Abstract view of layered software

You're right, let's zoom out and talk about layered architecture in a more general, abstract way, moving beyond just the Spring Boot example. The concentric circle visualization still applies, but the labels of the circles become more general concepts.

Here's a more abstract view of layered software, visualized with concentric circles:

                      +-----------------+ | Core | (e.g., Fundamental Logic, Data Structures) +--------+--------+ | +--------v--------+ | Abstraction | (e.g., Services, APIs, Interfaces) +--------+--------+ | +--------v--------+ | Implementation | (e.g., Concrete Classes, Modules) +--------+--------+ | +--------v--------+ | Interface | (e.g., User Interface, External Systems) +-----------------+

Concentric Circle Interpretation:

• Core (Innermost Circle): This represents the most fundamental and essential logic or data structures of your system. It's the heart of your application and is often highly stable. It should be as independent as possible from the outer layers. Think of this as the "what" of your system.

• Abstraction Layer: This layer provides an abstract interface to the core functionality. It defines how the core can be used without exposing the underlying implementation details. This could be services, APIs, or interfaces. This layer acts as a bridge between the core and the outer layers. It starts to define "how" the "what" is accessed.

• Implementation Layer: This layer contains the concrete implementations of the abstractions defined in the previous layer. This is where the actual code resides that performs the operations defined by the abstractions. It's the "how" of the system.

• Interface Layer (Outermost Circle): This represents how the system interacts with the outside world. It could be a user interface, an API for other systems to use, or any other way that external entities interact with your software. This is where the "who" interacts with the system.

Key Principles of Layered Architecture:

• Separation of Concerns: Each layer has a specific responsibility. This makes the code more modular, maintainable, and easier to understand.

• Abstraction: Inner layers are hidden from outer layers. Outer layers only interact with inner layers through well-defined interfaces. This reduces dependencies and allows for changes in one layer without affecting others (as much).

• Loose Coupling: Layers should have minimal knowledge of each other's internal workings. They should interact through well-defined interfaces.

• Dependency Direction: Dependencies generally flow inwards. Outer layers depend on inner layers, but inner layers should not depend on outer layers.

Benefits of Layered Architecture:

• Maintainability: Changes to one layer are less likely to affect other layers.

• Testability: Each layer can be tested independently.

• Reusability: Inner layers can be reused by different outer layers.

• Comprehensibility: The system is easier to understand and reason about because of the clear separation of concerns.

This more abstract view of layered architecture can be applied to a wide range of software systems, regardless of the specific technology or framework used. It's a fundamental principle of software design that helps to create well-structured and maintainable applications. Is this closer to what you were thinking about?