System Architecture

Architecture Principles

• Monolith-first: Phase 1 uses modular monolith, no microservices
• Dependency Inversion: Domain layer does not depend on infrastructure
• Replaceable Boundaries: Search and storage both have SPI abstractions

Module Structure

server/
├── skillhub-app/          # Startup, configuration assembly, Controllers
├── skillhub-domain/       # Domain models + domain services + application services
├── skillhub-auth/         # OAuth2 authentication + RBAC + authorization decisions
├── skillhub-search/       # Search SPI + PostgreSQL full-text implementation
├── skillhub-storage/      # Object storage abstraction + LocalFile/S3
└── skillhub-infra/        # JPA, utilities, configuration foundation

Module Dependencies

app → domain, auth, search, storage, infra
infra → domain
auth → domain
search → domain
storage → (independent)

Tech Stack

Layer	Technology	Version
Runtime	Java	21
Framework	Spring Boot	3.2.3
Database	PostgreSQL	16.x
Cache/Session	Redis	7.x

Deployment Architecture

┌──────────────┐
│ Browser / CLI│
└──────┬───────┘
       │
       ▼
┌──────────────┐
│  Web/Nginx   │
└──────┬───────┘
       │ /api/*
       ▼
┌──────────────┐
│ Spring Boot  │
└───┬────┬─────┘
    │    │
    ▼    ▼
PostgreSQL  Redis

Next Steps

• Domain Model - Core entities