In previous chapters, you have seen that one of Spring's goals is to allow you to develop applications by following one of the OOPs principles of coding to interfaces. Any enterprise application needs to read data and write data to any kind of database, and to meet this requirement, we have to write the persistence logic. Spring allows you to avoid the scattering of persistence logic across all the modules in your application. For this, we can create a different component for data access and persistence logic, and this component is known as a data access object (DAO). Let's see, in the following diagram, the best approach to create modules in layered applications:
As you can see in the preceding diagram, for a better approach, many enterprise applications consist of the following three logical layers:
- The service layer (or application layer): This layer of the application exposes high-level application functions like use-cases and business logic...