Synchronous and Asynchronous Express Workflows - AWS Step Functions

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 don't wait for the workflow to complete. To get the result, you must poll the service's CloudWatch Logs. You can use Asynchronous Express Workflows when you don't require immediate response output, such as messaging services or data processing that other services don't depend on. You can start Asynchronous Express Workflows 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, and then return the result. Synchronous Express Workflows can be used to orchestrate microservices. With Synchronous Express Workflows, you can develop applications without the need to develop additional code to handle errors, retries, or run parallel tasks. You can invoke Synchronous Express Workflows invoked from Amazon API Gateway, AWS 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 request using the AWS SDK or AWS Command Line Interface (AWS CLI) instead of the Step Functions console.

    Synchronous Express execution API calls don't contribute to existing account capacity limits. Step Functions provides capacity on demand and automatically scales with sustained workload. Surges in workload may be throttled until capacity is available.