What Is Spring Boot?

Spring Boot is an open-source micro framework maintained by a company called Pivotal. It provides Java developers with a platform to get started with an auto configurable production-grade Spring application. With it, developers can get started quickly without losing time on preparing and configuring their Spring application.

This post will guide you through understanding what the micro framework is and what it’s used for.

But before diving in, we’ll briefly discuss its underlying tool: Spring. Why? Understanding Spring is crucial to formulate a constructive opinion about Spring Boot.

What’s the Difference Between Spring and Spring Boot?

As I said at the start of this post, understanding the differences between Spring and Spring Boot is crucial for deciding whether to use this framework or not. Therefore, we should make the differences between both clear.

First, let’s talk about how they work together.

Spring Boot is built on top of the Spring framework, and it comes with many dependencies that can be plugged into the Spring application. Some examples are Spring Kafka, Spring LDAP, Spring Web Services, Spring Security, Spring Web Services, Spring REST Docs, and Spring HATEOAS. However, developers have to configure each building block themselves using a lot of XML configuration files or annotations.

Now, How Do They Differ?

Well, the Spring framework focuses on providing flexibility through its dependency injection feature. It helps to inject the required dependencies quickly but also to develop your application in a loosely coupled fashion. Some other benefits include:

A lightweight framework
Helps with loose coupling dependencies and testability. The modular architecture allows you to pick the parts you need and isolate them
Has support for both XML and annotation configuration
Provides abstraction on ORM software to develop the ORM persistence logic
Compatible with many middleware services
Supports the JDBC framework, which improves productivity and reduces errors

The micro framework, on the other hand, focuses on shortening the code length and providing you with an easy way to run your Spring application.

Do You Need to Learn One before the Other?

If you’re wondering if you need to learn Spring first, the short answer is no.

The Spring framework is significantly more user-friendly with the development of Spring Boot. Unless you have a specific reason for doing so, there is really no reason to use the old framework.

It also makes sense to stick to learning how to configure your libraries using Spring Boot, as it’s still an integration framework. This is easy to do, but sometimes these libraries require some configuration.

Notable Features of Spring Boot

Autoconfiguration: Developers can automatically configure their Spring application. However, the micro framework is also capable of changing the configuration based on the dependencies you list. For example, when you list “MySQL” as a dependency, it will configure your Spring application with the “MySQL connector” included. And if you want to add a custom configuration, you can create a class that overrides the default configuration for your “MySQL connector”.
Standalone: There’s no need to deploy your application to a web server. You simply enter the run command to start the application.
Opinionated: On the official page, we find that the micro framework decides for you which defaults to use for the configuration. Also, it decides which packages to install for the dependencies you require. For example, if you include the Spring Boot starter “pom” for “JPA”, it will autoconfigure an in-memory database, a hibernate entity manager, and a simple data source. This is an example of an opinionated default configuration that you can override. While some developers might feel this is too opinionated, Spring Boot’s opinionated setup helps developers to get started quickly on their projects.
Observability: With Spring Boot Observability, you can record application metrics such as memory usage, HTTP status codes, and cache hits and misses with Spring Boot Micrometer and implement tracing with Micrometer Tracing. You can configure the Micrometer Observation API to capture trace information, event logs, and relevant metrics by instrumenting the code once.
Performance: Spring Boot 3.0 and higher has GraalVM native image support that allows you to convert apps into GraalVM native images. This ensures instant app start-up, reduced memory footprint, and allows the app to reach peak performance immediately. The micro framework supports reactive programming with Spring WebFlux, enabling you to build non-blocking, event-driven applications that can handle concurrent requests. Also, features such as the @Async annotation and CompletableFuture facilitate asynchronous processing of web requests. The non-blocking nature of reactive processing keeps resource usage stable and predictable. Thus, with Spring Boot, you can achieve fast processing of a large number of requests with a small amount of resources.
Scalability: Spring Boot can scale to handle high request loads. For horizontal scaling in Spring Boot, you can deploy multiple instances of a Spring Boot app across different nodes to distribute load. You can also use orchestration and containerization tools such as Kubernetes and Docker Swarm to implement auto-scaling in Spring Boot based on metrics such as request rate, memory usage, and CPU usage.

Why Is Spring Boot So Popular?

First of all, it makes use of Java, which is one of the most popular programming languages in the world. Besides that, Spring Boot is an amazing tool that helps you to get enterprise-grade applications up and running quickly without having to worry about configuring your application correctly and safely.

Also, the user community is huge. If you want free learning materials and courses, you’ll find plenty out there. The accessibility of education has had a big impact on the framework’s popularity.

Spring Boot Benefits

Reduces development time and increases the overall productivity of the development team, especially with support for GraalVM native images, which enhances start-up times.
Helps you auto-configure all components for a production-grade Spring application.
Makes it easier for developers to create and test Java-based applications by providing a default setup for unit and integration tests.
Avoids writing lots of boilerplate code, annotations, and XML configuration.
Comes with embedded HTTP servers like Tomcat or Jetty to test web applications.
Adds many plugins that developers can use to work with embedded and in-memory databases easily. Spring allows you to easily connect with database and queue services like Oracle, PostgreSQL, MySQL, MongoDB, Redis, Solr, Elasticsearch, RabbitMQ, ActiveMQ, and many more. It offers support for reactive programming with R2DBC.
Allows admin support—meaning you can manage via remote access to the application.
Supports the deployment of applications to Kubernetes, with enhanced configuration management and cloud-native features.

Disadvantages of the Spring Boot Framework

The main struggle for many developers when using Spring Boot is the lack of control you have. The opinionated style installs many extra dependencies it assumes you’ll need. By installing all these extra dependencies (which sometimes go unused), the deployment binary size can become very large. However, you can enable the spring.main.lazy-initialization property to exclude unnecessary dependencies.

Next, the Spring Boot artifact can be directly deployed into Docker containers. This is great for quickly creating microservices. Besides, Spring Modulith allows the building of modular monolith applications. However, since the framework has been built to be agile and lightweight, some developers see Spring Boot as more of a microservices framework and less of a framework for building monolithic apps.

Learn more about microservices with Spring Boot here.

Last on the list of disadvantages is this: when you want to upgrade your legacy Spring code, it can be quite a struggle. Spring Boot tries to meet such use cases by providing several different tools, like a CLI tool that helps you with migrating your legacy code.

How the Micro Framework Compares to Other Java Frameworks?

While Spring Boot is a popular framework, developers can also explore alternatives such as Quarkus, Micronaut, and Struts. Here’s how the micro framework compares to these competitors.

Quarkus vs. Spring Boot

Optimized for Kubernetes and cloud-native environments, Quarkus manages the fast start-up times and low memory usage suited for serverless architectures. Like Spring Boot, Quarkus has strong support for GraalVM, allowing you to build native images.
Quarkus provides native support for Java libraries and standards like MicroProfile and Jakarta EE and has many community-developed extensions that enhance the framework. Spring Boot leverages the more mature and broader Spring ecosystem and offers a variety of integrations.
Quarkus uses Substrate VM and Graal to ensure reduced resource usage.

Micronaut vs. Spring Boot

Micronaut’s ecosystem is narrower and has fewer integrations, considering it’s a newer framework with a growing community, as opposed to Spring Boot, which has a large community of contributors.
Spring Boot supports reactive programming to enhance scalability and performance where latency and concurrency are needed. Micronaut also has native support for reactive programming. Micronaut relies on ahead-of-time (AOT) compilation to improve runtime performance, ensure application consistency, and simplify development.
Spring Boot uses Initializr to create Spring Boot projects. Micronaut provides a CLI tool to generate Micronaut projects.

Struts vs. Spring Boot

Struts is a heavyweight framework that relies on XML configurations. Auto-configuration and annotations ensure minimal configuration in Spring Boot.
Struts can be integrated with other Java EE technologies like Hibernate, JSP, JSTL, and JDBC, and it supports dependency injection through frameworks like Spring. Spring Boot has a broader integration support with modern tools and frameworks.
Struts uses a Model-View-Controller (MVC) architecture that may struggle with modern scalability. It’s, therefore, better suited for monolithic applications. Spring Boot’s AOP architecture is highly scalable, which is critical for microservices.

Application Monitoring

Although Spring Boot by default comes with some basic tools for monitoring logs and the health of your application, these aren’t sufficient. A tool like Stackify Retrace helps teams easily monitor Java applications. Retrace helps you to detect slow SQL queries, gives you reports about performance and CPU usage, and shows the most commonly occurring errors by interpreting the logs. To learn more, start your free Stackify Retrace trial today.

In a Nutshell

The main goal of the Spring Boot framework is to reduce overall development time. The micro framework also increases efficiency by having a default setup for unit and integration tests. Get started quickly with your Java application, easily accept all defaults and avoid the XML configuration completely. If you want to get started with your first Spring Boot application, you can find a 15-minute tutorial in the official documentation.