the two devices for the duration of the communication. There are two main types of circuit switching: time-division switching and space-division switching.

Time-division switching involves dividing a communication channel into time slots and allocating each time slot to a particular user. The channel is shared among multiple users, but each user is assigned a dedicated time slot to transmit their data. The advantage of time-division switching is that it is efficient in utilizing the available bandwidth. However, it may result in delays if there are many users sharing the same channel.

Space-division switching involves dividing a communication channel into physical sections and allocating each section to a particular user. Each user has their own physical section of the channel to transmit their data. The advantage of space-division switching is that it can handle high traffic volumes without delays, as each user has their own dedicated section of the channel. However, it is not as efficient in utilizing the available bandwidth as time-division switching.

Both time-division and space-division switching have their own advantages and disadvantages, and the choice between the two depends on the specific requirements of the communication network.

13] TDM Bus

A TDM (Time-Division Multiplexing) bus is a communication protocol that enables multiple devices to share a single communication channel by dividing it into multiple time slots. Each device is assigned a specific time slot, and during that time, it can transmit or receive data over the shared channel.

TDM buses are commonly used in telecommunications and networking to increase the efficiency of data transmission. By allowing multiple devices to use a single communication channel, TDM buses reduce the cost and complexity of network infrastructure.

One of the advantages of TDM buses is that they can accommodate different types of data, including voice, video, and data signals. They are also highly scalable and can easily accommodate additional devices as the network grows