[openstack-dev] [Keystone] Domains, Projects, and Groups are all collections

David Chadwick d.w.chadwick at kent.ac.uk
Wed Jan 23 20:38:23 UTC 2013

On 23/01/2013 20:23, Adam Young wrote:
> Users, Groups and projects are owned by a domain.  This is an attribute
> hierarchy.

this is not the type of hierarchy I was talking about. Attribute 
hierarchies are object oriented hierarchies in which subtypes inherit 
all the properties of the supertypes. So for example, the surname 
attribute type is a subtype of the name attribute type.

What you are talking about is a containment hierarchy, in which domains 
contain projects, and projects contain users. A Venn diagram can be used 
to nicely depict the containment hierarchy.



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