如何使用 Java 将错误消息移动到 Azure 死信队列（主题 - 订阅）？

Question

我需要将消息从 Azure 主题订阅发送到死信队列，以防在读取和处理来自主题的消息时出现任何错误。所以我尝试测试直接向DLQ推送消息。

我的示例代码会是这样的

static void sendMessage()
{
    // create a Service Bus Sender client for the queue 
    ServiceBusSenderClient senderClient = new ServiceBusClientBuilder()
            .connectionString(connectionString)
            .sender()
            .topicName(topicName)
            
            .buildClient();

    // send one message to the topic
    
    
    senderClient.sendMessage(new ServiceBusMessage("Hello, World!"));    


}
static void resceiveAsync() {
    ServiceBusReceiverAsyncClient receiver = new ServiceBusClientBuilder()
            .connectionString(connectionString)
            .receiver()
            .topicName(topicName)
            .subscriptionName(subName)
            .buildAsyncClient();

        // receive() operation continuously fetches messages until the subscription is disposed.
        // The stream is infinite, and completes when the subscription or receiver is closed.
        Disposable subscription = receiver.receiveMessages().subscribe(message -> {

            System.out.printf("Id: %s%n", message.getMessageId());
            System.out.printf("Contents: %s%n", message.getBody().toString());
        }, error -> {
                System.err.println("Error occurred while receiving messages: " + error);
            }, () -> {
                System.out.println("Finished receiving messages.");
            });

        // Continue application processing. When you are finished receiving messages, dispose of the subscription.
        subscription.dispose();

        // When you are done using the receiver, dispose of it.
        receiver.close();
    
    
    
}

我尝试获取死信队列路径

    String dlq = EntityNameHelper.formatDeadLetterPath(topicName);

我得到了死信队列的路径，例如 = "mytopic/$deadletterqueue"

但是在将路径作为主题名称传递时它不起作用。它抛出一个Entity topic not found异常。

谁能给我建议

参考： How to move error message to Azure dead letter queue using Java?

https://docs.microsoft.com/en-us/azure/service-bus-messaging/service-bus-dead-letter-queues#moving-messages-to-the-dlq

How to push the failure messages to Azure service bus Dead Letter Queue in Spring Boot Java?

https://docs.microsoft.com/en-us/azure/service-bus-messaging/service-bus-java-how-to-use-topics-subscriptions-legacy#receive-messages-from-a-subscription

Answer 1

您可能知道，如果您在处理过程中抛出异常，并且超出了最大传递计数，则消息将自动移至死信队列。如果您想明确地将消息移动到 DLQ，您也可以这样做。一个常见的情况是，如果您知道消息由于其内容而永远不会成功。

您不能直接向 DLQ 发送 新 消息，因为这样您的系统中就会有两条消息。您需要对父实体调用特殊操作。此外，<topic path>/$deadletterqueue 不起作用，因为这将是所有订阅的 DLQ。正确的实体路径是这样构建的：

<queue path>/$deadletterqueue
<topic path>/Subscriptions/<subscription path>/$deadletterqueue

https://github.com/Azure/azure-service-bus/blob/master/samples/Java/azure-servicebus/DeadletterQueue/src/main/java/com/microsoft/azure/servicebus/samples/deadletterqueue/DeadletterQueue.java

此示例代码适用于队列，但您应该能够很容易地将其适应主题：

    // register the RegisterMessageHandler callback
    receiver.registerMessageHandler(
            new IMessageHandler() {
                // callback invoked when the message handler loop has obtained a message
                public CompletableFuture<Void> onMessageAsync(IMessage message) {
                    // receives message is passed to callback
                    if (message.getLabel() != null &&
                            message.getContentType() != null &&
                            message.getLabel().contentEquals("Scientist") &&
                            message.getContentType().contentEquals("application/json")) {

                        // ...
                    } else {
                        return receiver.deadLetterAsync(message.getLockToken());
                    }
                    return receiver.completeAsync(message.getLockToken());
                }

                // callback invoked when the message handler has an exception to report
                public void notifyException(Throwable throwable, ExceptionPhase exceptionPhase) {
                    System.out.printf(exceptionPhase + "-" + throwable.getMessage());
                }
            },
            // 1 concurrent call, messages are auto-completed, auto-renew duration
            new MessageHandlerOptions(1, false, Duration.ofMinutes(1)),
            executorService);