rabbitmq-patterns

name	rabbitmq-patterns
description	Elly'deki RabbitMQ queue, exchange, retry ve DLQ pattern'leri. Yeni queue ekleme, consumer yazma, retry mekanizması veya mesaj akış sorunlarında otomatik aktif et.
version	1.0.0

Elly RabbitMQ Patterns

Mimari

Producer (Service)
  → RabbitTemplate.convertAndSend(exchange, routingKey, message)
  → DirectExchange → Queue → @RabbitListener Consumer

Hata durumunda:
  Consumer → retry-exchange → retry-queue (TTL=30sn) → ana exchange → ana queue
  MAX_RETRY aşıldığında:
  Consumer → FAILED status (DB) + DLQ'ya düşer

Mevcut Queue Yapısı (email örneği)

Bean	Adı	Amacı
emailQueue	email-queue	Ana iş kuyruğu, DLX=email-dead-letter-exchange
emailRetryQueue	email-retry-queue	Gecikmeli retry (TTL=30sn), DLX=email-exchange
emailDeadLetterQueue	email-dead-letter-queue	Max retry aşılınca son durak
emailExchange	email-exchange	Ana DirectExchange
emailRetryExchange	email-retry-exchange	Retry DirectExchange
emailDeadLetterExchange	email-dead-letter-exchange	DLX

Tüm tanımlar: com.cms.config.RabbitMQConfig

Yeni Queue Ekleme Pattern'i

// 1. RabbitMQConfig'e constant ekle
public static final String XXX_QUEUE = "xxx-queue";
public static final String XXX_EXCHANGE = "xxx-exchange";
public static final String XXX_ROUTING_KEY = "xxx-routing-key";
public static final String XXX_DLQ = "xxx-dead-letter-queue";
public static final String XXX_DLX = "xxx-dead-letter-exchange";
public static final String XXX_RETRY_QUEUE = "xxx-retry-queue";
public static final String XXX_RETRY_EXCHANGE = "xxx-retry-exchange";

// 2. Ana queue — DLX ile
@Bean
public Queue xxxQueue() {
    return QueueBuilder.durable(XXX_QUEUE)
        .withArgument("x-dead-letter-exchange", XXX_DLX)
        .withArgument("x-dead-letter-routing-key", XXX_ROUTING_KEY)
        .build();
}

// 3. Retry queue — TTL + DLX=ana exchange (geri dönsün)
@Bean
public Queue xxxRetryQueue() {
    return QueueBuilder.durable(XXX_RETRY_QUEUE)
        .withArgument("x-dead-letter-exchange", XXX_EXCHANGE)
        .withArgument("x-dead-letter-routing-key", XXX_ROUTING_KEY)
        .withArgument("x-message-ttl", 30_000) // 30 saniye
        .build();
}

// 4. DLQ — durable, argümansız
@Bean
public Queue xxxDeadLetterQueue() {
    return new Queue(XXX_DLQ, true);
}

// 5. Exchange'ler (DirectExchange)
// 6. Binding'ler (queue → exchange, routing key ile)

Consumer Pattern'i

@Slf4j
@Service
@RequiredArgsConstructor
public class XxxQueueService {

    private final RabbitTemplate rabbitTemplate;
    private static final int MAX_RETRY_COUNT = 3;

    @RabbitListener(queues = RabbitMQConfig.XXX_QUEUE)
    public void processMessage(XxxMessage message) {
        // Multi-tenant: consumer başında tenant set et
        TenantContext.setTenantId(message.getTenantId());
        try {
            // İş mantığı
            doWork(message);
        } catch (Exception e) {
            handleRetry(message, e);
        } finally {
            // ZORUNLU: TenantContext temizle
            TenantContext.clear();
        }
    }

    private void handleRetry(XxxMessage message, Exception e) {
        message.setRetryCount(message.getRetryCount() + 1);
        if (message.getRetryCount() > MAX_RETRY_COUNT) {
            log.error("Max retry aşıldı: {}", message);
            // DB'de FAILED olarak işaretle
        } else {
            log.info("Retry kuyruğuna gönderiliyor: deneme={}/{}", 
                message.getRetryCount(), MAX_RETRY_COUNT);
            rabbitTemplate.convertAndSend(
                RabbitMQConfig.XXX_RETRY_EXCHANGE,
                RabbitMQConfig.XXX_ROUTING_KEY,
                message);
        }
    }
}

Kritik Kurallar

1. Mesaj formatı: Jackson2JsonMessageConverter — tüm mesajlar JSON
2. TenantContext: Consumer başında setTenantId(), finally'de clear() — ZORUNLU
3. Retry: Doğrudan ana queue'ya değil, retry-exchange'e gönder (TTL gecikmesi için)
4. DLQ: Max retry aşılınca mesaj otomatik DLQ'ya düşer (ana queue'nun DLX argümanı sayesinde)
5. Idempotency: Consumer'lar idempotent olmalı — aynı mesaj birden fazla işlenebilir
6. Log: Her adımda log.info/log.error ile izlenebilirlik sağla