A kingfisher-creek checkout service wants other municipal apps to react to an OrderPlaced event. Where should it publish that application event?
Select an answer to reveal the explanation.
Short Explanation
Your own app events belong on a custom (or namespace) topic. Keep the payload small and reactive—don’t shove OrderPlaced down an Event Hubs telemetry pipe by default.
Full Explanation
Application-defined discrete events such as OrderPlaced belong on an Event Grid custom topic (or a namespace topic in the pull/push namespace model). The kingfisher-creek checkout service publishes to that topic so other municipal apps subscribe and react without turning business events into a telemetry firehose.
Publishing into Event Hubs as a multi-megabyte telemetry firehose for every click fails the discrete-event model: Event Hubs is for high-throughput streams, not the default fabric for a single OrderPlaced reaction topic.
Publishing only into Blob append logs with no event fabric fails because append logs are durable storage, not push/pull event delivery to subscribers.
Publishing as a Graph mail tip so Outlook acts as the event bus fails: Microsoft Graph mail tips are not Event Grid custom topics and are not the municipal event fabric for OrderPlaced.
Exam caveat: choose system topics for Azure resource events and custom/namespace topics for your app’s own events—mixing them confuses ownership and schema. Operational check: create a custom topic, publish a sample OrderPlaced event, attach a Function or webhook subscription, and confirm only interested municipal apps receive it.