Core Concepts

Producer & Consumer

// Producer
const { Kafka } = require('kafkajs')

const kafka = new Kafka({
  clientId: 'my-app',
  brokers: ['localhost:9092']
})

const producer = kafka.producer()
await producer.connect()
await producer.send({
  topic: 'user-events',
  messages: [
    { key: 'user1', value: JSON.stringify({ action: 'signup' }) }
  ],
})

// Consumer
const consumer = kafka.consumer({ groupId: 'my-group' })
await consumer.connect()
await consumer.subscribe({ topic: 'user-events' })

await consumer.run({
  eachMessage: async ({ topic, partition, message }) => {
    console.log({
      value: message.value.toString(),
    })
  },
})

Common Patterns

Best Practices

• Use appropriate partition keys
• Set retention policies per topic
• Monitor consumer lag
• Use consumer groups for scalability