How to send Java object from Android device to App Engine database and push to other Android devices?

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http://stackoverflow.com – I want to make a really simple Android app where on one Android device, I send myObject to Google App Engine, it gets stored in the database there, and pushed to all the other devices registered on that database. How do I do this? I've looked everywhere. All I want is an extremely simple example. Thank you! (HowTos)