In this video, you will be able to learn Top 20 ReactJS Interview Questions and Answers !
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Category: Nodejs
React Interview Questions | Top 50 ReactJS Interview Questions and Answers !
In this video, you will be able to learn Top 50 ReactJS Interview Questions and Answers !
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What Are Microservices ? | Monolith vs Microservices | Microservices Architecture In Node.js!
In this video, we will learn about,
- Node.JS Microservices overview
- Monolithic versus Microservices in Node.js
- Why Microservices in Node.js?
- Frameworks for building Microservices in Node.js
- Microservices architecture in Node.js
- How multiple services communicate through HTTP API
- Connecting to the database
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All You Need To Know About Node.js
- Node.js is a JavaScript runtime built on Chrome’s V8 JavaScript engine. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient.
- Node.js uses the “Single Threaded Event Loop” architecture to handle multiple concurrent clients.
- Node.js Processing Model is based on the JavaScript event-based model along with the JavaScript callback mechanism.
- Event Queue in a Node.js server stores incoming client requests and passes those requests one-by-one into the Event Loop.
- Thread pool consists of all the threads available for carrying out some tasks that might be required to fulfill client requests.
- Event Loop indefinitely receives requests and processes them, and then returns the responses to corresponding clients.
- Node.js retrieves the incoming requests and adds those requests to the Event Queue.
- The requests are then passed one-by-one through the Event Loop. It checks if the requests are simple enough to not require any external resources.
- Event Loop processes simple requests (non-blocking operations), such as I/O Polling, and returns the responses to the corresponding clients.
- A single thread from the Thread Pool is assigned to a single complex request. This thread is responsible for completing a particular blocking request by accessing the external resources, such as compute, database, file system, etc.
- Once, the task is carried out completely, the response is sent to the Event Loop that in turn sends that response back to the Client.
- Handling multiple concurrent client requests is fast and easy – With the use of Event Queue and Thread Pool, the Node.js server enables efficient handling of a large number of incoming requests.
- Event Loop handles all requests one-by-one, so there is no need to create multiple threads. Instead, a single thread is sufficient to handle a blocking incoming request.
- The main feature of Node.js are:
- Event Driven Architecture
- Non Blocking I/O Model
- Asynchronous by Default
Node.js Event Loop Overview
The event loop in Node.js is a fundamental concept that allows it to handle multiple concurrent I/O operations without blocking the execution of the program. It continuously checks for new events and executes them one by one in a non-blocking manner.
Event Loop Features:
- Node.js operates on a single thread, but it uses an event loop to execute multiple tasks efficiently.
- The event loop continuously checks for any new tasks and executes them one by one.
- If a task takes too long to complete, the event loop moves on to the next task instead of waiting for the first one to finish.
- The event loop uses non-blocking I/O operations to perform tasks without stopping the program’s execution.
- The event loop allows Node.js to handle large numbers of requests simultaneously without overwhelming the system.
Example :
console.log('Starting the program...');
setTimeout(() => {
console.log('First task completed.');
}, 3000);
console.log('Second task is being executed...');
setTimeout(() => {
console.log('Second task completed.');
}, 1000);
console.log('End of the program.');In this example, we have two tasks that are being executed using setTimeout method, which simulates a delay. The first task has a delay of 3 seconds, while the second task has a delay of 1 second.
When we run this program, the output will be:
Starting the program...
Second task is being executed...
End of the program.
Second task completed.
First task completed.The program starts by printing “Starting the program…” to the console. Then, it executes the first setTimeout method, which has a delay of 3 seconds. While waiting for the first task to complete, the program moves on to execute the second setTimeout method, which has a delay of 1 second.
After printing “End of the program.” to the console, the program then completes the second task and prints “Second task completed.” Finally, it completes the first task and prints “First task completed.”
This example demonstrates how the event loop in Node.js allows for non-blocking execution of multiple tasks, even with delays, without blocking the program’s execution.
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