Does logging water a third-party service and 0Auth?

[AJorg]

I am trying to build my first FitBit app for my Versa. It is a simple app where I want to be able to quickly input a set number of ounces or milliliters and sync it to my FitBit app. In my mind, this is a simple app that passes data from my Fitbit watch to the Fitbit app on my phone - no third party integration. I think my lack of understanding with oAuth might be causing my confusion. 

Here are my questions... 

1. Do I have to create some third-party application to accept and handle the oAuth tokens or can't I just handle that within that watch app and let those two communicate?
2. I know that I have to use oAuth since I'd be passing data back and forth, but is there a simpler way to do that?

I look forward to any guidance you guys can provide me. 

Thanks!

[Gondwana · Accepted solution]

The Fitbit app doesn't store food and drink data on your phone. That data is stored on Fitbit's servers on the internet. Your phone gets the data from there.

For flow of info you need is roughly:

• Send info from watch to companion app on phone using messaging or file transfer API.
• Send into from companion app to Fitbit's servers using Fitbit's Web API. You can use the Oauth settings component for the authentication.

You don't have to use any third-party service.

Although your idea sounds simple, it will require fairly advanced development to implement.

[AJorg]

Thank you, Gondwana. That makes sense.