Application Integration Flashcards
What is Amazon SQS?
A fully managed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications.
What are the two types of SQS queues?
Standard Queues: Offer high throughput, best-effort ordering, and at-least-once delivery.
FIFO Queues: Strict message ordering and exactly-once processing.
What is the maximum message size for SQS?
256 KB (can be larger with SQS Extended Client)
What is a Dead Letter Queue (DLQ)?
An SQS queue that stores messages that failed to process after a number of attempts. Useful for debugging and troubleshooting.
What are message attributes in SQS?
Metadata that can be attached to SQS messages for filtering and routing.
Explain ‘at-least-once delivery’ in SQS.
SQS guarantees that messages will be delivered at least once, but duplicates are possible in rare cases.
What is the purpose of the ‘Delay Seconds’ attribute in SQS?
Allows you to delay the delivery of a message to a queue for a specified number of seconds.
How can you achieve ‘exactly-once delivery’ with SQS?
Use FIFO queues, which provide inherent message deduplication and ordering.
How can you scale SQS consumers?
By adding more consumers to poll the queue, SQS automatically handles the distribution of messages.
What are some ways to monitor SQS queues?
Use Amazon CloudWatch metrics (e.g., NumberOfMessagesSent, NumberOfMessagesReceived, ApproximateNumberOfMessagesVisible)
What is Amazon SNS?
A fully managed pub/sub messaging service that enables you to fan out messages to a large number of subscribers, including SQS queues, Lambda functions, and email addresses.
What are some benefits of using SNS?
High scalability
Message durability
Integration with various AWS services.
What types of endpoints can subscribe to an SNS topic?
SQS queues, Lambda functions, HTTP/S endpoints, email addresses, SMS numbers, mobile push notifications.
What is the purpose of message filtering in SNS?
Allows subscribers to receive only messages that match specific criteria defined in a filter policy.
How does SNS handle message delivery retries?
SNS retries failed deliveries to HTTP/S endpoints with exponential backoff.