Subscribe/Unsubscribe with ajax request

Hi,

I need to put a button “subscribe” on each categories archive page so logged-in users may subscribe/unsubscribe to the current category with a click on it. Is there an “easy” way to do so natively ? If I have to do it, and before I dive in your code to figure out how to do that, can you tell me where to look for at first ?

Thanks for your help 🙂

Séb.