Strayer University CIS110 Computer Programming Design slide Presentation

1. Programming Logic and Design
Eighth Edition
Chapter 13
System Modeling with the UML

2. Objectives
2
In this chapter, you will learn about:
• System modeling
• The Unified Modeling Language (UML)
• UML use case diagrams
• UML class and object diagrams
• Other UML diagrams
• Deciding when to use the UML and which UML
diagrams to use
Programming Logic and Design, Eighth Edition

3. Understanding System Modeling
3
• Most computer programs are part of a larger system
– Each program is related to others
– Produce input or output
– Require careful planning
• System design
– Detailed specification of how all parts of a system are
implemented and coordinated
Programming Logic and Design, Eighth Edition

4. Understanding System Modeling
(continued)
4
• Basic principles:
– Large systems are easier to understand when you break
them down into subsystems
– Good modeling techniques are increasingly important as
the size and complexity of systems increase
– Good models promote communication among technical
and nontechnical workers while ensuring professional
and efficient business solutions
Programming Logic and Design, Eighth Edition

5. 5
Understanding System Modeling
(continued)
• The Unified Modeling Language (UML) allows you to:
– Envision systems with an object-oriented perspective
– Break a system into subsystems
– Focus on the big picture
– Hide the implementation detail
– Communicate between programmers and businesspeople
about system design
– Divide responsibilities for large systems
Programming Logic and Design, Eighth Edition

6. 6
What Is the UML?
• A standard way to specify, construct, and document
systems that use object-oriented methods
• A modeling language, not a programming language
• Has its own notation
– Consists of a set of specialized shapes and conventions
• Construct different kinds of software diagrams and
model different kinds of systems
Programming Logic and Design, Eighth Edition

7. 7
What Is the UML? (continued)
• Create top-view diagrams of business processes
• Hide details and focus on functionality
• Start with a generic view of an application
– Introduce details and complexity later
• Useful as you begin designing business systems
• Very large
– Documentation is more than 800 pages
– 14 diagram types allowing you to “see” the business
process from a different angle
Programming Logic and Design, Eighth Edition

8. 8
What Is the UML? (continued)
• Structure diagrams
– Emphasize the “things” in a system and include:
• Class diagrams
• Object diagrams
• Component diagrams
• Composite structure diagrams
• Package diagrams
• Deployment diagrams
• Profile diagrams
Programming Logic and Design, Eighth Edition

9. 9
What Is the UML? (continued)
• Behavior diagrams
– Emphasize what happens in a system and include:
• Use case diagrams
• Activity diagrams
• State machine diagrams
• Interaction diagrams
– Emphasize the flow of control and data, and include:
• Sequence diagrams
• Communication diagrams
• Timing diagrams
• Interaction overview diagrams
Programming Logic and Design, Eighth Edition

10. Using UML Use Case Diagrams
10
• Use case diagrams show how a business works
– From the perspective of those who actually interact with
the business (employees, customers, suppliers, etc.)
• Users are called actors
– Represented by stick figures
• Use cases
– Represented by ovals
– System functions or services that are visible to the
system’s actors
Programming Logic and Design, Eighth Edition

11. Using UML Use Case Diagrams (continued)
11
Figure 13-1 Use case diagram for librarian
Programming Logic and Design, Eighth Edition

12. Using UML Use Case Diagrams (continued)
12
• Establishing use cases usually follows from analyzing
the main events in a system
• Two main events from a librarian’s point of view:
– acquireNewBook()
– checkOutBook()
• Variations in use cases:
– Extend
– Include
– Generalization
Programming Logic and Design, Eighth Edition

13. Using UML Use Case Diagrams (continued)
13
• Extend variation
– Shows functions beyond those found in a base case
– Scenario
• A variation in the sequence of actions required in a use case
– Use case has at least one main scenario
• Stereotype
– Can add <<extend>> near the line that shows a
relationship extension
Programming Logic and Design, Eighth Edition

14. Using UML Use Case Diagrams (continued)
14
Figure 13-2 Use case diagram for librarian with scenario extension
Figure 13-3 Use case diagram for librarian using stereotype
Programming Logic and Design, Eighth Edition

15. 15
Using UML Use Case Diagrams (continued)
• Include variation
– Case can be part of multiple use cases
– Like subroutine or submodule
– Include use case in an oval with a dashed arrow pointing
to the subroutine use case
Figure 13-4 Use case diagram for librarian using include relationship
Programming Logic and Design, Eighth Edition

16. Using UML Use Case Diagrams (continued)
• Generalization
variation
– Use case is less specific
than others
– Substitute the more
specific case for a
general one
– More specific scenarios
are attached to the
general scenario with
open-headed dashed
arrows
16
Figure 13-5 Use case diagram for
librarian with generalizations
Programming Logic and Design, Eighth Edition

17. Using UML Use Case Diagrams (continued)
17
Figure 13-6 Use case diagram for librarian with multiple actors
Programming Logic and Design, Eighth Edition

18. Using UML Use Case Diagrams (continued)
18
• The use case diagram is only a tool to aid
communication
• There is no single “correct” use case diagram
• Elided
– Omit parts of diagrams for clarity
Programming Logic and Design, Eighth Edition

19. Using UML Use Case Diagrams (continued)
19
Figure 13-7 Use case diagram
emphasizing actors
Figure 13-8 Use case diagram
emphasizing system requirements
Programming Logic and Design, Eighth Edition

20. Using UML Class and Object
Diagrams
20
• Class diagram
– Illustrates the names, attributes, and methods of a class
– More useful to a system’s programmers than to its users
because it closely resembles code the programmers will
write
• Rectangle divided into three sections:
– Top section contains the name of the class
– Middle section contains the names of the attributes
– Bottom section contains the names of the methods
Programming Logic and Design, Eighth Edition

21. Using UML Class and Object
Diagrams (continued)
21
Figure 13-9 Book class diagram
Programming Logic and Design, Eighth Edition

22. Using UML Class and Object
Diagrams (continued)
• Use generalizations with class diagrams
– Open-headed arrow
– Show more general (or parent)
classes and more specific
(or child) classes
– Child classes contain all the
attributes of their parents
• Overriding
– The mechanism by which a child class method is used by
default when a parent class contains a method with the
same signature
22
Figure 13-10 LibraryItem class
diagram showing generalization
Programming Logic and Design, Eighth Edition

23. Using UML Class and Object
Diagrams (continued)
23
• Relationships between objects
– Association relationship
• Describes the connection or link between objects
• Represented by a straight line
• Arithmetical relationship or ratio included (called cardinality or
multiplicity)
– Whole-part relationship
• One or more classes make up the parts of a larger whole class
• Also called an aggregation or a has-a relationship
• Represented using an open diamond
Programming Logic and Design, Eighth Edition

24. Using UML Class and Object
Diagrams (continued)
24
Figure 13-11 Class diagram with
association relationship
Figure 13-12 Class diagram with several
association relationships
Programming Logic and Design, Eighth Edition

25. Using UML Class and Object
Diagrams (continued)
25
Figure 13-13 Class diagram with whole-part
relationship
Figure 13-14 Object diagram for Library
• Object diagrams
– Similar to class
diagrams
– Model specific
instances of classes
– Show a snapshot of
an object at one
point in time
Programming Logic and Design, Eighth Edition

26. Using Other UML Diagrams
26
• Sequence diagram
– Shows the timing of events in a single use case
– Makes it easier to see the order in which activities occur
– Horizontal axis (x-axis)
• Represents objects
– Vertical axis (y-axis)
• Represents time
Programming Logic and Design, Eighth Edition

27. Using Other UML Diagrams (continued)
27
• Create sequence diagram
– Place objects across the top of the diagram along the x-axis
– Start at the left with the object or actor that begins the
action
– Beneath each object, place a vertical dashed line
• Represents the period of time the object exists
– Use horizontal arrows to show how the objects
communicate with each other over time
Programming Logic and Design, Eighth Edition

28. 28
Figure 13-15 Sequence diagram for checking out a Book for a Patron
Using Other UML Diagrams (continued)
Programming Logic and Design, Eighth Edition

29. • Communication
diagram
– Emphasizes the
organization of objects
in a system
– Similar to a sequence
diagram but contains
numbers to represent
the precise order in
which activities occur
– Focuses on object roles
29
Figure 13-16 Communication diagram
for checking out a Book for a Patron
Using Other UML Diagrams (continued)
Programming Logic and Design, Eighth Edition

30. 30
• State machine diagram
– Shows the different statuses
of a class or an object at
different points in time
• Rounded rectangles
– Represent each state
• Arrows
– Show sequence
• Solid dot
– Start and stop states Figure 13-17 State machine diagram
for states of a Book
Using Other UML Diagrams (continued)
Programming Logic and Design, Eighth Edition

31. 31
• Activity diagram
– Shows the flow of actions of a system
• Symbols
– Flowchart stop and start symbols
– Diamonds describe decisions
– Fork
• Defines a branch in which all paths are followed simultaneously
– Join
• Reunites the flow of control after a fork
Using Other UML Diagrams (continued)
Programming Logic and Design, Eighth Edition

32. 32
• Time signal
– Indicates that a specific amount of time should pass
before an action starts
– Looks like two
stacked triangles
Figure 13-20 A time signal starting an action
Using Other UML Diagrams (continued)
Programming Logic and Design, Eighth Edition

33. • Component and deployment
diagrams
– Document physical aspects of
systems
– Component diagram
• Emphasizes the files, database
tables, documents, and other
components
– Deployment diagram
• Focuses on a system’s hardware
33
Figure 13-21 Component diagram
Using Other UML Diagrams (continued)
Programming Logic and Design, Eighth Edition

34. 34
Figure 13-21 Component diagram Figure 13-22 Deployment diagram
Using Other UML Diagrams (continued)
Programming Logic and Design, Eighth Edition

35. 35
Using Other UML Diagrams (continued)
• Profile diagram
– A newer type of UML diagram
– Extends a UML model:
• For a particular domain
– Like for financial or healthcare applications
• For a particular platform
– Like for .NET or Java
Programming Logic and Design, Eighth Edition

36. 36
Diagramming Exception Handling
• Exception handling
– The set of the object-oriented techniques used to handle
program errors
• Protected node
– try block in the UML
• Handler body node
– catch block in the UML
Programming Logic and Design, Eighth Edition

37. 37
Diagramming Exception Handling
(continued)
Figure 13-23 Exceptions in the Book check-out activity
Programming Logic and Design, Eighth Edition

38. 38
Deciding When to Use the UML
and Which UML Diagrams to Use
• Criticisms:
– Size – too large and complex
– Imprecision – combination of rules and English
– Complexity – difficult to learn
• Under the right circumstances, the UML can
increase communication
• Users, managers, designers, and technicians each
prefer specific system views
• Very few systems require diagrams of all UML types
Programming Logic and Design, Eighth Edition

39. Summary
39
• System design: a detailed specification of how all parts of
a system are implemented and coordinated
• UML (Unified Modeling Language)
– A standard modeling language for object-oriented systems
– Has its own notation
– 14 diagram types
• Use case
– Shows how a business works from the perspective of those who
interact with the business
– Includes actors
– Variations: extend relationships, include relationships,
generalizations
Programming Logic and Design, Eighth Edition

40. Summary (continued)
40
• Class diagram
– Illustrates names, attributes, and methods of a class
– Contains the name of the class, the names of the
attributes, and the names of the methods
– Can show generalizations and relationships between
objects
– Object diagrams model specific instances of classes at
one point in time
Programming Logic and Design, Eighth Edition

41. Summary (continued)
41
• Sequence diagram
– Shows timing of events
• Communication diagram
– Emphasizes organization of objects in a system
• State machine
– Shows different statuses of a class or an object at
different points in time
• Activity diagram
– Shows the flow of actions, including decision branches
Programming Logic and Design, Eighth Edition

42. Summary (continued)
42
• Component diagram
– Emphasizes files, database tables, documents used by a
system’s software
• Deployment diagram
– Focuses on a system’s hardware
• Profile diagram
– Extends the UML for a particular domain or platform
• Each UML diagram provides a different view of a
system
Programming Logic and Design, Eighth Edition