SNS SNS SWF Flashcards
What is SQS?
Web service that gives access to a message queue to store messages while waiting for a computer to process them
SQS Message size
Up to 256Kb of text in any format
Downside of SQS
Not guaranteed first in first out
How does SQS pull task messages from the queue?
Asynchronously, receives named file, processes, completes and deletes
SQS timeout
12 hours visibility
SQS Billing size
at 64Kb chunks
Pricing for SQS
First million free per month
$.5 per 1 million each moth
SQS Default message visibility
30 seconds
To change visibility time
Use the ChangeMessageVisibility action to specify timeout time
Long polling
Way to retrieve messages, but doesn̥t until the poll times out.
For example ec2 sends a message to see if there are messages
Maximum long poll timeout
20 seconds
Polling in tight loops is burning CPU cycles and costing the company money, how would you fix this?
Long polling
Fanning out
Using SNS to pass along SQS messages to other SQS streams
SQS was the first service on the AWS platform?
TRUE
SQS What is the default visibility time out setting?
30 seconds
TF An SQS message can be delivered multiple times.
TRUE
You are designing a new application which involves processing payments and delivering promotional emails to customers. You plan to use SQS to help facilitate this. You need to ensure that the payment process takes priority over the creation and delivery of emails. What is the best way to achieve this.
Use 2 SQS queues first with a priority for payments
Your EC2 instances download jobs from the SQS queue, however they are taking too long to process them. What API call can you use to extend the length of time to process the jobs?
ChangeMessageVisibility
What is the maximum long poll timeout?
20 seconds
What amazon service can you use in conjunction with SQS to fan out” SQS messages to multiple queues.”
SNS
SNS SF
Simple Notification Services
SNS is
Mechanism for push notification system
Differences of SNS and SQS
SQS pull/polls
SNS pushes
SNS recipient grouping
Recipients are groups in topics
SNS topics
Top is an access point for allowing recipients to dynamically subscribe to the same notification
SNS Pricing
.50 per 1 million on SNS
.06 per 100K over HTTP
.75 per 100 on SMS
2.00 per 100k over email
SNS General Data type
JSON
TF SNS is pull based rather than push based?
FALSE
SWF SF
Simple workflow service
SWF Function
Coordinate work across distributed applications
SWF Workers
Programs that get tasks, process and return results
SWF Decider
Controls the coordination of tasks
Biggest difference between SWF and SQS
In SWF the tasks are only deployed once every time
SWF Domains
Parameters in JSON format sent to SWF
TF
SWF consists of a domain, workers and deciders?
TRUE
Maintaining your application̥s execution state (e.g. which steps have completed, which ones are running, etc.) is a perfect use case for SWF.
TRUE
