# Mappings Between SMN Operations and APIs

Table 1 Mappings between SMN operations and APIs
Operation | API | Function
--- | --- | ---
SMN:UpdateTopic | UpdateTopic | Modify the topic. Currently, only the display_name field value can be changed.
SMN:DeleteTopic | DeleteTopic | Delete a topic and its subscribers. If a topic is deleted, any pending messages may fail to send to the topic subscribers.
SMN:QueryTopicDetail | QueryTopicDetail | Query details about a topic.
SMN:ListTopicAttributes | ListTopicAttributes | Query the list of topic attributes.
SMN:UpdateTopicAttribute | UpdateTopicAttribute | Modify topic attributes.
SMN:DeleteTopicAttributes | DeleteTopicAttributes | Delete all topic attributes.
SMN:DeleteTopicAttributeByName | DeleteTopicAttributeByName | Delete a specified topic attribute.
SMN:ListSubscriptionsByTopic | ListSubscriptionsByTopic | Query the subscription list of a specified topic by page. The list is sorted by time when the subscriptions are added in ascending order. You can specify values of offset and limit. If no subscription has been added, an empty list is returned.
SMN:Subscribe | Subscribe | Add a subscription to a specified topic and send a confirmation message to the subscriber. After confirming the subscription, the subscriber can receive notification messages published to the topic.
SMN:Unsubscribe | Unsubscribe | Delete a subscription. This operation requires identity authentication. Only the subscriber or the topic owner can delete a subscription.
SMN:Publish | Publish | Publish messages to a topic. After a message ID is returned, the message has been saved and is to be delivered to subscribers of the topic. The message form varies depending on the protocol of each subscription.

Parent topic: Appendix