Step Functions

Question 1

What is AWS Step Functions

Answer 1

• Build serverless visual workflow to orchestrate your Lambda functions
• Represent flow as a JSON state machine
• Features: sequence, parallel, conditions, timeouts, error handling…
• Maximum execution time of 1 year
• Possibility to implement human approval feature
• If you chain Lambda functions using Step Functions, be mindful of the added latency to pass the calls

Question 2

What can Step Function integrate with

Answer 2

Optimized Integrations
* Can invoke a Lambda function
* Run an AWS Batch job
* Run an ECS task and wait for it to complete
* Insert an item from DynamoDB
* Publish message to SNS, SQS
* Launch an EMR, Glue, or SageMaker jobs
* Launch another Step Function workflow…

AWS SDK Integrations
* Access 200+ AWS services from your State
Machine
* Works like standard AWS SDK API call

Question 2

How can you invoke a Step Function workflow

Answer 2

• AWS Management Console
• AWS SDK (StartExecution API call)
• AWS CLI (start-execution)
• AWS Lambda (StartExecution API
  call)
• API Gateway
• EventBridge
• CodePipeline
• Step Function

Question 2

What are some tasks in which Step Functions can do

Answer 2

Lambda Tasks:
* Invoke a Lambda function

Activity Tasks:
* Activity worker (HTTP), EC2 Instances, mobile device, on premise DC
* They poll the Step functions service

Service Tasks:
* Connect to a supported AWS service
* Lambda function, ECS Task, Fargate, DynamoDB, Batch job, SNS topic, SQS queue

Wait Task:
* To wait for a duration or until a timestamp

Question 2

Does Step Functions integrate with AWS Mechanical Turk?

Answer 2

No, Step Functions does not integrate natively with AWS Mechanical Turk. Instead use SWF

Question 3

Within an Express Workflow, there is a Synchnonous vs Asynchronous Express Workflows, what are the difference between both

Answer 3

Synchronous Express Workflows
* Wait until the Workflow completes, then return the result
* Examples: orchestrate microservices, handle errors, retries, parallel tasks

Asynchronous Express Workflows
* Doesn’t for the Workflow to complete
* Examples: Workflows that don’t require immediate response, messaging

Question 4

How do we conduct error handling within Step Functions

Answer 4

You can enable error handling, retries, and add alerting to Step Function State Machine
* Example: set up EventBridge to alert via email if a State Machine execution fails