ACD and OD

Analysis Class Diagrams
Class based model

• Node are classes and they have different relationships with each other
• High-level view of the system’s structure

Object Diagrams
Object based model

• Created by instantiating the classes and objects that are defined in the analysis class diagram
• Concrete view of the system’s structure at a specific point in time

Syntax

Element	Analysis Class Diagram	Object Diagram
Class / Object	A rectangle with the class name at the top and the class attributes and methods below	A rectangle with the object name at the top with a colon and class name in trailing and the object attributes and values below
Association	A line connecting two classes with an optional arrowhead indicating the direction of the relationship	A line connecting two objects with an optional arrowhead indicating the direction of the relationship
Multiplicity	A notation indicating how many objects participate in the association, represented as a range of values or a fixed value	Same as in analysis class diagrams
Inheritance	A line with an open arrowhead connecting a subclass to a superclass, indicating that the subclass inherits the attributes and operations of the superclass	Same as in analysis class diagrams
Aggregation	A line connecting a composite class (the whole) to its component classes (the parts), with a diamond at the composite class end	A line connecting a composite object (the whole) to its component objects (the parts), with a diamond at the composite object end
Composition	A line connecting a composite class (the whole) to its component classes (the parts), with a filled diamond at the composite class end	A line connecting a composite object (the whole) to its component objects (the parts), with a filled diamond at the composite object end

Shapes	Purpose
1..$x$	Multiplicity Range from 1 to $x$
1..*	1 or many
/{attribute} OR /{relationship}	Derived Attribute / Relationship

Syntactical Rules

• A class name should be a singular noun
  • Student not Students
• A class name has many compartments
  • The first one is for class name only. (Mandatory)
  • Second one would be the attributes
  • Third one would be the methods
• Class name should follow upper camel case
  • Example would be UndergradStudent
• Features of a class include attributes and method combined
• Relationship context name is written in italics, starts with capital letter
• Name of objects of classes should be underlined with class name in trailing after colon
• Object can be connected with line and the italic relationship context is labeled on it
  • The italic relationship should be underlined when connecting objects
• The constant value that will be same for all object will be underlined in the class box
• Constraints on attributes can be specified near class boxes
• Comments can be specified about an attribute in a folded card connected by a dashed line to that specific attribute

Association

• Self
• Binary
• Ternary
• Qualified

Multiplicity

• Defining the range constraints on the ends of a associative relationship.
• The constraint is read from left to right or right to left taking into account the relationship and the class names

Ternary Association

A diamond symbol connecting more than two classes
The relationship name will be follow the same syntax, italics and capital letter.
The multiplicity will be allotted keeping in view the context relating all of the classes
Association class can also be linked the to the same diamond.

• Fake Ternary Association
  • Not consists of all many multiplicity
• General Ternary Association
  • Consists of all many multiplicity

Constraints

Used when associating or defining multiplicity

• {ordered}
  • Order is important / Duplicates not allowed
• {sequence}
  • Order is important / Duplicates are allowed
• { }
  • Order not important / Duplicates not allowed
• {bag}
  • Order is not important / Duplicates are allowed
  • Multi Set

Inheritance

Same as the UML Structure
A hollow triangle is used to connect the parent class to child class with triangle on the side of the parent class.

Abstract Class

Italic Class Name
Cannot be instantiated

Tip

Generally all super classes should be abstract

Association Class

Verb class name ( exception from other classes )
Combines the two classes in such a way that methods that include involvement of both classes can be placed in a new associated class

Children Constraints

A dashed line is drawn between the inheritance relationship and constraints are written on top of that line

• {overlapping, incomplete}
• {overlapping, complete}
• {disjoint, incomplete}
• {disjoint, complete}

Aggregation

Makes use of object of other classes
Drawn with a hollow diamond symbol with the the diamond on the side of the class using the object

• Multiplicity Factor is Many on the acting class end

Composition

Instantiates the object of other classes within itself
Drawn with a filled diamond symbol with the the diamond on the the side of the class using the object

• Coincident Lifetime
• Multiplicity Factor is at-most 1 on the acting class end