In SWF the task is assigned only once and never duplicated.
SWF coordinates work across distributed application components.
It helps in implementing complex business processes and work flows.
It is suitable for long running execution and not for short batch jobs etc.
Enables complex interaction within different application on different platform, AWS or on-premise infrastructure and between different users.
Maximumworkflow can be 1 year and it is measured in seconds.
Features of SWF
Tasks executed with no duplicate
Routing and queueing of the task handled by the SWF.
It also provides timeout and status of the task.
The task workflow can have child process, and a list of hierarchy process.
It handles user data Input and execution result output.
SWF components
A workflow is control flow logic for execution of the task.
A domain contains of workflow or workflows.
Tasks can be performed by executable code, a webservices call or end user input. They can be performed parallel or serially.
Actors interact directly with SWF to coordinate tasks.
SWF Actors
Actors can be workflow starter, decider or activity workers
Starters can initiate the execution of work flow.
Deciders implement work flow logic and notify SWF changes during the workflow execution
Activity Workers perform activity tasks of the workflow.
SWF Task
Must be registered using either the console or the RegisterActivityType action (API/CLI).
When scheduled you can specify a task list (queue)
Decision and Activity task has separate lists (queue)
Task can be assigned to activity workers through task routing if required.
Application communication can be established to SWF through,
SDK
SWF API HTTP POST
Flow Framework (Java or Ruby)
CLI
SWF and SQS
SWF presents a task oriented API and SQS offers a message oriented API
SWF ensures that the task is assigned only once and never duplicated, with SQS you may get duplicate message and you will need to ensure that a message is process only once.
SWF keeps tracks of all the tasks and events in an application, in SQS we should implement our own application level tracking especially if the application uses multiple queues.
