Uniform Resource Names (URNs) are used to identify SMN resources.
After a topic is created, SMN generates a topic URN composed of the service name, region name, project ID, and topic name to uniquely identify the topic, for example, urn:smn:region:cffe4fc4c9a54219b60dbaf7b586e132:Mytopic. When you call an API to create a topic, a topic URN will be returned. The URN will also be used whenever a publisher or subscriber performs operations to a topic.
After a user subscribes to a topic, SMN will generate a URN for the subscription composed of the service name, region name, project ID, and topic name, for example, urn:smn:region:cffe4fc4c9a54219b60dbaf7b586e132:Mytopic:5293b436967f450abc51e0c36347b27a. A URN is displayed on the page for subscribers to confirm and cancel a subscription.