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

Recall & Review

beginner

What is Azure Event Grid?

Azure Event Grid is a service that routes events from sources to destinations, enabling apps to react to events in real time without polling.

beginner

What is an event source in Event Grid?

An event source is where events originate, such as Azure Blob Storage or custom apps sending events to Event Grid.

beginner

What is an event handler in Event Grid?

An event handler is the destination that receives and processes events, like Azure Functions, Logic Apps, or Webhooks.

intermediate

How does Event Grid improve application design?

Event Grid decouples event producers and consumers, allowing scalable, reactive, and efficient event-driven applications.

intermediate

What is a topic in Azure Event Grid?

A topic is a user-defined endpoint where event sources send events. Subscribers listen to topics to receive events.

What role does Azure Event Grid play in cloud applications?

A Routes events from sources to handlers

B Stores large amounts of data

C Manages virtual machines

D Provides database services

Azure Event Grid routes events from sources to handlers, enabling event-driven architectures.

Which of the following can be an event handler in Event Grid?

A Azure Functions

B Azure Virtual Machines

C Azure Blob Storage

D Azure SQL Database

Azure Functions can process events as event handlers in Event Grid.

What is the purpose of a topic in Event Grid?

A To create virtual networks

B To receive events from sources

C To run code on events

D To store event data permanently

A topic is where event sources send events for routing.

How does Event Grid help applications scale?

A By creating more virtual machines

B By increasing CPU power

C By storing data in databases

D By decoupling event producers and consumers

Decoupling producers and consumers allows independent scaling and flexibility.

Which service is NOT typically an event source for Event Grid?

A Azure Blob Storage

B Custom applications

C Azure Virtual Machines

D Azure Logic Apps

Azure Virtual Machines are not event sources; they can run event handlers but do not emit events directly.

Explain how Azure Event Grid routes events from sources to handlers.

Think about how messages travel from where they start to where they are used.

Describe the benefits of using Event Grid in cloud applications.

Consider how Event Grid helps apps respond quickly and grow easily.

Practice

1. What is the main purpose of Azure Event Grid in cloud applications?

easy

A. To route events from sources to event handlers automatically

B. To store large amounts of data for analytics

C. To create virtual machines for compute power

D. To manage user identities and access control

Solution

1. Step 1: Understand Event Grid's role

   Event Grid is designed to route events from sources to handlers automatically, enabling reactive applications.

2. Step 2: Compare with other services

   Other options describe different Azure services: storage, compute, and identity management, not event routing.

3. Final Answer:

   To route events from sources to event handlers automatically -> Option A

4. Quick Check:

   Event routing = To route events from sources to event handlers automatically [OK]

Hint: Event Grid moves events, not data or users [OK]

Common Mistakes:

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

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

easy

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

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

C. az eventgrid topic create --name mySub --source myTopic

D. az eventgrid event-subscription create --name mySub --source-resource-id /subscriptions/.../resourceGroups/.../providers/Microsoft.EventGrid/topics/myTopic

Solution

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

   The command requires the full resource ID for the source topic using --source-resource-id.

2. Step 2: Evaluate options

   az eventgrid event-subscription create --name mySub --source-resource-id /subscriptions/.../resourceGroups/.../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 lacks full resource ID, C creates a topic not subscription, D uses wrong command.

3. Final Answer:

   az eventgrid event-subscription create --name mySub --source-resource-id /subscriptions/.../resourceGroups/.../providers/Microsoft.EventGrid/topics/myTopic -> Option D

4. Quick Check:

   Full resource ID needed for subscription creation [OK]

Hint: Use full resource ID with --source-resource-id for subscriptions [OK]

Common Mistakes:

• Using topic creation command instead of subscription
• Omitting full resource ID in source
• Using incorrect command names

3. Given this Azure CLI command output snippet for an Event Grid subscription:

{
  "destination": {
    "endpointType": "WebHook",
    "properties": {
      "endpointUrl": "https://myapp.com/api/events"
    }
  },
  "filter": {
    "subjectBeginsWith": "orders/",
    "subjectEndsWith": ".json"
  }
}

Which events will be delivered to the webhook endpoint?

medium

A. Only events with subjects exactly 'orders/.json'

B. All events regardless of subject

C. All events with subjects starting with 'orders/' and ending with '.json'

D. Events with subjects containing 'orders/' anywhere

Solution

1. Step 1: Understand subject filters in Event Grid

   The filter uses subjectBeginsWith and subjectEndsWith to select events whose subject starts with 'orders/' and ends with '.json'.

2. Step 2: Analyze options

   All events with subjects starting with 'orders/' and ending with '.json' matches the filter exactly. Only events with subjects exactly 'orders/.json' is too strict (exact match), C ignores filters, D is incorrect because 'contains' is not used.

3. Final Answer:

   All events with subjects starting with 'orders/' and ending with '.json' -> Option C

4. Quick Check:

   Subject filters = startsWith + endsWith [OK]

Hint: Filters combine start and end patterns, not exact or contains [OK]

Common Mistakes:

• Assuming exact subject match required
• Ignoring subject filters and expecting all events
• Confusing contains with beginsWith or endsWith

4. You created an Event Grid subscription but your webhook endpoint is not receiving events. Which of these is the most likely cause?

medium

A. The Event Grid topic does not exist

B. The webhook endpoint URL is incorrect or unreachable

C. You forgot to create an Azure Storage account

D. The subscription filter matches all events

Solution

1. Step 1: Check webhook endpoint accessibility

   If the webhook URL is wrong or the endpoint is down, events cannot be delivered.

2. Step 2: Evaluate other options

   Topic existence is important but usually checked at creation; storage account is unrelated; a filter matching all events would not block delivery.

3. Final Answer:

   The webhook endpoint URL is incorrect or unreachable -> Option B

4. Quick Check:

   Endpoint must be reachable for event delivery [OK]

Hint: Check webhook URL and network access first [OK]

Common Mistakes:

• Assuming storage account is needed for Event Grid
• Ignoring endpoint network issues
• Thinking filters block all events by default

5. You want to route events from multiple Azure Blob Storage accounts to a single Azure Function using Event Grid. What is the best approach to achieve this?

hard

A. Create an Event Grid subscription for each storage account, all pointing to the same Azure Function endpoint

B. Create one Event Grid subscription on one storage account and expect it to receive events from all accounts

C. Use Azure Logic Apps to poll each storage account and forward events to the function

D. Configure the Azure Function to listen directly to all storage accounts without Event Grid

Solution

1. Step 1: Understand Event Grid subscription scope

   Event Grid subscriptions are scoped to a single resource, so each storage account needs its own subscription.

2. Step 2: Evaluate options

   Create an Event Grid subscription for each storage account, all pointing to the same Azure Function endpoint correctly creates multiple subscriptions pointing to one function. Create one Event Grid subscription on one storage account and expect it to receive events from all accounts is invalid because one subscription cannot cover multiple accounts. Use Azure Logic Apps to poll each storage account and forward events to the function adds unnecessary polling. Configure the Azure Function to listen directly to all storage accounts without Event Grid is not supported as functions rely on Event Grid for event routing.

3. Final Answer:

   Create an Event Grid subscription for each storage account, all pointing to the same Azure Function endpoint -> Option A

4. Quick Check:

   One subscription per source resource [OK]

Hint: Each source needs its own subscription to route events [OK]

Common Mistakes:

• Assuming one subscription covers multiple sources
• Using polling instead of event-driven routing
• Expecting Azure Function to listen without Event Grid