Spring Boot allows you to create standalone, production-ready applications by providing embedded servlet containers. This feature eliminates the need to deploy your application to an external web server like Apache or Nginx. With Spring Boot, you can choose from several embedded servers to host your web application. Here are the most common embedded servers you can use with Spring Boot:
1. Tomcat
Tomcat is the default embedded server in Spring Boot. It is a robust and widely-used servlet container, often chosen for its compatibility with Java-based web applications.
- Default Configuration: Spring Boot comes preconfigured with Tomcat, and you don’t need to specify any additional setup unless you want to change its configuration.
- Customization: You can customize Tomcat’s configuration by creating a
TomcatServletWebServerFactory bean or by adding specific properties in application.properties or application.yml. - Example: Spring Boot automatically uses Tomcat, so no additional configuration is needed unless you want to change the port, servlet context, or other Tomcat-specific properties.
properties
# Change Tomcat port
server.port=8081
- How to Switch to Tomcat: If you want to explicitly specify Tomcat (although it's already the default), you can add the following dependency in
pom.xml:
xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</dependency>
2. Jetty
Jetty is another popular embedded web server in Spring Boot. It's known for being lightweight and efficient. If you want to replace the default Tomcat server with Jetty, Spring Boot provides an easy way to do that.
- How to Use Jetty: To use Jetty, exclude Tomcat and add the Jetty starter dependency to your
pom.xml file:
xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jetty</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
- Jetty Customization: Once you’ve included the dependency, Spring Boot will automatically configure Jetty for your application. You can customize its settings in the same way you would with Tomcat by using properties in
application.properties or by defining a JettyServletWebServerFactory bean.
3. Undertow
Undertow is a lightweight, high-performance web server developed by JBoss. It is designed for high concurrency and is a great alternative for microservices or highly scalable applications.
- How to Use Undertow: To use Undertow as the embedded server in Spring Boot, you need to exclude Tomcat and add the Undertow starter dependency:
xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-undertow</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
- Undertow Customization: You can customize Undertow's settings by using a
UndertowServletWebServerFactory bean or by using Spring Boot's properties.
4. Using Multiple Embedded Servers
Spring Boot allows you to configure different embedded servers depending on the needs of your application. You can switch between Tomcat, Jetty, and Undertow easily, depending on your specific performance, scalability, or compatibility needs.
- Example Configuration in
pom.xml: - You can choose the embedded server of your choice by including the corresponding starter dependency while excluding the default Tomcat dependency:
- For Tomcat:
xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</dependency>
xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jetty</artifactId>
</dependency>
xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-undertow</artifactId>
</dependency>
5. Choosing the Right Server
- Tomcat is often chosen for its robustness, wide usage, and compatibility with legacy systems.
- Jetty is typically used for lightweight, high-performance applications where ease of setup and fast response time are crucial.
- Undertow is ideal for microservices and high-concurrency environments, offering great scalability and performance under load.
Conclusion
Spring Boot offers flexibility in choosing the embedded server for your application. Whether you use Tomcat, Jetty, or Undertow, Spring Boot makes it easy to configure and switch between these servers. You can adjust the server settings to match the requirements of your application for optimal performance. Simply choose the server that best fits your application's needs, and Spring Boot will handle the rest.