The IoT Hub platform provides a broadcast communication topic. The server can publish a broadcast message by calling the broadcast communication API, which can be received by online devices that have subscribed to the broadcast topic under the same product.
Broadcast Topic
The broadcast communication topic is `$broadcast/rxd/${ProductId}/${DeviceName}`, where ${ProductId} and ${DeviceName}` represent the specific product ID and device name.
Broadcast Communication Sample
The sample completes device connection through the device-side C-SDK on Linux and calls APIs together with Tencent Cloud API Explorer. The specific steps are as follows:
Creating device in console
Scenario description
If you have multiple air conditioner devices connected to the IoT Hub platform, then the server can send the same instruction to all of them for turning off.
The server calls the PublishBroadcastMessage API and specifies the ProductId and the Payload of the broadcast message. Then, all online devices that have subscribed to the broadcast topic under the product will receive the broadcast message with the Payload.
Creating product and device
Create an air conditioner product and airConditioner1, airConditioner2, and other devices as instructed in Device Interconnection.
Compiling and running demo (with key-authenticated device as example)
1. Compile the SDK
Modify CMakeLists.txt to ensure that the following options exist:
set(BUILD_TYPE "release")
set(COMPILE_TOOLS "gcc")
set(PLATFORM "linux")
set(FEATURE_MQTT_COMM_ENABLED ON)
set(FEATURE_BROADCAST_ENABLED ON)
set(FEATURE_AUTH_MODE "KEY")
set(FEATURE_AUTH_WITH_NOTLS OFF)
set(FEATURE_DEBUG_DEV_INFO_USED OFF)
Run the following script for compilation:
./cmake_build.sh
The demo output broadcast_sample is in the output/release/bin folder.
2. Enter the device information
Enter the information of the airConditioner1 device created above in a JSON file aircond_device_info1.json:
{
"auth_mode":"KEY",
"productId":"KL4J2****8",
"deviceName":"airConditioner1",
"key_deviceinfo":{
"deviceSecret":"zOZXUaycuwlePt****8dBA=="
}
}
Enter the information of the airConditioner2 device in another JSON file aircond_device_info2.json:
{
"auth_mode":"KEY",
"productId":"KL4J2****8",
"deviceName":"airConditioner2",
"key_deviceinfo":{
"deviceSecret":"+IiVNsyKRh0AW****IE07A=="
}
}
Enter the information of other devices in corresponding JSON files in turn.
3. Run the broadcast_sample demo
As this scenario involves multiple demos running simultaneously, you can open multiple terminals to run the broadcast_sample demo, and you will see that all the demos subscribe to the $broadcast/rxd/${productID}/${deviceName} topic and are in the waiting status.
The output of the airConditioner1 device is as follows:
