Step 1: Create your application

1. Create a new dedicated directory for your Node.js application called nodetutorial and another directory inside it called myapp.
2. To start the application setup, Open command prompt, Go to the myapp directory and execute npm init (Install node.js/npm) in the command line. This will walk you through creating a package.json file.

user@host:~/nodetutorial/myapp
=> npm init

Use the values from the table below. If no specific value for a property is needed at this point (# at the value table below) so just hit enter.

Field Name	Value
package	myapp
version	#
description	this is my first node app
entry point	server.js
test command	#
git repository	#
keywords	#
author	#
license	#

Open the package.json in your myapp directory and compare it to the shown result.

{
  "name": "myapp",
  "version": "1.0.0",
  "description": "this is my first node app",
  "main": "server.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
  }
}

All npm packages contain a file, usually in the project root, called package.json. This file holds various metadata relevant to the project. This file is used to > give information to npm that allows it to identify the project as well as handle the project’s dependencies. The package.json file is located at the root directory of a Node.js project.

Create a file called server.js (which will act as your web server) in the myapp folder and copy the following code to this file and save it:

const express = require('express');
const app = express();

app.get('/', function (req, res) {
  res.send('Hello World!');
});

const port = process.env.PORT || 3000;
app.listen(port, function () {
  console.log('myapp listening on port ' + port);
});

Step 2: Download dependencies

Your application is almost ready. Before you actually can access the web server, there’s the need to download the required modules. If you have a look at the server.js file you created in the previous step, the express-module is used there but not yet available on your machine. Therefore, run the following command to let npm take care of the dependencies:

user@host:~/nodetutorial/myapp
=> npm install express

You should now have a newly (automatically) created directory node_modules in the myapp directory, where all the dependency modules are located. The package.json will be updated with the installed module(s).

You should now have the following directory structure:

nodetutorial
└── myapp
    ├── node_modules
    ├── package-lock.json
    ├── package.json
    └── server.js

Step 3: Start your application

Now the application and can be started locally. Simply start it with the following command:

user@host:~/nodetutorial/myapp
=> node server.js

You should see myapp listening on port 3000 on your command line if everything went well. You should also get a Hello World response when accessing your web server at http://localhost:3000.

Step 4: Create the manifest file

Now we will start the deployment process of our nodejs app to cloud foundry.

Create a manifest.yaml file in the nodetutorial directory. This file is the deployment descriptor and contains all required information to deploy an application to a SAP Cloud Platform Cloud Foundry instance.

Copy the following content to the recently created file:

---
applications:
- name: myapp
  random-route: true
  path: myapp
  memory: 128M

The property random-route will generate a route, which does not conflict with any other application in the same Cloud Foundry instance.

You should now have the following directory structure:

nodetutorial
├── manifest.yaml
└── myapp
    ├── node_modules
    ├── package-lock.json
    ├── package.json
    └── server.js

Explanation for the manifest properties:

Property Name	Value
name	The application name with which the application will be deployed on Cloud Foundry.
host	Where the application (subdomain of the SAP Cloud Platform region) should be reachable.
path	The path of the local file system from which the content/artifact has to be deployed.
memory	The memory quota which should be allocated for this application.
random-route	if this property is set to true, Cloud Foundry will assign a random route (URL) to the application

Step 5: Push the app to your SAP Cloud Platform Cloud Foundry space

For pushing app to Cloud Foundry from Command Prompt you need to install CLI into your system You can find installation link below

For MacOSx and Linux https://docs.cloudfoundry.org/cf-cli/install-go-cli.html

For Windows https://packages.cloudfoundry.org/stable?release=windows64&version=v7&source=github

Login to your cloud foundry account in which you want to deploy the app. For detailed login step please refer the guide.

After login to Cf account run the below command inside the nodetutorial directory to start the deployment process:-

user@host:~/nodetutorial
=> cf push

Step 6: Figure out the application URL

After deployment is completed you should see the URL of the app in the console output.

Step 7: Protecting app by OAuth2.0 mechanism

Create a Authorization & Trust Management (xsuaa) service instance in Cloud Foundry Account

Bind application myapp to xsuaa instance created above

Add below code in server.js for protecting the app.

const passport = require('passport');
const { JWTStrategy } = require('@sap/xssec');
const xsenv = require('@sap/xsenv');

// XSUAA Middleware
passport.use(new JWTStrategy(xsenv.getServices({uaa:{tag:'xsuaa'}}).uaa));

app.use(passport.initialize());
app.use(passport.authenticate('JWT', { session: false }));

Final code will look like as below

const express = require('express');
const app = express();
const passport = require('passport');
const { JWTStrategy } = require('@sap/xssec');
const xsenv = require('@sap/xsenv');
const bodyParser = require('body-parser');
app.use(bodyParser.json({ extended: true }));

// XSUAA Middleware
passport.use(new JWTStrategy(xsenv.getServices({uaa:{tag:'xsuaa'}}).uaa));

app.use(passport.initialize());
app.use(passport.authenticate('JWT', { session: false }));

app.get('/', function (req, res) {
  res.send('Hello World!');
});

app.post('/GetData', function (req, res) {
   res.send('Hello World!');
});


const port = process.env.PORT || 3000;
app.listen(port, function () {
  console.log('myapp listening on port ' + port);
});

Step 8: Consume myapp service in RestClient

Fetch Client_id and Client_secret from xsuaa instance

Fetching access token from xsuaa instance using above credentials

Access myapp Service using above token