How to format my variable/metadata to make it flexible?

How to format my variable/metadata to make it flexible?

Hello,

I am starting to design my messages and data structure, however, to make it scalable as well as flexible to add new features, it would require a good data structure from the beginning. I think I need a kind of guideline with good practices from your experience might be what I need as a start.

In my case: One farm might have several cell phones which use few physical sensors and read the same quantity from some tank. I am unable to freeze a set cell phone + sensor to a specific water tank, the user of course will tell what is the tank he is going to acquire data. In other words, a farm can pick any cell phone, any physical sensor and acquire data from any water tank and the user will input in the app what is the tank and sensor that he is going to read. The farm people might buy more cell phones or sensors or replace them at any time as well.

Once these quantities are stored in the cell phone, they will be reported to Tago.io server though API.

My question is then, how I would generate tokens and data (variable and metadata) formats that make the system scalable and flexible?