Important Architecture Styles & patterns of Software Design in Microservices

In software design, various architecture styles and patterns are used to solve common problems and improve the quality of software systems. There are several types of software architectures, each with its own principles and goals. Here we discuss Four popular architectural styles are

Types of Important Architecture In Microservices:

*️⃣Clean Architecture,
*️⃣Onion Architecture
*️⃣Hexagonal Architecture
*️⃣Vertical Slice Architecture

Clean Architecture:

what is Clean Architecture:

💥Clean Architecture is a software design philosophy that emphasizes separation of concerns and maintainability. It was introduced by Robert C. Martin, also known as Uncle Bob. The key idea behind Clean Architecture is to create software that is independent of frameworks, UI, databases, and other external concerns, allowing it to be easily testable and adaptable to changing requirements.

Core Principle: The core principle of Clean Architecture is the separation of concerns, with a focus on the independence of the business logic from external concerns like frameworks, databases, and UI.

➡ Layers: Clean Architecture typically defines four layers:
➡ Entities: Represent the business objects or entities.
➡ Use Cases: Contain application-specific business rules and logic.
➡ Interface Adapters: Convert data from the format most convenient for the use cases to the format most convenient for entities and vice versa.
➡ Frameworks and Drivers: Contain all the details related to frameworks, tools, and UI.
➡ Dependency Rule: Dependencies must only point inward, toward higher-level policies. The inner layers should not know anything about the outer layers.
➡ Testability: The architecture promotes testability by keeping business logic isolated and independent of external dependencies.

Onion Architecture:

Core Principle: Onion Architecture also emphasizes the separation of concerns but organizes the layers differently, focusing on the domain at the center and building layers around it.

➡Layers: Onion Architecture typically consists of concentric circles, with the innermost layer representing the core domain and each outer layer representing more specific implementation details:
➡Core Domain: Contains the most essential and unique parts of the application, including domain entities and business logic.
➡Infrastructure: Provides implementations for external concerns like databases, frameworks, and services.
➡Application: Contains application-specific logic that does not belong in the core domain but is necessary for the application to function. ➡Presentation: Contains UI-related code.
➡Dependency Rule: Dependencies should flow toward the center, with inner layers having no knowledge of outer layers. The core domain should be independent of external concerns.
➡Testability: Onion Architecture promotes testability by keeping the core domain isolated and free from external dependencies, making it easier to test in isolation.

Onion Architecture	Clean Architecture
Dependencies flow inwards, with the core domain at the center and peripheral concerns like UI and infrastructure at the outer layers. The core domain is kept free from external dependencies.	Dependency Direction: Similar to Onion Architecture, Clean Architecture also advocates for dependencies pointing inwards. However, it emphasizes the independence of the inner layers from external frameworks and details, including the UI and data access mechanisms.
Layers: Onion Architecture: Typically consists of multiple layers, including core domain, application services, infrastructure, and UI. Each layer is responsible for a specific set of concerns.	Clean Architecture: Also consists of layers, such as entities, use cases, interface adapters, and frameworks/drivers. The layers in Clean Architecture are organized more around the flow of data and the dependencies between components.
Dependency Inversion: Encourages the use of dependency inversion to decouple high-level modules from low-level modules. This allows for easier testing and swapping of implementations.	Places a strong emphasis on dependency inversion, ensuring that high-level policies and abstractions are not dependent on low-level details. This enables the system to be more flexible and adaptable to change.
Focus: Focuses on the core domain and its interaction with application services. It emphasizes building the application from the inside out, starting with the core domain.	Focuses on separating concerns and isolating the core business logic from external details. It places a strong emphasis on maintaining independence from frameworks and tools.

In summary, both Onion Architecture and Clean Architecture aim to create systems that are modular, maintainable, and testable. While they share similarities in their principles, they differ in their approach to organizing layers, managing dependencies, and emphasizing certain aspects of software design.

In Next Series will discuss about Vertical Slice and Hexagonal Architecture.