How to force update on an app when backend-changes requires an updated app

Question

I have read different posts about forcing an update of an app, and the only idea that ppl has had (as far as I can tell) is to create a web service which the app calls to see what version is the current one. The WS must them manually be updated to reflect the versionCode.

This approach has several problems:

Problem 1:

When you upload an app to the Play Store, then it takes several hours before it is available for devices to download, and you never know when. Also, it seems to me like it becomes available at different times for different devices, so you really have no clue what so ever when its "available for all".

This means that you cannot immediately update the WS (that tells the app what is the "current" version) since directing them to Play Store won't be very constructive, as the updated app isn't available there anyways. And since you don't know when it will be available, you don't really know when to update the WS.

Problem 2:

Sometimes you do some changes to the back-end (comm protocol changes or something else) that requires you to upload the new version of the app and then update the backend so that they can talk to each other as expected. In this case, you really want some way to tell the app that "please update since you are out of date" and direct them to the Play Store.

So, the question is, how can I achieve this functionality?

Answer 1

As zapl has commented, the backend should ALWAYS allow backward compatibility. Whenever your app makes a call to the backend server the app should report its version number and the backend should respond accordingly.

As for forcing an app update, you should look at GCM to push a notification which will then take the user to the update although in reality this wouldn't actually 'force' the user to update.

Either way, as long as both the backend and app report their version numbers to each other (perhaps with a notification of 'update available') then you can design things so 1). they continue to work and 2). users will update ASAP when they need to.

I understand that publishing to Google Play can have delays but as long as the backend retains backward compatibility, it shouldn't be a problem.