Application Services - SWF

Question 1

What is SWF?

Answer 1

web service that makes it easy to coordinate work across distributed app components

Question 2

SWF enables apps to be designed as…

Answer 2

a coordination of tasks

Question 3

Tasks represent

Answer 3

invocations of various processing steps in an app which can be performed by executable code, web service calls, human actions, and scripts

Question 4

SQS vs SWF retention period

Answer 4

SQS - 14 days, SWF - 1 year

Question 5

SQS vs SWF - APIs

Answer 5

SQS - message oriented, SWF - task oriented

Question 6

SQS vs SWF - duplication

Answer 6

SWF - task assigned only once, never duplicated

SQS - need to handle duplicated messages, make sure message is processed only once

Question 7

SQS vs SWF - tracking

Answer 7

SWF - keeps track of all the tasks and events in an pp

SQS - need to implement your own app-level tracking, especially if your app uses multiple queues

Question 8

SWF Actors

Answer 8

Workflow Starters, Deciders, Activity Workers

Question 9

Workflow Starters

Answer 9

an app that can initiate (start) a workflow. example: e-commerce website when placing an order or a mobile app searching for bus times

Question 10

Deciders

Answer 10

control the flow of activity tasks in a workflow execution. if something has finished in a workflow (or fails) a decider decides what to do next

Question 11

Activity Workers

Answer 11

carry out the activity tasks