Azure Event Grid is a fully-managed intelligent event routing service offered by Microsoft Azure that reacts to status changes in services and applications. It can be described as a service that routes events from any source to any destination. As you study for the AZ-204 exam, understanding the implementation of Event Grid to create reactive applications is essential.
Azure Event Grid – Basics
Event Grid connects data sources and event handlers. For example, when a virtual machine changes its state to running, starting, or stopping, an event is immediately created. Event Grid allows you to select how you want to react to those events.
The primary components involved are:
- Event Sources: can be any service that generates the data (like Azure Blob storage, Azure Event Hubs etc.)
- Topics: The endpoint where the source sends the events.
- Event Subscription: It defines the event handler that needs to react to the events.
- Event Handlers: The receiver of the event (like Azure Functions, Logic Apps or your custom HTTP endpoint).
Implementation of Azure Event Grid
Implementing Azure Event Grid begins with creating an Event Grid subscription on the Azure Portal.
Go to the Azure Portal and select “Create a resource”, then select “Event Grid Topic”. Enter the name, choose the subscription, resource group and location. Once created, the topic endpoint and a key are available on the portal.
To generate events, you can add the following sample event data to any HTTP service:
[
{
“id”: “1807”,
“eventType”: “recordInserted”,
“subject”: “/myapp/vehicles/motorcycles”,
“eventTime”: “2020-06-26T21:03:07+00:00”,
“data”: {
“make”: “Ducati”,
“model”: “Monster”
}
}
]
An HTTP POST request with this payload to the Event Grid topic endpoint creates an event.
Event Grid Subscription
After creating a topic, you’ll need to subscribe to it. Select “+ Event Subscription” on the topic’s main page. Fill in the related details and select the type of endpoint where the event data will be sent.
Azure Event Handlers
Using Azure Functions, Logic Apps, or Azure Automation makes handling sent events easier. Azure Functions, for example, can be coded in various languages (like C#, JavaScript, or Python) and scale automatically.
An Azure Function in C# for handling Event Grid events can look like this:
// EventGridEvent data type
using Microsoft.Azure.EventGrid.Models;
// Json.NET’s JObject type
using Newtonsoft.Json.Linq;
public static class EventGridTriggerCSharp
{
[FunctionName(“EventGridTriggerCSharp”)]
public static void Run([EventGridTrigger]EventGridEvent eventGridEvent, TraceWriter log)
{
log.Info(eventGridEvent.Data.ToString());
// Parse data from eventGridEvent
JObject dataObject = JObject.Parse(eventGridEvent.Data.ToString());
}
}
Implementing solutions with Azure Event Grid allows for faster, real-time processing of changes, and for the AZ-204 Developing Solutions for Microsoft Azure exam, understanding Event Grid implementations becomes a key factor.
Practice Test
True or False: Azure Event Grid is used for routing messages from any source to any destination.
- True
- False
Answer: True
Explanation: Azure Event Grid allows applications to talk to each other through event messages, from any source to any destination.
Which of the following is the main purpose of using Azure Event Grid?
- a) Data storage
- b) Managing network traffic
- c) Managing and routing events
- d) For deploying applications
Answer: c) Managing and routing events
Explanation: Azure Event Grid is a service in Azure that provides routing of events from various sources to various destinations.
True or False: You can not route Custom Events through Azure Event Grid.
- True
- False
Answer: False
Explanation: Azure Event Grid supports routing of both system and custom events.
What format does Azure Event Grid use to send events?
- a) .csv
- b) XML
- c) JSON
- d) TXT
Answer: c) JSON
Explanation: Azure Event Grid sends events in JSON format to provide a common standard that’s easy to consume and read.
True or False: By using Azure Event Grid, we can’t implement a reactive programming model.
- True
- False
Answer: False
Explanation: Event Grid efficiently supports implementing reactive programming model by responding to the events as they occur.
Which of the following are advantages of using Azure Event Grid? (Multiple Select)
- a) High throughput
- b) Flexibility
- c) Scalability
- d) All of the above
Answer: d) All of the above
Explanation: Azure Event Grid offers high throughput, flexibility, and automatically scales to meet required needs.
True or False: Azure Event Grid does not allow filtering events at the source.
- True
- False
Answer: False
Explanation: Event Grid allows both source side filtering as well as handling filtering at the event handler.
The Azure Event Grid supports what type of programming model?
- a) Imperative
- b) Procedural
- c) Event-driven
- d) Object-oriented
Answer: c) Event-driven
Explanation: Azure Event Grid is designed to support event-driven programming model.
Which trigger type to use with Azure functions to respond to Event Grid events?
- a) Timer trigger
- b) HTTP trigger
- c) Event Grid trigger
- d) none of these
Answer: c) Event Grid trigger
Explanation: Event Grid trigger is specifically designed to respond to Event Grid events in Azure Functions.
True or False: Azure Event Grid guarantees the order of the delivery of the events.
- True
- False
Answer: False
Explanation: Azure Event Grid does not guarantee the order of event delivery. It only guarantees the delivery of the events.
Azure Event Grid is designed to be a _________ service in Azure.
- a) managing
- b) storing
- c) routing
- d) executing
Answer: c) routing
Explanation: Azure Event Grid is a routing service that simplifies event-based applications.
Can Azure Event Grid be used as an event source for Azure Logic Apps?
- a) Yes
- b) No
Answer: a) Yes
Explanation: Azure Event Grid can be used as an event source for many services including Azure Logic Apps.
True or False: Azure Event Grid can push the events to non-Azure services.
- True
- False
Answer: True
Explanation: Azure Event Grid provides support to push events to custom HTTP endpoints, which can be anywhere, not just Azure.
What is the purpose of system topics in Event Grid?
- a) Define the schema for the event data
- b) Store the event data
- c) Send the event data
- d) None of these
Answer: a) Define the schema for the event data
Explanation: System topics are built-in topics provided by Azure services that allow defining the schema of the event data.
Azure Event Grid requires explicit polling to check for new events. True or False?
- True
- False
Answer: False
Explanation: Azure Event Grid uses a push model. It doesn’t require explicit polling to check for new events.
Interview Questions
What is Azure Event Grid?
Azure Event Grid is a service that manages routing of all events from any source to any destination. It’s designed for high availability, consistent performance, and dynamic scalability.
What does Azure Event Grid majorly focus on?
Azure Event Grid primarily focuses on event-based programming and is designed to help build applications that respond to events.
How does Azure Event Grid work?
Azure Event Grid allows you to focus on your application logic by automatically handling the routing of events from a source to a destination. It can use a serverless endpoint for event handling.
What are the various components of Azure Event Grid?
Azure Event Grid includes Events, Sources, Topics, Subscriptions and Event Handlers as its main components.
What is the purpose of an Event Source in Azure Event Grid?
An Event Source in Azure Event Grid is where the event is created. It can be Azure services such as Cosmos DB, Blob Storage, or a custom application or service.
How is event handling in Azure Event Grid different from Polling methodology?
Unlike the traditional Polling methodology where the application needs to keep checking for changes or updates, Azure Event Grid pushes new events to the subscriber as they occur. It simplifies the event communication process by eliminating the need to constantly poll for changes.
Name some common event sources in Azure Event Grid.
Some common event sources in Azure Event Grid include Azure subscriptions, Resource groups, Azure Media Services, Azure IoT Hub, Azure Event Hubs, and Custom topics.
What is a ‘Topic’ in Azure Event Grid?
A ‘Topic’ in Azure Event Grid is the endpoint where the source sends events. The publisher creates the event grid topic, and decides on the name for the topic.
What is a ‘Subscription’ in Azure Event Grid?
‘Subscription’ in Azure Event Grid defines the relationship between a Topic and an Event Handler. It tells Event Grid which events to send to which endpoint.
What are Filters in Azure Event Grid?
Filters in Azure Event Grid help direct specific events to different endpoints. You can filter events based on the data in the event, like sending specific blob storage events to a specific endpoint.
How do you secure an Azure Event Grid?
Azure Event Grid uses SAS (Shared Access Signature) token or keys for event delivery authentication. The SAS token or keys validate whether the event grid has the correct permissions to push events to the endpoint.
What are Event Handlers in Azure Event Grid?
Event Handlers are the receivers that handle the response after receiving the event from Event Grid. They take actions depending upon the type and nature of the event received.
How can Azure Functions be used with Azure Event Grid?
Azure Functions can be used as an Event Handler in Azure Event Grid to build serverless architectures reacting to incoming events.
What is the maximum event size in Azure Event Grid?
The maximum event size supported by Azure Event Grid is 1 MB.
Is it possible to use Azure Event Grid with non-Azure applications?
Yes, using custom topics and webhooks, Azure Event Grid can integrate with non-Azure applications and services.
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