How can I integrate java with Openstack nova in my project?

Dears.

      my project wants to leverage Openstack-nova IaaS capacity. I have already installed and config the nova service in my server. and it works very well. but I don't know how can I integrate nova with my project? and my project is writing in java.
      their is some approach, is it reasonable?
      * java invoke REST service. but is their have any document for this. and what's the REST API document? how can I use and test it?
      * java invoke python
      * java invoke linux command
      * does have any other integration way? webservice, socket, MQ,

      thanks very much.