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
  • Email validation (RFC 5322 compliant)
  • Password strength requirements (min 8 chars, uppercase, lowercase, number)
  • JWT token-based authentication
FR-CATALOG-001 MUST Product Catalog Display
System must display product catalog with search, filters, and pagination
  • Full-text search across product names and descriptions
  • Filter by category, price range, availability
  • Paginate results (20 items per page)
FR-CART-001 MUST Shopping Cart Management
Users must be able to add/remove products to/from cart
  • Add product with quantity selection
  • Update quantities in cart
  • Remove items from cart
  • Cart persists across sessions (logged-in users)

📋 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