For a detailed breakdown of what to expect from the leading book on this topic, read the Medium review by Priya Shastri
Indian food is not just cuisine; it is medicine, religion, and class warfare rolled into one.
Instead of layers, imagine a hexagon.
Hexagonal Architecture solves these issues by placing the (business logic) at the center. It communicates with the outside world only through Ports (interfaces) and Adapters (implementations). designing hexagonal architecture with java pdf download
A port is an interface defined by the application core. It acts as a contract. There are two types of ports:
If you're ready to dive deep into these patterns, check out these essential resources:
✅ Test your domain logic in isolation without needing a real database or server. For a detailed breakdown of what to expect
You are now equipped with the foundational knowledge. To continue your journey:
Adapters are the glue code. They implement the ports or use the ports to bridge the gap between the core and the outside world.
The flaw lies in the dependency rule. The Business Layer depends on the Data Access Layer. This means your core business logic—your intellectual property—is tightly coupled to the database implementation. If you want to switch from MySQL to PostgreSQL, or if you want to test your business logic without spinning up a heavy database container, you are in for a world of pain. The database controls the code, rather than the code controlling the database. It communicates with the outside world only through
This is the heart of your application. It contains the pure business logic and remains completely unaware of any technical infrastructure. Hexagonal Architecture Template with Java and Spring Boot
// Inside domain/model/Order.java public class Order { private UUID id; private boolean paid; public void markAsPaid() { if (this.paid) throw new IllegalStateException("Already paid"); this.paid = true; // Business event DomainEventPublisher.publish(new OrderPaidEvent(this.id)); }
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