Auto-subscribed topics
Devices use MQTT to connect to Alibaba Cloud IoT Platform. To receive messages from the platform, a device must subscribe to topics. The Link SDK for C versions 3.1, 3.2, and 4.x supports automatic topic subscription. This topic lists the auto-subscribed topics.
Background information
In IoT Platform, servers and devices communicate using topics. A device must subscribe to topics to use platform features. The subscription process can be slow. To accelerate device startup, IoT Platform provides an automatic subscription service. This service allows the platform to send messages to a device without requiring a subscription request from the device.
- After a device that uses Link SDK for C 3.1, 3.2, or 4.x connects to IoT Platform, the system can send mobile terminated messages using the auto-subscribed topics.
The device can also subscribe to additional topics using the aiot_mqtt_sub interface. For more information, see Topic subscription example.
If a device is deleted, or if a device unsubscribes using the aiot_mqtt_unsub interface, IoT Platform no longer automatically sends messages to the device.
- When a device is brought online using the IoT Platform device emulator, IoT Platform automatically subscribes the device to the basic communication topics and Thing Specification Language model communication topics for which the device has permission. You can also use the Debug uplink instructions feature to subscribe to a Custom topic. For more information, see Device emulator.
- If a device is brought online using the MQTT.fx tool to connect to IoT Platform, device topics are not automatically subscribed. You can use the Subscribe feature to subscribe to device topics. For more information, see Connect to IoT Platform using MQTT.fx.
Topic list
| Feature | Topic |
| Thing Model Communication | /sys/${productKey}/${deviceName}/thing/model/down_raw |
| /sys/${productKey}/${deviceName}/thing/model/up_raw_reply | |
| /sys/${productKey}/${deviceName}/thing/event/+/post_reply | |
| /sys/${productKey}/${deviceName}/thing/deviceinfo/update_reply | |
| /sys/${productKey}/${deviceName}/thing/deviceinfo/delete_reply | |
| /sys/${productKey}/${deviceName}/thing/dynamicTsl/get_reply | |
| /sys/${productKey}/${deviceName}/rrpc/request/+ | |
| /sys/${productKey}/${deviceName}/thing/service/property/set | |
| /sys/${productKey}/${deviceName}/thing/event/property/history/post_reply | |
| /sys/${productKey}/${deviceName}/thing/service/+ | |
| Sub-device management | /sys/${productKey}/${deviceName}/thing/topo/change |
| /sys/${productKey}/${deviceName}/thing/sub/register_reply | |
| /sys/${productKey}/${deviceName}/thing/sub/unregister_reply | |
| /sys/${productKey}/${deviceName}/thing/topo/add_reply | |
| /sys/${productKey}/${deviceName}/thing/topo/delete_reply | |
| /sys/${productKey}/${deviceName}/thing/disable_reply | |
| /sys/${productKey}/${deviceName}/thing/topo/get_reply | |
| Firmware upgrade | /ota/device/upgrade/${productKey}/${deviceName} |
| Remote Configuration | /sys/${productKey}/${deviceName}/thing/config/push |
| /sys/${productKey}/${deviceName}/thing/config/get_reply | |
| Device shadow | /sys/${productKey}/${deviceName}/thing/property/desired/get_reply |
| /sys/${productKey}/${deviceName}/thing/property/desired/delete_reply | |
| /shadow/get/${productKey}/${deviceName} | |
| Product-level secret for sub-devices | /sys/${productKey}/${deviceName}/thing/proxy/provisioning/product_register_reply |
| Task management | /sys/${productKey}/${deviceName}/thing/job/notify |
| /sys/${productKey}/${deviceName}/thing/job/get_reply | |
| /sys/${productKey}/${deviceName}/thing/job/update_reply |