Synchronous and Asynchronous Express Workflows - Amazon Step Functions
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Synchronous and Asynchronous Express Workflows

There are two types of Express Workflows that you can choose, Asynchronous Express Workflows and Synchronous Express Workflows.

  • Asynchronous Express Workflows return confirmation that the workflow was started, but do not wait for the workflow to complete. To get the result, you must poll the service's CloudWatch Logs. Asynchronous Express Workflows can be used when you don't require immediate response output, such as messaging services, or data processing that other services don't depend on. Asynchronous Express Workflows can be started in response to an event, by a nested workflow in Step Functions, or by using the StartExecution API call.

  • Synchronous Express Workflows start a workflow, wait until it completes, then return the result. Synchronous Express Workflows can be used to orchestrate microservices, and allow you to develop applications without the need to develop additional code to handle errors, retries, or execute parallel tasks. Synchronous Express Workflows can be invoked from Amazon API Gateway, Amazon Lambda, or by using the StartSyncExecution API call.


    If you run Step Functions Express Workflows synchronously from the console, the StartSyncExecution request elapses after 60 seconds. To run the Express Workflows synchronously for a duration of up to five minutes, make the StartSyncExecution requests using the Amazon SDK or CLI instead of the Step Functions console.

    Synchronous Express execution API calls do not contribute to the existing account capacity limits. Step Functions will provide capacity on demand and will automatically scale with sustained workload. Surges in workload may be throttled until capacity is available.