Spring Boot is one of the most popular and most used frameworks of Java Programming Language. It is a microservice-based framework and to make a production-ready application using Spring Boot takes very less time. Spring Boot makes it easy to create stand-alone, production-grade Spring-based Applications that you can “just run“. So some of the main features of Spring boot are listed below.
- Create stand-alone Spring applications
- Embed Tomcat, Jetty, or Undertow directly.
- Provide ‘starter’ dependencies to simplify the build configuration.
- Configure Spring and 3rd party libraries Automatically whenever possible.
- Provide production-ready features like health checks, metrics, and externalized configuration.
- Almost no code generation and no requirement for XML configuration.
Apache Kafka is a publish-subscribe messaging system. A messaging system lets you send messages between processes, applications, and servers. Broadly Speaking, Apache Kafka is software where topics (A topic might be a category) can be defined and further processed. Applications may connect to this system and transfer a message onto the topic. A message can include any kind of information, from any event on your Personal blog or can be a very simple text message that would trigger any other event. here we will be discussing how we can publish messages to Kafka topics with Spring Boot where Kafka is a pre-requisite
Example:
Prerequisite: Make sure you have installed Apache Kafka in your local machine. Refer to this article How to Install and Run Apache Kafka on Windows?
Step 1: Go to this link https://start.spring.io/ and create a Spring Boot project. Add the following dependencies to your Spring Boot project.
- Spring Web
- Spring for Apache Kafka
Step 2: Now let’s create a controller class named DemoController.
Java
// Java Program to Illustrate Controller Classpackage com.amiya.kafka.apachekafkaproducer;// Importing required classesimport org.springframework.beans.factory.annotation.Autowired;import org.springframework.kafka.core.KafkaTemplate;import org.springframework.web.bind.annotation.*;// Annotation@RestController// Classpublic class DemoController { // Autowiring Kafka Template @Autowired KafkaTemplate<String, String> kafkaTemplate; private static final String TOPIC = "NewTopic"; // Publish messages using the GetMapping @GetMapping("/publish/{message}") public String publishMessage(@PathVariable("message") final String message) { // Sending the message kafkaTemplate.send(TOPIC, message); return "Published Successfully"; }} |
Step 3: Now we have to do the following things in order to publish messages to Kafka topics with Spring Boot
- Run the Apache Zookeeper server
- Run the Apache Kafka server
- Listen to the messages coming from the new topics
Run your Apache Zookeeper server by using this command
C:\kafka>.\bin\windows\zookeeper-server-start.bat .\config\zookeeper.properties
Similarly, run your Apache Kafka server by using this command
C:\kafka>.\bin\windows\kafka-server-start.bat .\config\server.properties
Run the following command to listen to the messages coming from the new topics
C:\kafka>.\bin\windows\kafka-console-consumer.bat --bootstrap-server localhost:9092 --topic NewTopic --from-beginning
Step 4: Now run your spring boot application. Make sure you have changed the port number in the application.properties file
server.port=8081
Let’s run the Spring boot application inside the ApacheKafkaProducerApplication file
Step 5:Browse this URL and pass your message after the /publish/.
http://localhost:8081/publish/Lazyroar
As we have passed “Lazyroar” here you can see we got “Published Successfully” in return. And in real-time you can see the message has been published on the server also. The streaming of the message is in real-time.
Similarly, if we have passed “Hello World” here you can see we got “Published Successfully” in return. And in real-time you can see the message has been published on the server also.
