Section 17: Decoupling applications:SQS,SNS,Kinesis,Active MQ

Question 1

What can you use to determine to scale up your consumers on a SQS queue?

Answer 1

• Making use of CloudWatch Metric which will give you the queue length

Question 2

What SQS Queue Access Policies do you get?

Answer 2

• Cross Account Access: Allowing users from other accounts to post message to your queue
• Publish S3 Event Notifications to SQS Queue

Question 3

SQS - What is message Visibility Timeout?

Answer 3

• The time after the consumer has polled, it becomes invisible to other consumers.

Question 4

AWS SQS - What is Dead Letter Queue?

Answer 4

• When a consumer has read the message but was not able to process it so it was placed back on the queue and at some stage the threshold will be reach on the number of times the message was placed back on the queue.

Question 5

AWS SQS - What is delay Queue?
P186

Answer 5

• Its a delay after a producer has send a message and the time the consumber can see/read it.

Question 6

AWS SQS - What is Request Response System and how do you implement it?
P188

Answer 6

• Making using of one Request queue and one or more response queue. You make use of AWS’s “SQS Temporary Queue Client” to implement this method.

Question 7

What is AWS SQS FIFO Queue?

Answer 7

• First in first out
• It has limited throughput
• Exactly once send capability
• Message are processed in order by the consumer

Question 8

What is SNS + SQS: Fan Out pattern?

Answer 8

• Push once in SNS, receive in all SQS queues that are subsribes
• Fully decoupled, no data loss.
• SQS allow for: data persistance,delayed processing
• Ability to add more SQS subscribers over time