I am unsure what you mean by "google cloud".
One way to achieve this would be to use Google App Engine. It allows you to run server applications developed in Java/Python on Google's infrastructure.
What this means is that you can develop the server side yourself, and therefore implement any protocol you like to communicate with clients, that is, create your own web service.
As Mighter mentioned you could perform raw HTTP requests. However, there are a number of existing protocols for remote procedure call: SOAP, XML-RPC, etc..
I personally tend to like JSON-based protocols. It's easy to make your own implementation for that type of protocol, but you may be interested by this JSON-RPC library for Android, as an example.
Also check this other question: How to call a SOAP web service on Android
Once you'll have your web service ready, whether using SOAP, JSON-RPC or else, then you should be able to create a client, and expose the remote service calls through Java classes. If well designed, it could 1. feel as if you were calling methods on a local object, and 2. allow you to swap with a local implementation in case the network is unavailable.