{"id":340,"date":"2024-06-10T18:48:23","date_gmt":"2024-06-11T01:48:23","guid":{"rendered":"http:\/\/184.72.63.26\/?p=340"},"modified":"2024-06-17T22:34:18","modified_gmt":"2024-06-18T05:34:18","slug":"building-a-serverless-event-driven-order-fulfillment-system-using-aws-eventbridge-part-2","status":"publish","type":"post","link":"https:\/\/www.wallacel.com\/index.php\/2024\/06\/10\/building-a-serverless-event-driven-order-fulfillment-system-using-aws-eventbridge-part-2\/","title":{"rendered":"Building a Serverless Event-Driven Order Fulfillment System using AWS EventBridge (Part 2)"},"content":{"rendered":"\n

This is part 2 of my last post, “Building a Serverless Event-Driven Order Fulfillment System using AWS Event Bridge<\/a>“. In Part 1, I’ve already setup the infrastructure to accept orders and publish them as events to EventBridge, along with routing them to an API destination and CloudWatch log group. For the next steps, we can build upon that foundation and add two more rules to further process the orders. <\/p>\n\n\n\n

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Step 4: Route Orders to Workflow<\/h2>\n\n\n\n

Here is a very simple workflow that listens to new order events from the EventBridge and publishes back an order processed event. In a more complicated case we can pass the content of the event from EventBridge and use the event payload in the Step Functions. <\/p>\n\n\n\n

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To create a workflow, go to Step Functions<\/strong> console and create a New State Machine<\/strong>.<\/p>\n\n\n\n

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With the Visual Designer, select Flow<\/strong> and drag a Pass<\/strong> state to the workflow:<\/p>\n\n\n\n

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Next we select Actions<\/strong> and choose Amazon EventBridge<\/strong> and add a PutEvents<\/strong>.<\/p>\n\n\n\n

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To write an event with a “Order Processed” type to your Orders event bus via the PutEvents API Parameters, you’ll need to provide the following JSON payload.<\/p>\n\n\n\n

{\n  \"Entries\": [\n    {\n      \"Detail\": {\n        \"OrderId\": \"new_id\",\n        \"OrderDetails.$\": \"$.detail\"\n      },\n      \"DetailType\": \"Order Processed\",\n      \"EventBusName\": \"Orders\",\n      \"Source\": \"com.aws.orders\"\n    }\n  ]\n}<\/code><\/pre>\n\n\n\n
Additionally, make sure to unselect the “Wait for callback” option if it’s selected, as you don’t need to wait for a callback in this scenario.<\/p>\n\n\n\n
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Now we can define a new event rule ‘EUOrdertoStepFunctions<\/strong>‘ specifically targeting orders with ‘EU’ locations to the workflow in Step Functions.<\/p>\n\n\n\n
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For event pattern, match orders with locations originating from ‘eu-west<\/strong>‘ only.<\/p>\n\n\n\n
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Choose Step Functions state machine<\/strong> as the target and workflow created earlier in State machine<\/strong>:<\/p>\n\n\n\n
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To trigger the execution of our workflow, let’s make a call to our Producer API with the following parameters:<\/p>\n\n\n\n
https:\/\/xxx.execute-api.ca-central-1.amazonaws.com\/dev?location=eu-west&category=office-supplies&value=300<\/code><\/pre>\n\n\n\n
Once the request is made successfully, our Producer API will publish the order event to EventBridge, triggering the associated event rule, which in turn will invoke the Step Functions workflow to process the order.<\/p>\n\n\n\n
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Step 5: Route Orders to Lambda Function and DynamoDB<\/h2>\n\n\n\n
To complete the order processing flow, we will create a new event rule that routes processed order events to a Lambda function. This Lambda function will store the order details in a DynamoDB table and then publish a dispatch order event to the Orders event bus.<\/p>\n\n\n\n
An order consists of an orderId<\/strong> with the following attributes:<\/p>\n\n\n\n