A service implementation is a spring bean that is annotated by @Service. Business logic for spring applications is most commonly put in a service implementation. A service, on the other hand, is an interface with function signatures for application behavior that must be implemented by implementing classes. A simple way to recall the differentiation between the two is to keep in mind that a service is an interface and a service implementation is a class that implements a service.
Now to create some services and service implementations. Create a service package. We will add both services and service implementations in here. Create a UserService interface as with the following codes within the package:
