I hope this helps! Let me know if you have any questions or need further clarification.
Software systems often start clean but degrade over time. Business logic mixes with database queries. UI components tightly couple with core algorithms.
: Ports are contracts or APIs that define how the outside world can interact with the core. They are interfaces that describe what the application can do. There are two types:
You can download a sample implementation of this architecture in Java from here . I hope this helps
You will need to map objects between layers (e.g., converting a Web Request DTO to a Domain Model, and a Domain Model to a Database JPA Entity). Do not cut corners by reusing your JPA Entity as your core Domain Model—this completely breaks the architectural isolation.
| Module | Focus Area | Key Topics | | :--- | :--- | :--- | | | Core Concepts | Deep dive into Entities, Use Cases, Ports, and Adapters; understanding SOLID principles in the context of hexagonal architecture. | | Building the Hexagons | Practical Implementation | Hands-on development of the Domain, Application, and Framework hexagons using real-world scenarios. | | Mastering the Mechanics | Advanced Techniques | Strategies for mapping between layers; using Java modules to enforce dependency inversion and ensure component isolation. | | Becoming Cloud-Native | Modern Integration | Turning a hexagonal application into a cloud-native system using Quarkus, managing ports and use cases with CDI beans, and integrating with REST and gRPC protocols. |
If you are looking for a deep-dive, hands-on guide focusing on implementing this architecture within the Java ecosystem, several resources from around 2021 provide excellent in-depth tutorials and code examples. Business logic mixes with database queries
Implement ArchUnit automated tests to ensure your domain layer never accidentally imports classes from the adapter or framework packages.
hexagonal-architecture |____pom.xml |____src | |____main | | |____java | | | |____com.hexagonal.architecture | | | | |____domain | | | | | |____User.java | | | | |____ports | | | | | |____primary | | | | | | |____AuthenticationService.java | | | | | |____secondary | | | | | | |____UserRepository.java | | | | |____adapters | | | | | |____primary | | | | | | |____AuthenticationServiceAdapter.java | | | | | |____secondary | | | | | | |____UserRepositoryAdapter.java | | | | |____application | | | | | |____AuthenticationApplicationService.java | |____test | |____java | |____com.hexagonal.architecture | |____AuthenticationApplicationServiceTest.java
: Swap out Spring Boot, Quarkus, or databases without altering core logic. They are interfaces that describe what the application
package com.example.order.ports.outbound; import com.example.order.domain.Order; public interface OrderRepositoryPort void save(Order order); Use code with caution. 3. The Core Service (Implementing Inbound Ports)
Understanding the structural blueprint allows you to build clean systems in any version of Java without relying on a specific book. Step-by-Step Java Implementation
The ports define how the application interacts with the outside world. In Java, this can be represented by an interface:
The official PDF eBook is not a standalone free download. However, you can obtain it legitimately through the following channels:
This is a pure Java object containing data and core validation logic.