Categories (was: ProtocolDataModel issues)

[Robert Sayre <mint@xxxxxxxxxxxxxxx>]

Ezra Cooper wrote:
> On Sep 14, 2004, at 2:45 PM, Robert Sayre wrote:
>
> > What properties does a category need?
> > - name
> > - URI
>
>
> Do we want to model categories as hierarchical or flat, or as DAGs? If 
> flat, then hierarchical tools might have to write out long path names 
> for their categories. Do we stop at having a single parent for each 
> category, or can we allow several parents (giving rise to DAGs)? Looks 
> like there are at least two or three possible models for categories.
>
> I favor a hierarchical model, possibly with a fallback for tools that 
> don't want to deal with hierarchies. For the fallback, it might be 
> enough just to make sure that each category has a unique human-readable 
> name so that users can select a category without seeing the hierarchy.

I meant DAG (I missed a many:parent property). We have a similar problem 
to users/principals[0] in WebDAV ACL, which defines a 
DAV:group-membership property[1]. We could revise this to:

Category
- URI
- many: memberOfURIs
- many: memberURIs (can be entrys or categories)
- name

Are you in favor of restricting categories to a hierarchical model, or 
just concerned about a requirement? I was thinking servers could 
restrict the model as they wish.

Robert Sayre

[0] http://webdav.org/specs/rfc3744.html#principal.properties
[1] http://webdav.org/specs/rfc3744.html#rfc.section.4.4