MQTT IoT Suite Product Introduction
Profile Architecture Advantages Definitions
QuickStart
Account and Login
Products and Devices
Create Product Create Device
Device Connection
User Guide
Data Stream and Data Point Protocol Adaptation Service
Service Introduction Operation Process Development Guide Examples
Device Image
Service Introduction Console Usage
Rule Engine
Service Introduction Rule Configuration Basic Data Format SQL Built-in Function
Security Authentication
Overview Token Algorithm Token Generator Algorithm Examples
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Application Management
Service Introduction Controls Introduction Operating Instructions
Device Development Guide
Protocol Specifications Development Guide Development Examples Topic Cluster
Overview Data Point Topic Cluster Device Command Topic Cluster Device Image Topic Cluster
Application Development Guide
Use of API Error Code API
Query Device Register Device Remove Device Update Device Key Device Command Query Device Image Update Device Image Query Device Data Points
Best Practices
Device Connection Upload Data Points Device Synchronization Command Device Image
Change Log

MQTT Protocol Specifications

Protocol Version

The platform supports Standard MQTT Version 3.1.1. Please refer to the Protocol Specifications for details.

Protocol Implementation

Supported Messages

  • connect, subscribe, publish, ping, unsubscribe and disconnect messages are supported.

  • pubrec, pubrel and pubcomp messages are not supported.

Supported Features

The platform supports the following protocol features:

Feature Supported or Not Description
will Not Supported will and will retain flags must be set to 0, and will qos must be set to 0.
session Not Supported cleansession flag must be set to 1.
retain Not Supported The related flag must be set to 0.
QoS0 Supported System topic messages received by device after successful subscription are all at QoS0. All messages published by device to system topic support QoS0
QoS1 Supported All messages published by device to system topic support QoS1
QoS2 Not Supported

Topic Convention

Topics are conventionalized as follows:

  • The platform does not support user-defined topic and uses only system topic.

  • All system topics start with $.

  • Users can use system topics concerned to access storage, command and other services in the access suite. For details, please refer to topic clusters
  • When using a system topic, the device can only subscribe and publish messages to its own topic, but cannot subscribe or publish across devices/products.

  • Illegal use of topic

    When a device subscribes to an illegal topic, the platform returns “Subscription Failed” by MQTT publish ack.

    When a device publishes a message to an illegal topic, the platform will disconnect the device.

  • Wildcards: The platform supports wildcards + and #.

    Note: The wildcards supported when using a system topic start only from the topic’s fourth level directory.

    • Subscriptions such as $sys/{pid}/{device-name}/#, $sys/{pid}/{device-name}/cmd/#, $sys/{pid}/{device-name}/cmd/request/+ are supported.

    • Subscriptions such as $sys/{pid}/#, $sys/#, # are not supported.

    A device can subscribe to a message as follows:

Topic-based Subscribe Effect
$sys/{pid}/{device-name}/dp/post/json/accepted Subscribe to the message that device data points are reported successfully
$sys/{pid}/{device-name}/dp/post/json/rejected Subscribe to the message that reporting device data points failed
$sys/{pid}/{device-name}/dp/post/json/+ Subscribe to device data point reports
$sys/{pid}/{device-name}/dp/post/json/accepted/+ Subscribe to all command messages of the device
$sys/{pid}/{device-name}/dp/post/json/rejected/+/+ Subscribe to all command responses of the device
$sys/{pid}/{device-name}/cmd/＃ Subscribe to all command-related messages of the device
$sys/{pid}/{device-name}/# Subscribe to all relevant messages of the device

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