What is Spring Boot?
Spring Boot is a module that reduces the complexity of development and the time required for development and testing. It is built upon the Spring framework. That means Spring Boot uses all modules of Spring framework such as Spring MVC, Spring Data, etc. It provides a more convenient method to set up and run Java applications.
It is used to make a standalone application without a lot of Spring configuration. It combines features of Spring Framework and Embedded Servers and also simplifies it by removing the XML requirement.
History of Spring Boot
Spring Boot was first released in April 2014. It is open-source software, currently maintained by a company called Pivotal.
What are the Advantages of Spring Boot?
- It uses the dependency injection (DI) approach – In this approach, the initialization of objects is ‘outsourced’ to a framework, such that when the implementation changes, other code does not need to be modified.
- It has powerful transaction management capabilities, especially when used with databases. Transaction management capabilities are useful in case of a power loss. For example, if the write operation to a database stops because of an interruption in the power, transaction management shall ensure that any modification made to the database is reversed.
- It simplifies integration with other Java frameworks.
What are the prerequisites to learn Spring Boot?
To learn Spring Boot, one must have a knowledge of Java (including OOP or object-oriented programming) as well as some basic knowledge of the Spring Framework.
What is Spring Boot used for?
- Web Development: Using Spring Boot, a self-contained HTTP application can be created. This application may be used as a web-based application. This application may use embedded servers for testing, such as Undertow or Tomcat. A module, known as spring-boot-starter-web can be used to kickstart the application.
- Bootstrapping an application: It provides a method to bootstrap a Spring application. Bootstrapping a Java application refers to a self-starting application that does not require any input. This means, Spring Boot helps to create an application that starts by itself and then continues to run without the need for any input.
- Admin Features: Spring boot allows an administrator to remotely manage applications.
- Externalized Configuration: Spring boot allows for externalized configuration. This means that the same application can be used in different environments and contexts.
- Logging and Security: Spring boot uses common logging for all internal logging. Common logging is a logging technology developed by Apache for Java-based applications.
What is the difference between Spring Framework and Spring Boot?
Despite the fact that Spring Boot is built upon the Spring framework, there are several differences between the two. The differences between Spring Framework and Spring Boot are as follows:
- Used to develop applications with Java Enterprise (JE).
- Aims to simplify and shorten the code.
- The primary feature for which Spring is used is the inversion of control (IOC) and dependency injection (DI). These programming concepts aim to make code more loosely coupled, thereby reducing programming complexity.
- A lot of boilerplate code is required. (Boilerplate code is code that can be reused without the need for modification). In this case, several lines of such code need to be written by the developer.
- To test the Spring project, a server needs to be explicitly set up for the task.
- Does not provide support for a database in memory.
- Dependencies need to be manually defined in pom.xml.
- Used to develop REST APIs. REST stands for representational state transfer. A REST API is an interface that allows for interaction with a RESTful web server.
- Aims to shorten the code.
- The primary feature of Spring Boot is used is autoconfiguration. This means that Spring Boot automatically configures the classes based on the requirement. This can help create a stand-alone application with less configuration.
- Aims to reduce the amount of boilerplate code needed to be written by the developer.
- Spring boot makes use of embedded servers, such as Tomcat during testing.
- Several plugins are available for embedded and in-memory databases, such as H2.
- Spring boot starts the pom.xml file automatically. This takes care of the initial dependencies required by Spring Boot.
Layers in Spring Boot Architecture
There are four layers in the Spring boot architecture as below. Each layer communicates with a layer directly above or below it.
The presentation layer handles HTTP requests, translates JSON parameters into objects and authenticates the request. Then passes it to the Business layer. This is known as the front end.
The business layer consists of service classes and uses services provided by data access layers. Authorization and validation are done here which involves business logic.
The persistence layer contains the storage logic and translates business objects to and from the database.
In the database layer, the actual CRUD (create, retrieve, update, and delete) operations take place.
Spring Boot Flow Architecture
Spring Boot is built on top of the core Spring framework and follows a layered architecture in which each layer communicates with other layers. The Spring Boot Architecture consists of a layered architecture where each layer only depends on the adjoining layer. As it is a layered architecture, each layer communicates only with the layer directly below or above it.
One specialty of Spring Boot is that it does not require DAO (Data Access Object) classes. In the standard Spring Framework, a DAO class is required to divide high-level business services from lower layers. Furthermore, Spring Boot also removes the need for XML and annotation-based configuration. The Spring Boot Flow Architecture can be described in the following diagram:
The client is a web browser/computer, on which the application is running. The client places an HTTP request on the controller. An example of this request is the ‘GET’ request, which is sent by the client to access a resource on the server.
The controller maps the request and handles it. Service logic can be used in the controller if required. In the service layer, the business logic is present. This logic is performed on the data that is mapped to JPA with model classes. If no error occurs, a JSP page is sent back to the user. Furthermore, the controller layer can also be used to develop APIs (Application Process Interfaces). Such APIs can then be used to develop extensions for the application. It can also be implemented such that other developers can use the service.
The service layer is where business logic is executed. This is the logic that manages the communication between an end user and a database. This logic is created based on the business rules and workflows.
What is Spring Initializr?
Spring Initializr is a tool developed by Pivotal & is accessible on the web. This tool helps to easily generate the structure of a Spring Boot project. It provides APIs for JVM-based projects and also supports various popular Integrated Development Environments (IDEs), such as IntelliJ and Eclipse.
How to use Spring Initializr?
The tool asks for some parameters pertaining to the project. The parameters are as follows:
- Project type
- Spring boot version
- Type of packaging
- The version of the language used
- Other project metadata, such as name and description
Once the appropriate parameters are entered, and the generate button is clicked, a zip file is downloaded. This zip file contains the file structure of the empty project. The code file (.java files) can then be added to the folders.
Advantages and Disadvantages of Spring Boot Architecture
- Spring Boot allows easy and faster development of spring-based applications in Java or Groovy
- Spring Boot can be built with the aid of tools like Gradle and Maven, as well as jBOSS. It also provides a lot of plugins that make effortless development and testing of Spring Boot applications possible
- It avoids a lot of manual labor involved in writing annotations, boilerplate codes, and XML configurations, helping to reduce the risk of errors.
- The Spring Boot Application with Spring Ecosystem, which includes Spring Security, Spring Data, Spring JDBC, and Spring ORM, is easy to integrate with Spring
- It would also be easier for developers to follow the ‘Opinionated Defaults Configuration’ (It is a strategy to eliminate boilerplate and configurations meant to improve unit testing, development, and integration test procedures)
- Development Web apps can be tested using Embedded HTTP servers such as Jetty, and Tomcat.
- The Spring Boot CLI is accessible through the Command Line Interface also
- Working with embedded and memory databases is extremely convenient and easily accomplished with the plugin
- It is possible to convert legacy or existing Spring Framework projects to Spring Boot applications but it is time-consuming
- The size of the application deployment file is increased because of the high number of unused dependencies caused by Spring Boot
- Some users argue that Spring Boot is not suitable for building large-scale applications because it is unsuitable for working with microservices (an architectural and organizational approach to software development where software is composed of small independent services that communicate over well-defined APIs)
- Spring Boot works well with small applications but may not be used in a large and complex application
In the next article, I am going to discuss Spring Boot Versions. Here, in this article, I try to explain What is Spring Boot and why we need Spring Boot. I hope you enjoy this article.