Producer

A producer is an application that sends messages to the messaging system.

Example:

Order Service → sends OrderCreated event

Producer does not know who consumes the event.

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Why Producers Exist

Producers allow services to publish events without knowing downstream services.

Example event:

OrderCreated event

Consumers might be:

Payment Service
Inventory Service
Notification Service

Producer stays independent.

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How Producer Works

Basic flow:

Application
↓
Producer
↓
Broker

• Producer sends event to broker.
• Broker stores it.
• Consumers read later.

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Example Producer (Spring Boot + Kafka)

Configuration

spring:
  kafka:
    bootstrap-servers: localhost:9092

Producer Code

@Autowired
private KafkaTemplate<String, String> kafkaTemplate;

public void sendEvent(String message) {
    kafkaTemplate.send("order-created", message);
}

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Real Producer Example

Banking system:

Transaction Service publishes:

account.transaction.completed

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Failure Scenario

Kafka Down

If Kafka becomes unavailable:

Case	Result
retry enabled	producer retries
retry disabled	message lost
broker cluster	another broker handles

Producer configuration controls behavior.

Example:

spring.kafka.producer.retries: 3

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Producer Best Practices

Enable reliable producer settings.

Example:

spring.kafka.producer.acks: all

Recommendations:

• enable retries
• use idempotent producers
• use acks=all for strong durability

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