How can an application server associate Google accounts to a user's device?

Question

I want users to be able to enter data from a web server and/or native PC app and transfer it to their chosen Android device in much the same way that Google Play\'s install

Answer 1

The user_id you get from the device when you register with GCM should be the same as the user_id you get with your OAuth token for your app. Just store the OAuth token and Registration ID in your user repository, associating both with the user_id.