Events and orchestration with Step Functions

Comments

• EventBridge decouples the producer of an event from its consumers. Bus rules filter which events reach each target.
• Step Functions stores the state of each execution and retries steps with backoff. If a step fails, the workflow can run a compensating action.
• Aurora Serverless v2 scales capacity in seconds. Lambda can open many connections, so consider RDS Proxy.
• The arrows represent control flow. For very large payloads, store the content in S3 and pass only a reference in the event.

Information flow

1. Amazon API Gateway

   API Gateway receives the HTTP request and publishes an event to EventBridge.

2. Amazon EventBridge

   EventBridge evaluates the bus rules and sends the event to Step Functions.

3. AWS Step Functions

   Step Functions starts the state machine and invokes the validation Lambda function.

4. AWS Lambda (validation and payment)

   If validation succeeds, Step Functions invokes the payment Lambda function.

5. Amazon Aurora Serverless v2

   The payment function records the transaction in Aurora.