Event Grid for event-driven architecture in Azure - Step-by-Step Execution

Process Flow - Event Grid for event-driven architecture

Event Source emits event

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Event Grid receives event

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Event Grid filters and routes event

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Event Handler receives event

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Event Handler processes event

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Optional: Event Handler sends response or triggers next event

Events are sent from a source to Event Grid, which routes them to subscribed handlers for processing.

Execution Sample

Azure

1. Event Source sends event
2. Event Grid receives and routes
3. Event Handler processes event

This flow shows how an event moves from source through Event Grid to a handler.

Process Table

Step	Action	Event State	Routing Decision	Handler Response
1	Event Source emits event	Event created	Not yet routed	No response
2	Event Grid receives event	Event received	Evaluates filters	No response
3	Event Grid routes event	Event routed to handler	Matches subscription	No response
4	Event Handler receives event	Event in handler	Processing started	No response yet
5	Event Handler processes event	Event processed	Handled successfully	Response or trigger sent
6	End	No new events	No routing	Process complete

💡 Event processed and handled; no further routing needed.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 5	Final
Event State	Created	Received	Routed	Processed	Handled
Routing Decision	None	Evaluating	Matched	Handled	Complete
Handler Response	None	None	None	Sent	Complete

Key Moments - 3 Insights

Why does Event Grid evaluate filters before routing?

Event Grid uses filters to decide which handlers should receive the event, as shown in step 2 and 3 of the execution_table.

What happens if no subscription matches the event?

If no subscription matches, Event Grid does not route the event to any handler, so processing stops after step 2 or 3.

Does the event handler send a response back to Event Grid?

Typically, the handler processes the event and may trigger other actions, but Event Grid does not require a response; see step 5.

Visual Quiz - 3 Questions

Look at the execution_table, what is the event state after Event Grid routes the event?

A Created

B Routed

C Received

D Processed

💡 Hint

Check the 'Event State' column at step 3 in the execution_table.

At which step does the event handler start processing the event?

A Step 4

B Step 3

C Step 2

D Step 5

💡 Hint

Look at the 'Action' column in the execution_table where processing starts.

If no subscription matches the event, what would change in the execution_table?

A Event handler processes event anyway

B Event would be routed to a default handler

C Routing Decision would be 'No match' and no handler response

D Event Grid retries routing

💡 Hint

Refer to the 'Routing Decision' and 'Handler Response' columns in steps 2 and 3.

Concept Snapshot

Event Grid routes events from sources to handlers.
It filters events based on subscriptions.
Handlers process events asynchronously.
No response is required back to Event Grid.
This enables scalable event-driven apps.

Full Transcript

Event Grid acts as a central hub for events. An event source sends an event to Event Grid. Event Grid receives the event and checks filters to decide which handlers should get it. If a subscription matches, Event Grid routes the event to the handler. The handler processes the event and may trigger further actions. This flow allows building scalable, loosely coupled applications where components communicate via events.