Systems Analysis & Design Methods UML diagrams. 2 System Analysis & Design Methods: UML diagrams...

Systems Analysis & Systems Analysis & Design MethodsDesign Methods

UML diagramsUML diagrams

2System Analysis & Design Methods: UML diagrams

BooksBooks

UML for JAVA ProgrammersUML for JAVA Programmers(Robert C. Martin © Copyright 2003.)(Robert C. Martin © Copyright 2003.)

A book you A book you shouldshould read, even if it is not read, even if it is not necessary for this course.necessary for this course.

UML distilledUML distilledMartin FowlerMartin Fowler


ContentsContents

Normalized data model (not UML)Normalized data model (not UML) Class Model, conceptual (very useful)Class Model, conceptual (very useful) Class Model, design (very useful)Class Model, design (very useful) Object Model (useful)Object Model (useful) Sequence DiagramSequence Diagram State diagram (very useful)State diagram (very useful) Collaboration diagrams (very useful)Collaboration diagrams (very useful) Using Collaboration diagrams Using Collaboration diagrams (very (very

useful)useful)


Just to compare with class Just to compare with class model:model:

normalized relational normalized relational database model (Not part of database model (Not part of

UML)UML)

Customer

name

address

CompanyCustomer

PrivateCustomer

Product

nameprice

OrderedItem

quantity

*

1

Order

date

*

1

*

1

0..1 0..

1

1 1

?

PK customer_id

FK customer_id

FK customer_id

FK customer_idPK order_id

PK product_id

FK order_id

FK product_id}PK


RemarksRemarks

I haven’t given the usual ERD I haven’t given the usual ERD diagram diagram notationnotation..Instead, I follow these rules:Instead, I follow these rules: Arrows start from the foreign key Arrows start from the foreign key

and end with the primary key.and end with the primary key. Why ?Why ? This way, the databasemodel can This way, the databasemodel can be directly compared to the OO class be directly compared to the OO class model. It also makes clear that the model. It also makes clear that the many-to-one-relations are realized using many-to-one-relations are realized using a field that sits on the many-side and a field that sits on the many-side and identifies the identifies the oneone side. Not vice-versa. side. Not vice-versa.


RemarksRemarks All my arrows go upAll my arrows go up

Why ?Why ? This way, because the arrows go from This way, because the arrows go from the foreign key to the primary key, the the foreign key to the primary key, the many many side –if there is one- is always lower than the side –if there is one- is always lower than the one-side.one-side.

Also, Also, the entity/table that is dependend is the entity/table that is dependend is always lower than the entity/table it depends always lower than the entity/table it depends onon..

This way, dependencies and (most) cardinalities This way, dependencies and (most) cardinalities can be derived at a glance. -> No arrow-can be derived at a glance. -> No arrow-staring nor diagram-deciphering required. staring nor diagram-deciphering required.


RemarksRemarks

I do not show…I do not show…In order to be able to compare to the UML

class model, certain details, that are part of ER-diagrams are not shown:

…Relationship-types Identifying Non identifying Informative


Differences with Class Differences with Class models at models at

specification/implementaiospecification/implementaion leveln level Every field is supposed to be persistent.Every field is supposed to be persistent.

Pointers/Navigatabilities are always UNIdirectional.Pointers/Navigatabilities are always UNIdirectional. One to many relationships always point to the one-One to many relationships always point to the one-

side.side. The other way around would brake first normal form.The other way around would brake first normal form.

Normalization demands ‘no data redundancy’ nor Normalization demands ‘no data redundancy’ nor calculated fields. (OO specification/implementation calculated fields. (OO specification/implementation level class models would allow private redundant level class models would allow private redundant attributes e.g. for cashing)attributes e.g. for cashing) E.g. no orderPrice field in order !!!E.g. no orderPrice field in order !!!

No process/methods/procedures/functionsNo process/methods/procedures/functions E.g. no getOrderPrice method !!!E.g. no getOrderPrice method !!!

Possible sub-type tables (if allowed) cannot exploit Possible sub-type tables (if allowed) cannot exploit polymorphismpolymorphism


Class DiagramClass Diagram

Class diagrams are static. This Class diagrams are static. This means they are independent of the means they are independent of the moment in runtime. E.g. even if you moment in runtime. E.g. even if you might have hundreds of orders for might have hundreds of orders for one customer, you would still draw one customer, you would still draw just one class diagram ‘Order’. just one class diagram ‘Order’.


Class DiagramClass Diagramconceptualconceptual level level

Customer

+creditRating:String

-name-adress

CompanyCustomer

+billForMonth(int)

PrivateCustomer

-contact

Product

+getPrice():double

-name-price

OrderedItem

+getOrderedItemPrice():double

-quantity

*

1

Order

+getOrderPrice:double

-date

*

1

*

1

Association

Attributes

Multiplicity –or- Cardinality

Generalization

Method


Class DiagramClass Diagramspecification specification levellevel

Customer

+creditRating:String

-name-adress

CompanyCustomer

+billForMonth(int)

PrivateCustomer

-contact

Product

+getPrice():double

-name-price

OrderedItem


-quantity

*

1

Order

+getOrderPrice:double

-date

*

1

*

1

*

Navigatability


Class DiagramClass Diagramspecificationspecification levellevel

‘‘Specification’ means ‘Design’Specification’ means ‘Design’

You make design decisions. You make design decisions.

The arrowheads show which class has the The arrowheads show which class has the attribute pointing to the other(s). An attribute pointing to the other(s). An association with a navigatability in 1 association with a navigatability in 1 direction is called: unidirectional direction is called: unidirectional association. association. E.g. A customer points to many orders means:E.g. A customer points to many orders means:

Each Customer object will have a List attribute Each Customer object will have a List attribute of Order-objects (rather than than each Order-of Order-objects (rather than than each Order-object has a Customer-attribute)object has a Customer-attribute)



OrderedItem


Order

+getOrderPrice:double *1

OrderedItem


Order


OrderedItem


Order


-orderedItems: List

-order: Order

Design solution n° 1

Design solution n° 2

Conceptual



Navigatablitities are important. With design solution Navigatablitities are important. With design solution n°2, the functionality of the following code in n°2, the functionality of the following code in Order would be hard to write. Thanks to right Order would be hard to write. Thanks to right navigatability, I can delegate to OrderedItem: navigatability, I can delegate to OrderedItem:

public class Order{ public class Order{

… …

public double getOrderPrice(){public double getOrderPrice(){

double orderPrice = 0; double orderPrice = 0;

OrderedItem oItem;OrderedItem oItem;

for(int i = 0; i < orderedItems.size(); i++){for(int i = 0; i < orderedItems.size(); i++){

oItem = (OrderdItem) orderedItems.get(i);oItem = (OrderdItem) orderedItems.get(i);

orderPrice += oItem.getOrderedItemPrice(); orderPrice += oItem.getOrderedItemPrice();

}}

return orderPrice;return orderPrice;

}}

… …

}}


Object DiagramObject Diagram

Object diagrams are dynamic. This Object diagrams are dynamic. This means they depend on the moment means they depend on the moment of time during the system run. At of time during the system run. At implementation level, they are a implementation level, they are a snapshot of memory. E.g. if at a snapshot of memory. E.g. if at a certain moment in time a customer certain moment in time a customer record has 42 orders and you want record has 42 orders and you want to model this, you should draw 42 to model this, you should draw 42 order rectangles. order rectangles.


Object DiagramObject Diagram

:PrivateCustomer

-name = “Scott”

:Order

-date = 1/1/2003 :Order

-date = 1/5/2003 :Order

-date = 20/1/2001

orders.get(0) orders.get(1) orders.get(2)

Link

:OrderedItem

-quantity=2 :OrderedItem

-quantity=3 :OrderedItem

-quantity=10

:OrderedItem

-quantity=250

…orderedItems.get(0)orderedItems.get(1)orderedItems.get(2)

orderedItems.get(0)

:Product

-name= “Dell Dim 2.0”-price = 1000.0

product

:Product

-name= “Compac X2”-price = 2000.0

productproduct


Sequence DiagramSequence Diagram

:OrderItem

time

getOrderedItemPrice()getOrderedItemPrice()

:Product

getPrice()getPrice()

:double

:double

:Order

Loop

Data token

Activation


Sequence Diagram Sequence Diagram (continued)(continued)

[[topNode==nultopNode==null]l]

[topNode![topNode!=null=null]]

:TreeMap

add(key,value)add(key,value)

Guard


Sequence diagram Sequence diagram (continued)(continued)

Sequence diagrams are generally Sequence diagrams are generally harder to understand than the code harder to understand than the code they try to model, especially when they try to model, especially when loops and conditions are involved.loops and conditions are involved.


State Diagram (FSM)State Diagram (FSM)

ReadingNormalCodeReadingNormalCode

ReadingStringReadingStringDoubleQuoteEncountered/DoubleQuoteEncountered/StartWritingStringStartWritingString

DoubleQuoteEncountered/DoubleQuoteEncountered/SaveWrittenStringSaveWrittenString

NonDoubleQuoteEncountered/NonDoubleQuoteEncountered/AppendToStringAppendToString

StartStart

NonDoubleQuoteEncountered/NonDoubleQuoteEncountered/AppendToStringAppendToString

Event Action

State

Transition


:Button

Collaboration diagramCollaboration diagram

:Button

send:Button

:Dialer :Radio

:Screen :Speaker

Example taken from UML for Java programmersRobert C. Martin (2003). The letter A means ‘separate process‘

1*:digit(n)

1.1:displayDigit(n)1.2:tone(n)

2.1:connect(pno)

A1: inUse

2: Send


using a Collaboration using a Collaboration DiagramDiagram

Class diagrams can be used as a basis Class diagrams can be used as a basis for implementation. for implementation.

We build class diagrams in small steps:We build class diagrams in small steps: Take a part of the problem (e.g. a use Take a part of the problem (e.g. a use

case)case) Build a collaboration diagram in a step by Build a collaboration diagram in a step by

step fashion. step fashion. Extract a class diagramExtract a class diagram Improve the design (not shown)Improve the design (not shown)



Example problem: Software that Example problem: Software that controls a celular phone.controls a celular phone.

Example Example partpart of the problem: ‘making of the problem: ‘making the phone call.’ the phone call.’ (adapted from UMLFJP R.C. (adapted from UMLFJP R.C. Martin )Martin )



building the diagrambuilding the diagramHow do you start making a phone call ?How do you start making a phone call ?

You press a You press a buttonbutton with a digit on it. We imagine with a digit on it. We imagine some controlling piece of machinery capable of some controlling piece of machinery capable of dialing, that remembers the digits we entered, say dialing, that remembers the digits we entered, say a a dialerdialer..

:Button :Button :Dialer 1*:digit(n)



building the diagram building the diagramAnything else happening when you press a Anything else happening when you press a

digit button ?digit button ?

Yes. The dialer needs to get the digit to be Yes. The dialer needs to get the digit to be displayed on displayed on screenscreen and maybe a sound to and maybe a sound to be emitted by a be emitted by a speakerspeaker..

:Button :Button :Dialer

:Screen :Speaker

1*:digit(n)




building the diagram building the diagramYou keep on hitting digit buttons forever ? You keep on hitting digit buttons forever ? No.No.

Eventually you press the green phone Eventually you press the green phone button, lets say button, lets say send send button. You expect button. You expect the dialer to do what needs to be done. the dialer to do what needs to be done.

:Button :Button

send:Button

:Dialer

:Screen :Speaker

1*:digit(n)


2: Send


using a Collaboration using a Collaboration Diagram: building the Diagram: building the

diagramdiagramLets say the dialer delegates the work of ‘sending the phone Lets say the dialer delegates the work of ‘sending the phone number to the network’. It delegates this to a piece called number to the network’. It delegates this to a piece called radioradio..

When a connection is finally established, the screen might need When a connection is finally established, the screen might need to show an ‘in Use’ message.to show an ‘in Use’ message.

This is beyond the direct control of the cellular phone (different This is beyond the direct control of the cellular phone (different thread).thread).

:Button :Button

send:Button

:Dialer :Radio

:Screen :Speaker

1*:digit(n)


2.1:connect(pno)

A1: inUse

2: Send


using a Collaboration using a Collaboration Diagram:Diagram:

Deriving an initial class Deriving an initial class diagramdiagram

+digit(n:int)

+send

+tone(n:int)

+displayDigit(n:int)

+connect(pno:String)

Button

Speaker

Screen

Dialer Radio-lastpno:String*

Directions of messages becomes navigatabilitiesDirections of messages becomes navigatabilities Sent messages become methodsSent messages become methods Object counts becomes cardinalitiesObject counts becomes cardinalities

Systems Analysis & Design Methods UML diagrams. 2 System Analysis & Design Methods: UML diagrams...

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