📨 AWS SQS

AWS SQS Glossary 

• Availability Zones (AZs) -
• Access Policy - defines the accounts, users, and roles that can access the queue. 
• At Least Once Delivery - Amazon SQS stores copies of your messages on multiple servers for redundancy and high availability. On rare occasions, one of the servers that stores a copy of a message might be unavailable when you receive or delete a message. If this occurs, the copy of the message isn't deleted on the server that is unavailable, and you might get that message copy again when you receive messages.
• Dead letter queues (DLQs) - which source queues can target for messages that are not processed successfully. DLQs are useful for debugging your application because you can isolate unconsumed messages to determine why processing did not succeed.
• Delivery Delay
• Maximum Message Size 
• Redrive Policy 
• maxReceiveCount - is the number of times a consumer can receive a message from a source queue before it is moved to a dead-letter queue.
• Message Retention Periods - in DQLs. The range is from 1 minute to 14 days. The default value is 4 days.
• Enqueue Timestamp - when a message is moved to a dead-letter queue, the enqueue timestamp is unchanged.
• Idempotency - 
• Standard Queues - it's default queue type. Ensure at-least-once message delivery, but due to the highly distributed architecture, more than one copy of a message might be delivered, and messages may occasionally arrive out of order. Supporting a nearly unlimited number of API calls.
• SendMessage (Queue Action) - When you send a message using that action, SQS redundantly stores the message in multiple availability zones (AZs) before acknowledging it. This redundancy ensures that no single computer, network, or AZ failure can render the messages inaccessible.
• ReceiveMessage (Queue Action) - You can provide the VisibilityTimeout parameter in your request. The parameter is applied to the messages that Amazon SQS returns in the response. If you don't include the parameter, the overall visibility timeout for the queue is used for the returned messages. The default visibility timeout for a queue is 30 seconds.
• DeleteMessage (Queue Action) -
• Long Polling - 
• Short Polling -
• Queue Identifier - 
• Message Identifier - 
• VisibilityTimeout - The range is from 0 seconds to 12 hours. The default value is 30 seconds.
• Tag - it's cost allocation tags can be added to the queue.