Why Event Grid?

In cloud-native and serverless architectures, applications must react to events in real time. Instead of polling resources, Azure Event Grid pushes events to subscribers. It’s lightweight, scalable, and designed for event-driven architectures (EDA).

1. Event Grid Basics

Definition:
Fully managed, serverless event routing service based on publish/subscribe model.

Key Features:

• Near real-time event delivery (<1 second latency).

• Push model (no polling required).

• Supports millions of events per second.

• Guaranteed at-least-once delivery.

• Native integration with Azure services.

2. Event Sources

Event Grid can capture events from:

• Azure services (Blob storage, Resource Groups, Event Hubs).

• Custom apps (via custom topics).

• Partner services (e.g., SaaS providers).

Example:

• Blob Storage event → fires when a new file is uploaded.

• Azure Resource Group event → fires when a VM is created.

3. Event Handlers (Subscribers)

Subscribers can be:

• Azure Functions (serverless processing).

• Logic Apps (workflow automation).

• Event Hubs (big data ingestion).

• Webhooks (custom apps).

Example:

• Blob upload event → triggers Function to resize image.

• New user signup event → triggers Logic App to send welcome email.

4. Event Filtering

• Supports event type filtering (only receive relevant events).

• Advanced filtering (prefix/suffix matching on subject, numbers, strings, Boolean).

5. Reliability & Security

• Retry policies with exponential backoff for failed deliveries.

• Event dead-letter destination (e.g., Blob or Storage Queue).

• Secure with Azure AD authentication or SAS tokens.

Example Enterprise Scenario

A media platform requires:

• Triggering image resizing when a user uploads a photo.

• Sending notifications when new content is published.

• Logging all failed event deliveries.

Correct design:

• Use Event Grid Blob trigger → Function for resizing.

• Use Event Grid Topic → Logic App for notifications.

• Configure dead-letter destination in Blob storage.

Confusion Buster

• Event Grid vs Event Hubs

  • Event Grid = discrete events, pub/sub, serverless.

  • Event Hubs = data streaming (telemetry, logs).

• Event Grid vs Service Bus

  • Event Grid = lightweight, fire-and-forget, millions/sec.

  • Service Bus = enterprise messaging, ordering, DLQ.

• Webhook vs Logic App Handler

  • Webhook = custom code subscriber.

  • Logic App = no-code automation subscriber.

Exam Tips

• “Which Azure service routes events in real time with low latency?” → Event Grid.

• “Which service provides pub/sub for lightweight eventing?” → Event Grid.

• “Which Event Grid feature handles undeliverable events?” → Dead-letter destination.

• “Which service is best for reacting to blob uploads in real time?” → Event Grid.

What to Expect in the Exam

• Direct Q: “Which Azure service uses publish/subscribe for event-driven integration?” → Event Grid.

• Scenario Q: “Retailer wants to trigger notifications when a new order is placed.” → Event Grid with Logic App.

• Scenario Q: “Media app must resize images when uploaded to Blob Storage.” → Event Grid + Function.

• Trick Q: “Event Grid is designed for streaming millions of telemetry events continuously.” → False (that’s Event Hubs).