How often should an Android app and server sync

Question

I'm developing an Android app that talks to a Play-framework app, the two apps are passing user data between one another using Volley requests, my question is this:

Is it desirable to have the Android app sync with the Play server constantly to check for changes to the user profile? (like syncing during a fragment change)

Or is it better practice to have the user on the Android app logout and back in before that changes occur.

Or is there some alternative solution that only syncs with the server if a change occurs?

I think the last option would be the most efficient and desirable, but I fail to see how could do the check without sending a request first to the server and if I'm sending a request to check for changes anyway, wouldn't it make sense to have the changes in the response.

Answer 1

You should not sync whenever a fragment changes. It is a waste of the user's battery and data. You also most likely don't want to force a logout/login all that often as it becomes inconvenient for the user.

If you are expecting very infrequent changes to the user profile, it might be better to send a push request from the server using GCM to inform the app that it should invalidate its local cache. Then query the server for new profile information.

If using push is unfeasible for some reason, you might want to look into using a SyncAdapter and syncing infrequently. In most cases, it should be okay if profile information is potentially behind unless the user is specifically checking the profile settings, in which case you might want to check the validity of your cache when they check their settings.