This topic lists the message types that are supported by Message Queue for Apache RocketMQ and precautions for using these message types.

Message types

Normal messages

Messages that do not have any special features are different from the following types of messages that have special features.

Scheduled messages and delayed messages

Message Queue for Apache RocketMQ allows producers to specify the length of time to wait before a scheduled or delayed message is delivered.

Ordered messages

Message Queue for Apache RocketMQ allows consumers to consume messages in the order in which messages are delivered.

Transactional messages

Message Queue for Apache RocketMQ provides a distributed transaction processing function that is similar to X/Open XA to ensure transaction consistency.

Precautions

When you use Message Queue for Apache RocketMQ SDK to send and subscribe to messages, note that a topic for one type of messages cannot be used to send and subscribe to another type of messages. For example, a topic for normal messages can only be used to send and subscribe to normal messages. Similarly, a topic for transactional messages can only be used to send and subscribe to transactional messages.