Node.js is one of the most popular JavaScript-driven technologies nowadays. It was created in 2009 by Ryan Dahl and since then, the framework has evolved into a well-developed ecosystem. Its package manager is full of useful modules and developers around the world have started using Node.js in their production environments. In this series, we will learn about the following:

  • Node.js building blocks
  • The main capabilities of the environment
  • The package management of Node.js

Understanding the Node.js architecture

Back in the days, Ryan was interested in developing network applications. He found out that most high performance servers followed similar concepts. Their architecture was similar to that of an event loop and they worked with nonblocking input/output operations. These operations would permit other processing activities to continue before an ongoing task could be finished. These characteristics are very important if we want to handle thousands of simultaneous requests.

Most of the servers written in Java or C use multithreading. They process every request in a new thread. Ryan decided to try something different—a single-threaded architecture. In other words, all the requests that come to the server are processed by a single thread. This may sound like a nonscalable solution, but Node.js is definitely scalable. We just have to run different Node.js processes and use a load balancer that distributes the requests between them.

Ryan needed something that is event-loop-based and which works fast. As he pointed out in one of his presentations, big companies such as Google, Apple, and Microsoft invest a lot of time in developing high performance JavaScript engines. They have become faster and faster every year. There, event-loop architecture is implemented. JavaScript has become really popular in recent years. The community and the hundreds of thousands of developers who are ready to contribute made Ryan think about using JavaScript. Here is a diagram of the Node.js architecture:


In general, Node.js is made up of three things:

On top of these three blocks, we have several bindings that expose low-level interfaces. The rest of Node.js is written in JavaScript. Almost all the APIs that we see as built-in modules and which are present in the documentation, are written in JavaScript.

Installing Node.js

A fast and easy way to install Node.js is by visiting and downloading the appropriate installer for your operating system. For OS X and Windows users, the installer provides a nice, easy-to-use interface. For developers that use Linux as an operating system, Node.js is available in the APT package manager. The following commands will set up Node.js and Node Package Manager (NPM):

sudo apt-get update
sudo apt-get install nodejs
sudo apt-get install npm

Running Node.js server

Node.js is a command-line tool. After installing it, the node command will be available on our terminal. The node command accepts several arguments, but the most important one is the file that contains our JavaScript. Let’s create a file called server.js and put the following code inside:

var http = require('http');
http.createServer(function (req, res) {
   res.writeHead(200, {'Content-Type': 'text/plain'});
   res.end('Hello World\n');
}).listen(9000, '');
console.log('Server running at ');

If you run node ./server.js in your console, you will have the Node.js server running. It listens for incoming requests at localhost ( on port 9000. The very first line of the preceding code requires the built-in http module. In Node.js, we have the require global function that provides the mechanism to use external modules. We will see how to define our own modules in a bit. After that, the scripts continue with the createServer and listen methods on the http module. In this case, the API of the module is designed in such a way that we can chain these two methods like in jQuery.

The first one (createServer) accepts a function that is also known as a callback, which is called every time a new request comes to the server. The second one makes the server listen.

thats it now node js is running on your server or local enviroment