Overview
The figure below shows the subscription and push process.

Push mechanism: The platform pushes QoS 0 messages to users. If a user does not establish a connection or does not subscribe to the topic after the connection is established, the platform stores only the data that is generated within 24 hours and occupies less than 1 GB disk space. If the user does not obtain data within 24 hours, the platform deletes all stacked data.
Data Subscription
- You can create a rule and add an MQTT message queue as the forwarding target on the console to subscribe to data. For details, see MQTT Server Configuration.
- Call APIs to subscribe to data. For details, see Calling APIs, Creating a Rule Triggering Condition, Creating a Rule Action, and Modifying a Rule Triggering Condition.
Format of Pushed Data
For details on the format of data pushed by the platform to applications after data subscription is created, see Data Transfer APIs.
Constraints
| Description | Constraint |
|---|---|
| Supported MQTT version | 3.1.1 |
| Differences from the standard MQTT protocol |
|
| Security level supported by MQTTS | The system establishes a secure channel using the TLS protocol (v1.2, v1.3) built upon a TCP foundation. GMTLS is supported by the enterprise edition using Chinese cryptographic algorithms. Supported cipher suites:
Cipher suites supported by enterprise edition using Chinese cryptographic algorithms:
|
| MQTT connection requests for an account per second | 10 |
| MQTT connections for an account | 10 per access credential |
| Push rate of an MQTT connection | 1,000 TPS |
| Message cache duration and size | The cache is limited by a maximum duration of 1 day or a maximum volume of 1 GB, whichever limit is reached first. For example, if the cache duration exceeds one day, data will not be cached even if the size does not reach 1 GB. |
| Recommended heartbeat interval for MQTT connections | Range: 30s to 1200s; recommended: 120s |
| Message publishing and subscription |
|
| Subscriptions per subscription request | Maximum number of topics supported by an account |
| Topics subscribed to by an account (created during rule action creation) | 100 |
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