Receive and process Amazon S3 event notifications by using an Amazon SDK.

This example show how to process S3 notification event by using Amazon SQS.

    /**
     * This method receives S3 event notifications by using an SqsAsyncClient.
     * After the client receives the messages it deserializes the JSON payload and logs them. It uses
     * the S3EventNotification class (part of the S3 event notification API for Java) to deserialize
     * the JSON payload and access the messages in an object-oriented way.
     *
     * @param queueUrl The URL of the AWS SQS queue that receives the S3 event notifications.
     * @see <a href="https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/eventnotifications/s3/model/package-summary.html">S3EventNotification API</a>.
     * <p>
     * To use S3 event notification serialization/deserialization to objects, add the following
     * dependency to your Maven pom.xml file.
     * <dependency>
     * <groupId>software.amazon.awssdk</groupId>
     * <artifactId>s3-event-notifications</artifactId>
     * <version><LATEST></version>
     * </dependency>
     * <p>
     * The S3 event notification API became available with version 2.25.11 of the Java SDK.
     * <p>
     * This example shows the use of the API with AWS SQS, but it can be used to process S3 event notifications
     * in AWS SNS or AWS Lambda as well.
     * <p>
     * Note: The S3EventNotification class does not work with messages routed through AWS EventBridge.
     */
    static void processS3Events(String bucketName, String queueUrl, String queueArn) {
        try {
            // Configure the bucket to send Object Created and Object Tagging notifications to an existing SQS queue.
            s3Client.putBucketNotificationConfiguration(b -> b
                    .notificationConfiguration(ncb -> ncb
                            .queueConfigurations(qcb -> qcb
                                    .events(Event.S3_OBJECT_CREATED, Event.S3_OBJECT_TAGGING)
                                    .queueArn(queueArn)))
                            .bucket(bucketName)
            ).join();

            triggerS3EventNotifications(bucketName);
            // Wait for event notifications to propagate.
            Thread.sleep(Duration.ofSeconds(5).toMillis());

            boolean didReceiveMessages = true;
            while (didReceiveMessages) {
                // Display the number of messages that are available in the queue.
                sqsClient.getQueueAttributes(b -> b
                                .queueUrl(queueUrl)
                                .attributeNames(QueueAttributeName.APPROXIMATE_NUMBER_OF_MESSAGES)
                        ).thenAccept(attributeResponse ->
                                logger.info("Approximate number of messages in the queue: {}",
                                        attributeResponse.attributes().get(QueueAttributeName.APPROXIMATE_NUMBER_OF_MESSAGES)))
                        .join();

                // Receive the messages.
                ReceiveMessageResponse response = sqsClient.receiveMessage(b -> b
                        .queueUrl(queueUrl)
                ).get();
                logger.info("Count of received messages: {}", response.messages().size());
                didReceiveMessages = !response.messages().isEmpty();

                // Create a collection to hold the received message for deletion
                // after we log the messages.
                HashSet<DeleteMessageBatchRequestEntry> messagesToDelete = new HashSet<>();
                // Process each message.
                response.messages().forEach(message -> {
                    logger.info("Message id: {}", message.messageId());
                    // Deserialize JSON message body to a S3EventNotification object
                    // to access messages in an object-oriented way.
                    S3EventNotification event = S3EventNotification.fromJson(message.body());

                    // Log the S3 event notification record details.
                    if (event.getRecords() != null) {
                        event.getRecords().forEach(record -> {
                            String eventName = record.getEventName();
                            String key = record.getS3().getObject().getKey();
                            logger.info(record.toString());
                            logger.info("Event name is {} and key is {}", eventName, key);
                        });
                    }
                    // Add logged messages to collection for batch deletion.
                    messagesToDelete.add(DeleteMessageBatchRequestEntry.builder()
                            .id(message.messageId())
                            .receiptHandle(message.receiptHandle())
                            .build());
                });
                // Delete messages.
                if (!messagesToDelete.isEmpty()) {
                    sqsClient.deleteMessageBatch(DeleteMessageBatchRequest.builder()
                            .queueUrl(queueUrl)
                            .entries(messagesToDelete)
                            .build()
                    ).join();
                }
            } // End of while block.
        } catch (InterruptedException | ExecutionException e) {
            throw new RuntimeException(e);
        }
    }