Evolution of Software Architecture

🌐 Exploring the Evolution of Software Architecture

Hello everyone! 👋 Welcome back to the channel where we dive into the world of software development, one fascinating concept at a time. Today, we're embarking on a journey through the evolution of software architecture—from the foundational Layered Architecture, through Hexagonal and Onion Architecture, all the way to the increasingly popular Clean Architecture.

Have you ever wondered:

• How did these architectural patterns come to be?
• Why do some designs suit certain applications better than others?

As Jamie, my colleague, says: "It depends—no one architecture fits all."

By the end of this article, you'll have a clear understanding of these styles, their historical progression, key principles, and practical applications. Whether you're new to software architecture or a seasoned developer looking for a refresher, this one's for you! 🎉

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🏗️ Layered Architecture: The Starting Point

The Layered Architecture (a.k.a. N-tier architecture) breaks a system into distinct layers like:

• Presentation Layer
• Business Logic Layer (BLL)
• Data Access Layer (DAL)

Key Features:

• Simplicity: Easy to understand, implement, and use.
• Structure: The Presentation Layer depends on the BLL, which in turn depends on the DAL.

However, this creates tight coupling between layers, making the system rigid and hard to scale. Architects have since evolved designs to address these limitations.

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🔧 Making Business Logic the Focal Point

To improve the architecture:

• Shift dependency to the business logic layer.
• Introduce interfaces like:
  • IRepository in the core, with its implementation in the DAL.
  • IEmailService to abstract email communication systems.

This strategy gives rise to Hexagonal Architecture, enhancing modularity and flexibility.

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🔷 Hexagonal Architecture: Breaking Free from Coupling

Also called the Ports and Adapters pattern, Hexagonal Architecture emphasises business logic as the core of the system.

Visualising the Structure:

• Primary (Driving) Adapters: User interfaces like CLI or APIs.
• Secondary (Driven) Adapters: External systems like databases or email services.
• Core Application: Processes requests and directs flows.

The system interacts with external dependencies via ports (interfaces) and adapters (implementations), enabling a loosely coupled design.

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🌀 Onion Architecture: A Step Further

Building on hexagonal principles, Onion Architecture arranges systems into concentric circles:

1. Domain Models and Business Rules: At the centre.
2. Application Services and Infrastructure: Surrounding layers.

Core Principles:

• Dependency Inversion: Outer layers depend on inner layers.
• Flexibility: Changes to UI or external systems don't affect business logic.

This design supports testability and aligns well with Agile development practices. 🎯

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🌟 Clean Architecture: The Best of All Worlds

Clean Architecture simplifies earlier patterns while retaining their strengths.

Highlights:

• Business Rules at the Centre: The domain layer handles all core logic.
• Focus on Use Cases: Emphasises what the system does rather than how it achieves it.

For example:

• Multiple implementations for IEmail can exist, but the Web UI layer decides which to use dynamically.
• Independence from frameworks makes systems more maintainable and adaptable.

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🛠️ From Hexagonal to Clean Architecture

The journey from Hexagonal to Clean Architecture focuses on:

• Making the application core resilient to changes.
• Enhancing maintainability by layering the core logically.

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🎯 Summary of the Journey

• Layered Architecture: Introduced clear separations but had tight coupling.
• Hexagonal Architecture: Decoupled business logic via ports and adapters.
• Onion Architecture: Emphasised domain models with dependency inversion.
• Clean Architecture: Focused on simplicity, use cases, and maintainability.

Each pattern represents a step forward in designing robust, scalable, and adaptable systems. 💡

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That wraps up our deep dive into software architecture! From foundational layers to the elegance of Clean Architecture, we've traced how these patterns evolved and adapted over time. Hopefully, you've gained insights to inspire your next project.

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Thanks for reading, and I'll see you in the next one. Cheers! ☕