In ApsaraMQ for RocketMQ, a topic is a first-level identifier that is used to classify messages. ApsaraMQ for RocketMQ supports the publish-subscribe (pub/sub) model. In this model, message publication and subscription are implemented based on topics. Producers send messages to topics and consumers subscribe to topics to consume messages. This topic describes how to create and delete a topic in the ApsaraMQ for RocketMQ console. This topic also describes how to update the information about a topic and view the details of a topic in the console.
Usage notes
A topic cannot be used across instances. For example, Topic A created on Instance A cannot be used on Instance B.
The message type of a topic must be consistent with the type of messages that the topic sends and receives. For example, if you create a topic to send and receive normal messages, you must specify normal messages as the message type of the topic when you create the topic. Otherwise, O&M issues, such as the loss of scheduled messages during endpoint change or instance migration, may occur.
Billing rules
The billing rules of topics vary based on the billing methods of the ApsaraMQ for RocketMQ instances to which the topics belong.
Subscription and pay-as-you-go instances
You are charged only for topics that exceed the free topic quota. For more information, see Topic fees.
Serverless instances
You are charged based on the number of topics that you created. For more information, see Topic fees.
Create a topic
Log on to the ApsaraMQ for RocketMQ console. In the left-side navigation pane, click Instances.
In the top navigation bar, select a region, such as China (Hangzhou). On the Instances page, click the name of the instance that you want to manage.
In the left-side navigation pane, click Topics.
On the Topics page, click Create Topic.
In the Create Topic panel, configure the Name, Description, and Message Type parameters and click OK.
View the list of topics
Log on to the ApsaraMQ for RocketMQ console. In the left-side navigation pane, click Instances.
In the top navigation bar, select a region, such as China (Hangzhou). On the Instances page, click the name of the instance that you want to manage.
In the left-side navigation pane, click Topics.
On the Topics page, view all topics that are created on the instance.
View the details of a topic
On the Topics page, find the topic that you want to manage and click Details in the Actions column.
On the Topic Details page, view the details of the topic.
Modify the information about a topic
On the Topics page, find the topic that you want to manage and click Details in the Actions column.
On the Topic Details page, click the Basic Information tab. In the upper-right corner of the Basic Information section of the tab, click Edit.
In the Modify Topic panel, modify the information about the topic based on your business requirements and click OK.
Delete a topic
After you delete a topic, producers cannot send messages to the topic and consumers cannot consume messages from the topic. The metadata and messages in the topic are also deleted and cannot be restored. Exercise caution when you delete a topic.
You can create a topic with the same name 5 minutes after you delete a topic.
On the Topics page, find the topic that you want to manage and click Details in the Actions column.
On the Topic Details page, click the Basic Information tab. In the upper-right corner of the Basic Information section of the tab, click Delete Topic.
In the Note message, click OK.
Quickly send and receive messages
ApsaraMQ for RocketMQ allows you to quickly send and receive normal messages in the console. You can use SDKs to send other types of messages. For more information, see Overview.
On the Topics page, find a topic whose Message Type parameter is set to Normal Message an click Details in the Actions column.
In the upper-right corner of the Basic Information section of the Topic Details page, click Quick Start.
In the Start Message Production and Consumption panel, perform operations based on the setting of the Sending Method parameter.
Console
Configure the Body, Message Key and Message Tag parameters and click OK.
SDK
View the sample code for sending and receiving messages based on the SDK that you use. Then, send and receive messages based on the description in the documentation.
View the dashboard of a topic
The dashboard displays metrics that are related to message production and producer clients of a specific topic. For more information, see Dashboard.
On the Topics page, find the topic that you want to manage and click Details in the Actions column.
On the Topic Details page, click the Dashboard tab.
More operations
You can also export and import topic data. For more information, see Export and import topic data.
References
You can also call the following API operations to manage topics: