Setting up Spring and Jetty

Oct 13, 2025 by magicalceylontours.com 107 views

Introduction

In this article, we will explore how to implement a plain WebSocket using Spring and Jetty. WebSockets provide a way for web applications to establish a persistent, low-latency connection between a client and a server. This allows for real-time communication and bi-directional data exchange between the client and server. Spring provides a simple and efficient way to implement WebSockets using the Spring WebSocket API, which is built on top of the Jetty WebSocket implementation.

What is Spring WebSocket?

Spring WebSocket is a part of the Spring Framework that provides a simple and efficient way to implement WebSockets. It provides a programming model for building WebSocket applications and integrates with the Spring MVC framework. Spring WebSocket is built on top of the Jetty WebSocket implementation, which provides a robust and scalable WebSocket engine.

What is Jetty?

Jetty is a Java-based web server and servlet container that provides a lightweight and flexible way to deploy web applications. Jetty is designed to be highly scalable and performant, making it an ideal choice for building high-traffic web applications. In the context of Spring WebSocket, Jetty is used as the underlying WebSocket engine to provide a robust and scalable WebSocket implementation.

Setting up Spring and Jetty

To set up Spring and Jetty, you will need to add the following dependencies to your project:

Spring Web
Spring WebSocket
Jetty

You can add these dependencies to your project using the following Maven coordinates:

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-websocket</artifactId>
    </dependency>
    <dependency>
        <groupId>org.eclipse.jetty</groupId>
        <artifactId>jetty-server</artifactId>
    </dependency>
    <dependency>
        <groupId>org.eclipse.jetty</groupId>
        <artifactId>jetty-websocket</artifactId>
    </dependency>
</dependencies>

Configuring Spring WebSocket

To configure Spring WebSocket, you will need to create a configuration class that extends the WebsocketConfigurer class. This class provides a number of methods that you can use to configure the WebSocket endpoint.

Here is an example of a configuration class that sets up a simple WebSocket endpoint:

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
@Override
public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
    registry.addHandler(chatHandler(), &quot;/chat&quot;).addInterceptors(new MyHandlerInterceptor());
}

@Bean
public WebSocketHandler chatHandler() {
    return new ChatHandler();
}

}

Implementing the WebSocket Handler

The WebSocket handler is responsible for handling incoming WebSocket messages. In this example, we will implement a simple handler that echoes back any messages it receives.

Here is an example of a WebSocket handler that echoes back any messages it receives:

@Component
public class ChatHandler implements WebSocketHandler {
@Override
public void afterConnectionEstablished(WebSocketSession session) throws Exception {
    System.out.println(&quot;Client connected&quot;);
}

@Override
public void handleMessage(WebSocketSession session, WebSocketMessage&lt;?&gt; message) throws Exception {
    System.out.println(&quot;Received message: &quot; + message.getPayload());
    session.sendMessage(new TextMessage(&quot;Echo: &quot; + message.getPayload()));
}

@Override
public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
    System.out.println(&quot;Error occurred: &quot; + exception.getMessage());
}

@Override
public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
    System.out.println(&quot;Client disconnected&quot;);
}

@Override
public boolean supportsPartialMessages() {
    return false;
}

}

Testing the WebSocket Endpoint

To test the WebSocket endpoint, you will need to use a tool such as wscat or ws to connect to the endpoint and send messages.

Here is an example of how you can use wscat to connect to the endpoint and send messages:

wscat -c ws://localhost:8080/chat

Conclusion

In this article, we have explored how to implement a plain WebSocket using Spring and Jetty. We have covered the basics of Spring WebSocket, including how to set up the dependencies, configure the WebSocket endpoint, and implement the WebSocket handler. We have also provided an example of how to test the WebSocket endpoint using a tool such as wscat.

Troubleshooting

If you encounter any issues while implementing the WebSocket endpoint, here are a few things you can try:

Make sure that the dependencies are correctly configured in your project.
Check that the WebSocket endpoint is correctly configured in the WebSocketConfig class.
Verify that the WebSocket handler is correctly implemented and that it is handling incoming messages correctly.

Common Issues

Here are a few common issues that you may encounter while implementing the WebSocket endpoint:

NullPointerException: If you encounter a NullPointerException when trying to access the WebSocket session, it may be because the session is not properly initialized. Make sure that the WebSocket endpoint is correctly configured and that the WebSocket handler is correctly implemented.
IOException: If you encounter an IOException when trying to send messages over the WebSocket connection, it may be because the connection is not properly established. Make sure that the WebSocket endpoint is correctly configured and that the WebSocket handler is correctly implemented.

Best Practices

Here are a few best practices to keep in mind when implementing the WebSocket endpoint:

Use a robust WebSocket engine: Make sure that the WebSocket engine you choose is robust and scalable.
Implement a proper WebSocket handler: Make sure that the WebSocket handler is correctly implemented and that it is handling incoming messages correctly.
Test the WebSocket endpoint thoroughly: Make sure that the WebSocket endpoint is thoroughly tested to ensure that it is working correctly.
Q&A: Implementing Plain Websocket with Spring/Jetty =====================================================

Q: What is the difference between Spring WebSocket and Spring MVC?

A: Spring WebSocket and Spring MVC are two separate frameworks provided by the Spring Framework. Spring MVC is a web framework that provides a programming model for building web applications, while Spring WebSocket is a framework that provides a programming model for building WebSocket applications. While Spring MVC can be used to build WebSocket applications, Spring WebSocket provides a more efficient and scalable way to build WebSocket applications.

Q: What is the difference between Jetty and Tomcat?

A: Jetty and Tomcat are two separate web servers that can be used to deploy web applications. Jetty is a lightweight web server that is designed to be highly scalable and performant, while Tomcat is a more traditional web server that is designed to be highly configurable. In the context of Spring WebSocket, Jetty is used as the underlying WebSocket engine to provide a robust and scalable WebSocket implementation.

Q: How do I configure the WebSocket endpoint in Spring WebSocket?

A: To configure the WebSocket endpoint in Spring WebSocket, you need to create a configuration class that extends the WebsocketConfigurer class. This class provides a number of methods that you can use to configure the WebSocket endpoint. You can use the registerWebSocketHandlers method to register a WebSocket handler with the endpoint, and the addInterceptors method to add interceptors to the endpoint.

Q: How do I implement a WebSocket handler in Spring WebSocket?

A: To implement a WebSocket handler in Spring WebSocket, you need to create a class that implements the WebSocketHandler interface. This interface provides a number of methods that you can use to handle incoming WebSocket messages. You can use the afterConnectionEstablished method to handle the establishment of a new WebSocket connection, the handleMessage method to handle incoming WebSocket messages, and the afterConnectionClosed method to handle the closure of a WebSocket connection.

Q: How do I test the WebSocket endpoint in Spring WebSocket?

A: To test the WebSocket endpoint in Spring WebSocket, you can use a tool such as wscat or ws to connect to the endpoint and send messages. You can also use a testing framework such as JUnit to write unit tests for the WebSocket endpoint.

Q: What are some common issues that I may encounter when implementing the WebSocket endpoint in Spring WebSocket?

A: Some common issues that you may encounter when implementing the WebSocket endpoint in Spring WebSocket include:

NullPointerException: If you encounter a NullPointerException when trying to access the WebSocket session, it may be because the session is not properly initialized. Make sure that the WebSocket endpoint is correctly configured and that the WebSocket handler is correctly implemented.
IOException: If you encounter an IOException when trying to send messages over the WebSocket connection, it may be because the connection is not properly established. Make sure that the WebSocket endpoint is correctly configured and that the WebSocket handler is correctly implemented.

Q: What are some best practices that I should follow when implementing the WebSocket endpoint in Spring WebSocket?

A: Some best practices that you should follow when implementing the WebSocket endpoint in Spring WebSocket include:

Use a robust WebSocket engine: Make sure that the WebSocket engine you choose is robust and scalable.
Implement a proper WebSocket handler: Make sure that the WebSocket handler is correctly implemented and that it is handling incoming messages correctly.
Test the WebSocket endpoint thoroughly: Make sure that the WebSocket endpoint is thoroughly tested to ensure that it is working correctly.

Q: Can I use Spring WebSocket with other web frameworks such as Spring MVC?

A: Yes, you can use Spring WebSocket with other web frameworks such as Spring MVC. Spring WebSocket provides a programming model for building WebSocket applications that can be used with other web frameworks.

Q: Can I use Spring WebSocket with other WebSocket engines such as Tomcat?

A: Yes, you can use Spring WebSocket with other WebSocket engines such as Tomcat. However, you will need to configure the WebSocket engine in your application and use the WebsocketConfigurer class to configure the WebSocket endpoint.

Q: How do I handle errors in the WebSocket endpoint in Spring WebSocket?

A: To handle errors in the WebSocket endpoint in Spring WebSocket, you can use the handleTransportError method in the WebSocketHandler interface. This method is called when an error occurs on the WebSocket connection.

Q: How do I handle disconnections in the WebSocket endpoint in Spring WebSocket?

A: To handle disconnections in the WebSocket endpoint in Spring WebSocket, you can use the afterConnectionClosed method in the WebSocketHandler interface. This method is called when a WebSocket connection is closed.

Q: Can I use Spring WebSocket with other protocols such as WebRTC?

A: Yes, you can use Spring WebSocket with other protocols such as WebRTC. However, you will need to configure the protocol in your application and use the WebsocketConfigurer class to configure the WebSocket endpoint.