Event Grid Topic Vs Event Grid System Topic

Question

1. What's the difference between Event Grid Topic and Event Grid System Topic.

When I select resource type "Event Grid Custom Topic" then Event Grid Topic type is getting created.

but when I use Service Bus Premium->Event Registration . The Event Grid System Topic type is getting created.

Question is which one is more efficient and which one to use. As I am using endpoint type webhook and calling my logic app event whenever the message is posted to my service bus queue/topics.

Whereas in EventGrid Custom Topic I have to use the Event Grid Trigger in my logic app and the event custom topic automatically gets created.

Please tell me the difference between these two and when to use which and which is more efficient

Palaeogene

Answer 1

System Topics are used by Azure Services like Azure Storage, etc. Previously they were implicit but have recently been exposed as Azure Resources.

From a performance aspect, there should be no difference between the topic types. Both types support the same type of event handlers as well.

One major difference is that there is no endpoint or access keys for system topics to publish events like for custom topics.

Horsefly

I'm trying to setup DeadLettering for a System Topic. Following the instructions here. Results are ERROR: The Resource 'Microsoft.EventGrid/topics/system-topic-test-dev' under resource group 'TEST_DEV' was not found.. Is DeadLettering possible with System Topics? – Darrel

Answer 2

It seems that Event Grid Topic provides more features in Settings and Monitoring.

Only Azure services can publish events to system topics. Therefore, you don't get an endpoint or access keys that you can use to publish events like you do for custom topics or event domains.

Event Grid Topic Event Grid System Topic

Holmann

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