"Another pain point is the user has to wait 30 seconds in the worst case for their folders to be populated with images. This is because each of our handleUser threads poll the Dropbox API every 30 seconds. While this is bad from a user experience perspective it’s also bad from an engineering perspective. This will cause the load we induce on the Dropbox API to increase linearly with the number of users using our app, we’d instead like it to increase linearly with the number of active users using our app. Currently there’s no way to get around this issue but we’re working on it!"

To me this suggests they're working on some sort of notification-like API (WebHooks possibly?). Am I misinterpreting this? Because if not, this would be a really nice thing to have and has been asked for for awhile.

Or simply defining what an active user is, and polling in relation to that.

Excellent article! Really enjoyed the explanation of how all the different parts fit together.

This is excellent, thank you!

Very thorough and interesting!