aws-sdk-java-v2-messaging

SQS messaging in Java uses the AWS SDK v2 to create queues, send messages to them, and poll for incoming messages. Set up a client, create or reference a queue, use SendMessageRequest to publish and ReceiveMessageRequest to consume, then process or delete messages from the queue.

SQS is a queue for point-to-point messaging where consumers pull messages; SNS is a pub-sub service where publishers push to multiple subscribers simultaneously. Use SQS for task queues and guaranteed delivery; use SNS for event broadcasting to many endpoints.

FIFO queues guarantee message ordering and exactly-once delivery in SQS. Java applications configure FIFO by creating queues with .FifoQueue(true) and providing a MessageDeduplicationId and MessageGroupId for each message to prevent duplicates and maintain sequence.

Spring Boot integration with SQS and SNS uses spring-cloud-aws or direct SDK v2 configuration. Configure credentials and endpoints in application properties, inject SqsClient or SnsClient beans, and use them in service classes to send, receive, or publish messages.

Dead-letter queues (DLQs) capture messages that fail processing after a set number of retries. In Java, create a separate queue for failed messages and configure the main queue's RedrivePolicy to point to the DLQ, then monitor and handle problematic messages separately.

Test messaging locally using LocalStack or Testcontainers, which provide containerized AWS services. Point your Java client to the local endpoint, create test queues and topics, and verify send, receive, and publish operations without hitting live AWS.