1. Introduction An event-driven architecture using Azure Cosmos DB, Azure Functions, and Azure Service Bus is the enterprise standard for designing highly decoupled, scalable, and resilient systems in the Microsoft Cloud. In this tutorial, you will construct a complete, asynchronous data flow from scratch using Azure's analogous features to the AWS ecosystem. The process begins when modifications occur in a Cosmos DB container, which automatically surfaces through the Cosmos DB Change Feed. This feed is continuously monitored by a producer Azure Function, which processes the change and publishes a message to a Service Bus Topic. The Service Bus Topic acts as a high-availability message router (similar to AWS SNS), performing a fan-out distribution of this notification to a Service Bus Subscription (acting as the queue, similar to AWS SQS). Finally, a second consumer Azure Function reads the messages from the subscription to perform the final business logic processing.…