In Node.js, we can easily create child processes to run separate applications or commands. This feature comes in handy when we want to run a web server as a child process, allowing our main application to continue executing without being blocked.

In this tutorial, we will demonstrate how to run a web server as a child process in Node.js, using the child_process module. Let’s get started!

Table of Contents

• Prerequisites
• Creating a Web Server
• Running the Web Server as a Child Process
• Handling Communications
• Conclusion

Prerequisites

To follow along, you need to have Node.js installed on your machine. You can download it from the official Node.js website.

Creating a Web Server

Before running a web server as a child process, let’s first create a basic web server in Node.js. Create a new file called server.js and add the following code:

const http = require('http');

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello, World!');
});

server.listen(3000, () => {
  console.log('Server running on port 3000');
});

Save the file and run the server using the command node server.js. This will start the web server on port 3000.

Running the Web Server as a Child Process

Now, let’s modify our main application to run the web server as a child process. Open a new file called main.js and add the following code:

const { spawn } = require('child_process');

const serverProcess = spawn('node', ['server.js']);

serverProcess.stdout.on('data', (data) => {
  console.log(`Server output: ${data}`);
});

serverProcess.stderr.on('data', (data) => {
  console.error(`Server error: ${data}`);
});

serverProcess.on('close', (code) => {
  console.log(`Server process exited with code ${code}`);
});

In this code, we use the spawn function from the child_process module to start the server.js file as a separate child process. The spawn function takes the command (node) and the arguments (['server.js']) as parameters.

We also attach event listeners to the child process to handle the output and errors. The stdout event is triggered when there is output from the child process, while the stderr event handles any errors that occur in the child process.

To run the main application, execute the command node main.js. This will start the web server as a child process.

Handling Communications

To communicate between the main application and the child process, you can use inter-process communication (IPC) channels. These channels allow you to send messages back and forth.

To send a message from the child process to the main application, use the process.send() method. In the main application, you can listen for messages using the process.on('message') event.

For a more detailed explanation of how to handle communications between the main application and the child process, refer to the official Node.js documentation.

Conclusion

Running a web server as a child process in Node.js is a powerful technique that allows us to separate the server logic from the main application. This helps to improve the performance and stability of our applications by keeping them non-blocking.

In this tutorial, we learned how to create a basic web server, run it as a child process, and handle communications between the main application and the child process.

If you have any further questions or want to dive deeper into this topic, feel free to explore the official Node.js documentation. Happy coding!

#NodeJS #ChildProcess