My simple order fulfillment system consists of the following processes:<\/p>\n\n\n\n
- \n
- API endpoint that accepts order requests and publishes event to an event router via a Lambda function<\/li>\n\n\n\n
- The event router is built using AWS EventBridge event bus that matches incoming requests’ location and routes them to target destinations for processing:\n
- \n
- Orders originating from the US will be routed to an API destination.<\/li>\n\n\n\n
- Orders originating from Europe will be routed to a Step Functions workflow.<\/li>\n\n\n\n
- All orders, regardless of their locations, will be routed to a Lambda Function to store the order details into a DynamoDB table and send back an order dispatch event to the event bus.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n
By following this approach, we can create a robust and flexible order fulfillment system capable of handling various requirements and scaling efficiently.<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/EDA-8.png\")
<\/figure>\n\n\n\nObjectives<\/h2>\n\n\n\n
- \n
- Create an Event Bus:\n
- \n
- Set up an AWS EventBridge event bus named Orders<\/strong>.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- Implement Event Rules:\n
- \n
- Create four event rules using AWS EventBridge:\n
- \n
- OrdertoCloudWatch<\/strong><\/li>\n\n\n\n
- USOrdertoAPI<\/strong><\/li>\n\n\n\n
- EUOrdertoStepFunctions<\/strong><\/li>\n\n\n\n
- ProcessedOrderstoLambda<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- Create Lambda Functions:\n
- \n
- Develop two Lambda functions:\n
- \n
- ProduceOrder<\/strong> to publish events to the event bus.<\/li>\n\n\n\n
- ProcessedOrder<\/strong> to handle events from the event bus.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- Develop REST APIs:\n
- \n
- Set up two REST APIs:\n
- \n
- OrderProducer<\/strong> to accept order requests.<\/li>\n\n\n\n
- OrderConsumer<\/strong> to process order requests.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- Implement a Workflow:\n
- \n
- Use AWS Step Functions to create a workflow for processing orders.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- Create a DynamoDB Table:\n
- \n
- Set up a DynamoDB table named OrderDetails<\/strong> to store order information.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- Establish IAM Policies:\n
- \n
- Create and configure IAM policies to grant necessary permissions to all services involved.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n
Step 1: Create Event Bus and CloudWatch Event Rule<\/h2>\n\n\n\n
Go to EventBridge<\/strong> console, select Event buses<\/strong> and click Create event bus<\/strong><\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image.png\")
<\/figure>\n\n\n\nTo easily test the event bus, I will create an event rule that act as a ‘catch-all’ for every event that passes to the event bus and writes it to a CloudWatch log.<\/p>\n\n\n\n
Select the newly created Orders<\/strong> event bus and click Create rule<\/strong>:<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-3.png\")
<\/figure>\n\n\n\n![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-4.png\")
<\/figure>\n\n\n\nIn the Event pattern, all events that come from source “com.aws.order<\/strong>” will be written to the CloudWatch log:<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-6.png\")
<\/figure>\n\n\n\nSelect CloudWatch log group as the target for the event rule and name the log group suffix as \/aws\/events\/orders<\/strong><\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-8.png\")
<\/figure>\n\n\n\nNow, every event sent to the Orders event bus will be logged to CloudWatch, making it easier to test and verify the events. To see the action, select Orders<\/strong> and click Send events<\/strong> with the following JSON payload:<\/p>\n\n\n\n
Event Source: com.aws.orders\nDetail Type: Order Notification\nEvent detail:\n{\n \"category\": \"pencil\",\n \"value\": 200,\n \"location\": \"ca-central\"\n}<\/code><\/pre>\n\n\n\n![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-9.png\")
<\/figure>\n\n\n\nOpen CloudWatch console, choose the log group \/aws\/events\/orders and select the last log stream to verify that the event has been received by the event bus.<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-10.png\")
<\/figure>\n\n\n\n![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-11.png\")
<\/figure>\n\n\n\nBy following these steps, you can confirm that your ‘catch-all’ rule is working and that events are being properly logged to CloudWatch.<\/p>\n\n\n\n
Step 2: Create Producer REST API and Lambda Function<\/h2>\n\n\n\n
I will create a Lambda function as a event producer to publish new order request to the event bus. Go to Lambda Function<\/strong> console and select Create function<\/strong>. The function reads an order details (location, category, value) from its parameters and publish the details to the Orders<\/strong> event bus.<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-17.png\")
<\/figure>\n\n\n\n![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-16.png\")
<\/figure>\n\n\n\nI will use API to simulate external parties making order requests and invoke my Lambda function to publish the order to the event bus. Go to API Gateway and click Create REST API.<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-14.png\")
<\/figure>\n\n\n\nSelect the ProduceOrder<\/strong> Lambda Function for integration.<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-15.png\")
<\/figure>\n\n\n\nSelect Deploy API<\/strong> and create a new stage for deployment.<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-18.png\")
<\/figure>\n\n\n\n![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-19.png\")
<\/figure>\n\n\n\nAfter deploying the API, we can find the Invoke URL<\/strong> in Stages<\/strong>. To test the API, simply open the URL from the browser.<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/stage.png\")
<\/figure>\n\n\n\n![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/browser.png\")
<\/figure>\n\n\n\nBy following these steps, you can simulate external parties making order requests through the API, which will invoke the Lambda function to publish the order to the event bus.<\/p>\n\n\n\n
Step 3: Event Rule to Route Orders to API Gateway<\/h2>\n\n\n\n
EventBridge event rules use event patterns to select events and route them to targets. Events in AWS EventBridge are presented as JSON objects with following structure:<\/p>\n\n\n\n
{\n \"version\": \"0\",\n \"id\": \"6a7e8feb-b491-4cf7-a9f1-bf3703467718\",\n \"detail-type\": \"Order Notification\",\n \"source\": \"com.aws.orders\",\n \"account\": \"111111111111\",\n \"time\": \"2024-06-08T18:43:48Z\",\n \"region\": \"ca-central-1\",\n \"resources\": [],\n \"detail\": {\n \"category\": \"supplies\",\n \"value\": 100,\n \"location\": \"us-east\",\n }\n}<\/code><\/pre>\n\n\n\nI will create my first event rule to route orders with location matching ‘us-east’ to an API destination. My event pattern looks like this:<\/p>\n\n\n\n
{\n \"source\": [\"com.aws.orders\"],\n \"detail\": {\n \"location\": [\"us-east\"]\n }\n}<\/code><\/pre>\n\n\n\nFirst I will setup the API destination by creating a dummy REST API. Go to API Gateway console and choose Create API.<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-24.png\")
<\/figure>\n\n\n\n![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-26.png\")
<\/figure>\n\n\n\nDeploy the API to obtain the API destination endpoint (e.g., https:\/\/<app-id>.execute-api.<region>.amazonaws.com\/dev<\/em>).<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-27.png\")
<\/figure>\n\n\n\nNow we create the event rule, select EventBridge Rules<\/strong> and click on Create rule<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-21.png\")
<\/figure>\n\n\n\nCopy and paste the above event pattern and select Next.<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-23.png\")
<\/figure>\n\n\n\nTo configure the event rule to route to an API destination, we need to create a new API destination. Under API destination, choose Create a new API destination with the following:<\/p>\n\n\n\n
- \n
- API destination endpoint: <https:\/\/<app-id>.execute-api.<region>.amazonaws.com\/dev><\/strong><\/em><\/li>\n\n\n\n
- HTTP method: POST<\/strong><\/li>\n\n\n\n
- Connection type: Create a new connection<\/li>\n\n\n\n
- Authorization type: Basic (Username\/Password)<\/strong><\/li>\n\n\n\n
- Username: myUsername<\/strong><\/li>\n\n\n\n
- Password: myPassword<\/strong><\/li>\n<\/ul>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-32-1.png\")
<\/figure>\n\n\n\n![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-31.png\")
<\/figure>\n\n\n\nTo verify the event rule, I can simply call our Producer API with the following parameters:<\/p>\n\n\n\n
https:\/\/xxx.execute-api.ca-central-1.amazonaws.com\/dev?location=us-east&category=office-supplies&value=200<\/code><\/pre>\n\n\n\nTo see the log, open CloudWatch Log Group console and select the Log group API-Gateway-Execution-Logs<\/strong> prefix. The log event shows the API responds successfully with a 200 status.<\/p>\n\n\n\n
![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/image-33-1.png\")
<\/figure>\n\n\n\n![\"\"](\"http:\/\/184.72.63.26\/wp-content\/uploads\/2024\/06\/cloudwatchlog.png\")
<\/figure>\n\n\n\nNow, any order event with the location set to us-east will be routed to the API Gateway endpoint. This setup ensures that orders from the specified region are correctly processed by the designated API. <\/p>\n\n\n\n
Thank you for reading my post. Stay tuned for Part 2, where I’ll cover the remaining implementation steps.<\/p>\n","protected":false},"excerpt":{"rendered":"
In this blog post, I will walk through the journey to build a simple order fulfillment system using an Event-Driven Architecture (EDA). EDA is an architecture pattern designed to decouple and decentralize application components by allowing loosely couple services to communicate through asynchronously publishing and subscribing to events via an event router. EDA offers several […]<\/p>\n","protected":false},"author":1,"featured_media":402,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[28,29],"class_list":["post-277","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-aws","tag-event-driven-architecture","tag-eventbridge"],"_links":{"self":[{"href":"https:\/\/www.wallacel.com\/index.php\/wp-json\/wp\/v2\/posts\/277","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wallacel.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.wallacel.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.wallacel.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wallacel.com\/index.php\/wp-json\/wp\/v2\/comments?post=277"}],"version-history":[{"count":28,"href":"https:\/\/www.wallacel.com\/index.php\/wp-json\/wp\/v2\/posts\/277\/revisions"}],"predecessor-version":[{"id":494,"href":"https:\/\/www.wallacel.com\/index.php\/wp-json\/wp\/v2\/posts\/277\/revisions\/494"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.wallacel.com\/index.php\/wp-json\/wp\/v2\/media\/402"}],"wp:attachment":[{"href":"https:\/\/www.wallacel.com\/index.php\/wp-json\/wp\/v2\/media?parent=277"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.wallacel.com\/index.php\/wp-json\/wp\/v2\/categories?post=277"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.wallacel.com\/index.php\/wp-json\/wp\/v2\/tags?post=277"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
- HTTP method: POST<\/strong><\/li>\n\n\n\n
- API destination endpoint: <https:\/\/<app-id>.execute-api.<region>.amazonaws.com\/dev><\/strong><\/em><\/li>\n\n\n\n
- Establish IAM Policies:\n
- Set up a DynamoDB table named OrderDetails<\/strong> to store order information.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- OrderConsumer<\/strong> to process order requests.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- OrderProducer<\/strong> to accept order requests.<\/li>\n\n\n\n
- ProcessedOrder<\/strong> to handle events from the event bus.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- ProduceOrder<\/strong> to publish events to the event bus.<\/li>\n\n\n\n
- USOrdertoAPI<\/strong><\/li>\n\n\n\n
- OrdertoCloudWatch<\/strong><\/li>\n\n\n\n
- Implement Event Rules:\n
- Set up an AWS EventBridge event bus named Orders<\/strong>.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- Create an Event Bus:\n