SQS Advanced Patterns

Introduction

Amazon Simple Queue Service (SQS) is a fully managed message queuing service that enables decoupling and scaling of microservices, distributed systems, and serverless applications. This lesson focuses on advanced patterns for utilizing SQS effectively in AWS Serverless architectures.

Key Concepts

1. Queues

Queues are temporary storage for messages. There are two types of queues in SQS:

Standard Queues: Provide maximum throughput, offering at least once delivery.
FIFO Queues: Ensure that messages are processed exactly once and in the exact order that they are sent.

2. Message Attributes

Message attributes allow you to provide additional metadata for messages, which can be useful for routing and processing logic.

3. Long Polling

Long polling reduces the number of empty responses and increases the efficiency of your application by waiting for messages to arrive before returning a response.

Common Patterns

1. Fan-out Pattern

This pattern allows a single message to be consumed by multiple subscribers, improving scalability and reliability.

Tip: Use Amazon SNS in conjunction with SQS for implementing fan-out.

aws sns create-topic --name MyTopic
aws sns subscribe --topic-arn  --protocol sqs --notification-endpoint

2. Dead Letter Queue (DLQ)

DLQs are used to isolate messages that cannot be processed successfully after a specified number of retries.

aws sqs create-queue --queue-name MyDLQ
aws sqs set-queue-attributes --queue-url  --attributes '{"RedrivePolicy":"{\"maxReceiveCount\":\"5\", \"deadLetterTargetArn\":\"\"}"}'

3. Message Filtering

By using message attributes, you can filter messages at the subscriber level, ensuring that only relevant messages are processed.

Best Practices

Use FIFO queues for applications that require strict ordering of messages.
Implement DLQs to handle message processing failures gracefully.
Enable long polling to reduce costs and improve the efficiency of message retrieval.
Utilize message batching for lower latency and reduced costs.
Monitor and adjust the visibility timeout based on the processing time of messages.

FAQ

What is the maximum number of messages that can be sent in a single request?

You can send up to 10 messages in a single SendMessageBatch request.

How can I ensure messages are processed in the order they are sent?

Use FIFO queues, which guarantee that messages are processed in order.

What happens to messages in a DLQ?

Messages in a DLQ can be analyzed, retried, or deleted to ensure they don't block the processing of other messages.