Application Services

Question 1

What is SQS ?

Answer 1

It is web service that you access to a message queue, that can be used to store messages.
Pulled based, not push based
messages are 256kb in size
messages are kept in the queue between 1 min - 14days
default retention period = 4 days
SQS guarantees delivery once.

Question 2

SQS Queues types?

Answer 2

1) Standard

2) FIFO Queues

Question 3

Characteristics of the SQS Standard Queue?

Answer 3

1) It is the standard queue.
2) nearly unlimited transactions per second
3) guarantees message delivery (once)
4) provides best effort ordering.

Question 4

Characteristics of the SQS FIFO Queue?

Answer 4

1) Compliments the standard queue
2) uses first in first out, not best effort.
3) support message queue groups
4) 300 Transactions per second.

Question 5

visibility timout

Answer 5

default = 30 seconds if your tasks take longer than 30 seconds then increase this.

Question 6

What is SWF?

Answer 6

Amazon Simple Workflow Service. (used to fulfil orders in amazon.com warehouses)

Question 7

What is an SWF Worker ?

Answer 7

A program that interacts with SWF to get tasks, process received tasks and return the results.

Question 8

What is an SWF Decider?

Answer 8

A program that controls the coordination of tasks. (i.e. ordering, concurrency, and scheduling according to the application logic).

Question 9

What is SNS ?

Answer 9

Simple Notification Service ?

Question 10

What is the role of SNS?

Answer 10

It is a web service that makes it easy to setup operate and send notifications from the cloud.

Question 11

SNS Capabilities?

Answer 11

Can deliver messages via sms, email or SQS queues.
can also trigger lambda functions. (message payload is the lambda input)
It is the service that notifies you about autoscaling and instance health.

Question 12

SNS benefits:

Answer 12

Pushed based delivery (no polling)
simple API + easy integration
flexible message delivery
inexpensive (pay as you go) 
web-based AWS management console

Question 13

SNS vs SQS :

Answer 13

Push (SNS) vs Pull (SQS)

Question 14

Elastic Transcoder:

Answer 14

It allows you to convert media files from their original source format into different formats that will play on different devices.
* Pay based on minutes spent transcoding.

Question 15

What is the API Gateway

Answer 15

A fully managed service that makes it easy for developers to publish maintain and monitor APIs at scale.

Question 16

What is API Caching ?

Answer 16

This allows you to reduce the number of calls made to your endpoint, by caching its response. TTL is used to determine how fast the cache is stored.

Question 17

API gateway scaling

Answer 17

API gateway scales automatically (low cost)

Question 18

API gateway features

Answer 18

Throttle API gateway to prevent attacks.
log results to cloudwatch
if you use Javascript or AJAX scross multiple domains then you need to enable CORS on the gateway.

Question 19

Kinesis

Answer 19

A platform on AWS to send your streaming data too, it makes it easy to load and analyze streaming data and for you to build your own custom application.

Question 20

Core Kinesis Services

Answer 20

1) Kinesis Streams
2) Kinesis Firehose
3) Kinesis Analytics

Question 21

What is Kinesis Streams

Answer 21

Stream data is sent from devices to Kinesis streams (shards) where it is stored in shards. Data is stored for up to 24 hours (can extend to 7 days) and then delivered to EC2 instances.

Question 22

What is Kinesis Firehose?

Answer 22

Stream data is sent from devices to Kinesis firehose, no shards or data retention, when it arrives it is immediately analysed and moved to an S3 bucket or send it to RedShift or ElasticSearch. No data consumers like streams.

Question 23

What is Kinesis Analytics?

Answer 23

It is provides you with an SQL to query the data in Firehose or streams and place in S3, RedShift or Elastic.