Along with the EC2 Query interface, OpenNebula natively includes a second remote interface, called OCCI.
The Open Cloud Computing Interface (OCCI) is a RESTful protocol, and a comprehensive API for managing cloud resources. Unlike the Amazon EC2 Query interface, OCCI is being developed through the Open Grid Forum (http://www.ogf.org/), which actually maintains a lot of standards, mainly for the Grid interoperability environments (http://en.wikipedia.org/wiki/Open_Grid_Forum#Standards).
If you do not need EC2 compatibility, or if you are starting from scratch in developing ad-hoc integrations with OpenNebula, using the OCCI interface is highly recommended for its openness.
Like the EC2 Query interface, the OCCI service is implemented upon the OpenNebula Cloud API (OCA) and Sinatra, a widely used lightweight Ruby web framework.
The OCCI interface included in the OpenNebula 3.x distribution does not implement the latest OCCI specification, but it is based on the draft 0.8 of the...