How to design a service provider system in Java?

Could you please give me some pointers or links to understand how to design a service provider software?

My requirement is simple.

1. Our solution should support various clouds like: AWS, Azure, and Google. Any other cloud like RakcSpace can be added in future so it is extendable.

2. Resources categories: a. VM b. Network. c. Storage So resources are also extendable. I mean a new resource can be added?

3. Interfaces: a. REST b. JAVA SDK c. Python

4. User can subscribe to any cloud like AWS or Azure or Google

Based on subscription, the user will be provided services. If he has subscribed for AWS, the cloud services from AWS will be provided.

Please help and provider some pointers.

Thanks you very much reading my question.