Notice: This Wiki is now read only and edits are no longer possible. Please see: https://gitlab.eclipse.org/eclipsefdn/helpdesk/-/wikis/Wiki-shutdown-plan for the plan.
Difference between revisions of "Attribute"
(→Definition) |
|||
| Line 4: | Line 4: | ||
== Definition == | == Definition == | ||
* Defines a property of an [[Node]] or a [[Context]]. | * Defines a property of an [[Node]] or a [[Context]]. | ||
| − | * Has a URI-valued type | + | * Has a URI-valued type |
| − | * | + | * Values |
| − | * | + | ** Has one or more values all of which MUST be unique |
| − | * Has one or more values all of which MUST be unique | + | ** The types of the values of an [[Attribute]] are indicated by a URI |
| − | * The types of the values of an [[Attribute]] | + | ** The allowed value(s) are defined by an [[Attribute Value Datatype]] |
| − | ** | + | * A given type of [[Attribute]]: |
| − | ** | + | ** MAY define the minimum cardinality of an [[Attribute]]--the minimum number of values that are allowed (e.g. >=3 values) |
| − | + | ** MAY define the maximum cardinality of an [[Attribute]]--the minimum number of values that are allowed (e.g. <=100 values) | |
| − | * | + | |
==Examples== | ==Examples== | ||
Revision as of 21:42, 7 February 2008
Contents
Introduction
This page describes the Higgins concept of Attribute.
Definition
- Defines a property of an Node or a Context.
- Has a URI-valued type
- Values
- Has one or more values all of which MUST be unique
- The types of the values of an Attribute are indicated by a URI
- The allowed value(s) are defined by an Attribute Value Datatype
- A given type of Attribute:
- MAY define the minimum cardinality of an Attribute--the minimum number of values that are allowed (e.g. >=3 values)
- MAY define the maximum cardinality of an Attribute--the minimum number of values that are allowed (e.g. <=100 values)
Examples
The physical Entity Bob Smith might be represented as a Node in the Context of his employer, the Port Control Authority. This Node might have the following types of Attributes (and associated values) in this Context:
- email-address = bob@portcontrol.gov
- phone number = {617-555-1234, 617-333-4321} <-- multi-valued attribute example
- passport information = ...etc.
- fingerprint data = ...etc.
- surname = "Smith"
The surname Attribute in the example above might have a type of http://openschemas.org/2006/person/surname. The schema associated with the containing Context provides metadata about this URI.
This same Entity Bob Smith might also be represented as a Node in a "customer-to-Clothes-R-Us" Context (this customer's relationship with the Clothes-R-Us merchant. In this Context Bob has these Attributes:
- platinumCustomer = True
- preferredColor = "blue"
HOWL
Open Issues
- At present an Attribute cannot have N>1 values if the values are the same. For example a very odd father might name each of his three kids "frank". Thus the father Node cannot have an attribute "names-of-children" whose values are "frank, frank, frank".
- We need to be able to describe the reality that "real world" context providers must restrict attributes to be "closed"