(also known as Ports and Adapters) in Java, the specific book titled Designing Hexagonal Architecture with Java Davi Vieira is a commercial publication by Packt Publishing Accessing the Book
├── model/ # (Pure Java) Contains domain entities and value objects ├── application/ # (Pure Java) Contains the domain services and ports ├── adapters/ # (Framework-aware) Contains REST, JPA, and in-memory adapters └── bootstrap/ # (Framework-aware) Contains configuration and startup logic
class AccountTest @Test void shouldWithdrawFunds() Account account = new Account(UUID.randomUUID(), new BigDecimal("100.00")); account.withdraw(new BigDecimal("30.00")); assertEquals(new BigDecimal("70.00"), account.getBalance()); Use code with caution. Mocking Driven Ports
: Integrating DDD building blocks like Aggregates and Domain Services to ensure the domain model reflects real-world problems accurately. Dependency Inversion
Ports are Java interfaces that define how the outside world interacts with the domain, or how the domain interacts with the outside world. (also known as Ports and Adapters) in Java,
The primary goal is to create an application where the "Domain" is the and the "Technology" is the slave . If you decide to switch your Relational Database (RDBMS) for a NoSQL alternative or move from REST to gRPC, you should be able to do so without touching a single line of the code that runs your business.
@Override public VideoGame findById(VideoGameId id) // Convert JPA Entity to Domain Object
Hexagonal architecture, also known as the pattern, has become a cornerstone of modern, maintainable, and testable software development. As applications grow in complexity, adhering to strict architectural boundaries becomes essential. This article explores the fundamentals of designing hexagonal architecture with Java, providing insights often sought in resources like "Designing Hexagonal Architecture with Java PDF Free 2021 Download," focusing on domain-driven design, decoupling, and modern Java best practices. What is Hexagonal Architecture?
Demystifying Hexagonal Architecture in Java: Building Decoupled, Testable, and Maintainable Enterprise Applications The primary goal is to create an application
Database Repositories, Message Brokers, External Service Clients. They are driven by the application. Designing the Domain Model (The Core)
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public interface WithdrawMoneyPort void withdraw(Long accountId, Money amount);
: The complete code examples and project repositories for the book are available for free on Core Concepts Covered As applications grow in complexity, adhering to strict
| 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. |
// Secondary Adapter (JPA Repository) @Repository public class JpaGameRepository implements GameRepository // Implements the OUT port private final JpaGameRepositorySpringData jpa;
package com.bank.domain.service; import com.bank.domain.model.Account; import com.bank.ports.inbound.TransferUseCase; import com.bank.ports.outbound.AccountRepositoryPort; import java.math.BigDecimal; import java.util.UUID; public class TransferService implements TransferUseCase private final AccountRepositoryPort accountRepositoryPort; public TransferService(AccountRepositoryPort accountRepositoryPort) this.accountRepositoryPort = accountRepositoryPort; @Override public void transfer(UUID sourceId, UUID targetId, BigDecimal amount) Account sourceAccount = accountRepositoryPort.load(sourceId); Account targetAccount = accountRepositoryPort.load(targetId); sourceAccount.withdraw(amount); targetAccount.deposit(amount); accountRepositoryPort.save(sourceAccount); accountRepositoryPort.save(targetAccount); Use code with caution. 4. The Driving Adapter (REST Controller)