How to implement data exchange between mini-programs?

[spyx1]

Hello. I can’t find in the documentation how to implement data exchange (json) between mini-programs. localstorage and files (/assets, /data) are isolated by one mini-program.
Can I access a file from another app? Is it possible to get the full path to a file so that it can be read from any mini-program?
Or some other modes of existence could be created between the mini-programs and the dial.

[spyx1]

Zepp os 2

[MyoungXUE]

Zepp OS 3 implemented this function, @zos/fs module openSync can specify the Mini Program ID, access to the target Mini Program /data directory files.

https://docs.zepp.com/docs/reference/device-app-api/newAPI/fs/openSync/

What is your device? GTR4 has been gradually updated to Zepp OS 3.

[jdemaeyer]

@MyoungXUE I am trying to implement two-way communication. Reading from another app's data directory with the appId option as you suggest works great, but it doesn't seem to work for writing into another app's data directory. Is there an undocumented restriction that the appId option only works for reading?

(I'm using API 4.0 on an Active 2 NFC)

[spyx1]

My device bip 5.