UML Notations

Activity diagramsState diagramsClass diagrams

Use-case diagrams

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Background UML

• Unified Modeling Language (UML) is a standard language for specifying, visualizing , and constructing, and documenting the artifacts of software systems.– http://www.uml.org/

• UML represents the collection of best engineering practices, mainly used for object oriented software development

• UML uses graphical notations to express the design of software projects.

Goals of UML

• Provide users with a ready-to-use visual modeling language to exchange meaningful models

• Provide extensibility and specialization mechanisms to extend the core concepts

• Be independent of particular programming languages and development processes.

• The development of UML began in 1994 by Grady Booch and Jim Rumbaugh from Rational Software Corporation

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UML Diagrams

• Activity diagram– combined function/control view

• State diagram– highly interactive control

• Class diagram– static information structure (“data”)

• Use-case diagram– high level view of system services (functional)

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Activity diagram

• Model control and information flow of a procedure or process

• It describes the state of activities by showing the sequence of activities performed.

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Action state

• State in which some work is being done– activity, task

• State terminates when the work is finished– difference with state diagrams

• After termination the action state can lead to another action state– “state transition”

• Special symbols for being and end of a procedure or process

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Basic notation for activity diagram

data entry

processinggenerateoutput

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Decision

• State transition is deterministic• If transition depends on outcome of the work,

then introduces a decision

data entry

dump in waste basket

furtherprocessing

[data correct]

[data incorrect]

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Introducing concurrencybuy food

and drinks

cook dinneropen wine

bottle

have dinner

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Swim lanes

• Process can sometimes be distributed over several agents or organizational units

• Notation: use compartments• Use to model a business process (e.g. in

organization model)

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Notation for swim lanes

write tender

get customerinformation

SALESDEPARTMENT

calculatecost

DESIGNDEPARTMENT

designelevator

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Object flow

standarddesign

write tender

get customerinformation

SALESDEPARTMENT

decide about design type

customdesign

costcalculation

elevatordesign

DESIGNDEPARTMENT

non-standard standard

CUSTOMER

tender

customerinformation

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Business process “Housing”primaryprocess

secondaryprocess

data entryof applications

magazineproduction

applicationassessment

residenceassignment

statisticalanalysis

policyinformation

:residenceassignments

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State diagrams

• Synonyms: “state chart”, “state-transition diagram”

• Purpose: model of dynamic behavior• Use if control is heavily influenced by

“external” events

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State

watching football match

duration

entry/switch on TVdo/watchexit/turn off TV

state name

state variables

state actions& activities

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State transition

• Event: comes from outside the object modeled• Message: generates event for another object• Guard: outcome of internal object computation

ready fortake off

check: boolean

entry/final check

airborne

do/fly

permission-from-control-tower[check -= OK] / take-off control-tower.confirm-takeoff(flightID)

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Actions and activities

• Action: instantaneous, not interruptible– on transition– on state entry = action on all incoming transitions– on state exit = action on all outgoing transitions – on event

• Activity: takes time, interruptible

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State diagram of ticket machine

idle inserting money

timerbalance

insert(coin)/add to balance

processing selection

do/compute change

dispensingchange

do/dispense change

dispensingticket

do/dispense ticket

cancelling

do/return balanceselect(ticket)

cancel buttonpressed

time out

[balance < ticket price]

insert(coin)/new balance

[balance = ticket price]

[balance > ticket price]

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State concurrencyentering

transactiondata

processing

take outcash

take outcard

idle

cash cardentered

cash taken card taken

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State diagram “Housing”

applicationassessment

waiting for case data

application received/order assessment

data needed/ask

data received / reply

assessment finished/report decision

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Class diagram

• Describe the types of objects in a system and their relationships

• Model class structure and contents• Class has three things: a name, attribute, and

operations

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Objects and classes

Fokker 100:airplane

airplane

#seats: integer

Fokker 70:airplane

#seats = 80

:airplane

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Object class

• Describes a group of objects with similar properties– Abbreviation: "class"

• Rationale for introducing classes: – it provides a means for abstraction

• Terminology: “object” is often used in an ambiguous way, pointing to both objects (in the strict sense) and object classes.

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Attributes

• An attribute describes a value held by objects belonging to the class.

• Attribute specification consists of:– Class it is defined on (student)– Attribute name (name)– Admissible values (string)– Optional: default value

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Values and Value Sets

• Values are the primitive things with no internal structure from the viewpoint of the application

• Admissible values are defined through a value set

• Typical predefined value-sets:– string, number, integer, real, range, boolean, ….

• User-defined:– set or list of strings

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Object Identifiers

• In O-O modeling you assume that every object has an identity.

• Consequence: introduce only attributes that act as identifiers, iff the identifier is something that exists in the real world.

• Examples: student card number, social security number.

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Operations

• Definition: – operation is "a function or a transformation that

can be applied to objects of a class".• Objects in a class share the same operations.• Method: implementation of an operation

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Class notationclass name

attribute-1: value-setattribute-2: value-set

operation-1(Par1:Type, Par2:Type): ReturnType

library book

catalog#: stringtitle: stringauthor: stringcategory: Categorycover-type: {hard-cover, paperback}

available(): Boolean

librarybook

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Associations

• Associations are used to link objects to other objects

• Majority of associations:– binary (between two objects)– directional (should be read in a particular direction

• Ternary associations come up occasionally.• Associations between more than three objects

are rare.

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Association notation

man woman0-1 0-1

wifehusband

man womanhusband wife

married-to

General notation for association

Notation for a binary association

married-to 0-10-1

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Multiplicity examples

student course

person

major

address<< has address

married-to

major subject >>

enrolled in >>

0+

0-1

1+

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Multiplicity

• Also called: "cardinality".• Always connected to one of the classes

involved.• Typical types of multiplicity:– 0-1 Zero or one (optional).– 1 Precisely one.– 0+ Zero or more,– 1+ One or more.

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Association class

• Modeling an association as a class if the association has an internal information structure

• Advantage: associations become first-class objects.

• Attributes and methods can be defined for the association class.

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Notation association class

man woman0-1 0-1

wifehusband

marriage

date: Date

cityregistered in >>

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Use of an association classcompany

name

person

namesocial security #addresssalaryjob title

person

namesocial security #address

company

name

<< works for

employer employee

1+1

employer employee

1+ 1+

works for

salary:job title

if you want to model thata person can work for

more than one company,then change to

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Associations with specific semantics

• Associations provide a general, "neutral", way of connecting object classes.

• Semantics of the association are defined through argument typing, multiplicity and (implicitly) the name of the association.

• Class diagrams provide specific types of associations, with predefined semantics:– generalization ("is a").– aggregation ("part of").

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Generalization

• Purpose: sharing similarities while preserving differences

• Is an association between a class that acts as super-class and one or more classes called the sub-classes.

• Super-classes show the features that the sub-classes have in common.

• Each sub-class inherits the attributes and operations defined on its super-class(es).

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Notation for generalizationagent

humancomputerprogram

man woman

taskexecutor-of >>

1+ 0+

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Aggregation

• Aggregation denotes a binary association in which one side is an "assembly" and the other side a "part".

• "Assembly" and "part" act as predefined roles involved in the aggregation association.

• Cardinality of a part can be defined – precisely one; optional (0-1); many, ...

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Notation for aggregationaudiosystem

tape deck

CD player

tuner

amplifier

speakerheadphones

recordplayer

0-1

0-1

0-1

0-1 0-1 2,4

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Composition

• Sub-type of aggregation• Existence of part depends on aggregate

document

nametype

openprint

paragraph

style0+

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Aggregation and generalization

• Similarities:– Tree-like structure

• Differences:– AND-tree (aggregation) vs. OR-tree

(generalization)– instance tree (aggregation) vs. class tree

(generalization)

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Combined aggregation and generalization

audiosystem

tape deck

CD player

tuner

amplifier

speakerheadphones

recordplayer

0-1 2,4input

system

1+

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Use-case diagram

• shows services that can be expected from a system

• provides outsider view (customer)• terminology

use case service provided by systemactor agent using a system service

• used in early phases of system analysis

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Use cases for a librarylibrary system

lend book

make bookreservation

search librarycatalog

add bookto catalog

remove bookfrom cataloglender librarian

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A small case study

• Course administration system (CAS)• Context: university department• Required services:

STUDENT: update personal data, inspect exam results, inspect course info, enroll in course

TUTOR: inspect exam results, update course info, inspect enrollments

ADMIN STAFF: enter exam results, inspect exam results, update personal data students, inspect enrollments

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Use cases

student

tutor

updatestudent data

inspectcourse info

updatecourse info

enrollin course

enterexam results

browseenrollments

browseexam results

browseindividual

results

browsecourseresults

administrativestaff

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Class diagram

student

student-card#: stringname: stringaddress: stringdate-of-birth: datamajor: Major.........

course

course-code: stringyear: integertrimester: 1-3study-points: integerlearning-goals: stringdescription: textliterature: textmaximum-#students: integer

exam

date: dateresult: [0..10]

enrollment

date: date

universitystaff member

title: stringposition: stringdepartment: stringtelephone: stringroom: stringe-mail: string

0+ 0+

course-exam1

0+

tutor

0+

1+

0+

requires

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Activity diagram for course enrollment procedure

submitenrollment

request

checkstudent limit

checkpreconditions

inform aboutprerequisites

inform aboutstudent limit

registerenrollment

inform aboutenrollment

[preconditionsOK]

[preconditionsnot OK] [above limit]

[limit notyet reached]

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State diagram:“update student data”

waiting fornotification

timer

received(new student data) send message to

central university database

localprocessing

do/update local databasedo/display results

OK message received from central database

[timer = time-out or not OK]/notify failure

Tools to draw UML

• Powerpoint• MS Visio: http://www.youtube.com/watch?

v=FPB0Tw9jFE8• Online: – http://creately.com/Draw-UML-and-Class-Diagram

s-Online– http://www.gliffy.com/uses/uml-software/