Application Services - SWF Flashcards
What is SWF?
web service that makes it easy to coordinate work across distributed app components
SWF enables apps to be designed as…
a coordination of tasks
Tasks represent
invocations of various processing steps in an app which can be performed by executable code, web service calls, human actions, and scripts
SQS vs SWF retention period
SQS - 14 days, SWF - 1 year
SQS vs SWF - APIs
SQS - message oriented, SWF - task oriented
SQS vs SWF - duplication
SWF - task assigned only once, never duplicated
SQS - need to handle duplicated messages, make sure message is processed only once
SQS vs SWF - tracking
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
SWF Actors
Workflow Starters, Deciders, Activity Workers
Workflow Starters
an app that can initiate (start) a workflow. example: e-commerce website when placing an order or a mobile app searching for bus times
Deciders
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
Activity Workers
carry out the activity tasks