PHP Architecture 🏗️

Structure a full PHP application as a modular monolith with clean module boundaries, event-driven communication, and SOLID principles.

What You'll Learn in This Lesson

• Compare monolith, modular monolith, and microservices
• Organize code into independent modules with clear boundaries
• Use events for cross-module communication
• Apply SOLID principles to real PHP architecture
• Structure a production project directory

Note: PHP runs on a server. Our examples simulate PHP logic using JavaScript. To run real PHP, install PHP.

🎯 Real-World Analogy: A modular monolith is like an office building. Each floor (module) has its own department — sales, engineering, finance. They share the same building (codebase) and elevator (database), but each floor is self-contained. If a department grows too large, you can move it to its own building (microservice) without redesigning the others.

Modular Monolith

A modular monolith organizes code into independent modules (User, Order, Payment, Notification) that communicate through events rather than direct method calls. Each module owns its own controllers, services, repositories, and database tables. This gives you the simplicity of a monolith with the organization of microservices.

Try It: Module Design

Design application modules with services, events, and dependencies

Try it Yourself »

JavaScript

// Modular Monolith Architecture
console.log("=== Architecture Styles ===");
console.log();
console.log("  Monolith      → Everything in one codebase");
console.log("  Modular Mono  → One codebase, but organized into independent modules");
console.log("  Microservices → Separate services communicating over network");
console.log();
console.log("  For most PHP apps, Modular Monolith is the sweet spot:");
console.log("  ✅ Simpler than microservices (no network overhead)");
console.log("  ✅ More or
...

Clean Architecture & SOLID

A well-structured project separates concerns into layers: controllers handle HTTP, actions implement use cases, services contain business logic, and repositories handle data access. SOLID principles ensure each class has one reason to change and depends on abstractions, not implementations.

Try It: Project Structure

Explore a production directory layout and SOLID principles

Try it Yourself »

JavaScript

// Clean Architecture Directory Structure
console.log("=== Project Structure ===");
console.log();
let tree = [
  "myapp/",
  "├── app/                         # Application layer",
  "│   ├── Modules/",
  "│   │   ├── User/",
  "│   │   │   ├── Controllers/     # HTTP controllers",
  "│   │   │   ├── Actions/         # Single-purpose use cases",
  "│   │   │   ├── Models/          # Eloquent models",
  "│   │   │   ├── Repositories/    # Data access",
  "│   │   │   ├── Services/        # Busin
...

⚠️ Common Mistakes

⚠️

Cross-module direct queries — Module A should not query Module B's database tables directly. Use Module B's public API (service methods) or events instead.

⚠️

Starting with microservices — Most projects don't need microservices on day one. Start with a modular monolith; extract services only when a module truly needs independent scaling or deployment.

💡

Pro Tip: Write Architecture Decision Records (ADRs) for major choices. Future developers (including your future self) will thank you for documenting WHY you chose a modular monolith over microservices.

📋 Quick Reference — Architecture

Concept	Description
Module	Self-contained feature area with its own code
Action	Single-purpose use case class
DTO	Data Transfer Object — typed data bag
Domain Event	Signal that something happened in a module
ADR	Architecture Decision Record

🎉 Lesson Complete!

You now understand production PHP architecture! Time for the final project — build a complete real-world PHP application.