This topic describes the announcement for the Message Queue for MQTT upgrade from V2.x.x to V3.x.x, and the changes in using the service after this upgrade.
Announcement
Message Queue for MQTT was upgraded from V2.x.x to V3.x.x starting from July 23, 2020. This upgrade does not affect client messaging functions. However, if you have special requirements on the timing and window of the upgrade, submit a ticket for help.
Overview
The service procedure of Message Queue for MQTT will change after its upgrade from V2.x.x to V3.x.x. The following figure shows the change details.

Description
Compared with V2.x.x, V3.x.x. versions of Message Queue for MQTT implement independent message storage without needing to be bound to Message Queue for Apache RocketMQ. Therefore, you can create a resource immediately after you purchase and create a Message Queue for MQTT instance. This reduces your costs for using and familiarizing yourself with the service.
Apart from independent storage, V3.x.x versions abstract the data exchanging feature between Message Queue for MQTT and Message Queue for Apache RocketMQ implemented by V2.x.x. versions. Therefore, you can configure rules to forward the data of Message Queue for MQTT to other Alibaba Cloud services, and import data from other Alibaba Cloud services into Message Queue for MQTT. Message Queue for Apache RocketMQ is supported for such rule-based data exchanges.
- Changes in using resources
Resource usage is highly related to billing. After the upgrade, Message Queue for MQTT topics of V3.x.x do not incur fees, but the rest billing items remain unchanged. This change saves your cost for the original Message Queue for Apache RocketMQ topics. For more information about the billing methods, see Billing.
- Changes in the message publish-subscribe process
If your service involves interactions between Message Queue for MQTT and Message Queue for Apache RocketMQ clients, see Changes in the message publish-subscribe process to configure your rules promptly.
- Changes in using the OpenAPIs
You must transform your code by following the migration guidelines in Changes in using the OpenAPIs.