So I am currently building my first web app where I will be using a Pi to be a interface between a few different devices around my house.
The first one is an air conditioner unit that provides it's status in JSON format when requested and makes changes by sending JSON data using a CURL command. My first question is there a normal time frame people use to retrieve data to update my web app? I was thinking every 500ms, so if somebody else makes a change - it should be almost instantaneous on my app (or is that too often?)
The second device will be another Pi (or more likely just a micro controller) reporting the status of several parameters. How do you store your data? I was thinking of using a MySQL database, and running an update to keep the current status - or am I better off using a text file, or just storing it in memory? The MySQL (or other DB) would allow for data logging but would it be overkill for unlogged data?