Semantic Objects
Software : TableDesigner
3/16/2016
1
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
3/16/2016
2
More definitions
• Simple attributes have a single element
– DateOfHire, InvoiceNumber, SalesTotal
• Group attributes are composites of other
attributes
– Address which contains Street, City, State, Zip
• Semantic object attributes are attributes that
establish a relationship between one semantic
object and another
– STUDENT, TEACHER
3/16/2016
3
Example to consider
• What are the simple
attributes?
• What are the group
attributes?
• What are the
semantic object
attributes?
3/16/2016
4
Attribute Cardinality
•
•
•
•
Each attribute has a minimum cardinality
– usually 0 or 1
– PLAYER in BASEBALL_TEAM might be 9
– PLAYER in BASKETBALL_TEAM 5
– Soccer 11
– Football 11
Each attribute has a maximum cardinality
– usually 1 or n
– PLAYER in BASEBALL_TEAM might be 25
– Football 53
– Soccer 16
– Basketball 12
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
3/16/2016
5
Same Example w. Cardinalities
• 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.
3/16/2016
6
Object Instance
3/16/2016
7
Paired Attributes
• THERE ARE NO ONE-WAY OBJECT
RELATIONSHIPS.
• IF AN OBJECT CONTAINS ANOTHER
OBJECT, THEN THE SECOND OBJECT
WILL CONTAIN THE FIRST.
3/16/2016
8
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
3/16/2016
9
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.
3/16/2016
10
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
3/16/2016
11
Seven Types of Objects
•
•
•
•
•
•
•
Simple
Composite
Compound
Hybrid
Association Objects
Parent Subtype Objects
Archetype/Version Objects
3/16/2016
12
Simple Objects
• A simple object is a semantic object that
contains only single-value, simple or group
attributes.
3/16/2016
13
Transformation of Simple Object
3/16/2016
14
Composite Objects
• A composite object is a semantic object that
contains one or more multivalue simple or group
attributes but no object attributes.
3/16/2016
15
Transformation of a Composite
Object
3/16/2016
16
Transformation of a Composite
Object - separate group attributes
3/16/2016
17
Transformation of a Composite Object - nested
group attributes this diagram doesn’t correspond
exactly to figure 4-18 – it just shows nesting
3/16/2016
18
Compound Objects 1:1
• A compound object contains at least one
object attribute.
3/16/2016
19
Transformation of a Compound
Object – 1:1
3/16/2016
20
Transformation of a Compound
Object – 1:1 – Two ways
3/16/2016
21
Compound Objects 1:N or N:1
3/16/2016
22
Transforming a Compound Object
1:N or N:1
3/16/2016
23
Compound Objects N:M
3/16/2016
24
Transformation of Compound
Objects N:M
3/16/2016
25