AWS SQS

Question 1

What is SQS?

Answer 1

It is a managed message queue.

Question 2

What is SQS used for?

Answer 2

• Distributed and decoupling applications

- Buffering incoming load, so slower services like a database can deal with the write load more evenly.

Question 3

What is the max size of a message?

Answer 3

• 256K

Question 4

How can we store large amounts of data?

Answer 4

• Store the data in S3 and reference it in the SQS message.

Question 5

What options have I for receiving messages from SQL, can I have SQL push messages to me?

Answer 5

No, there is no push methods available form SQL, you have to use long or short poll methods to get a message from SQS.

Question 6

What is the difference between long and short poll?

Answer 6

• Long poll means when you make a call to SQL the call will not return until the number of messages specified in the call are available or the time out occurs.
• Short pool means it will return if there is no messages available

Question 7

What types of SQS queues are available?

Answer 7

• Standard queue

- FIFO queue

Question 8

What is the difference between FIFO and standard queues?

Answer 8

Standard queues have infinite capacity, messages are not guaranteed to be delivered just once, messages are not guaranteed to be delivered in order.
- FIFO queues have a limited capacity, guarantee message order and only one comply of the message will be delivered.

Question 9

What is the capacity of FIFO queue?

Answer 9

300 messages per sec for single messages and 3K mps for batched messages.

Question 10

I have an SNS topic, is it possible to have messages delivered to an SQL queue?

Answer 10

Yes, SNS supports SQS as an endpoint.

Question 11

Explain what the visibility time out is?

Answer 11

The visibility time out is the amount of time a message stays invisible after it is received by a consumer if the consumer does not delete the message from the SQS queue before the visibility time out expires the message will become visible on the SQS queue and another consumer can consume it.

Question 12

How long can I have a long poll for?

Answer 12

1 - 20 seconds

Question 13

Are messages retained for a period and what is the period?

Answer 13

Default is 4 days and max is 14 days

Question 14

I would like to move away from using EC2 instances for processing SQS messages, what options do I have?

Answer 14

You can now use Lambda, in the model Lambda is automatically invoked to process the message in the SQS queue, this is no need to poll.

Question 15

I have a solution thet has EC2 instances thet process messages, I wnat to make this solution more dynamic and have the number of EC2 instances be elastic and grow and shrink based on the number of messages in the SQS queue, how can this solution be modified?

Answer 15

Create an autoscaling group and set it scaling policy to use cloud watch alarms, we also set up cloudwatch alarms to trigger on the number of messages in the SQS queue.

Question 16

I have a VPC and I wnat to access the SQS privately without going over the internet as my VPC is a private VPC, how cna I achieve this?

Answer 16

Use a VPC endpoint, this will pace an interface in the VPC and you can access the SQS via the endpoint.

Question 17

I wnat to delay a message form the time it is received until it is visible on the SQS queue?

Answer 17

You can use the delivery delay.

Question 18

I some times have EC2 instances they are unable to process messages, I would like to have these messages automatically handled by a lambda function I have created, how can I architect this?

Answer 18

You will need to,

• Set up a dead letter queue to received the unprocessed messages
• Register the lambda function on this dead letter queue to process the dead letter messages.

Question 19

What is a deal letter queue?

Answer 19

Unprocessed messages are sent to this queue to be handled.

Question 20

My orgnization has a policy that means all data at rest is to be encrypted, I am using SQS, what options do I have?

Answer 20

You cna have SQS use server-side encryption to transparently encrypt and decrypt messages.

Question 21

What I create an SQS queue, how do I interact with the queue?

Answer 21

Each SQS queue will get a URL at the time of creation.

Question 22

I wnat to have better visibility into my SQS queue, what options do I have?

Answer 22

You cna use cloud watch metrics to see,
- NumOfMessagesSent
- NumOfMessagesReceived
etc

Question 23

I wnat to have multiple consumers consuming the same messages from an SQS queue, how can I architect this?

Answer 23

You cna not do this with SQS, this is a kinesis type ability.

Question 24

What is the default, min and max visibility time outs?

Answer 24

default is 30 sec, min is 0 and max is 12hrs.

Question 25

I am using a standard queue, is order preserved?

Answer 25

No

Question 26

I am using a FIFO queue, is order preserved?

Answer 26

Yes

Question 27

I am using a FiFO queue, am I guaranteed to only received a message once?

Answer 27

Yes

Question 28

I am using a standard queue, am I guaranteed to only received a message once?

Answer 28

No, you can receive the message multiple times, you have to deal with this in code.

Question 29

My orgnization has a policy of ensuring all traffic is encrypted in transit and at rest, what do I have to do in SQS to meet this requirement?

Answer 29

• Enable encryption at rest

- HTTPS is used for all traffic in transit so this is already meeting the in-transit requirement.

Question 30

I am using a FIFO queue, how can I deliver the max number of messages to the SQS queue?

Answer 30

Use the batch API/CLI command when sending messages

Question 31

How are messages globally identified?

Answer 31

As SQS receives a message it gives each message a global ID.

Question 32

How can I add small amounts of extra metadata to a message?

Answer 32

Metadata (key/value) can be added to to a message

Question 33

I have two producers of messages sending messages to a SQS queue, how can I group these messages and ensure order for the consumers?

Answer 33

You can use the group ID to group the me3ssages and preserve the order.

Question 34

Is SQS PCI and HIPPA certified?

Answer 34

Yes