Have you worked with AWS SNS and SQS? What is the process of implementing a publish/subscribe pattern for strategy execution, and how do you handle transient failures?

Yes, I have used AWS SNS and SQS together to build a decoupled publish/subscribe system for trading strategies. The typical pattern is: a producer publishes a message to an SNS topic; the topic fan‑outs the message to one or more SQS queues that are subscribed to it. Consumers poll the SQS queue, process the strategy execution, and delete the message upon success. To handle transient failures, I configure a dead‑letter queue (DLQ) for messages that exceed the maximum receive count. I also set an appropriate visibility timeout so that a message is invisible to other consumers while being processed. If processing fails, the message becomes visible again after the timeout, allowing retries. I implement exponential back‑off and idempotent processing to avoid duplicate executions. Additionally, I monitor CloudWatch metrics for SQS and SNS to detect spikes or errors and adjust the batch size or concurrency accordingly.