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Re: [higgins-dev] entityID not an attribute?

So there are a couple of things here, we have always talked about the EntityID as being a reference to the Entity and not the unique identifier. There are many ways to reference an Entity, so I don't believe that this is limited to 0..1. I also believe that the EntityID encapsulates a given set of attributes.The unique identifier is only has to be unique within a context. So I believe that the unique identifier is an attribute, not a way to reference the Entity.

Anthony Nadalin | Work 512.838.0085 | Cell 512.289.4122

Inactive hide details for Paul Trevithick ---09/10/2008 05:51:39 PM---Raj has suggested the need to clarify the language here. Paul Trevithick ---09/10/2008 05:51:39 PM---Raj has suggested the need to clarify the language here. So here is a restatement. Additions in red. Substitutions in blue. All


From:
Paul Trevithick <paul@xxxxxxxxxxxxxxxxx>

To:
higgins-dev <higgins-dev@xxxxxxxxxxx>

Date:
09/10/2008 05:51 PM

Subject:
Re: [higgins-dev] entityID not an attribute?



Raj has suggested the need to clarify the language here. So here is a restatement. Additions in red. Substitutions in blue. All defined terms in initial caps.

Background: We remain committed to these two principles:
    • An Entity has 0..1 unique identifier (called an EntityId) (...and we expect almost all Entities will have an EntityId).
        • [Raj: you asked about why this EntityId is optional. The answers are (1) that our “complex” Attributes have values that are themselves Entities and we didn’t want to require developers to explicitly “name” these values (especially in situations where there was no need for N>1 Entities to share (link to the same) value/Entity and (2) we need this in order that our model remain a pure super-set of RDF/OWL (and thus allows IdAS to losslessly “adapt” the Semantic Web (including all Linked Data).]
    • An Entity has 0..N Attributes some of which may be used singly or in combination to identify an Entity or a set of Entities within a Context.
        • [Raj: To date we have decided not to define an explicit “Identifier” Attribute type. The reason for not defining it is twofold: First, the distinction between an Identifier and an Attribute has so far proved impossible to agree on. Second, Context Provider developers are free to create their own Attribute Definitions and thus a developer could define their own “Identifier” sub-Attribute]

The proposal remains:
    • To no longer consider the one, optional EntityId as an Attribute.
    • To have an IdAS getEntityId() method to return this EntityId (or return null if it doesn’t exist) whereas other getAttribute methods return Attributes/values
    • NOTE: CP developers remain free to present the EntityId value as the value of some Attribute type that they define and use within their Context

With the above clarified and annotated definitions, I’m interested to hear Tony’s, Raj’s and anyone else’s reactions.

-Paul


On 9/9/08 1:20 PM, "Nataraj Nagaratnam" <natarajn@xxxxxxxxxx> wrote:

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