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Semantic Objects

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  1. Semantic Objects

  2. Definitions • A semantic object is a named collection of attributes that sufficiently describes a distinct identity • Semantic objects are grouped into classes each of which has a name • A semantic object has a collection of attributes • Objects represent distinct identities that users recognize as independent and separate and that they want to track and report

  3. More definitions • Simple attributes have a single element • Group attributes are composites of other attributes • Semantic object attributes are attributes that establish a relationship between one semantic object and another

  4. Example to consider • What are the simple attributes? • What are the group attributes? • What are the semantic object attributes?

  5. Attribute Cardinality • Each attribute has a minimum cardinality • ususally 0 or 1 • Each attribute has a maximum cardinality • usually 1 or n • Cardinalities are shown in format n.m where • n is the minimum cardinality and • m is the maximum cardinality • Cardinalities of groups and attributes of groups can be subtle

  6. Example • What is the minimum cardinality of CampusAddress? • What is the minimum cardinality of Building? • Note: cardinalities operate only between the attribute and the container of the attribute.

  7. Object Instance

  8. Paired Attributes • THERE ARE NO ONE-WAY OBJECT RELATIONSHIPS. • IF AN OBJECT CONTAINS ANOTHER OBJECT, THEN THE SECOND OBJECT WILL CONTAIN THE FIRST.

  9. More definitions • An object identifier is one or more object attributes that the users employ to identify object instances. • A group identifier is an identifier that has more than one attribute • The domain of an attribute is a description of the attribute’s possible values • The domain of a simple attribute consists of both a physical and a semantic description • The domain of a group attribute also consists of both a physical and a semantic description

  10. Still more definitions • The portion of an object that is visible to a particular application is called the semantic object view or simply the view.

  11. Types of Attributes • Necessary to describe types of objects • A single-value attribute is an attribute whose maximum cardinality is one • A multivalue attribute is one whose maximum cardinality is greater than one • A nonobject attribute is a simple or group attribute

  12. Types of Objects • Simple • Composite • Compound • Hybrid • Association Objects • Parent Subtype Objects • Archetype/Version Objects

  13. Simple Objects • A simple object is a semantic object that contains only single-value, simple or group attributes.

  14. Transformation of Simple Object

  15. Composite Objects • A composite object is a semantic object that contains one or more multivalue simple or group attributes but no object attributes.

  16. Transformation of a Composite Object

  17. Transformation of a Composite Object - separate group attributes

  18. Transformation of a Composite Object - nested group attributes

  19. Compound Objects 1:1 • A compound object contains at least one object attribute.

  20. Transformation of a Compound Object – 1:1

  21. Transformation of a Compound Object – 1:1 – Two ways

  22. Compound Objects 1:N or N:1

  23. Transforming a Compound Object 1:N or N:1

  24. Compound Objects N:M

  25. Transformation of Compound Objects N:M

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