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Hello World

Your very first NodeArch app!

We'll build, configure, and extend Apps from scratch in the Guides section, but here, we'll just do our usual introductory piece of code. The good old Hello, world!

We'll generate a template app using the CLI as our playground to take a look at the basic structure of a NodeArch App.

nodearch new

You'll be asked for the project name, which will be used as the directory name for your project. You'll also be asked to choose between one of the available templates. We'll use express just to try things out. Next, the CLI will start generating your new app and install all the required dependencies.

Once done, open up the new app directory, and you should see something like this:

+-- src
| +-- components
| | +-- user.controller.ts
| | +-- user.spec.ts
| +-- main.ts
| +-- start.ts
+-- .gitignore
+-- package.json
+-- tsconfig.json
  • tsconfig.json Specifies the root files and the compiler options required to compile the project.
  • package.json Your Node.JS package info, like name, version, and dependencies, etc.
  • .gitignore Specifies intentionally untracked files to ignore.
  • src The project source code root directory.
  • main.ts That is where we define and configure our app. It works as the entry point for the CLI to load and start our app.
  • start.js Used to start the app directly instead of using the CLI. It's useful in production as it's faster and doesn't require the CLI to be installed.
  • components An optional directory to group the project components away from non-components source code.
  • user.spec.ts an example suite of test cases.
  • user.controller.ts an example controller.

Let's take a look at how the main.ts file looks like.

import { App, LogLevel } from '@nodearch/core';
import { ExpressServer, ExpressHook, OpenAPICli } from '@nodearch/express';
import path from 'path';
import express from 'express';
import http from 'http';

// Extending the base class App to create our new App
export default class MyApp extends App {

constructor() {
* Create and configure Express instance
* to pass it to the Express Extension
const app = express();
app.use(express.urlencoded({ extended: true }));

// Create an HTTP server out of the Express instance
const server = http.createServer(app);

* The super() call is to init and configure the base class
* That we inherited, that is where we configure the new
* App instance that will be created.
// specify where the framework will look for the components
classLoader: {
classpath: path.join(__dirname, 'components')
// logging configurations
logging: {
logLevel: LogLevel.Debug
* extensions are also apps provided locally or through
* npm modules to extend our app.
extensions: [
app: new ExpressServer({
expressApp: app,
port: 3001
include: [ExpressHook, OpenAPICli]


Now, to start the app

nodearch start

The app will load and starts an express server. If you go to http://localhost:3000/users in your browser, you should now see Hello, World!.