Reactive Architecture

Event Grid is a highly scalable, serverless event broker that you can use to integrate applications using events.

1. Subscribing to Azure Events

Event Grid is the 'Glue' of Azure. You can subscribe to native events like 'New File in Storage', 'New User in Entra ID', or 'App Deployment Failed'. Your .NET code (via a Webhook or Azure Function) is then triggered instantly to handle that event. No polling required.

2. Custom Topics

You can also create your own **Custom Topics**. When a user's credit card is charged in your .NET app, publish an event to Event Grid. Any number of other services (Analytics, Billing, CRM) can subscribe to that event independently. This is the heart of the 'Cloud-Native' reactive pattern.

3. Architect Insight

Q: "Event Grid vs Service Bus?"

Architect Answer: "Use **Service Bus** when you are 'Pushing' work to a specific consumer that might be offline or slow (Command pattern). Use **Event Grid** when you are 'Broadcasting' that something happened and you don't care who (if anyone) is listening (Event pattern). Event Grid is lighter, faster, and much cheaper for massive event streams."