What are the main interaction patterns of Kafka with microservices that you know?

Main interaction patterns of Kafka with microservices:

1. Event-Driven Architecture (EDA) — microservices publish events to Kafka, and other microservices subscribe to these events and react to them. This is an asynchronous message exchange that reduces coupling between services.

2. Command Query Responsibility Segregation (CQRS) — commands and queries are processed by different microservices, with Kafka used for transmitting commands or state change events.

3. Event Sourcing — all state changes of a microservice are stored as a sequence of events in Kafka, allowing for state recovery or auditing.

4. Log Aggregation — Kafka is used for collecting logs and metrics from microservices for subsequent analysis.

Example of a simple producer in Go using the sarama library:

package main

import (
    "github.com/Shopify/sarama"
    "log"
)

func main() {
    producer, err := sarama.NewSyncProducer([]string{"localhost:9092"}, nil)
    if err != nil {
        log.Fatal(err)
    }
    defer producer.Close()

    msg := &sarama.ProducerMessage{
        Topic: "events",
        Value: sarama.StringEncoder("Hello Kafka"),
    }

    partition, offset, err := producer.SendMessage(msg)
    if err != nil {
        log.Fatal(err)
    }
    log.Printf("Message is stored in partition %d, offset %d\n", partition, offset)
}