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Overview
Message Queue MQTT Edition (TDMQ for MQTT, abbreviated as TDMQ MQTT Edition) is a distributed and highly available message queue service. It adopts the "publish/subscribe" mode to establish an extremely lightweight message transfer protocol. TDMQ MQTT Edition is fully compatible with the standard MQTT protocol, supports zero-modification client access for open-source communities and mainstream MQTT clients, and enhances features such as stability, low delay, and high performance, supporting millions of clients online simultaneously.
This section introduces the MQTT API interfaces, which are all API 3.0 interfaces. You can call APIs to operate MQTT, such as creating a cluster or granting authorization.
For all supported API information of Message Queue MQTT, please refer to the API overview.

Glossary

Common terminology for Message Queue MQTT API interface, see the table below.

Terminology Description
|---------|---------|
MQTT is an industry standard protocol in the IoT and mobile Internet field, suitable for data transmission between mobile devices.
MQTT server, which implements the MQTT protocol, is responsible for maintaining persistent connections with MQTT Clients and routing messages to corresponding clients or forwarding messages to other MQTT server nodes, while also handling offline message storage.
MQTT Client: A device or application that uses the MQTT protocol to connect to the MQTT server.
A Topic is used to identify the classification and structure of messages. Publishers send messages to specific topics, and subscribers receive related messages by subscribing to specific topics.

For other relevant terminology, please see basic concept.

Usage limits
For usage limits of Message Queue MQTT, please refer to Quotas and Limits.
For parameter limits, refer to the parameter descriptions in the API documentation.

Getting Started with APIs

You can use the API Explorer tool to call APIs online.
This document uses Message Queue MQTT as an example. The steps to make an API call via the API Explorer Tool are as follows:

1. Go to the API Explorer tool page. For more information about API Explorer tool usage, see Using API Explorer.
   Call CreateMQTTInstance to create an MQTT cluster.
2. Call CreateMQTTUser to create a user.
3. Call CreateAuthorizationPolicy to grant the user permission to connect to the cluster and produce/consume messages.
4. Use client to send/receive messages (This operation cannot be completed through API interface).
5. Call DescribeMessageByTopic to query messages.