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README.md

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+# hexagonal-architecture-ddd-springboot
+
+The main idea behind this architecture is to isolate domain logic from external components when designing software applications.
+
+Access to domain logic from the outside is available through ports and adapters.
+
+<img src="https://miro.medium.com/max/640/1*N7tlxqOLXiPLy_yrb0q7-Q.png"/>
+
+A port is just an interface to be implemented by an adapter. There are two types of ports: input and output. We implement the first ones in the domain layer, while the infrastructure module will contain the implementation of the second ones.
+
+## Example
+Let’s consider a simple Product REST Service to understand this architecture. Resources of the product service are:
+
+Create a Product
+Get the Product by Id
+
+We start creating the three layers: application, infrastructure, and domain.
+
+## Application
+The application layer will contain the ports, which are interfaces that allow inbound or outbound flow.
+
+We created use cases inside the input package, defining what the user would like to do in the application. 
+In our example, create new products and get them by Id.
+
+On the other hand, we use the output package to connect to some external components.
+In our example, ProductOutputPort will get data from the database.
+
+## Infrastructure
+The infrastructure layer represents the outer part of the hexagonal architecture through adapters.
+
+Adapters interact with the core application only by using the inbound and outbound ports.
+
+We divide the infrastructure.adapters package into three new ones:
+
+  1. config: it contains the beans of the application
+  2. input: it drives the application by invoking the corresponding use case (input port)
+  3. output: it provides an implementation of the output ports (databases or messaging queues)
+  
+## Domain
+The domain layer is the center of the system. It handles the business logic and represents the application core.  
+
+The domain layer is wholly decoupled from application and infrastructure layers, so changes in the other layers have no impact on the Product domain object unless there is a change in the business requirements.
+
+The ProductService is a crucial component inside the domain, as it implements the input ports and uses the output interfaces implemented by the output adapters to return the result to the input adapters