Project Summary
The Problem
Traditional e-commerce platforms struggle with scalability during peak traffic, complex payment integrations, and fragmented inventory management across multiple channels. Businesses need a unified platform that handles high concurrent loads while maintaining data consistency and security.
Our Solution
An enterprise-grade e-commerce platform built with modern web technologies and modular architecture. The system provides seamless online shopping experiences through stateless API design, robust payment processing with PCI DSS compliance, real-time inventory synchronization, and comprehensive customer analytics.
Business Value
- Scalability: Support 10,000+ concurrent users with horizontal scaling
- Reliability: 99.9% uptime SLA with automated failover
- Speed to Market: Modular architecture enables rapid feature delivery
- Cost Efficiency: Optimized infrastructure reduces operational costs by 30%
Technology Stack
React 18
Node.js
PostgreSQL
Redis
Docker
TypeScript
Key Stakeholders
Project Owner
John Smith
Business Sponsor
Lead Architect
Jane Doe
Technical Lead
Development Lead
Alex Johnson
Engineering Manager
Product Manager
Sarah Williams
Product Strategy
Project Quick Facts
In Progress
Project Status
7
Total Epics
Cloud
Deployment Model
Web + Mobile
Target Platforms
Requirements
Functional Requirements
| ID | Priority | Requirement | Acceptance Criteria |
|---|---|---|---|
| FR-AUTH-001 | MUST | User Registration and Login Users must be able to register with email/password and login to access personalized features |
|
| FR-CATALOG-001 | MUST | Product Catalog Display System must display product catalog with search, filters, and pagination |
|
| FR-CART-001 | MUST | Shopping Cart Management Users must be able to add/remove products to/from cart |
|
Non-Functional Requirements (forbidden)
Not generated: project policy forbids formal Non-Functional Requirements. Capture quality-related decisions only in architecture narratives, not as requirement tables.
📋 Architecture Decision Records
🎯 Strategic Decisions
ADR-001: Microservices vs Monolith Architecture
Date: 2025-09-15 | Status: Accepted | Category: Strategic
Context
Need to choose architecture pattern for e-commerce platform considering team size, scaling requirements, and deployment complexity.
Decision
Use modular monolith architecture with clear domain boundaries.
Rationale
- Small team (5 developers) - microservices overhead too high
- Faster time to market with simplified deployment
- Clear module boundaries allow future microservices extraction
Alternatives Considered
| Alternative | Pros | Cons | Rejection Reason |
|---|---|---|---|
| Microservices | Independent scaling, technology diversity | Operational complexity, team overhead | Team too small, premature optimization |
| Traditional monolith | Simplest to build | Difficult to scale, tight coupling | No clear boundaries for future evolution |
Consequences
Positive:
- Faster development and deployment
- Easier testing and debugging
- Lower infrastructure costs
Negative:
- Cannot scale individual modules independently
- Requires discipline to maintain module boundaries
🔧 Technical Decisions
ADR-002: Database Choice - PostgreSQL vs MongoDB
Date: 2025-09-18 | Status: Accepted | Category: Technical
Context
Need to select database for e-commerce transactional data considering ACID requirements, scalability, and query complexity.
Decision
Use PostgreSQL 15.x as primary database.
Rationale
- Strong ACID guarantees for transactions (orders, payments)
- JSON support for flexible product attributes
- Excellent performance for complex queries
Alternatives Considered
| Alternative | Pros | Cons | Rejection Reason |
|---|---|---|---|
| MongoDB | Schema flexibility, horizontal scaling | Weak transaction support, complex queries difficult | E-commerce requires strong ACID for financial data |
| MySQL | Widely adopted, good performance | Limited JSON support, fewer features | PostgreSQL offers better feature set |
Consequences
Positive:
- Data integrity guaranteed for financial transactions
- Rich ecosystem and tooling
Negative:
- Vertical scaling limitations (mitigated by read replicas)
- Schema migrations require careful planning
Success Criteria
- ✅ MVP handles 1,000+ daily active users
- ✅ 99.5% uptime in first 3 months
- ✅ Average checkout time < 3 minutes
- ✅ 85%+ test coverage (E2E + Integration + Unit)
- ✅ Zero critical security vulnerabilities
Architecture
System Context (C4 Level 1)
High-level view of the e-commerce platform and its external dependencies.
graph TD
Customer[Customer]
Admin[Administrator]
PaymentGateway[Payment Gateway
Stripe] EmailService[Email Service
SendGrid] System[E-Commerce Platform] Customer -->|Browse products,
Place orders| System Admin -->|Manage products,
View analytics| System System -->|Process payments| PaymentGateway System -->|Send notifications| EmailService
Stripe] EmailService[Email Service
SendGrid] System[E-Commerce Platform] Customer -->|Browse products,
Place orders| System Admin -->|Manage products,
View analytics| System System -->|Process payments| PaymentGateway System -->|Send notifications| EmailService
Container Diagram (C4 Level 2)
Containers within the e-commerce platform showing technologies and communication.
graph TD
Customer[Customer
Web Browser] Admin[Administrator
Web Browser] WebApp[Web Application
React 18 SPA] API[REST API
Node.js + Express] Database[(Database
PostgreSQL 15)] Cache[(Cache
Redis)] Customer -->|HTTPS| WebApp Admin -->|HTTPS| WebApp WebApp -->|JSON/HTTPS| API API -->|SQL| Database API -->|Cache queries| Cache
Web Browser] Admin[Administrator
Web Browser] WebApp[Web Application
React 18 SPA] API[REST API
Node.js + Express] Database[(Database
PostgreSQL 15)] Cache[(Cache
Redis)] Customer -->|HTTPS| WebApp Admin -->|HTTPS| WebApp WebApp -->|JSON/HTTPS| API API -->|SQL| Database API -->|Cache queries| Cache
Component Diagram (C4 Level 3) - Optional for Technical Audiences
Components within the REST API container showing internal structure.
graph TD
API[REST API Container]
AuthController[Authentication
Controller] ProductController[Product Catalog
Controller] CartController[Shopping Cart
Controller] OrderController[Order
Controller] AuthService[Auth Service] ProductService[Product Service] CartService[Cart Service] OrderService[Order Service] ProductRepo[Product
Repository] UserRepo[User
Repository] CartRepo[Cart
Repository] OrderRepo[Order
Repository] Database[(PostgreSQL)] Cache[(Redis)] ProductController --> ProductService CartController --> CartService OrderController --> OrderService AuthController --> AuthService ProductService --> ProductRepo CartService --> CartRepo OrderService --> OrderRepo AuthService --> UserRepo ProductRepo --> Database UserRepo --> Database CartRepo --> Cache OrderRepo --> Database
Controller] ProductController[Product Catalog
Controller] CartController[Shopping Cart
Controller] OrderController[Order
Controller] AuthService[Auth Service] ProductService[Product Service] CartService[Cart Service] OrderService[Order Service] ProductRepo[Product
Repository] UserRepo[User
Repository] CartRepo[Cart
Repository] OrderRepo[Order
Repository] Database[(PostgreSQL)] Cache[(Redis)] ProductController --> ProductService CartController --> CartService OrderController --> OrderService AuthController --> AuthService ProductService --> ProductRepo CartService --> CartRepo OrderService --> OrderRepo AuthService --> UserRepo ProductRepo --> Database UserRepo --> Database CartRepo --> Cache OrderRepo --> Database
Deployment Diagram
Infrastructure and deployment architecture on AWS.
graph TD
subgraph "AWS Cloud"
subgraph "Public Subnet"
ALB[Application Load
Balancer] CloudFront[CloudFront CDN] end subgraph "Private Subnet" ECS1[ECS Container 1
Node.js API] ECS2[ECS Container 2
Node.js API] RDS[(RDS PostgreSQL
Primary)] RDSReplica[(RDS PostgreSQL
Read Replica)] ElastiCache[(ElastiCache
Redis)] end subgraph "Storage" S3[S3 Bucket
Static Assets] end end CloudFront --> S3 ALB --> ECS1 ALB --> ECS2 ECS1 --> RDS ECS2 --> RDS ECS1 --> RDSReplica ECS2 --> RDSReplica ECS1 --> ElastiCache ECS2 --> ElastiCache
Balancer] CloudFront[CloudFront CDN] end subgraph "Private Subnet" ECS1[ECS Container 1
Node.js API] ECS2[ECS Container 2
Node.js API] RDS[(RDS PostgreSQL
Primary)] RDSReplica[(RDS PostgreSQL
Read Replica)] ElastiCache[(ElastiCache
Redis)] end subgraph "Storage" S3[S3 Bucket
Static Assets] end end CloudFront --> S3 ALB --> ECS1 ALB --> ECS2 ECS1 --> RDS ECS2 --> RDS ECS1 --> RDSReplica ECS2 --> RDSReplica ECS1 --> ElastiCache ECS2 --> ElastiCache
Key Architecture Highlights
| Aspect | Approach | Rationale |
|---|---|---|
| Architecture Pattern | Modular Monolith | Clear domain boundaries (Auth, Catalog, Cart, Orders) - see ADR-001 in Requirements |
| API Design | Stateless API | Enables horizontal scaling without session affinity |
| Database Strategy | PostgreSQL with read replicas | ACID transactions + scalability through read replicas |
| Caching | Redis | Session/cart data and frequently accessed product catalog |
| Infrastructure | Docker containers | Cloud-native orchestration with Kubernetes |
Quality attributes (Performance, Security, Scalability, Maintainability) are described in architecture narratives; formal Non-Functional Requirements are intentionally excluded.
Technical Specification
Technology Stack
| Category | Technology | Version | Purpose |
|---|---|---|---|
| Frontend | React | 18.2 | UI framework for SPA |
| Frontend | TypeScript | 5.2 | Type-safe JavaScript |
| Backend | Node.js | 20.x | Runtime environment |
| Backend | Express | 4.18 | REST API framework |
| Database | PostgreSQL | 15.x | Primary transactional database |
| Cache | Redis | 7.x | Session & cart caching |
| Infrastructure | Docker | 24.x | Containerization |
| Infrastructure | AWS ECS | - | Container orchestration |
| DevOps | GitHub Actions | - | CI/CD pipeline |
API Endpoints
Authentication
| Endpoint | Method | Description |
|---|---|---|
/api/auth/register |
POST | Register new user |
/api/auth/login |
POST | Login and get JWT token |
/api/auth/refresh |
POST | Refresh JWT token |
Products
| Endpoint | Method | Description |
|---|---|---|
/api/products |
GET | List all products (paginated) |
/api/products/:id |
GET | Get product details |
/api/products |
POST | Create new product (admin only) |
/api/products/:id |
PUT | Update product (admin only) |
Shopping Cart
| Endpoint | Method | Description |
|---|---|---|
/api/cart |
GET | Get current user's cart |
/api/cart/items |
POST | Add item to cart |
/api/cart/items/:id |
PUT | Update item quantity |
/api/cart/items/:id |
DELETE | Remove item from cart |
Authentication
Method: JWT Bearer Token
Authorization: Bearer <token>Token expires in 15 minutes. Use /api/auth/refresh with refresh token to get new access token.
Error Codes
| Code | Message | Description |
|---|---|---|
| 400 | Bad Request | Invalid request payload |
| 401 | Unauthorized | Missing or invalid JWT token |
| 403 | Forbidden | Insufficient permissions |
| 404 | Not Found | Resource not found |
| 500 | Internal Server Error | Unexpected server error |
Data Models
Entity Relationship Diagram
erDiagram
USER ||--o{ ORDER : places
USER ||--o{ CART : has
CART ||--|{ CART_ITEM : contains
PRODUCT ||--o{ CART_ITEM : "in"
PRODUCT ||--o{ ORDER_ITEM : "in"
ORDER ||--|{ ORDER_ITEM : contains
ORDER ||--|| PAYMENT : has
USER {
uuid id PK
string email
string password_hash
string first_name
string last_name
timestamp created_at
}
PRODUCT {
uuid id PK
string name
text description
decimal price
int stock_quantity
string category
timestamp created_at
}
CART {
uuid id PK
uuid user_id FK
timestamp updated_at
}
CART_ITEM {
uuid id PK
uuid cart_id FK
uuid product_id FK
int quantity
}
ORDER {
uuid id PK
uuid user_id FK
decimal total_amount
string status
timestamp created_at
}
ORDER_ITEM {
uuid id PK
uuid order_id FK
uuid product_id FK
int quantity
decimal price_at_purchase
}
PAYMENT {
uuid id PK
uuid order_id FK
string payment_method
string status
string transaction_id
timestamp created_at
}
Data Dictionary
| Entity | Key Attributes | Description |
|---|---|---|
| USER | email (unique), password_hash | Customer accounts |
| PRODUCT | name, price, stock_quantity | Product catalog items |
| CART | user_id | Shopping cart (1 per user) |
| ORDER | user_id, status, total_amount | Customer orders |
| PAYMENT | order_id, transaction_id, status | Payment transactions |
Testing Strategy
Risk-Based Testing approach - prioritize tests by business impact:
Test Pyramid
- E2E Tests (2-5 per Story): Critical user flows (checkout, payment, registration)
- Integration Tests (3-8 per Story): API endpoints, database interactions
- Unit Tests (5-15 per Story): Business logic, validators, utilities
Total: 10-28 tests per Story (max)
Priority Matrix
Test scenarios with Priority ≥ 15 MUST be tested:
Priority = Business Impact (1-5) × Probability (1-5)Test Focus
- ✅ Test OUR code (business logic, API endpoints)
- ❌ Skip framework code (Express middleware already tested)
- ❌ Skip trivial getters/setters (no business logic)
Roadmap
This roadmap shows the work order and scope boundaries for our project. Epics are organized by dependencies, with clear scope definition for each.
Epic 1: User Management
DoneUser registration, authentication, profile management, and session handling
In Scope
- JWT authentication
- Email/password registration
- Password reset flow
- User profile CRUD operations
- Session management
Out of Scope
- Social login (OAuth)
- Multi-factor authentication
- Single sign-on (SSO)
Epic 2: Product Catalog
DoneProduct listing, search, filters, and pagination
In Scope
- Full-text search across product names and descriptions
- Category filters
- Price range filters
- Pagination (20 items/page)
- Product detail pages
- 1000+ SKUs support
Out of Scope
- AI-powered recommendations
- Visual search
- Product reviews
Epic 3: Shopping Cart
In ProgressCart management with session persistence and inventory validation
In Scope
- Add/remove items from cart
- Update quantities
- Cart persistence across sessions
- Real-time inventory validation
- Cart subtotal calculation
Out of Scope
- Wishlist functionality
- Share cart
- Save for later
Epic 4: Admin Dashboard
In ProgressProduct management, inventory control, and analytics dashboard
In Scope
- Product CRUD operations
- Bulk product import (CSV)
- Inventory management
- Role-based access control
- Real-time analytics dashboard
- Sales reports
Out of Scope
- Customer support tickets
- Email campaigns
- Advanced BI reports
Epic 5: Payment Gateway
TodoIntegrate Stripe for secure payment processing with PCI DSS compliance
In Scope
- Stripe payment integration
- Credit/debit card payments
- Digital wallets (Apple Pay, Google Pay)
- PCI DSS compliance
- Payment error handling
- Refund processing
Out of Scope
- Cryptocurrency payments
- Buy now, pay later (BNPL)
- Invoice payments
Epic 6: Order Management
TodoOrder processing, tracking, and fulfillment workflows
In Scope
- Order creation and confirmation
- Real-time order tracking
- Email notifications
- Order history
- Automated fulfillment workflows
- Cancellation and refund flows
Out of Scope
- Advanced shipping integrations
- Returns management portal
- International shipping
Epic 7: Advanced Analytics
BacklogCustomer behavior analytics and recommendations engine
In Scope
- Customer behavior tracking
- Product recommendations engine
- Conversion funnel analytics
- A/B testing framework
- Personalized user experience
Out of Scope
- Machine learning models
- Predictive analytics
- Customer data platform (CDP)
Out of Project Scope
The following items are explicitly NOT included in the current project phase:
Mobile Native Apps
iOS and Android native applications
Reason: Focus on responsive web first, native apps planned for Phase 2
Multi-Currency Support
International payments and currency conversion
Reason: Current scope limited to USD, internationalization in future release
Social Commerce Integration
Social media selling and live shopping features
Reason: Not in MVP scope, evaluate after core features stable
B2B Wholesale Portal
Bulk ordering and wholesale pricing for business customers
Reason: B2C focus first, B2B features separate project phase
Status Legend
Done Completed and deployed
In Progress Currently being developed
Todo Approved and ready to start
Backlog Under evaluation
Guides & Resources
Getting Started
Prerequisites
- Node.js 20.x or higher
- PostgreSQL 15.x
- Redis 7.x (optional for development)
- Docker (optional)
Installation
git clone https://github.com/example/ecommerce-platform.git
cd ecommerce-platform
npm install
cp .env.example .env
# Edit .env with your database credentials
npm run db:migrate
npm run devVerification
After starting the server, verify installation:
- ✅ Server running at
http://localhost:3000 - ✅ API health check:
curl http://localhost:3000/api/health - ✅ Database migrations applied:
npm run db:status
How-To Guides
How to Add a New Product
- Login as admin:
POST /api/auth/loginwith admin credentials - Get JWT token from response
- Create product:
curl -X POST http://localhost:3000/api/products \ -H "Authorization: Bearer <token>" \ -H "Content-Type: application/json" \ -d '{ "name": "Product Name", "description": "Product Description", "price": 29.99, "stock_quantity": 100, "category": "Electronics" }' - Verify product created:
GET /api/products/:id
How to Test API Endpoints
- Start development server:
npm run dev - Run tests:
- All tests:
npm test - E2E tests only:
npm run test:e2e - Integration tests:
npm run test:integration - Unit tests:
npm run test:unit
- All tests:
- View coverage report:
npm run test:coverage
How to Deploy to Production
- Build Docker image:
docker build -t ecommerce-api . - Push to registry:
docker push ecommerce-api:latest - Update ECS task definition with new image
- Deploy via GitHub Actions (automatic on merge to main)
- Verify deployment: Check CloudWatch logs for startup
Best Practices
Code Style
- Follow KISS/YAGNI/DRY principles
- Use TypeScript for type safety
- Keep functions small and focused (< 30 lines)
- Use meaningful variable names (no single letters except loops)
Testing Approach
- Follow Risk-Based Testing (Priority ≥ 15 scenarios MUST be tested)
- E2E tests (2-5 per Story): Critical user flows
- Integration tests (3-8 per Story): API endpoints
- Unit tests (5-15 per Story): Business logic only
- Test OUR code, not frameworks (Express already tested)
Design Patterns
- Layered architecture: Controller → Service → Repository
- Dependency Injection for testability
- Repository pattern for database access
- DTO (Data Transfer Objects) for API requests/responses
Troubleshooting
Database Connection Errors
Problem: "Unable to connect to PostgreSQL"
Solution:
- Check PostgreSQL is running:
pg_isready - Verify .env credentials match database
- Check firewall allows port 5432
Port Already in Use
Problem: "Port 3000 is already in use"
Solution:
- Change PORT in .env to different port (e.g., 3001)
- Or kill process using port:
lsof -ti:3000 | xargs kill
JWT Token Expired
Problem: "401 Unauthorized - Token expired"
Solution:
- Use refresh token:
POST /api/auth/refreshwith refresh token - Get new access token from response
- Tokens expire after 15 minutes for security
Tests Failing Randomly
Problem: Tests pass locally but fail in CI
Solution:
- Check test isolation (no shared state between tests)
- Use transactions in tests (rollback after each test)
- Seed database with consistent test data
Contributing Guidelines
- Fork the repository
- Create branch:
git checkout -b feature/your-feature - Write code following style guide
- Write tests: All new code must have tests (85%+ coverage)
- Run tests:
npm test(all must pass) - Commit:
git commit -m "Add your feature" - Push:
git push origin feature/your-feature - Submit PR with description of changes