Semantic Objects
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
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
Example to consider
• What are the simple
attributes?
• What are the group
attributes?
• What are the
semantic object
attributes?
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
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.
Object Instance
Paired Attributes
• THERE ARE NO ONE-WAY OBJECT
RELATIONSHIPS.
• IF AN OBJECT CONTAINS ANOTHER
OBJECT, THEN THE SECOND OBJECT
WILL CONTAIN THE FIRST.
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
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.
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
Types of Objects
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Simple
Composite
Compound
Hybrid
Association Objects
Parent Subtype Objects
Archetype/Version Objects
Simple Objects
• A simple object is a semantic object that
contains only single-value, simple or group
attributes.
Transformation of Simple Object
Composite Objects
• A composite object is a semantic object that
contains one or more multivalue simple or group
attributes but no object attributes.
Transformation of a Composite
Object
Transformation of a Composite
Object - separate group attributes
Transformation of a Composite
Object - nested group attributes
Compound Objects 1:1
• A compound object contains at least one
object attribute.
Transformation of a Compound
Object – 1:1
Transformation of a Compound
Object – 1:1 – Two ways
Compound Objects 1:N or N:1
Transforming a Compound Object
1:N or N:1
Compound Objects N:M
Transformation of Compound
Objects N:M