Скачать или смотреть Can Multiple Subscriptions Share the Same EventType in Azure EventGrid?

Discover how Azure EventGrid handles subscriptions with the same EventType. Learn about the Fan-Out pattern and how it can enhance your event-driven architecture.
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Understanding Azure EventGrid Subscriptions and EventTypes

In today's guide, we're tackling an important aspect of Azure EventGrid, specifically around the topic of subscriptions and EventTypes. If you're working on a project using Azure EventGrid, you might wonder whether each subscription must have a unique EventType or if multiple subscriptions can share the same EventType. This question is fundamental for setting up effective event-driven architectures and ensuring that events are distributed as intended.

The Fan-Out Pattern in Azure EventGrid

To understand how multiple subscriptions can interact with the same EventType, we first need to look at the Fan-Out pattern employed by Azure EventGrid.

What is the Fan-Out Pattern?

The Fan-Out pattern is a design principle where a single event message is sent to multiple subscribers. When an event is published to a topic, all subscriptions linked to that topic can receive the same event message, based on their filtering criteria. This allows developers to create scalable systems that can efficiently handle messages from a small number of events to potentially thousands of subscribers.

Your Use Case: Multiple Subscriptions on Same EventType

From your example, you have two existing subscriptions:

SubscriptionName: CR_Account

EventType: CreateAccount

Endpoint: Endpoint1

SubscriptionName: UP_Account

EventType: UpdateAccount

Endpoint: Endpoint2

You are considering adding a third subscription:

SubscriptionName: CRNew_Account

EventType: UpdateAccount

Endpoint: Endpoint3

Key Takeaways:

Multiple subscriptions can share the same EventType: In your case, having both CR_Account and CRNew_Account subscribe to the same event (i.e., CreateAccount) is perfectly fine. When an event is published to the topic, both of these subscriptions will receive the event as expected.

Reliable Delivery: Azure EventGrid guarantees reliable delivery of events. This means that even if multiple subscribers are listening to the same events, Azure manages the distribution effectively, ensuring all endpoints get the messages they are subscribed to.

Implementation Example:

Creating Subscriptions: When setting up your subscriptions in EventGrid, you can define the EventType for each subscription. If multiple subscriptions need to respond to the same event type, just set them accordingly:

CR_Account listens for CreateAccount events

CRNew_Account can also listen for CreateAccount events if that’s a requirement.

Testing and Verification: Once you have your subscriptions set up, test them by publishing events to the topic and verifying that both endpoints respond as expected. This ensures that your architecture works as intended.

Conclusion

Azure EventGrid is designed to facilitate easy event handling and distribution through its unique subscription model. With the ability to have multiple subscriptions for the same EventType, developers can create more modular and flexible applications. The Fan-Out pattern not only simplifies event distribution but also scales efficiently, accommodating various subscriber needs.

By understanding the capabilities of Azure EventGrid, you can enhance your event-driven architecture and ensure a smooth flow of information within your applications. Happy coding!