Kafka Consumer and Producer

This repository contains code examples for implementing a Kafka consumer and producer in a Spring Boot application.

Kafka Producer

The Kafka producer is responsible for publishing messages to Kafka topics. It uses the following configuration:

The KafkaProducerConfig class is a configuration class that sets up the necessary configuration for the Kafka producer. It includes the following:

bootstrapServers: This field is populated with the value of the property spring.kafka.bootstrap-servers from the configuration properties file.
producerConfig(): This method returns a Map of producer configurations, including the bootstrap servers, key serializer, and value serializer.

The provided code is a configuration class for a Kafka producer in a Spring Boot application. Let's break it down:

Import Statements:
- org.apache.kafka.clients.producer.ProducerConfig: This class provides constants for configuring the producer.
- org.apache.kafka.common.serialization.StringSerializer: This class serializes objects of type String to bytes.
Annotations:
- @Configuration: This annotation indicates that the class is a configuration class and should be processed by the Spring container.
Field:
- @Value("${spring.kafka.bootstrap-servers}"): This annotation injects the value of the property spring.kafka.bootstrap-servers from the configuration properties file into the bootstrapServers field.
Method:
- producerConfig(): This method returns a Map of producer configurations.
- Configuration properties are set in the props map using constant keys from ProducerConfig.
- ProducerConfig.BOOTSTRAP_SERVERS_CONFIG: Specifies the list of Kafka brokers to connect to. It is set to the value of bootstrapServers field.
- ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG: Specifies the serializer class for the message key. In this case, it's set to StringSerializer.
- ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG: Specifies the serializer class for the message value. Also set to StringSerializer.
- The props map is returned to be used as Kafka producer configuration.

The Kafka consumer is responsible for subscribing to Kafka topics and processing incoming messages. It uses the following configuration:

The KafkaConsumerConfig class is a configuration class that sets up the necessary configuration for the Kafka consumer. It includes the following:

bootstrapServers: This field is populated with the value of the property spring.kafka.bootstrap-servers from the configuration properties file.
consumerConfig(): This method returns a Map of consumer configurations, including the bootstrap servers, group ID, key deserializer, and value deserializer.

The KafkaMessageListener class is a Spring @Component that listens to Kafka topics and processes incoming messages. It includes the following:

@KafkaListener annotation: This annotation is used to specify the Kafka topic(s) to listen to and the method to handle the incoming messages.
@Payload annotation: This annotation is used to specify the payload of the Kafka message.
@Headers annotation: This annotation is used to specify any headers associated with the Kafka message.

To run the Kafka consumer and producer examples, follow these steps: