Azure Event Grid

Azure Event Grid is a fully managed, serverless event routing service. It connects event sources to event handlers using a publish-subscribe model with per-event pricing, sub-second delivery, and built-in retry logic. Event Grid is the backbone of reactive, event-driven architectures on Azure, enabling services to respond automatically when something happens.

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Core Concepts

Understanding Event Grid requires familiarity with five key concepts:

1. Events

An event is the smallest unit of information — a notification that something happened. Every event contains:

Field	Description
id	Unique identifier for the event
source	Where the event originated (e.g., a storage account)
type	The kind of event (e.g., Microsoft.Storage.BlobCreated)
subject	Additional context (e.g., the blob path)
data	Event-specific payload
eventTime	When the event occurred
dataVersion	Schema version of the data

Events are typically small — Event Grid enforces a maximum event size of 1 MB (64 KB per event in most scenarios).

2. Event Sources (Publishers)

An event source is the system where the event originates. Azure has built-in sources: