Re: [higgins-dev] IdAS: One attribute per type per DS

["Jim Sermersheim" <jimse@xxxxxxxxxx>]

>>> Valery Kokhan <vkokhan@xxxxxxxxxxxxxx> 4/27/07 9:22 AM >>>
>Jim,
>
>As I can remember our original assumption was that main difference
>between attributes and values is that attributes *can* hold metadatas
>while values *can not*. Regardless from the fact that I do not see any
>way to model metadata on values using .owl I believe that our original
>assumption was 100% correct and just leave it at this.
>
>Now about multiple attributes of the same type on any digital subject.
>
>Take into consideration above assumption I personally believe that on
>API level we should allow both approach: multiple attributes of the
>same type and multiple values in single attribute.
 
So, historically at first the API allowed one attribute per type.  Then we decided we needed to allow metadata to differ on same-typed attributes, and thus introduced the ability to have multiple attributes per type.  This led to much confusion and rendered the IDigitalSubject.getAttribute method fairly useless. Why?  Because now we have to indicate the attribute's type along with all it's metadata to distinguish it from other attributes of the same type. Otherwise, which occurrence of that attribute should the CP return?

So, a couple of phone calls ago, we agreed to revert back to allowing only one attribute per type, and at that time I believe we decided to allow metadata to be placed on values.

>As a use case for multiple attributes of the same type I'd consider
>attribute like "relationship" where we need to keep track of when or
>by whom each particular relationship was created or modified.

In this case, we could put the metadata on the values.

>As a use case for multiple values in single attribute I see attribute
>like "favoriteDrinks" where we don't care of when each particular
>value was modified by still want to know when entire list was changed.
<snip>

Jim