System design for Jira - System design interview

Below is a high-level overview of the components and the tech stack involved, along with simplified code snippets to illustrate basic concepts when building Jira like system.

Components of a Jira-like System

1. Backend Server

   • Manages user authentication, project management, issue tracking, collaboration features (boards, sprints), and notifications.
   • Tech Stack: Node.js, Express.js, MongoDB or PostgreSQL (for data storage), WebSocket for real-time updates.

2. Database

   • Stores user profiles, projects, issues, boards, sprints, comments, etc.
   • Tech Stack: MongoDB or PostgreSQL for relational data storage.

3. Authentication

   • Registers users, manages login/logout, and access control.
   • Tech Stack: JSON Web Tokens (JWT) for authentication, bcrypt for password hashing.

4. Project and Issue Management

   • Handles CRUD operations for projects, boards, issues, sprints, etc.
   • Tech Stack: Express.js (RESTful APIs), WebSocket for real-time updates.

5. Collaboration Features

   • Enables collaboration through issue assignment, comments, attachments, and notifications.
   • Tech Stack: WebSocket (for real-time updates), RESTful APIs for CRUD operations.

6. Frontend Client (Web Interface)

   • Provides user interface for project management, issue tracking, boards, and collaboration.
   • Tech Stack: React.js, Redux for state management, Material UI or Bootstrap for UI components.

7. Notifications

   • Sends notifications for issue updates, assignments, mentions, and other activities.
   • Tech Stack: WebSocket (for real-time notifications), Email notifications.

Low-Level Overview and Sample Code

Here's a simplified outline with sample code snippets for key components:

Backend Server (Node.js with Express)

1. User Authentication and Registration

   const express = require('express');
   const bcrypt = require('bcrypt');
   const jwt = require('jsonwebtoken');
   const User = require('./models/User');
   
   const app = express();
   const secretKey = 'your_secret_key';
   
   // Register a new user
   app.post('/api/register', async (req, res) => {
       try {
           const { username, password } = req.body;
           const hashedPassword = await bcrypt.hash(password, 10);
           const newUser = new User({ username, password: hashedPassword });
           await newUser.save();
           res.status(201).json({ message: 'User registered successfully' });
       } catch (err) {
           res.status(500).json({ error: err.message });
       }
   });
   
   // User login
   app.post('/api/login', async (req, res) => {
       try {
           const { username, password } = req.body;
           const user = await User.findOne({ username });
           if (!user) {
               return res.status(404).json({ message: 'User not found' });
           }
           const isMatch = await bcrypt.compare(password, user.password);
           if (!isMatch) {
               return res.status(401).json({ message: 'Invalid credentials' });
           }
           const token = jwt.sign({ userId: user._id }, secretKey, { expiresIn: '1h' });
           res.json({ token });
       } catch (err) {
           res.status(500).json({ error: err.message });
       }
   });
   
   app.listen(3000, () => {
       console.log('Server started on port 3000');
   });
   

2. Project and Issue Management

   const express = require('express');
   const Project = require('./models/Project');
   const Issue = require('./models/Issue');
   
   const app = express();
   
   // Create a new project
   app.post('/api/projects', async (req, res) => {
       try {
           const { projectName, description } = req.body;
           const newProject = new Project({ projectName, description });
           await newProject.save();
           res.status(201).json({ message: 'Project created successfully' });
       } catch (err) {
           res.status(500).json({ error: err.message });
       }
   });
   
   // Create a new issue
   app.post('/api/issues', async (req, res) => {
       try {
           const { projectId, title, description, assignedTo } = req.body;
           const newIssue = new Issue({ projectId, title, description, assignedTo });
           await newIssue.save();
           res.status(201).json({ message: 'Issue created successfully' });
       } catch (err) {
           res.status(500).json({ error: err.message });
       }
   });
   
   app.listen(3000, () => {
       console.log('Server started on port 3000');
   });
   

Frontend Client (React.js)

1. Project and Issue Management

   import React, { useState, useEffect } from 'react';
   import axios from 'axios';
   
   const ProjectList = () => {
       const [projects, setProjects] = useState([]);
   
       useEffect(() => {
           axios.get('/api/projects')
               .then(res => setProjects(res.data))
               .catch(err => console.error('Error fetching projects:', err));
       }, []);
   
       return (
           <div>
               <h1>My Projects</h1>
               <ul>
                   {projects.map(project => (
                       <li key={project.id}>
                           <a href={`/project/${project.id}`}>{project.projectName}</a>
                       </li>
                   ))}
               </ul>
           </div>
       );
   };
   
   export default ProjectList;