This version is still in development and is not considered stable yet. For the latest stable version, please use Korvet 0.12.5!

Producing Messages

This guide shows how to produce messages to Korvet using Kafka clients.

Using kafka-console-producer

The simplest way to produce messages:

kafka-console-producer --bootstrap-server localhost:9092 --topic my-topic

Type messages and press Enter to send each one.

Java Producer

Properties props = new Properties();
props.put("bootstrap.servers", "localhost:9092");
props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");

KafkaProducer<String, String> producer = new KafkaProducer<>(props);

ProducerRecord<String, String> record =
    new ProducerRecord<>("my-topic", "key", "value");

producer.send(record, (metadata, exception) -> {
    if (exception == null) {
        System.out.println("Sent to partition " + metadata.partition() +
                         " at offset " + metadata.offset());
    } else {
        exception.printStackTrace();
    }
});

producer.close();

Python Producer

from kafka import KafkaProducer

producer = KafkaProducer(bootstrap_servers='localhost:9092')

producer.send('my-topic', b'Hello, Korvet!')
producer.flush()

Message Format

Messages consist of:

  • Key (optional): Used for partitioning

  • Value: The message payload

  • Headers (optional): Key-value metadata

  • Timestamp: Automatically set if not provided

Partitioning

Messages are distributed across partitions based on:

  • Key hash: If a key is provided, messages with the same key go to the same partition

  • Round-robin: If no key is provided, messages are distributed evenly

Next Steps