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AWS Developer Associate > SQS/SNS/Kinesis > Flashcards

SQS/SNS/Kinesis Flashcards

1
Q

What are the 2 main ways applications can communicate with each other?

A
  • Synchronously (app to app)
  • Asynchronously / Event Base (app to queue to app)
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2
Q

Explain SQS

A
  • SQS is used for application integrations
  • It lets decoupled apps and services talk to each other.
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3
Q

Is SQS a push or pull service? Explain.

A
  • SQS is a pull service.
  • You must pull or ‘poll’ for new messages using the SDK.
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4
Q

What are the 2 main types of SQS messages?

A

Standard and FIFO

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5
Q

Explain Standard SQS

A
  • nearly unlimited messages/second
  • does NOT guarnatee order of delvery
  • always delivers at least once
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6
Q

FIFO

A
  • First In, First Out
  • Limited to 300 messages/sec (3000/sec if batch)
  • Exactly-once send capability (by removing duplicates)
  • Messages are processed in order by the consumer
  • FIFO Names must end in .fifo
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7
Q

What are the 2 types of polling? Which one is recommended?

A
  • Short polling & Long Polling.
  • When a consumer requests messages from the
    queue, it can optionally “wait” for messages to
    arrive if there are none in the queue.
  • Short Polling returns immediately even if queue is empty.
  • Long polling is recomended because its less API calls which will reduce latency.
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8
Q

What is Visibility Timeout in SQS?

A
  • After a message is polled by a consumer, it becomes invisible to other consumers.
  • By default, the message visibility timeout is 30 sec.
  • After timeout period ends, the message is available in SQS.
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9
Q

What happens if the SQS visibiity timeout is to high or too low?

A
  • If to high (hours), then comsumer may crash and it will take time to reload
  • If too low then we may get duplicates
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10
Q

What happens if a consumer fails to process a message within the visibility timeout period?

A

Message goes back into the queue.

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11
Q

How many times can a message go back into the queue?

What happens once this limit is reached?

A
  • You set the threshold.
  • Once the threshold is met, the message goes into a Dead Letter Queue (DLQ).
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12
Q

When should you NOT use dead letter queues?

A
  • Don’t use a dead-letter queue with standard queues when you want to be able to keep retrying the transmission of a message indefinitely.
  • Don’t use a dead-letter queue with a FIFO queue if you don’t want to break the exact order of messages or operations. For example, don’t use a dead-letter queue with instructions in an Edit Decision List (EDL) for a video editing suite, where changing the order of edits changes the context of subsequent edits.
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13
Q

What are Dead Letter Queues useful for?

A

Dead-letter queues are useful for debugging your application or messaging system because they let you isolate problematic messages to determine why their processing doesn’t succeed.

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14
Q

What is the default, min, and max visibility timeout settings - SQS?

A
  • Default: 30 seconds
  • Minimum: 0 seconds
  • Maximum: 12 hours
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15
Q

What is a delay queue?

A
  • The ability to delay a message (so consumers don’t see it immediately) for up to 15 minutes.
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16
Q

When are new messages available for consumers to view?

A
  • Immediately, unless a delay is set (aka Delay Queue).
  • Can delay up to 15 minutes.
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17
Q

What is the maximum size of an SQS message? What are your options if a larger message size is needed?

A
  • The maximum message size in 256kb.
  • You can use the extended client library to send a message size of up to 2GB in size.
  • The large message is actually stored in an S3 bucket and a small message gets put into the queue that acts as a pointer to the actual message.
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18
Q

What is the SQS API call to delete all messages in a queue?

A

PurgeQueue

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19
Q

What is the SQS API call to change the message timeout?

A

ChangeMessageVisibility

20
Q

What is the SQS API call to create a new queue?

A
  • CreateQueue
  • use MessageRetentionPeriod to set the time the message is retained
21
Q

What is the API call to delete a message from an SQS Queue?

A

DeleteQueue

22
Q

What API call would Producers use to send a message through SQS?

A

SendMessage

They can also set a DelaySeconds parameter.

23
Q

What SQS API calls can consumers use to get and remove messages?

A
  • ReceiveMessage
  • DeleteMessage
  • ReceiveMessageWaitTimeSecond: Consumers can also take advantage of long polling
24
Q

What are the three common batch API calls for SQS?

A
  • SendMessage
  • DeleteMessage
  • ChangeMessageVisibility
25
Q

What is AWS SNS?

A
  • Simple Notification Service
  • Pub/Sub - one topic can be published and then subscribed to by many subscribers
  • Event driven
  • “Push” service
26
Q

How many subscription are allowed per topic (SNS)?

A

10,000,000

27
Q

What is the maximum number of topics you can have in SNS?

A

10,000

28
Q

Who can subscribe to an SNS topic?

A
  • AWS SQS
  • HTTP / HTTPS (with delievery retries - how many times)
  • Lambda
  • Emails
  • SMS messages
  • Mobile Notifications
29
Q

How can SNS topics be encrypted/secured?

A
  • In-flight using HTTPS API
  • At-rest using KMS keys
  • Client-side encryption if the client want to perform the encryption/decryption itself.
  • IAM Policies
  • SNS Access policies can also be used to allow for cross-account access to SNS topics. This is also useful for allowing other services to write to an SNS topic.
30
Q

How can the same message be pushed into many SQS queues?

A
  • Using SNS, Fan Out pattern
  • Push message once to SNS. This message is then received by all SQS subscribers.
  • Fully decoupled = no data loss
  • By doing it this may, SQS allows for data persistence, delayed processing and retries of work
31
Q

What security measure must be in place in order for SNS to to write to SQS?

A

SQS queue must have an access policy that allows SNS to write

32
Q

Can SNS send messages to an SQS FIFO queue?

A

No. This is an AWS limitation

33
Q

What is AWS Kinesis?

A
  • Solution for collecting, processing and analyzing streaming data in the cloud.
  • Think ‘real-time’, ‘Big Data’, analytics, and ETL processes
  • Amazon Kinesis enables you to ingest, buffer, and process streaming data in real-time
  • Fully managed
  • Scalable
  • A tool to move big data streams from a source to a final destination like S3, redshift etc.
34
Q

What are the properties of Kinesis Streams?

A
  • Streams are divided in ordered Shards/Partitions (1 stream = many shards)
  • Shards are provisioned (paid for)
35
Q

What is Kinesis Firehose?

A
  • The easiest way to reliably load streaming data into data lakes, data stores, and analytics services.
  • Pay for only the data ingested, data immediately disappears once processed.
  • Consumer of choice is from a predefined set of services: S3, RedShift, Elasticsearch or Splunk
36
Q

What is Kinesis Analystics?

A
  • allows you to perform queries in real-time.
  • Needs a kinesis data stream/firehose as the input/output.
37
Q

What is Kinesis Video analystics

A
  • securly ingests and stores video and audio encoded data to consumers such as SageMaker, Rekognition or other services to apply machine learning and video processing.
38
Q

What is KPL (Kinesis Producer Library)

A
  • A Java library to write data to a stream.
  • You can write data to a stream using AWS SDK, but KPL is more efficent.
39
Q

Does SQS scale automatically or does it require you to enable autoscaling?

A

SQS is a fully managed service that scales automatically. You do not need to enable autoscaling.

40
Q

Which SQS FIFO message attribute (API call) allows two messages to be processed in order?

A

MessageGroupId

41
Q

Which SQS FIFO message attribute allows two messages to be de-duplicated ?

A

MessageDeduplicationId

42
Q

If you currently have 10 active group messages (defined by GroupID) in your SQS FIFO queues, how many consumers can consume simultaneously?

A

10

43
Q

On an SNS topic with a delivery-retry policy configured, in which phase would SNS wait for an increasing amount of time between retries?

A

During the backoff phase

44
Q

What is the kinesis data retention policy?

A

Data retention is 1 day (default) to 7 days (max)

45
Q

How much data can a single kinesis shard ingest?

A
  • Up to 1 MB of data per second (reads), or
  • 1,000 records per second for writes.
46
Q

How are records ordered in kinesis?

A

Records are ordered per shard

AWS Developer Associate (25 decks)

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