Clean architecture

The architecture implemented in the generated application follows the Clean Architecture principles, originally described by Robert C. Martin.

It aims to reduce the dependencies between your business logic and the services you consume (API, database, framework, third-party libraries), to maintain a stable application during its evolutions, its tests but also during changes or updates from external resources.

The code is divided into layers, each having their responsibility. The lower layers should not be aware of the upper layers, in order to not be impacted when they change.

Core principles

Dependency rule

The fundamental rule of Clean Architecture is that dependencies must point inward. Inner layers should never know anything about outer layers.

Important

The Domain layer is the core of your business. It must remain independent of any external concern (database, UI, application layer). This ensures that your business logic can be tested in isolation and remains stable over time.

Benefits

Benefit	Description
Testability	Business logic can be tested without database, UI, or external services
Maintainability	Changes in external systems don't affect core business logic
Flexibility	Easy to swap implementations (e.g., change database provider)
Independence	Business rules don't depend on UI, or infrastructure

Generated application architecture

When Neos generates an application from your YAML metadata, it produces code that follows the same Clean Architecture principles as the framework itself:

Layer responsibilities

Layer	Generated/Business Code
Domain	Entities, Entity validation rules, Entity event rules
Application	Entity views, Server methods, Entity view rules
Infrastructure	Generated repositories, Database context
Presentation	Generated REST API endpoints

flowchart TB
    subgraph Presentation["Presentation Layer"]
        direction LR
        API[REST API<br/>Controllers]
        SPA[Vue.js SPA<br/>Frontend]
    end
    
    subgraph Application["Application Layer"]
        direction LR
        EV[Entity Views]
        SM[Server Methods]
        REPO_IMPL[Entity View Repository<br/>Implementations]
        EVVR[Entity View<br/>Validation Rules]
        EVER[Entity View<br/>Event Rules]
        COMM[Inter-cluster Communication]
        NOT[Notifications]
    end
    
    subgraph Domain["Domain Layer"]
        direction LR
        E[Entities]
        EVR[Entity<br/>Validation Rules]
        EER[Entity<br/>Event Rules]
        REPO_INT[Repository<br/>Interfaces]
    end
    
    subgraph Infrastructure["Infrastructure Layer"]
        direction LR
        DB[(Database)]
        EXT[External<br/>Services]
    end
    
    Presentation --> Application
    Application --> Domain
    Infrastructure --> Domain
    
    style Domain fill:#e8f5e9,color:#000
    style Application fill:#e3f2fd,color:#000
    style Presentation fill:#fff3e0,color:#000
    style Infrastructure fill:#fce4ec,color:#000

Table of Contents