java 35 lines · 7 steps

The transactional outbox pattern in Spring

How a Spring listener reliably records domain events by writing them to an outbox table only after the triggering transaction commits.

Explained by highlit
Spring Advanced transactional-outbox event-driven reliability serialization dependency-injection
1@Component
2required to import
3public class OutboxEventPublisher {
4 
5 private final OutboxMessageRepository outboxRepository;
6 private final ObjectMapper objectMapper;
7 
8 public OutboxEventPublisher(OutboxMessageRepository outboxRepository, ObjectMapper objectMapper) {
9 this.outboxRepository = outboxRepository;
10 this.objectMapper = objectMapper;
11 }
12 
13 @TransactionalEventListener(phase = TransactionPhase.AFTER_COMMIT)
14 @Transactional(propagation = Propagation.REQUIRES_NEW)
15 public void onOrderPlaced(OrderPlacedEvent event) {
16 OutboxMessage message = new OutboxMessage();
17 message.setId(UUID.randomUUID());
18 message.setAggregateType("Order");
19 message.setAggregateId(event.orderId().toString());
20 message.setEventType("order.placed");
21 message.setPayload(serialize(event));
22 message.setCreatedAt(Instant.now());
23 message.setStatus(OutboxStatus.PENDING);
24 
25 outboxRepository.save(message);
26 }
27 
28 private String serialize(OrderPlacedEvent event) {
29 try {
30 return objectMapper.writeValueAsString(event);
31 } catch (JsonProcessingException e) {
32 throw new IllegalStateException("Failed to serialize outbox payload for order " + event.orderId(), e);
33 }
34 }
35}
01 / 01
STEP 01

Walkthrough

Space play ←→ step click any line
Three takeaways
  1. 1Writing events to an outbox table lets you publish messages atomically with your business data, avoiding dual-write inconsistency.
  2. 2Reacting AFTER_COMMIT in a fresh transaction ensures you never record an event for work that later rolled back.
  3. 3Turning serialization failures into unchecked exceptions keeps the happy path clean while still failing loudly on bad payloads.

Related explainers

python 
from flask import Blueprint, jsonify, request, abort
 
v1 = Blueprint("users_v1", __name__)
v2 = Blueprint("users_v2", __name__)

Versioning a Flask API with Blueprints

api versioning blueprints rest
Intermediate 7 steps
java 
public class SlidingLogRateLimiter {
 
    private final int maxRequests;
    private final long windowMillis;

How a sliding-log rate limiter works

rate-limiting concurrency sliding-window
Advanced 8 steps
typescript 
import { Injectable, UnauthorizedException } from '@nestjs/common';
import { PassportStrategy } from '@nestjs/passport';
import { ExtractJwt, Strategy } from 'passport-jwt';
import { ConfigService } from '@nestjs/config';

How a JWT strategy authenticates in NestJS

authentication jwt passport
Intermediate 7 steps
java 
public final class Slugifier {
 
    private static final Pattern NON_LATIN = Pattern.compile("[^\\w-]");
    private static final Pattern WHITESPACE = Pattern.compile("[\\s]+");

Building a URL slugifier in Java

regex unicode-normalization string-processing
Intermediate 8 steps
java 
@Repository
public interface OrderRepository extends JpaRepository<Order, Long> {
 
    @Query("""

Keyset pagination with Spring Data JPA

pagination cursor jpa
Advanced 8 steps
python 
import os
from datetime import timedelta
 
 

Class-based config in a Flask app factory

configuration app-factory inheritance
Intermediate 7 steps

Share this explainer

Here's the card — post it anywhere.

The transactional outbox pattern in Spring — share card
Made with highlit — turn any snippet into a walkthrough like this in about a minute.
Explain your code