software engineering zhang shuang [email protected]
TRANSCRIPT
Object-Oriented Design (OOD)
Aim Design product in terms of objects
extracted during OOA
Object-Oriented Design Steps
OOD consists of four steps:
1. Construct interaction diagrams.
The designer creates a sequence diagram or a
collaboration diagram for each of the use case
scenarios defined during the analysis phase.
Object-Oriented Design Steps
OOD consists of four steps:
2. Construct a detailed class diagram.
The preliminary class diagram created during the
analysis phase is elaborated to include a full list of
methods (including their signatures and return
types) and data members (including their types).
Additional classes and relationships are added
where necessary.
Object-Oriented Design Steps
OOD consists of four steps:
3. Construct a client-object relation diagram.
The designer then arranges the classes in a
diagram that emphasizes their hierarchical
relationship; this corresponds to the motion of a
control flow diagram (CFD) in structured analysis.
Object-Oriented Design Steps
OOD consists of four steps:
4. Complete a detailed design.
The designer then specifies the algorithms to be
implemented for each method, along with the
internal variables and data structures required by
each method.
Object-Oriented Design Steps
One of the main activities of software design is to partition the functionalities identified in the requirements specification and analysis phases into specific software modules.
Module In traditional structured programming, a
particular function or program in a particular language.
In object-oriented programming, an object, or perhaps a method associated with a particular object.
Elevator Problem: OOD
Step 1. Construct interaction diagrams for each scenario Sequence diagrams Collaboration diagrams
Comparison Both show the same thing Objects and messages passed between
them But in a different way
Normal scenario
Sequence Diagram
object1:C1
Sel f-cal l ing
oper()
Sequence Diagram
object1:C1 object2:C2
[x>y] message1()
[el se] message2()
Guard-condi tion expression
Sequence Diagram
object1:C1 object2:C2
[for al l order l ines] message1()
[i := 1..n] message2()
Loop expression
Sequence Diagram
object1 object2
m1()
m2()
Loop expression
[for al l order l ines]
[i := 1..n]
Sequence Diagram
object1:C1 object2:C2
Oper1()
Oper2(x, y)
:C3
[condi tion1] Oper3()
Case Study: Sequence Diagram
Use case scenario:
Login
Elevator Problem: OOD (contd)
Collaboration diagram
Zhang Shuang, [email protected]