Box 1: Azure Event Grid -
Blob storage events are pushed using Azure Event Grid to subscribers such as Azure Functions, Azure Logic Apps, or even to your own http listener. Event Grid provides reliable event delivery to your applications through rich retry policies and dead-lettering.
Box 2: Azure Logic App -
Event Grid uses event subscriptions to route event messages to subscribers. This image illustrates the relationship between event publishers, event subscriptions, and event handlers.
Box 3: Azure Service Bus -
The Event Grid service doesn't store events. Instead, events are stored in the Event Handlers, including ServiceBus, EventHubs, Storage Queue, WebHook endpoint, or many other supported Azure Services.
Reference:
https://docs.microsoft.com/en-us/azure/storage/blobs/storage-blob-event-overview
https://docs.microsoft.com/en-us/java/api/overview/azure/messaging-eventgrid-readme
