Expecting the Unexpected! Building Resiliency into Your Messaging Solutions - Zoe Vance & Andrea Nodari

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8. Components that
create messages and
deliver them to
RabbitMQ Broker.

9. Exchanges are the
routing instructions for
message distribution.
Bindings are the rules
about which queues are
relevant for the
message.

10. Direct exchange delivers
messages to queues when the
message routing key exactly
matches the queue’s binding key.
images.crop cropper
Routing key
resizer
images.resize

11. Topic exchange delivers
messages to queues when the
wildcard matches between the
routing key and the queue’s
binding key.
*.*.error errors
Routing pattern
geos
eu.de.*

12. Fanout exchange delivers
messages to all queues
regardless of routing keys or
pattern matching.

18. 100% Message Loss

31. ProducerApplication.java
[...]
@Bean
DirectExchange exchange() {
return new DirectExchange("transactions-x", true, false);
}
@Autowired
private RabbitTemplate template;
template.convertAndSend(exchange.getName(), routingKey, message);

32. ProducerApplication.java
template.convertAndSend(
exchange.getName(),
routingKey,
message,
(m) -> {
m.getMessageProperties()
.setDeliveryMode(MessageDeliveryMode.NON_PERSISTENT);
return m;
},
correlationData
);

33. Consumer.java
[...]
@RabbitListener(
bindings = {
@QueueBinding(
value = @Queue(value = "transactions", durable = "true"),
exchange = @Exchange(value = "transactions-x"),
key = {"transactions"}
)
}
)
public class Consumer { ... }

36. PUT /api/policies/VHOST/my-ha-policy
{
"pattern": ".*",
"definition": {"ha-mode":"exactly","ha-params":2,"ha-sync-mode":"automatic"}
}

40. ProducerApplication.java
[...]
template.setConfirmCallback((correlationData, ack, cause) -> {
// Business logic
});
[...]
template.convertAndSend(
exchange.getName(), routingKey, message, correlationData
);
application.yml
spring.rabbitmq.publisher-confirms: true

41. ProducerApplication.java
t.convertAndSend(
exchange.getName(), routingKey, message,correlationData
);
boolean ack = t.waitForConfirms(500);
if (!ack) {
System.out.printf("Timed out!");
}

42. ❓

43. ProducerApplication.java
[...]
template.setReturnCallback(
(message, replyCode, replyText, exchange, routingKey) -> {
// Message has been returned
}
);
application.yml
spring.rabbitmq.mandatory: true

46. @RabbitHandler

47. @RabbitHandler

50. redelivered

51. Consumer.java
[...]
@RabbitHandler
public void handleMessage(
@Payload String content,
@Header(AmqpHeaders.REDELIVERED) boolean redelivered) {
if (redelivered) {
// handle possible duplicates
} else {
}
}

52. '{ not a json

53. Consumer.java
@RabbitListener(
bindings = {
@QueueBinding(
value = @Queue(value = "transactions",
durable = "true",
arguments = {
@Argument(
name = "x-dead-letter-exchange",
value = "transactions-x.dead-letters"),
@Argument(
name = "x-dead-letter-routing-key",
value = "dead")
}),
[...]
)
public class Consumer {

54. DeadLetterConsumer.java
@RabbitListener(
bindings = {
@QueueBinding(
value = @Queue(value = "transactions.dead-letters"),
exchange = @Exchange(value = "transactions-x.dead-letters"),
key = {"dead"})
}
)
public class DeadLetterConsumer {
@RabbitHandler
public void handleMessage(String msg) {
// handle rejected message
}
}

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