Order Processing System

Introduction

What is Order Processing System? Order API emits OrderCreated; payment, inventory, and fulfillment consume independently.

Understanding the topic

What happens — Order Processing System:

• Order API emits OrderCreated; payment, inventory, and fulfillment consume independently.
• Configure clients and topics for your use case.
• Process records with clear offset and error handling.
• Monitor lag and broker health in production.

Visual explanation

Pipeline view:

Region A Kafka
  ↓ replicate selected topics
Region B Kafka
  ↓
local consumers + DR plan
Trade-off: latency, cost, consistency

Step-by-step explanation

1. Define the event contract and topic/key strategy.
2. Build the producer with idempotent settings (acks=all, enable.idempotence=true).
3. Build consumers with manual commits and idempotent processing.
4. Add retry topics, dead letter topics, and integration tests.
5. Deploy with monitoring for lag, errors, and throughput.

Informative example

Example:

public record OrderProcessingSystemEvent(
    String eventId,
    String aggregateId,
    Instant occurredAt,
    String eventType,
    Map<String, Object> payload
) {}

Execution workflow

Best practices

• Define RPO/RTO before choosing replication design.
• Replicate only topics with clear ownership and purpose.
• Document failover and failback procedures.
• Model event sourcing around immutable business facts.

Common mistakes

• Bi-directional replication without loop/conflict strategy.
• Event sourcing every table instead of meaningful domain events.
• Ignoring replay cost during capacity planning.

Summary

Order Processing System — Make trade-offs explicit: RPO/RTO, ordering, sovereignty, replay cost, schema governance, and operational ownership.