If you need to achieve the features as shown below in a smart home scenario (this is not a real product but only used to demonstrate IoT Hub's capabilities), you can follow the steps in this document.
Two types of smart devices (door and air conditioner) can be created in the IoT Hub SDK and connected with each other based on cross-device messaging and the rule engine as shown below:
airConditioner1cannot achieve message communication by directly subscribing to the update messages of
door1. For the reason, please see Feature Components - Permission Management.