UML

Sections of this presentation were adapted from Martin Fowler UML Distilled: A Brief Guide to the Standard Object Modeling Language, 3rd Edition

History

Design notation of various kinds used since programming began:• Flow charts, Pseudo code, Structure

Diagrams …With advent of OO, many conflicting notations (1980s , 1990s)These notations were combined and unified (late 1990’s)UML extensively taught in universities(2000 - now).

UML: Unified Modeling Language An industry-standard graphical language for specifying, visualizing, constructing, and documenting the artifacts of software systems, as well as for business modeling.

The UML uses mostly graphical notations to express the OO analysis and design of software projects. 

Simplifies the complex process of software designUML can be used to describe: the organization of a program how a program executes how a program is used how a program is deployed over a network …and more

What is UML?

Why UML for Modeling?

A diagram/picture = thousands wordsUses graphical notation to communicate more clearly than natural language (imprecise) and code(too detailed).Makes it easier for programmers and software architects to communicate.Helps acquire an overall view of a system.UML is not dependent on any one language or technology.UML moves us from fragmentation to standardization.

3 Ways to Use UML(Both forward & reverse engineering)1) Sketch e.g. at white board

1) Most common, quick and informal2) Communication & understanding

2) Blueprint1) Detailed design, implemented by programmer2) May have tools supporting diagramming

3) Programming Language1) Tools translate diagrams to executable code

During Software Lifecycle: UML Can Be Used at Various StagesAnalysis: OOA• What is system to do? What services is it to

provide? Provide requirements for designer.Design: OOD• What will be the parts & structure of the system?

How will they interact? Provide blueprint for programmer.

Programming: OOP

Classification of UML Diagrams

Structure1) Class diagram2) Component diagram (cmpts can be

independently purchased and replaced)

3) Component structure diagram4) Deployment diagram (what goes on what

machine & place)

5) Object diagram6) Package diagram (pkg = group of classes,

e.g. namespace)

There are 13 + Kinds of UML Diagrams

Classification of UML Diagrams(cont.)

Behavior7) Activity diagram (flow chart)

8) Use Case diagram (scenarios for use of system)

9) State Machine diagram10)Sequence diagram11)Communication diagram (data flow diagrams)

12) Interaction diagram (activity + sequence diagrams)

13)Timing diagram

Class Diagrams

Class diagrams

A class diagram is often all that is needed to describe a particular Design PatternA class diagram shows classes, interfaces, and their relationshipsWe’ll cover most of classes and interfaces, and a few of the most important relationshipsThe purpose of the class diagram is to show the types being modeled within the system.

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"classifiers."

UML models types may include:

a classan interfacea data typea component.

Class

Class Name

Attribute : type

Operation (arg list) : return type

Abstract operation

Various parts are optional

Example UML Class Diagram

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http://www.ibm.com/ -http://www.ibm.com/developerworks/rational/library/content/RationalEdge/sep04/bell/bell_fig5.jpg

Instance Specification(Object)

ObjectName: Class Name

Attribute : type

Operation (arg list) : return type

Abstract operation

Various parts are optional

An example of Class

Account_Name- Custom_Name- Balance

+AddFunds( )+WithDraw( )+PayInvoice( )

Name

Attributes

Operations

Class Example

class Checking {private:

char Customer_name[20]; float Balance; public: AddFunds(float); WithDraw(float); PayInvoice(float);

set_name(string);

get_name();

set_balance(float);

get_balance();

};

Relationships between Class Diagrams

Association -- a relationship between instances of the two classes. There is an association between two classes if an instance of one class must know about the other in order to perform its work. In a diagram, an association is a link connecting two classes.

Aggregation -- an association in which one class belongs to a collection. An aggregation has a diamond end pointing to the part containing the whole.

Generalization -- an inheritance link indicating one class is a superclass of the other. A generalization has a triangle pointing to the superclass.

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Notation of Class Diagram: association

Bi-directional associationAssociations are assumed to be bi-directional e.g. Flight and plane notation:

Uni-directional associatione.g. Order and item notation:

Associations represent relationships between instances of classes .

Association: Multiplicity and Roles

University Person

1

1

*

*

Multiplicity

Symbol Meaning

1 One and only one

0..1 Zero or one

M..N From M to N (natural language)

* From zero to any positive integer

0..* From zero to any positive integer

1..* From one to any positive integer

0…8.. From zero to eight

8..14 From eight to fourteen

teacheremployer

RoleRole

“A given university groups many people; some act as students, others as teachers. A given student belongs to a single university; A given staff belongs to a single university; a given teacher may or may not be working for the university at a particular time.”

student

staff

*0..1

Notation of Class Diagram: Aggregation

AGGREGATION

Aggregation: expresses a relationship among instances of related classes.

Containee Classes

Flat

Rooms Storage Room

Example 1

Containee Classes

Car

Motor Wheels

Example2

AGGREGATION

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Generalization (Inheritance)

Supertype

Subtype 1 Subtype 2

Generalization expresses a relationship among related classes. It is a class that includes its subclasses.

Generalization Example

http://www.ibm.com/developerworks/rational/library/content/RationalEdge/sep04/bell/bell_fig10.gif

Elements of Sequence Diagrams

Name: Class

New objectCreate

Message

Return

Delete

Self-call

Lifelines The dotted line that extends down the

vertical axis from the base of each object. Messages Labeled as arrows, with the arrowhead

indicating the direction of the call.

Activation bar The long, thin boxes on the lifelines are

method-invocation boxes indicting that indicate processing is being performed by the target object/class to fulfill a message.

Rectangle also denotes when object is deactivated.

Deletion (X)Object’s life ends at that point

Activation bar

Sequence Diagrams

Example for Sequence Diagram[Fowler]

We have an order and are going to invoke a command on it to calculate its price. To do that, the order needs to look at all the line items on the order and determine their prices, which are based on the pricing rules of the order line’s products. Having done that for all the line items, the order then needs to compute an overall discount, which is based on rules tied to the customer.

Example for Sequence Diagram[Fowler]

We have an order and are going to invoke a command on it to calculate its price. To do that, the order needs to look at all the line items on the order and determine their prices, which are based on the pricing rules of the order line’s products. Having done that for all the line items, the order then needs to compute an overall discount, which is based on rules tied to the customer.

Example Sequence Diagram

anOrder anOrderLine aProduct aCustomer

calculatePrice getQuantity

getProduct

getPricingDetails

getBasePrice

calculateDiscountsgetDiscountInfo

aProductFound

message

Participant Lifeline

ReturnActivation

Self call

MessageOperations

Object: Class

Message

USE CASES DIAGRAM

Use cases. A use case describes a sequence of actions that provide something of measurable value to an actor and is drawn as a horizontal ellipse.

Actors. An actor is a person, organization, or external system that plays a role in one or more interactions with your system. Actors are drawn as stick figures

Website Administration

Who manages the website?What type of different roles of admin and help desk have

Website Administration

gwww.uml-diagrams.or

Business Use Case Diagram for Airport Check-In and Security Screening

Business actors :?Business use cases ?PLEASE DISCUSS AND EXPLAIN WHY?

Business Use Case Diagram for Airport Check-In and Security Screening

Business actors :Passenger, Tour Guide, Minor (Child), Passenger with Special Needs (all playing external roles in relation to airport business.)

Business use cases are Individual Check-In, Group Check-In (for

groups of tourists), Security Screening

Baggage Check-in and Baggage Handling extend Check-In use cases, WHY?

Business Use Case Diagram for Airport Check-In and Security Screening

Activity Diagram

Activity diagram is used to show message flow from one activity to another.Activity Diagrams:Draw the activity flow of a system.Describe the sequence from one activity to another.Describe the parallel, branched and concurrent flow of the system.

http://www.sparxsystems.com/resources/uml2_tutorial/uml2_activitydiagram.html

An initial or start node Activity final node

Object

Decision Node Fork/Branch and Join Nodes

Merger Node