Creating a RocketMQ Topic

• Topics cannot be used across instances. For example, topic A of instance A cannot be used in instance B.
• The topic type and message type (see Table 2) must be consistent when a client uses gRPC to send and receive messages in v5.x. For example, to create a topic for sending and receiving normal messages, the message type of this topic must be normal. Otherwise, node failover or scheduled message loss during instance migration may occur.

A RocketMQ instance has been purchased.

1. Log in to the console.
2. Click in the upper left corner to select a region.

   DMS instances in different regions cannot communicate with each other over an intranet. Select a nearest location for low latency and fast access.

3. Click and choose Application > Distributed Message Service for RocketMQ to open the DMS for RocketMQ page.
4. Click a RocketMQ instance name to go to the instance overview page.
5. In the navigation pane, choose Instance > Topics.
6. Click Create Topic.
7. Configure the topic name and other parameters by referring to Table 1 or Table 2.

   Figure 1 Creating a topic (RocketMQ 4.8.0)

   
   

   Figure 2 Creating a topic (RocketMQ 5.x)

   
   
   Table 1 Topic parameters (RocketMQ 4.8.0)

   Parameter	Description
   Topic Name	Name of the topic. A topic name must meet the following requirements: Contains 3 to 64 characters. Contains only letters, digits, percent signs (%), vertical bars (|), hyphens (-), and underscores (_). A percent (%) or vertical bar (|) contained in a topic name will be converted to an underscore (_) by Cloud Eye. For example, if a topic name is test%01, it will be displayed as test_01 on Cloud Eye. Cannot start with rmq_sys_. Cannot be the same as the following strings: TBW102 SCHEDULE_TOPIC_XXXX BenchmarkTest RMQ_SYS_TRANS_HALF_TOPIC RMQ_SYS_TRACE_TOPIC RMQ_SYS_TRANS_OP_HALF_TOPIC TRANS_CHECK_MAX_TIME_TOPIC SELF_TEST_TOPIC OFFSET_MOVED_EVENT The topic name must be unique. Otherwise, the topic cannot be created. Once the topic is created, you cannot modify its name.
   Permission	Permissions for the topic. Options: Publish/Subscribe: Producers can send messages to this topic. Consumers can consume them from this topic. Publish: Producers can send messages to the topic, but consumers cannot consume them from this topic. Subscribe: Producers cannot send messages to this topic, but consumers can consume messages from this topic. Default: Publish/Subscribe
   Brokers	Specify the broker to create the topic on, and the number of queues in the topic. If the instance is deployed on multiple brokers, click Add to add more brokers and set the number of queues in the topic. To add associated brokers, increase the broker quantity. For details, see Modifying RocketMQ Specifications. Increasing the broker quantity increases the maximum topics supported. For example, increasing the broker quantity from 1 to 2 increases the maximum topics from 4,000 of one broker to 8,000 of two brokers.
   Description	Topic description. The value contains 0 to 200 characters.

   Table 2 Topic parameters (RocketMQ 5.x)

   Parameter	Description
   Topic Name	Name of the topic. A topic name must meet the following requirements: Contains 3 to 64 characters. Contains only letters, digits, percent signs (%), vertical bars (|), hyphens (-), and underscores (_). A percent (%) or vertical bar (|) contained in a topic name will be converted to an underscore (_) by Cloud Eye. For example, if a topic name is test%01, it will be displayed as test_01 on Cloud Eye. Cannot start with rmq_sys_. Cannot be the same as the following strings: TBW102 SCHEDULE_TOPIC_XXXX BenchmarkTest RMQ_SYS_TRANS_HALF_TOPIC RMQ_SYS_TRACE_TOPIC RMQ_SYS_TRANS_OP_HALF_TOPIC TRANS_CHECK_MAX_TIME_TOPIC SELF_TEST_TOPIC OFFSET_MOVED_EVENT The topic name must be unique. Otherwise, the topic cannot be created. Once the topic is created, you cannot modify its name.
   Message Type	Select the message type. Options: Normal: Messages that do not have any features of scheduled messages, ordered messages, or transactional messages. Scheduled: Messages that are delivered to consumers only after a specific period after being sent from producers to DMS for RocketMQ. Ordered: Messages that are consumed in the exact order that they are produced. Transactional: Messages that achieve eventual consistency, delivering distributed transaction processing similar to X/Open XA. Default: Normal
   Description	Topic description. The value contains 0 to 200 characters.

8. Click OK.