Applications Flashcards
What AWS Services allows you to decouple your application workloads?
SQS
Which AWS service allows you to define and coordinate synchronous and asynchronous tasks?
AWS SWF
What are the actors of an SWF?
Starters - Initiate the workflow
Deciders - Control flow
Workers - Perform work
True or False: A SWF can only be assigned once?
True; a SWF task is never duplicated
Which AWS Service pushes notifications?
SNS
Which AWS Service requires polling?
SQS
What order does a Standard SQS Queue provide?
Loose -FIFO (and is the default FIFO); order is not guaranteed
What is the standard guarantee QoS for SQS?
At Least Once
What are dead letter queues?
Dead letter queues are queues that receive messages from other source queues; they’re used to collect messages that never got processed in the source queues for analytics later
What is a Visibility Timeout?
A visibility timeout is a period of time that SQS prevents other consumers from receiving or processing a message. Increase the visibility timeout >1 second for messages that may take a long time to process.
What is Long Polling?
Long polling allows you not to return a response until a message shows up in the queue or the poll times out. Use long polling to decrease your overall costs by reducing the number of empty receives (which you still pay for)
What is the deduplication interval for FIFO queues?
5 minutes
What are the throughput limits for FIFO queues?
3000 mps for batching, or up to 300 mps for non batched messages
How can you deliver messages to different consumers?
Use message groups
What is the default retention for an SQS message?
4 days (1 m to 14 days range)
