Application Layers

In software development an application is divided into separate layers, which represent different parts of functionality. The new Application Core can also be separated into layers like it's shown in the picture below:

Framework / Infrastructure

The framework or infrastructure layer includes general tools and components to execute the shop software. It contains no specific business logic and can't tell you anything about the exact functionality of its software. This layer will include elements handling incoming HTTP requests, logging, sessions, or the database connection.

Application Core

Deeper in the Application Core layer, the components execute certain main functionalities of the application. The tasks performed here are still very technical and far away from specific business rules. Parts of this layer are controllers or actions for the incoming HTTP requests, application services, or database readers and writers.

Use Cases / Domain Services

The (Domain-driven design) domain starts with the layer for use cases. The entirety of domains shows what this application is about; therefore, this layer provides information about the use cases and possibilities of interacting with these domains. Domain services, interfaces of repositories and factories are typical components of this layer.

Domain Model

When using Domain-driven design, the model is a fundamental part of the software because it contains the business logic of the whole software. This is also less volatile than the outer parts of the software. The components of this layer are entities, value objects, events and the aggregate root.