Amazon S3, SQS and EventBridge: processing deliveries asynchronously

At Sawa Express, a customer swears she never received her parcel, which the rider says he handed to her neighbor. Nobody can prove anything, and the company pays her back. Mireille wants a photo for every delivery, and a text message to the customer as soon as the parcel is delivered, without anyone at the office pressing a button. You build a chain that works on its own, in the background. The rider's app uploads the photo straight into a private Amazon S3 bucket, through a presigned URL. S3 triggers an AWS Lambda function that marks the parcel as delivered and publishes the event on an Amazon EventBridge bus. A rule routes it to an Amazon SQS queue, from which a second function sends the text message. Along the way, you meet what the exam asks about again and again: the event received twice, the event published before the rule exists, the mistyped number that fails over and over. You make every step idempotent, and you set failed messages aside in a dead-letter queue without blocking the others. The second lab of the AWS path for developers, which prepares you for the AWS Certified Developer - Associate certification (DVA-C02).