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Re: [higgins-dev] Higgins data model for attribute values
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Hmm I know higgins.owl better than I know IdAS I think.
The first thing that comes to my mind when I read this is that the classes "higgins:Attribute" and "higgins:AttributeMetadata" have absolutely nothing to do with values.
When speaking of values, only the property "higgins:attribute" (+subproperties) and the class "higgins:Value" (+subclasses) are important. The data types that are allowed for values of an attribute are determined by the rdfs:range of the attribute.
For example, if you define novell:firstName (subproperty of "higgins:attribute") with an rdfs:range of higgins:String (subclass of "higgins:Value"), then the values of firstName can only be strings. However
higgins.owl by itself does not prevent you from defining multiple rdfs:range's for an attribute, or even from saying that the rdfs:range is higgins:Value (in which case any data type is allowed). The same is true for cardinality. You can define the number of allowed values of an attribute, but you don't have to (well strictly speaking, in RDF a single property never has multiple values, but you can have the same property multiple times with different values).
There is no way in RDF/RDFS/OWL to force subproperties of higgins:attribute to use only one subclass of higgins:Value as rdfs:range.
As I said I don't know the IdAS interfaces very well, so I can't really say what all that means for them.
By the way, I think Paul has ideas on how to make higgins.owl simpler, but I don't know what's the current state of this.
Markus
On Jan 4, 2008 9:19 PM, Jim Sermersheim <
jimse@xxxxxxxxxx> wrote:
Before addressing bug #190594, I need to know more about what the Higgins data model allows in an attribute's instance data.
In IdAS, my understanding is that a Digital Subject may have 0..1 occurrence of a particular Attribute, and that an Attribute may have 1..N occurrences of a particular type of Value.
It's my understanding that each of an Attribute's values must be of the same data type, but that restriction isn't obvious to me in the Higgins OWL, and in fact, the opposite is reflected in the IdAS APIs. In IdAS, one can state the data type of each value they add to an attribute.
So, we need to agree on the Higgins data model regarding the types of attribute values. Should the Higgins data model dictate that they all be of the same type, or should it allow their types to be mixed?
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