Event Grid for event-driven architecture in Azure - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Azure Event Grid?

Azure Event Grid is a service that allows applications to react to events from various sources in real time by routing those events to event handlers or subscribers.

beginner

How does Event Grid support event-driven architecture?

Event Grid enables event-driven architecture by delivering events from publishers to subscribers instantly, allowing systems to respond to changes without polling or manual checks.

intermediate

What are the main components of Azure Event Grid?

The main components are: Event Sources (publishers), Event Grid Topic (event routing), and Event Handlers (subscribers) that process the events.

intermediate

Why is Event Grid considered scalable and reliable?

Event Grid is scalable because it can handle millions of events per second and reliable because it guarantees at-least-once delivery with retry policies.

beginner

Give an example of a real-life scenario where Event Grid is useful.

For example, when a new file is uploaded to Azure Blob Storage, Event Grid can notify a function app to process the file automatically without delay.

What role does Event Grid play in event-driven architecture?

A Routes events from sources to handlers instantly

B Stores data permanently

C Manages virtual machines

D Creates databases

Event Grid routes events from publishers to subscribers instantly, enabling event-driven workflows.

Which component in Event Grid receives events from publishers?

A Event Grid Topic

B Event Source

C Event Handler

D Event Processor

The Event Grid Topic acts as the central point that receives events from sources and routes them to handlers.

How does Event Grid ensure event delivery reliability?

A By storing events indefinitely

B By requiring manual confirmation

C By sending events only once without retries

D By retrying delivery until acknowledged

Event Grid retries event delivery until the subscriber acknowledges receipt, ensuring reliable delivery.

Which Azure service can be an event handler for Event Grid events?

A Azure Virtual Machines

B Azure Functions

C Azure SQL Database

D Azure Blob Storage

Azure Functions can automatically run code in response to Event Grid events.

What is a benefit of using Event Grid over polling for changes?

A Increased network traffic

B More manual checks required

C Lower latency and less resource use

D Slower event processing

Event Grid delivers events instantly, reducing latency and resource use compared to polling.

Explain how Azure Event Grid enables event-driven architecture in simple terms.

Think about how messages travel from one app to another without waiting.

Describe a practical example where Event Grid can improve an application workflow.

Consider a file upload triggering a process automatically.

Practice

1. What is the main purpose of Azure Event Grid in event-driven architecture?

easy

A. To store large amounts of data for analytics

B. To connect event sources to event handlers for instant reactions

C. To create virtual machines automatically

D. To manage user identities and access

Solution

1. Step 1: Understand Event Grid's role

   Event Grid is designed to route events from sources to handlers quickly and efficiently.

2. Step 2: Compare options with Event Grid's function

   Only To connect event sources to event handlers for instant reactions describes connecting event sources to handlers for instant reactions, which matches Event Grid's purpose.

3. Final Answer:

   To connect event sources to event handlers for instant reactions -> Option B

4. Quick Check:

   Event routing = Connect sources to handlers [OK]

Hint: Event Grid routes events instantly between sources and handlers [OK]

Common Mistakes:

• Confusing Event Grid with data storage services
• Thinking Event Grid manages virtual machines
• Mixing Event Grid with identity management

2. Which Azure CLI command correctly creates an Event Grid subscription named mySub for a topic myTopic?

easy

A. az eventgrid event-subscription create --name mySub --source-resource-id /subscriptions/{subId}/resourceGroups/{rg}/providers/Microsoft.EventGrid/topics/myTopic

B. az eventgrid event-subscription create --name mySub --source-resource-id myTopic

C. az eventgrid topic create --name mySub --resource-group myTopic

D. az eventgrid subscription create --topic myTopic --name mySub

Solution

1. Step 1: Identify correct CLI syntax for event subscription creation

   The command requires the full resource ID for the source topic, not just the name.

2. Step 2: Analyze options for correct parameters

   az eventgrid event-subscription create --name mySub --source-resource-id /subscriptions/{subId}/resourceGroups/{rg}/providers/Microsoft.EventGrid/topics/myTopic uses the full resource ID format, which is required. az eventgrid event-subscription create --name mySub --source-resource-id myTopic uses only the topic name, which is invalid. Options C and D use incorrect commands or parameters.

3. Final Answer:

   az eventgrid event-subscription create --name mySub --source-resource-id /subscriptions/{subId}/resourceGroups/{rg}/providers/Microsoft.EventGrid/topics/myTopic -> Option A

4. Quick Check:

   Full resource ID needed for source in CLI [OK]

Hint: Use full resource ID for source in event-subscription create [OK]

Common Mistakes:

• Using only topic name instead of full resource ID
• Confusing topic creation with subscription creation
• Using wrong CLI commands like 'subscription create'

3. Given this Azure CLI command:

az eventgrid event-subscription create --name sub1 --source-resource-id /subscriptions/123/resourceGroups/rg1/providers/Microsoft.EventGrid/topics/topic1 --endpoint https://myapp.com/api/events

What happens after running this command?

medium

A. The endpoint URL is registered as a new event source

B. A new Event Grid topic named 'sub1' is created

C. An event subscription named 'sub1' is created to send events from 'topic1' to the specified endpoint

D. The command fails due to missing resource group parameter

Solution

1. Step 1: Understand the command purpose

   The command creates an event subscription named 'sub1' for the existing topic 'topic1'.

2. Step 2: Analyze the effect of parameters

   The endpoint URL is where events will be delivered. The command does not create a topic or register an endpoint as a source.

3. Final Answer:

   An event subscription named 'sub1' is created to send events from 'topic1' to the specified endpoint -> Option C

4. Quick Check:

   Event subscription sends events to endpoint [OK]

Hint: Event subscription links topic events to endpoint URL [OK]

Common Mistakes:

• Thinking the command creates a new topic
• Assuming endpoint is an event source
• Believing resource group is mandatory in this command

4. You wrote this Azure CLI command to create an Event Grid subscription:

az eventgrid event-subscription create --name sub2 --source-resource-id myTopic --endpoint https://myapp.com/api/events

But it fails with an error. What is the most likely cause?

medium

A. The source resource ID must be a full Azure resource ID, not just the topic name

B. The endpoint URL must be an Azure service URL

C. The subscription name cannot contain numbers

D. The command requires a resource group parameter

Solution

1. Step 1: Check the source-resource-id parameter format

   The source-resource-id must be the full Azure resource ID, not just the topic name.

2. Step 2: Validate other parameters

   The endpoint can be any valid HTTPS URL. Subscription names can include numbers. Resource group is not required here if full resource ID is used.

3. Final Answer:

   The source resource ID must be a full Azure resource ID, not just the topic name -> Option A

4. Quick Check:

   Full resource ID needed for source-resource-id [OK]

Hint: Always use full resource ID for source-resource-id [OK]

Common Mistakes:

• Using only topic name instead of full resource ID
• Thinking endpoint must be Azure URL
• Believing subscription names cannot have numbers

5. You want to build an app that reacts instantly when a new blob is uploaded to Azure Storage. Which Event Grid setup is best to achieve this?

hard

A. Create an Event Grid subscription on the Storage Account's blob deleted event

B. Create a Storage Queue and poll it every minute for new blobs

C. Use Azure Functions timer trigger to check blobs hourly

D. Create an Event Grid subscription on the Storage Account's blob created event, with your app's webhook as endpoint

Solution

1. Step 1: Identify event source and event type

   The Storage Account emits blob created events when new blobs upload.

2. Step 2: Choose subscription and endpoint

   Creating an Event Grid subscription for blob created events with your app's webhook endpoint enables instant reaction.

3. Step 3: Evaluate other options

   Polling or timer triggers cause delays. Subscribing to blob deleted events does not detect new uploads.

4. Final Answer:

   Create an Event Grid subscription on the Storage Account's blob created event, with your app's webhook as endpoint -> Option D

5. Quick Check:

   Blob created event subscription = instant reaction [OK]

Hint: Subscribe to blob created events for instant upload notifications [OK]

Common Mistakes:

• Using polling instead of event-driven subscription
• Subscribing to wrong event type like blob deleted
• Relying on timer triggers causing delays