This topic describes terms that are related to Message Service (MNS) topics. You can familiarize yourself with related terms and use MNS topics based on your needs.

The destination address where published messages are sent and stored. Publisher clients send messages to topics and subscriber clients receive messages from the topics.
The Alibaba Cloud account that is identified by the account ID.
The client that sends messages to a topic.
The client that receives messages from a topic. By default, a topic owner is authorized to create subscriptions to the topic.
A subscription must be created if a subscriber client want to receive messages that are published to a topic.
The address that a subscriber client uses to receive messages from a topic, such as an HTTP endpoint, email address, and mobile number.
topic URL
The syntax of a topic URL: http://$AccountId.mns. $$TopicName
  • $AccountId specifies your Alibaba Cloud account ID.
  • $Region specifies the region where MNS is deployed, such as China (Beijing), China (Hangzhou), and China (Qingdao).
  • $TopicName specifies the name of a topic.
message ID
A message ID is used to identify a message in a topic. Each message in a topic has a unique message ID and messages in different topics may have the same message ID. After a message is published to a topic, the maximum retention period of the message in the topic is one day. After the retention period ends, the message expires and is collected by the garbage collector.