Spring Boot - Architecture

Spring Boot is a framework built on top of the Spring Framework that simplifies application development by providing auto-configuration, embedded servers, and production-ready features. Its architecture is designed to reduce boilerplate code, making it easier to build standalone, scalable, and maintainable Java applications

Spring Boot Architecture Layers

Spring Boot consists of the following four layers:

1. Presentation Layer

The Presentation Layer acts as the entry point of the Spring Boot application, also known as the controller layer. It is responsible for handling all incoming HTTP requests and sending appropriate responses back to the client.

Responsibilities:

• Handles HTTP methods such as GET, POST, PUT, DELETE
• Exposes RESTful APIs using controllers
• Performs request validation
• Manages authentication entry points
• Converts Java objects to JSON and vice versa
• Forwards validated requests to the Business Layer

Common Components:

• @RestController / @Controller
• @RequestMapping, @GetMapping, @PostMapping
• @RequestBody, @PathVariable

2. Business Layer

The Business Layer, also known as the Service Layer, contains the core business logic of the application. It acts as an intermediary between the Presentation and Persistence layers.

Responsibilities:

• Implements business rules and workflows
• Processes and validates data
• Handles authentication and authorization logic (using Spring Security if required)
• Manages transactions using @Transactional
• Communicates with the Persistence Layer to retrieve or store data

Common Components:

• @Service
• @Transactional

3. Persistence Layer

The Persistence Layer is responsible for database interaction and data access logic. It abstracts the underlying database operations from the rest of the application.

Responsibilities:

• Maps Java objects to database tables using ORM frameworks
• Performs CRUD (Create, Read, Update, Delete) operations
• Manages database transactions
• Supports both relational and NoSQL databases

Technologies Used:

• Spring Data JPA
• Hibernate
• R2DBC (for reactive applications)

Common Components:

• @Repository
• JpaRepository, CrudRepository
• @Entity, @Id, @Table

4. Database Layer

The Database Layer contains the actual database where the application data is stored. It can support:

• Relational Databases (MySQL, PostgreSQL, Oracle, SQL Server).
• NoSQL Databases (MongoDB, Cassandra, DynamoDB, Firebase).
• Cloud-based databases for scalability.

Spring Boot Flow Architecture

Explanation:

• The client (frontend or API consumer) sends an HTTP request (GET, POST, PUT, DELETE) to the application.
• The request is handled by the Controller Layer, which maps the request to a specific handler method.
• The Service Layer processes business logic and communicates with the Persistence Layer to fetch or modify data.
• The Persistence Layer interacts with the Database Layer using Spring Data JPA or R2DBC, often through a Repository Class that extends CRUD services.
• The processed response is returned as JSON.
• Spring Boot Actuator can be used for monitoring and health checks.

Monitoring with Spring Boot Actuator

Spring Boot provides Spring Boot Actuator, which adds production-ready features to the application.

Actuator Features:

• Health checks
• Application metrics
• Environment details
• Thread and memory monitoring
• Custom management endpoints
• Actuator helps monitor application health and performance in real-time.