Simple Message Queue (formerly MNS) topics use a publish/subscribe (pub/sub) messaging model. Publishers send messages to a topic, and subscribers receive those messages through subscriptions.
The following table summarizes all terms. See the sections below for details.
| Term | Description |
|---|---|
| Topic | The destination where published messages are sent and stored |
| Publisher | The client that sends messages to a topic |
| Subscriber | The client that receives messages from a topic |
| Subscription | The link between a subscriber and a topic |
| Message filtering tag | A tag that controls which messages a subscription delivers |
| Endpoint | The address where a subscriber receives messages |
| Account | The Alibaba Cloud account ID, used as part of the TopicURL |
| TopicURL | The endpoint of Simple Message Queue (formerly MNS) |
| Message ID | The identifier for a message within a topic |
Topic
A topic is the destination where published messages are sent and stored. Publishers send messages to a topic, and subscribers receive messages from the topic.
Publisher
A publisher is the client that sends messages to a topic.
Subscriber
A subscriber is the client that receives messages from a topic. By default, a topic owner is authorized to create subscriptions to the topic.
Subscription
A subscription links a subscriber to a topic. A subscriber client must create a subscription before it can receive messages published to a topic.
Message filtering tag
A message filtering tag controls which messages a subscription delivers. When a filtering tag is set on a subscription, only messages with a matching tag are pushed to the subscriber.
Endpoint
An endpoint is the address where a subscriber receives messages from a topic.
Account
The ID of an Alibaba Cloud account. The account ID is used as part of the TopicURL.
TopicURL
The endpoint of Simple Message Queue (formerly MNS) is in the following format:
http://$AccountId.mns.$Region.aliyuncs.com/topics/$TopicName| Variable | Description |
|---|---|
$AccountId | The ID of your Alibaba Cloud account |
$Region | The region where Simple Message Queue (formerly MNS) is deployed, such as China (Beijing), China (Hangzhou), and China (Qingdao) |
$TopicName | The name of the topic |
Message ID
A message ID identifies a message within a topic. Message IDs are unique within each topic but are not unique across topics.