Background

I am trying to learn MERN stack in 150 Days, about which I posted a while ago. In this series posts, I will be sharing What and How I have been learning.

MERN - 150 Days Challenge

Prakirth Govardhanam ・ May 13

#webdev #beginners #learning #discuss

I am open to feedback to make this post better for readability/content quality.

DAY 17/150 ⏳

• Today, I have brief summaries of concepts which were either unclear/unknown to me, until now. 🏄
• In the below sections, I share the challenges I faced with Context, Reason and Solution wherever relevant.

Challenge 1 - Backend Testing fundamentals

• Context : Backend-testing using node:test, node:assert and supertest.
• Reason : Completely new topic and zero-experience from previous projects
• Solution :
  • After every topic in each section of Part 4, practice tests for 'Notes App' in a different context. For example on the current project in Part 4 exercises, 'Blogs App'
  • Seek coding assistance from GitHub CoPilot
  • Read through example tests from documentations

Challenge 2 - HTTP status codes

• Context : HTTP Methods use similar status codes

• Reason :

  HTTP Method	Response Status Codes
  GET	200, 304, 400, 404, 500
  POST	200, 201, 400, 403, 404, 500
  PUT	200, 204, 400, 404, 409, 500
  PATCH	200, 204, 400, 404, 409, 500
  DELETE	200, 202, 204, 400, 404, 500

• Common status codes happen because HTTP method can have multiple response status codes because the outcome of a request can vary based on different factors.

  • 200 OK: The request has succeeded.
  • 400 Bad Request: The server could not understand the request due to invalid syntax.
  • 404 Not Found: The server could not find the requested resource.
  • 500 Internal Server Error: The server encountered an unexpected condition which prevented it from fulfilling the request.

Challenge 3 - Data re-initialization in test DB using beforeEach

• Context :
  • For Testing purposes, Test-database needs to be re-initialized before each test for executing assertions successfully.
  • However, due to differences in the order of execution of the Promise the data can be initialized in different ways.
• Reason : Depends on the sequence preferences, if any, of execution of Promises
• Solution :

1. Using for loop for control over execution order of Promise
   

       beforeEach(async() => {
           // executed in no specific order
           for(let blog of helper.initialBlogs){
               let blogObject = new Blog(blog)
               await blogObject.save()
           }
       })
   
       // tests to verify HTTP methods 
       ...
   

2. using Promise.all method to allow the completion of every Promise in the registered order
   

       beforeEach(async() => {
               // executed in specific order promises registred
               await Promise.all(helper.initialBlogs.map(async (blog) => {
                   let blogObject = new Blog(blog)
                   blogObject.save()
               }))
           })
   
           // tests to verify HTTP methods 
           ...
   

3. most ideal method, using mongoose built-in methods for insert and delete
   

           beforeEach(async() => {
               await Blog.deleteMany({})
               await Blog.insertMany(helper.initialBlogs)
               })
   
               // tests to verify HTTP methods 
               ...
   

Challenge 4 - Password Hashing fundamentals

• Context : Hashing passwords (manually) using external libraries
• Reason : Obviously, user data such as passwords must be encrypted, hence an enhanced level of encryption ensures user security

• Solution : In the current context (FullStackOpen-core-part4), for user administration in saving blog posts, we are using bcrypt to ensure password hashing through Salt Rounds, as simplified below.

  • Purpose : Salt rounds are used to 'thwart brute force attacks' by making the hashing process slower.
  • How It Works :
    • Number of salt rounds is the exponent in the calculation of how many times the hashing algorithm is executed.
    • More rounds = more hashing iterations,
    • Brute force attacks slowed down and more secure.
  • Example : If you choose 10 salt rounds, the algorithm will run 2^10 (or 1024) times.

  • Balance between Security and Performance :

    • Higher salt rounds increase security but also make the hashing process take longer.
    • The cost of increasing rounds on 2 GHz core :

        rounds=8 : ~40 hashes/sec
        rounds=9 : ~20 hashes/sec
        rounds=10: ~10 hashes/sec
        rounds=11: ~5  hashes/sec
        rounds=12: 2-3 hashes/sec
        rounds=13: ~1 sec/hash
        rounds=14: ~1.5 sec/hash
        rounds=15: ~3 sec/hash
        rounds=25: ~1 hour/hash
        rounds=31: 2-3 days/hash
    

Challenge 5 - Process Flow between Backend-Database to Implement new Feature

• Context :
  • In MERN, if every new concept is implemented from the granular level, unlike Django, the sequence of operations to know are essential.
  • In current context, we use MongoDB-mongoose for establishing backend-database communications
  • If a new table/collection is introduced to implement a new feature, such as user administration, then the sequence of actions for an efficient process flow is as shown below.

Challenge 6 - Generating JSON Web Token

• Context : What is included in 'process.env.SECRET'?
• Reason : For user authentication, a jsonwebtoken (JWT) must be generated

• Solution :

  • Any string, preferably auto-generated as a cryptic string
  • Using node built-in library for auto-generating a cryptic string as follows:

      const crypto = require('crypto')
      crypto.randomBytes(32).toString('hex')  // SECRET
  

  • NEVER save it in the source code. Generate in the terminal. Save it in .env

Challenge 7 - Authorization Header and Authentication Scheme fundamentals

• Context : How to retrieve the 'Authentication Header' value for implementing tests with backend API using Postman/REST Client ?
• Reason : To authenticate the user when a POST request is generated

• Solution :

  • HTTP request has Authorization headers in the format - <auth-schemes> <auth-parameters>
  • There are multiple <auth-schemes> (Authentication Schemes) available in a HTTP request Authorization header.
  • Most common ones are - Basic, Bearer, Digest

  Feature	Basic	Bearer*	Digest
  SECURITY	Credentials sent as base64 encoded (plain text)	Credentials tokenized on server-side and stored on client side. Can be set to expire.	Password saved on server as plain-text/reversibly-encrypted format for verification with hashed-version.
  USAGE	Simple, credentials sent with each request	Simple & safe, token sent with each request	Complex due to hashing process
  STATE	Stateful, since credentials required for each request	Stateless, request contains credentials-encrypted token to authenticate user for each request	Stateful, random new hashed value different for each request
  API Suitability	Only simple authentication, Not suitable for modern APIs	Suitable, specifically for APIs with JWTs and Single Sign-On (SSO)	Not Suitable, due to server-side storage

  • Based on the project (Reading list - Blogs App), the Bearer <auth-scheme> would be suitable for our User Authentication considering its beginner-friendly secure state of tokenizing user access.

Until next time! ✍️
Live Long and Prosper 🖖

Cover Photo by 'Leeloo The First' from Pexels