Step Function Basics

How do Step Functions work?

Typically, each AWS Lambda function is designed to perform a single action and run within a limited amount of time. However, sometimes we need to perform tasks that involve multiple steps and take several minutes, or even hours, to run. For example, we may want to perform an ETL process on a large volume of data. AWS uses Step Functions for this functionality.

Step Functions work by running multiple AWS services in a coordinated fashion. Typically, the output from one service represents an input to another service. AWS Lambda is frequently used in Step Functions to execute specific steps of the process.

There are two ways a Step Function can be configured:

• A visual drag-and-drop diagram

• A JSON-based Amazon States Language (ASL)

We’ll take a look at some examples of both.

Step Function visual diagram

The easiest way to set up a Step Function in AWS is with a visual drag-and-drop diagram. This is a low-code, intuitive solution. All we need to do is search for “Step Function” in AWS to find the configuration page for the resource. Then we can either create a new diagram from scratch or access the default diagram as an example. Here’s what the default diagram looks like.