AWS Lambda Functions and AWS Step Functions

AWS Lambda Function

Amazon Web Services (AWS) Lambda is a serverless compute service that lets you run your code without provisioning or managing servers. It allows developers to easily create and deploy event-driven applications at scale. In this section, we will focus on AWS Lambda functions and their execution patterns.

Exactly-Once vs At-Least-Once Execution

There are two types of workflows available in AWS Step Functions: Standard Workflows and Express Workflows.

Standard Workflows

Standard workflows have exactly-once workflow execution and can run for up to one year. This means each step in a Standard workflow executes exactly once. These workflows are ideal for long-running, auditable workflows as they show execution history and visual debugging.

Express Workflows

Express workflows have at-least-once workflow execution and can run for up to five minutes. This means that one or more steps in an Express workflow can potentially run more than once, while each step executes at least once. These workflows are ideal for high-event-rate workloads.

Service Integrations

AWS Step Functions supports integrating with other AWS services, such as Lambda, through Task states. You can call any AWS service or API from your state machine using the AWS SDK integrations or Optimized integrations. The AWS SDK integrations let you call any of the over two hundred AWS services directly from your state machine, giving you access to over nine thousand API actions. Optimized integrations are customized to simplify usage in your state machines.

Service Integration Patterns

Standard Workflows and Express Workflows support different integration patterns. Standard Workflows support Run a Job (.sync) and Wait for Callback (.waitForTaskToken), while Express Workflows do not support these integration patterns. For more information on the differences between Standard and Express workflows, see the AWS documentation.

In summary, AWS Lambda functions are part of the AWS serverless compute service that allows you to run your code without provisioning or managing servers. They can be used in conjunction with other AWS services through the AWS Step Functions service, which offers two types of workflows that have different execution patterns and support various integration patterns.

Learn about AWS Lambda functions and AWS Step Functions, including the differences between exactly-once and at-least-once execution patterns, service integrations with other AWS services, and integration patterns for Standard Workflows and Express Workflows.