AWS Step Functions and Lambda Integration

Overview:

• Topic: Building a transaction processor state machine for credit card transactions.
• Objective: Integrate AWS Step Functions with Lambda functions to process purchase and refund transactions.
• State Machine Input: JSON object with an event type (purchase or refund).

Process Overview:

1. Input Event:
   • JSON object indicating event type (purchase or refund).
2. State Machine:
   • Initial step is a choice task.
   • Decision is made based on whether the event type is a purchase or refund.
3. Lambda Functions:
   • Two lambda functions for processing: process_purchase and process_refund.
   • Each function logs the input, constructs a response object, and returns the result to the state machine.

Implementing in AWS Console:

1. **Creating Lambda Functions:

   • Navigate to AWS Console.
   • Create two functions: process_purchase and process_refund.
   • Use Python 3.6 and basic Lambda permissions.

2. Writing Lambda Code (process_purchase):

   • Log the input message.
   • Construct a response object with:
     • transaction_type set to input value.
     • timestamp using current date/time.
     • Custom message: "hello from lambda inside process_purchase".
   • Return the response object.

3. Duplicate for Refund Function:

   • Create process_refund with identical logic, named accordingly.**

Setting Up IAM Role:

1. Role Creation:
   • Create a role for step functions to invoke lambda functions.
   • Use default Step Functions role with Lambda invocation permissions.

Configuring Step Functions:

1. Gather ARNs:
   • Copy ARNs of both lambda functions.
2. **Create State Machine:
   • Amazon States Language to define state machine.
   • Decision step (process_transaction) routes to correct Lambda based on event type.
   • Terminal states for both processes.
3. Paste Python Code into State Machine:
   • Use ARNs gathered for reference in resource fields.**

Testing:

1. Run Instances:
   • Start execution with input (transaction_type set to purchase or refund).
   • Monitor the process in real time with visual cues.
2. Validate Outputs:
   • Confirm inputs and outputs in each state.
   • Verify custom message and timestamp in Lambda outputs.

Conclusion:

• Next Steps: Upcoming videos will cover high-level overviews and advanced capabilities of step functions.