Box 1: Azure Blob Storage -
Azure event publishers and event handlers are at the core of the Event Grid routing-service. Event Grid listens to Azure event publishers, such as Blog Storage, then reacts by routing specific events to Azure event handlers, such as WebHooks. You can easily control this entire process at a granular level through event subscriptions and event filters.
Box 2: Azure Event Grid -
Azure Event Grid is a highly scalable event-routing service that listens for specific system events, then reacts to them according to your precise specifications. In the past, event handling has relied largely on polling - a high latency, low-efficiency approach that can prove prohibitively expensive at scale.
Box 3: Azure Logic App -
Event Grid's supported event handlers currently include Event Hubs, WebHooks, Logic Apps, Azure Functions, Azure Automation and Microsoft Flow.
Reference:
https://www.appliedi.net/blog/using-azure-event-grid-for-highly-scalable-event-routing
