Understanding Node.js Architecture

Node.js is an extremely powerful JavaScript-based platform that’s built on Google Chrome's JavaScript V8 Engine, used to develop I/O intensive web applications like video streaming sites, single-page applications, online chat applications, and other web apps. 

Node.js is used by large, established companies and newly-minted startups alike. Open-source and completely free, the platform is used by thousands of developers around the world. It brings plenty of advantages to the table, making it a better choice than other server-side platforms like Java or PHP in many cases.

This article will help you to get familiar with the architecture of Node.js. You’ll also get a basic understanding of how things work in a web application and how a server handles incoming user requests.

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Web Applications

A web application, as you may already know, is a program that runs on a server and is rendered by a client browser, using the internet to access all the resources of that application. It usually can be easily broken down into three parts:

1. Client
2. Server
3. Database

Fig: Web application

Client

The user interacts with the front-end part of a web application. The front-end is usually developed using languages like HTML and CSS styles, along with extensive usage of JavaScript-based frameworks like ReactJS and Angular, which help with application design.

Server

The server is responsible for taking the client requests, performing the required tasks, and sending responses back to the clients. It acts as a middleware between the front-end and stored data to enable operations on the data by a client. Node.js, PHP, and Java are the most popular technologies in use to develop and maintain a web server.

Database

The database stores the data for a web application. The data can be created, updated, and deleted whenever the client requests. MySQL and MongoDB are among the most popular databases used to store data for web applications.

Node.js Server Architecture

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.

Fig: Node.js architecture

Now let’s understand each part of the Node.js architecture and the workflow of a web server developed using Node.js.

Parts of the Node.js Architecture:

• Requests: Incoming requests can be blocking (complex) or non-blocking (simple), depending upon the tasks that a user wants to perform in a web application
• Node.js Server: Node.js server is a server-side platform that takes requests from users, processes those requests, and returns responses to the corresponding users
• Event Queue: Event Queue in a Node.js server stores incoming client requests and passes those requests one-by-one into the Event Loop
• Thread Pool: Thread pool consists of all the threads available for carrying out some tasks that might be required to fulfill client requests
• Event Loop: Event Loop indefinitely receives requests and processes them, and then returns the responses to corresponding clients
• External Resources: External resources are required to deal with blocking client requests. These resources can be for computation, data storage, etc.

The Workflow of Node.js Architecture:

A web server developed using Node.js typically has a workflow that is quite similar to the diagram illustrated below. Let’s explore this flow of operations in detail.

Fig: Node.js Architecture Workflow

• Clients send requests to the webserver to interact with the web application. Requests can be non-blocking or blocking:

            -Querying for data

            -Deleting data 

            -Updating the data

• 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

Advantages of Node.js Architecture 

Node.js Architecture comes with several advantages that give the server-side platform a distinct upper-hand when compared to other server-side languages:

• 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.
• No need for creating multiple threads: 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.
• Requires fewer resources and memory: Node.js server, most of the time, requires fewer resources and memory due to the way it handles the incoming requests. Since the requests are processed one at a time, the overall process becomes less taxing on the memory. 

All of these advantages contribute to making the servers developed using Node.js much faster and responsive when compared to those developed using other server development technologies.

Get Ahead of the Curve and Master Node.js Today

Now that you have a basic understanding of how the Node.js architecture works to keep up with high client requests, you may be wondering how you can obtain the skills necessary to take advantage of its rising popularity. 

Fortunately, there are some great options for learning this exciting and practical skill set at your own pace. Simplilearn’s Node.js Certification Training will give you a great foundation in this popular platform, combining live, instructor-led training, self-paced tutorials, and hands-on projects to help you become career-ready upon completion. Get started today and seize your future!