Event Grid for event-driven architecture in Azure - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

Event Grid Event Delivery Behavior

What happens if an Azure Event Grid event subscriber endpoint is temporarily unavailable?

A Event Grid retries delivery for up to 24 hours with exponential backoff.

B Event Grid immediately drops the event and does not retry.

C Event Grid retries delivery indefinitely until the endpoint is available.

D Event Grid queues the event permanently until the subscriber manually acknowledges.

💡 Hint

Think about how cloud services handle temporary failures to avoid losing events.

Azure Event Grid retries event delivery for up to 24 hours using exponential backoff. This ensures temporary issues do not cause event loss.

❓ Architecture

intermediate

Choosing Event Grid for Event Routing

You want to build a system where multiple microservices react to events from blob storage changes. Which feature of Event Grid makes it the best choice?

A Event Grid stores all events permanently for audit purposes.

B Event Grid supports multiple event handlers subscribing to the same event source with low latency.

C Event Grid requires polling to detect new events.

D Event Grid only supports one subscriber per event source.

💡 Hint

Consider how events are delivered to multiple services efficiently.

Event Grid supports multiple subscribers to the same event source and delivers events with low latency, enabling event-driven microservices.

❓ security

advanced

Securing Event Grid Event Subscriptions

Which method provides the strongest security for authenticating Event Grid event delivery to a webhook endpoint?

A Use Azure Active Directory (AAD) token-based authentication for the webhook.

B Use a shared access signature (SAS) token in the webhook URL.

C Use IP filtering on the webhook endpoint only.

D Use HTTP Basic Authentication with a username and password.

💡 Hint

Think about modern, secure token-based authentication methods supported by Azure services.

Azure Active Directory token-based authentication provides strong, managed identity-based security for Event Grid webhook endpoints.

❓ Configuration

advanced

Event Grid Subscription Filtering Configuration

You want to configure an Event Grid subscription to only receive events where the subject starts with 'orders/' and the event type is 'OrderCreated'. Which filter configuration is correct?

A {"subjectBeginsWith": "OrderCreated", "includedEventTypes": ["orders/"]}

B {"subjectEndsWith": "orders/", "includedEventTypes": ["OrderCreated"]}

C {"subjectBeginsWith": "orders/", "includedEventTypes": ["OrderCreated"]}

D {"subjectContains": "orders/", "excludedEventTypes": ["OrderCreated"]}

💡 Hint

Check the filter properties for subject prefix and event types.

The correct filter uses 'subjectBeginsWith' for the prefix and 'includedEventTypes' to specify the event type to receive.

✅ Best Practice

expert

Designing for High Availability with Event Grid

You design an event-driven system using Event Grid with multiple subscribers. To ensure no event loss during regional outages, what is the best architectural practice?

A Use Event Grid with only one subscriber to simplify recovery.

B Use a single Event Grid topic in one region and rely on Event Grid's internal replication.

C Configure subscribers to poll Event Grid for missed events after an outage.

D Deploy Event Grid topics and subscribers in multiple Azure regions and use geo-redundant storage for event data.

💡 Hint

Think about spreading resources across regions to handle failures.

Deploying Event Grid topics and subscribers across multiple regions with geo-redundant storage ensures high availability and no event loss during regional failures.

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