How does the background program of WeChat public platform interact with other public accounts to obtain data?

How does the background program of the public platform interact with other public accounts to obtain data? For example, send an inquiry message to the public account related to "Weather" and then obtain the returned weather data. How can we establish a connection with the public number related to the weather? How does the background program of the public platform interact with other public accounts to obtain data? For example, send an inquiry message to the public account related to "Weather" and then obtain the returned weather data. How can we establish a connection with the public number related to the weather?

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How does the background program of the public platform interact with other public accounts to obtain data? For example, send an inquiry message to the public account related to "Weather" and then obtain the returned weather data. How can we establish a connection with the public number related to the weather?

Method 1: simulate a protocol to send messages to other public accounts and obtain the returned information. This is what many marketing software do.

Method 2: Obtain the secretkey of other public accounts in some way, and simulate requests from the server. This is not actually a method.