AWS SDK for Java 2.x - Messaging (SQS & SNS)

Overview

Provides patterns for SQS queues and SNS topics with AWS SDK for Java 2.x: client setup, queue management, message operations, subscriptions, and Spring Boot integration.

When to Use

• Setting up SQS queues (standard or FIFO) for message buffering
• Implementing pub/sub with SNS topics and subscriptions
• Processing messages from SQS queues with long polling
• Configuring dead letter queues (DLQ) for error handling
• Integrating AWS messaging with Spring Boot applications
• Building event-driven architectures with SQS/SNS

Examples

Quick Setup

Dependencies:

xml
<dependency>
    <groupId>software.amazon.awssdk</groupId>
    <artifactId>sqs</artifactId>
</dependency>
<dependency>
    <groupId>software.amazon.awssdk</groupId>
    <artifactId>sns</artifactId>
</dependency>

Client Configuration:

java
SqsClient sqsClient = SqsClient.builder()
    .region(Region.US_EAST_1)
    .credentialsProvider(DefaultCredentialsProvider.create())
    .build();

SnsClient snsClient = SnsClient.builder()
    .region(Region.US_EAST_1)
    .build();

SQS Operations

Create and Send Message:

java
String queueUrl = sqsClient.createQueue(CreateQueueRequest.builder()
    .queueName("my-queue")
    .build()).queueUrl();

String messageId = sqsClient.sendMessage(SendMessageRequest.builder()
    .queueUrl(queueUrl)
    .messageBody("Hello, SQS!")
    .build()).messageId();

Receive and Delete Message:

java
ReceiveMessageResponse response = sqsClient.receiveMessage(ReceiveMessageRequest.builder()
    .queueUrl(queueUrl)
    .maxNumberOfMessages(10)
    .waitTimeSeconds(20)
    .build());

response.messages().forEach(message -> {
    processMessage(message.body());
    sqsClient.deleteMessage(DeleteMessageRequest.builder()
        .queueUrl(queueUrl)
        .receiptHandle(message.receiptHandle())
        .build());
});

FIFO Queue:

java
Map<QueueAttributeName, String> attributes = Map.of(
    QueueAttributeName.FIFO_QUEUE, "true",
    QueueAttributeName.CONTENT_BASED_DEDUPLICATION, "true"
);

String fifoQueueUrl = sqsClient.createQueue(CreateQueueRequest.builder()
    .queueName("my-queue.fifo")
    .attributes(attributes)
    .build()).queueUrl();

sqsClient.sendMessage(SendMessageRequest.builder()
    .queueUrl(fifoQueueUrl)
    .messageBody("Order #12345")
    .messageGroupId("orders")
    .messageDeduplicationId(UUID.randomUUID().toString())
    .build());

SNS Operations

Create Topic and Publish:

java
String topicArn = snsClient.createTopic(CreateTopicRequest.builder()
    .name("my-topic")
    .build()).topicArn();

snsClient.publish(PublishRequest.builder()
    .topicArn(topicArn)
    .subject("Test Notification")
    .message("Hello, SNS!")
    .build());

SNS to SQS Subscription:

java
String queueArn = sqsClient.getQueueAttributes(GetQueueAttributesRequest.builder()
    .queueUrl(queueUrl)
    .attributeNames(QueueAttributeName.QUEUE_ARN)
    .build()).attributes().get(QueueAttributeName.QUEUE_ARN);

snsClient.subscribe(SubscribeRequest.builder()
    .protocol("sqs")
    .endpoint(queueArn)
    .topicArn(topicArn)
    .build());

Spring Boot Integration

java
@Service
@RequiredArgsConstructor
public class OrderNotificationService {
    private final SnsClient snsClient;
    private final ObjectMapper objectMapper;

    @Value("${aws.sns.order-topic-arn}")
    private String orderTopicArn;

    public void sendOrderNotification(Order order) throws JsonProcessingException {
        snsClient.publish(PublishRequest.builder()
            .topicArn(orderTopicArn)
            .subject("New Order Received")
            .message(objectMapper.writeValueAsString(order))
            .messageAttributes(Map.of(
                "orderType", MessageAttributeValue.builder()
                    .dataType("String")
                    .stringValue(order.getType())
                    .build()))
            .build());
    }
}

Instructions

Implement Message Processing (with Validation)

1. Create queues/topics with appropriate configuration
2. Send messages and validate messageId is returned
3. Receive messages with long polling (waitTimeSeconds: 20)
4. Process messages - validate payload before processing
5. Delete messages only after successful processing - verify deletion response
6. Check DLQ periodically for failed messages using redrivePolicy
7. Verify delivery - monitor CloudWatch NumberOfMessagesSent metric

Validation Checklist:

java
// After send
if (messageId == null || messageId.isEmpty()) {
    throw new MessagingException("Message send failed - no messageId returned");
}

// After receive
if (response.messages().isEmpty()) {
    log.debug("No messages available - normal with long polling");
}

// After delete
if (!deleteResponse.sdkHttpResponse().isSuccessful()) {
    throw new MessagingException("Message deletion failed");
}

Setup Credentials

bash
export AWS_ACCESS_KEY_ID=your-access-key
export AWS_SECRET_ACCESS_KEY=your-secret-key
export AWS_REGION=us-east-1

Monitor and Debug

• CloudWatch metrics: ApproximateNumberOfMessages, NumberOfMessagesSent, NumberOfMessagesReceived
• Enable SDK logging: software.amazon.awssdk at DEBUG level
• Use X-Ray for distributed tracing

Best Practices

SQS:

• Use long polling (20-40s) to reduce empty responses and costs
• Always delete messages after successful processing
• Implement idempotent processing for duplicate handling
• Configure DLQ (redrivePolicy) for failed messages
• Use FIFO queues when order matters (300 msg/sec limit)

SNS:

• Use filter policies to reduce unnecessary deliveries
• Keep messages under 256KB
• Implement retry with exponential backoff
• Monitor NumberOfNotificationFailed metric

General:

• Use IAM roles over static credentials
• Reuse clients (they are thread-safe)
• Test with LocalStack or Testcontainers

Detailed References

• references/detailed-sqs-operations.md
• references/detailed-sns-operations.md
• references/spring-boot-integration.md
• references/aws-official-documentation.md

Constraints and Warnings

• Message Size: Maximum 256KB for SQS and SNS
• Visibility Timeout: Undeleted messages reappear after timeout - always delete after processing
• Input Validation: Sanitize message body before processing - messages may contain untrusted payloads
• FIFO Naming: Must end with .fifo suffix
• FIFO Throughput: 300 msg/sec per queue (use partitioning for higher throughput)
• Message Retention: SQS retains messages max 14 days
• DLQ Required: Configure dead letter queue to prevent message loss
• Region-Specific: SQS queues are region-specific; cross-region requires SNS