Spring Boot Architecture
Tags: java, webdev, programming
Published: 2021-11-14 19:38:00

Spring Boot is a more user-friendly version of the Spring Framework. With Spring Boot, you can create autonomous and easy to run applications. 

**WHAT IS THE DIFFERENCE BETWEEN  SPRING AND SPRING BOOT?**

If you've ever tried to write a Java application time ago, you would have noticed how much work you had to do to perform database operations. It's a tiring process! 

The Spring Framework simplifies these operations, thanks to the Spring JDBC module. 

Spring is the combination of multiple sub-frameworks. It has many modules, for example, Spring MVC, Spring  JDBC, Spring  AOP, Spring  ORM, and Spring Test. The core feature of the Spring Framework is *Dependency Injection*.  

Even though Spring has made the development of Java applications easier, I think that it is vast and complicated to master.  In the past, I tried to learn the Spring Framework from scratch, and I found it a long experience. This is where **Spring Boot** comes in handy, though. 😁 

**WHAT IS SPRING BOOT?**

Spring Boot is built on top of the Spring Framework. It's a more automated and simplified version of Spring. Spring Boot makes it easy to create an up and running application in a few minutes. You go to  [Spring Initializr](https://start.spring.io/)

![springInitializr.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1636841347347/XD_UTMM8P.png)

And the website will generate the application for you in an instant. 

If you're undecided on whether to learn Spring or Spring Boot, I'd say to at least know the basics of the Spring Framework and then jump onto Spring Boot. 

Now let's talk about Spring Boot Architecture.

**SPRING BOOT ARCHITECTURE**

Spring Boot Architecture has four layers:

- **Presentation Layer**
- **Business Layer**
- **Persistence Layer**
- **Database Layer**


![Spring Boot Architecture.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1636840785484/hxIUT9R03.png)

**PRESENTATION LAYER**

This layer is at the top of the architecture. This tier is responsible for:

✔️ Performing authentication.

✔️ Converting JSON data into an object (and vice versa).

✔️ Handling HTTP requests.

✔️ Transfering authentication to the business layer.

The presentation layer is the equivalent of the Controller class. The Controller class handles all the incoming REST API requests (GET, POST, PUT, DELETE, PATCH) from the Client. 

**BUSINESS LAYER**

The business layer is responsible for:

✔️ Performing validation.

✔️ Performing authorization.

✔️ Handling the business logic and rules.


This layer is the equivalent to the Service class. It's where we handle the business logic. If you're wondering what do we mean by "business logic", I found an interesting discussion on [StackExchange](https://softwareengineering.stackexchange.com/questions/234251/what-really-is-the-business-logic). In short, the business logic in software engineering is where we decide what the software needs to do. An example of this is validation. If you are ever requested to validate something, this needs to happen inside the Service class. 

The Business layer communicates with both the Presentation layer and the Persistence Layer. 

**PERSISTENCE LAYER**

This layer is responsible for:

✔️ Containing storage logic.

✔️ Fetching objects and translating them into database rows (and vice versa).

This layer is the equivalent of the Repository interface. We write database queries inside this interface. 

The Persistence layer is the only layer that communicates with the Business layer and the Database layer.

**DATABASE LAYER**

This layer is responsible for:

✔️ Performing database operations (mainly CRUD operations).

This layer is simply the actual database that you decide to use to build your application. 

**SPRING BOOT WORKFLOW**


![Spring Boot workflow.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1636842342576/7ShwFxJxx.png)

Spring Boot workflow acts like this:

1. The Client makes an HTTP request.
2. The Controller class receives the HTTP request.
3. The Controller understands what type of request will process, and then it deals with it.
4. If it is needed, it calls the service class.
5. The Service Class is going to handle the business logic. It does this on the data from the database.
6. If everything goes well, we return a JSP page.

Thanks for reading my article. Until next time! 👋🏾

P.S: did you enjoy this article? If so, I invite you to subscribe to my [newsletter](https://techwithmaddy.com/newsletter). I share interesting stuff around career development, software engineering and technical writing.

**FURTHER READING:**

- [How to Create a Spring Boot REST API](https://techwithmaddy.com/how-to-create-a-spring-boot-rest-api)

- [Testing With Spring Boot](https://techwithmaddy.com/testing-with-spring-boot)

- [Replace a JPA Entity with a DTO object](https://techwithmaddy.com/replace-persistence-entity-with-a-dto-object)