How to make multi-tenant service based on Keystone?

We all know that the Openstack services are multi-tenant based, for example Nova, etc. The basic support is based on Keystone. However for most people, they want to know more about how to build such multi-tenant service (RESTFUL API etc) based on such mechanism by themselves.
We learn lots of high level concepts and architecture knowledge. If we can provide more valuable presentation as what I mentioned above, that will encourage more people to contibute more to the Openstack ecosystem.
I suggest 余兴超 from UnitedStack to give us a more detailed introduction which can be presented based on the project - BoneDragon.