Unfortunately you cannot create a public app at the moment which allows the end-user to customise where the data is being pulled from. Only the apps built by Smart Atoms can do this at present. The only thing you can do is create a private app to do this, and 'hard code' the url of your server into that.
No news on this project yet? Would be my reason to buy it
I made something pretty similar if you wanna take a look at my repo : https://github.com/DarkStowner/lametricminecraft/tree/master