A computer programming language known as object-oriented programming (OOP) is described as a data field with particular features and behaviors. Implementing real-world concepts like inheritance, hiding, polymorphism, etc. in programming is the goal of object-oriented programming.

Concepts for OOPs

• Category Objects
• Abstraction of Data
• Encapsulation
• Inheritance
• Polymorphism
• Adaptive Binding
• Message Transfer

API stands for “application programming interface. It has protocols and resources that let various software programs converse and cooperate with one another. with each other. APIs define the methods and data structures that developers can use to integrate their own applications with external services, libraries, or platforms without needing to understand the internal workings of those services.

CORS stands for “Cross-Origin Resource Sharing. It is a security feature implemented by web browsers to control and manage how web pages from one domain (or origin) can request and access resources (such as data, fonts, scripts, or APIs) from another domain.

Pair programming is a software development technique in which two programmers work together on a single computer, collaborating on the same piece of code. In pair programming, one programmer assumes the role of the “driver,” responsible for typing and implementing the code, while the other programmer takes on the role of the “navigator,” providing guidance, reviewing the code, and suggesting improvements.

Long polling is a web communication technique used to achieve real-time updates or push notifications from a server to a client, even in situations where traditional HTTP request-response cycles might not be well-suited. It’s a workaround for achieving asynchronous communication in environments where full-duplex communication (simultaneous two-way communication) might not be natively supported.

A RESTful API (Representational State Transfer API) is a design pattern for creating web services that follow the principles of the REST architectural style. REST is an approach to designing networked applications that focuses on simplicity, scalability, and the use of standard HTTP methods. RESTful APIs are widely used for building web applications, mobile apps, and other distributed systems that require communication between different components over the internet.

Multithreading is a programming concept that allows multiple threads (smaller units of a process) to execute concurrently. It is useful for improving the efficiency and responsiveness of applications that perform tasks concurrently, such as handling multiple user interactions, processing data in the background, or performing I/O operations.

Common Use Cases of Multithreading:

• User Interfaces
• Networking
• Parallel Computing
• I/O Operations
• Real-Time Systems

Inversion of control is a software design principle that asserts a program can benefit in terms of pluggability, testability, usability, and loose coupling if the management of an application’s flow is transferred to a different part of the application. Instead of the developer directly controlling the flow of execution by calling functions and methods, IoC shifts the responsibility of controlling the flow to a framework or container.

The Java Virtual Machine (JVM) is a crucial component of the Java Runtime Environment (JRE) that enables Java applications to be platform-independent by providing a virtualized execution environment. It allows Java bytecode (compiled Java source code) to be executed on various operating systems and hardware architectures without requiring developers to write platform-specific code.

GraphQL	REST
1. GraphQL is an application-layer server-side technology developed by Facebook for executing queries with existing data.	1. REST is a software architectural style that defines a set of constraints for creating Web services.
2. It follows a client-driven architecture.	2. It follows a server-driven architecture.
3. GraphQL can be organized in terms of a schema.	3. REST can be arranged in terms of endpoints.
4. GraphQL is a growing community.	4. REST is a large community.
5. The development speed of GraphQL is fast.	5. The development speed of REST is slow.
6. The learning curve in GraphQL is difficult.	6. The learning curve in REST is moderate.

Angular:

Angular is a popular open-source web application framework maintained by Google. It is used for building dynamic and responsive single-page applications (SPAs) and progressive web applications (PWAs). Angular provides a comprehensive set of tools and libraries for front-end development, allowing developers to create rich and interactive user interfaces.

Key Features Included:

• Component-Based Architecture
• Templates and Data Binding
• Dependency Injection
• Directives
• Routing
• Forms
• HTTP Client
• State Management
• Testing

Spring Boot

Spring Boot is an open-source Java framework designed to simplify the process of building production-ready applications with minimal configuration. It is part of the larger Spring Framework ecosystem, providing conventions and defaults for common tasks along with a range of features to streamline development.

Key Features Included:

• Auto-Configuration
• Standalone Applications
• Embedded Web Servers
• Spring Boot Starters
• Spring Boot Actuator
• Production-Ready Features
• Simplified Data Access
• Microservices

Blue-Green Deployment and Green-Blue Deployment are two strategies for releasing new versions of software or applications while minimizing downtime and risk. The key difference between the two strategies lies in the order of deployment and the switch between environments.

Blue-Green Deployment:

In a blue-green deployment, the current production version (blue) is serving live traffic, while the new version (green) is deployed in a separate environment.

Green-Blue Deployment:

In a green-blue deployment, the new version (green) is deployed and tested in a separate environment while the current production version (blue) is still serving live traffic.

Both blue-green and green-blue deployments are commonly used in continuous integration and continuous delivery (CI/CD) pipelines to ensure smooth and reliable software releases. The choice between the two strategies depends on factors such as the level of risk tolerance, the ability to quickly roll back, and the complexity of the deployment process.

A rolling deployment is a software deployment strategy used to update or release a new version of an application in a controlled and incremental manner. In a rolling deployment, the new version of the software is deployed to a subset of servers or instances at a time while maintaining a certain level of availability.

Dependency injection (DI) is a design pattern in software engineering that focuses on providing the dependencies (i.e., objects or services) that a class requires from an external source rather than having the class create those dependencies itself.

Continuous Delivery (CD) is an extension of the Continuous Integration (CI) practice that focuses on automating the process of reliably and consistently delivering software changes to production or other environments. CD builds upon the foundation of CI by automating the deployment, testing, and release of code changes, ensuring that software can be released to users quickly and with minimal manual intervention.

Continuous integration (CI) is a software development practice that involves regularly integrating code changes from multiple developers into a shared repository. The primary goal of CI is to detect and address integration issues and bugs early in the development process, ensuring that the software remains in a consistent and functional state as new code is added.

DevOps is a set of practices, cultural philosophies, and tools aimed at improving collaboration and communication between development (Dev) and IT operations (Ops) teams throughout the software development lifecycle. DevOps is to enable the rapid and reliable delivery of high-quality software by breaking down silos, automating processes, and fostering a culture of continuous integration, continuous delivery, and continuous improvement.

DevOps Concepts:-

• Collaboration
• Automation
• Continuous Integration (CI)
• Continuous Delivery (CD)
• Infrastructure as Code (IaC)
• Microservices
• Monitoring and feedback
• Configuration Management
• Security

Reducing the load time of a web application is crucial for providing a better user experience, improving SEO rankings, and increasing user engagement.

There are several strategies you can implement to optimize the load time of your web application:

• Optimize Images
• Minimize HTTP Requests
• Enable browser caching
• Use content delivery networks (CDNs).
• Minify and compress assets.
• Optimize the Critical Rendering Path
• Reduce server response time.
• Lazy Loading of Non-Critical Resources
• Minimize external resources.
• Optimize CSS delivery
• Optimize JavaScript Execution
• Avoid Redirects
• Use a Content Management System (CMS) wisely.
• Regularly monitor and optimize

The Spring Framework is an open-source, comprehensive, and widely used Java-based framework that provides a robust platform for building enterprise-level applications. It addresses various challenges faced during the development of complex applications by offering a range of features and tools for different aspects of application development, such as dependency injection, aspect-oriented programming, transaction management, and more.