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© Chinese University, CSE Dept. Software Engineering / 5 - 1

Software Engineering

Topic 5:Software Design

Yor !a"e: #####################

Co"pter Science $ Engineering Depart"ent

The Chinese University of %ong &ong

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Prelude

♦ Software (esign sho)( *e *ase( on s/w engineeringprincip)es + igor an( for"a)ity

ppropriate notations for (esign

+ Separation of concerns, o()arity, *straction %an()e (esign co"p)e0ity, "ae s/w n(erstan(a*)e an(

re)ia*)e

+ nticipation of change, 2ncre"enta)ity 3ro(ce evo)va*)e s/w (esign

+ 4enera)ity 3ro(ct fa"i)y

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Prelude

♦ Software (esign sho)( *e *ase( on s/w engineeringprincip)es + igor an( for"a)ity

ppropriate notations for (esign

+ Separation of concerns, o()arity, *straction %an()e (esign co"p)e0ity, "ae s/w n(erstan(a*)e an(

re)ia*)e

+ nticipation of change, 2ncre"enta)ity 3ro(ce evo)va*)e s/w (esign

+ 4enera)ity 3ro(ct fa"i)y

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Prelude

♦%igh 7a)ity (esign + "o()ar strctre

+ (eco"position criteria

♦2nfor"ation hi(ing: a "o()e is characteri8e(*y the infor"ation it hi(es fro" other "o()es⇐ ########### + 2nfor"ation hi(ing 9 a*stract (ata type

⇒

- (esign + #############(esign

♦Stepwise refine"ent: ########## (esign

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Top-down vs. Bottom-up Designs

Top-(own (esign ;otto"-p (esign

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Software Design Activity

♦ Software (esign + syste" (eco"position into ############

♦ Description ofa=fnctions of each "o()e >? ####-"o()e

*=interfaces *etween "o()es >? ####-"o()e

⇒ the software strctre @architectre=

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♦2"p)e"ent

♦Design for change

+ (esign that is f)e0i*)e enogh to acco""o(ate

changes easi)ye.g. B########### for constant na"es in C

Software Design Activity

M

M

M

M

D ecom pose →

1

2

3

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What hanges!

♦ Change of a)gorith"s + to i"prove efficiency, genera)ity

+ e.g. sorting a)gorith" @############ → ############=

♦ Change of (ata strctre @1A "aintenance cost= + e.g. arrays vs )ine( )ists

+ Data strctres representing a Tree

♦ Change of n(er)ying a*stract "achine + %i(es (etai)s of the n(er)ying h/w

+ e.g. co"p)ier, (ata*ase, S

♦ Change of periphera) (evices + e.g. printers, ter"ina)s, icrosoft e0perience

♦ Change of socia) environ"ent + e.g. ta0, socia) ha*its, crrency changes

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What hanges!

♦ Change of a)gorith"s + to i"prove efficiency, genera)ity

+ e.g. sorting a)gorith" @############ → ############=

♦ Change of (ata strctre @1A "aintenance cost= + e.g. arrays vs )ine( )ists

+ Data strctres representing a Tree

♦ Change of n(er)ying a*stract "achine + %i(es (etai)s of the n(er)ying h/w

+ e.g. co"p)ier, (ata*ase, S

♦ Change of periphera) (evices + e.g. printers, ter"ina)s, icrosoft e0perience

♦ Change of socia) environ"ent + e.g. ta0, socia) ha*its, crrency changes

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Data Structure "epresenting a Tree #$%

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Data Structure "epresenting a Tree #&%

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Product 'amilies

♦ set of (ifferent versions of a progra", (e to + (ifferent h/w or s/w

+ (ifferent environ"ent with (ifferent re7ire"entson perfor"ance or resorce cons"ption

+ syste" evo)tion (e to new re7ire"ents or7a)ity i"prove"ent

+ Usa))y with the sa"e *asic set of fnctiona)

re7ire"ents

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Product 'amilies

♦The so)tion: + "ini"i8e the cost of changing (esign (ecisions

!ecessary too)s to "anage pro(ct fa"i)ies:

############################ too)s

S ti l l ti

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Se(uential ompletion)

A *raphical +iew

Requirements

1

2

3

Version 1

Version 1

Version 2 5

Requirements

1

2

3

4 6

7 Version 3

4

Requirements

1

2

3

Version 2 5

Version 1

4

____________

__________

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,odulariation Techni(ues

1= rchitectre (esign @overa)) strctre='= Detai)e( (esign @(esign of each "o()e *y

Binfor"ation hi(ing=

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#$% verall Structure

♦o()e - a we))-(efine( co"ponent of a s/wsyste"

+ se)f-containe(

+ with c)ear *on(ary

+ co))ection of otines @.c=

Data

Type#(efinitions @.h=

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♦!otation)et S *e a s/w syste", co"pose( of "o()es 1, ' ,H, n

i.e., S > I 1,',H,n J

re)ation r on S is a s*set of SKS

@ car(ina)ity > ############## =

i.e., r: "o()e K "o()e ;oo)ean

Le say i is re)ate( to M @*oth in S= iff i r M is tre.

@ e.g. r: Bca)) =

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♦ The re)ations for "o()esi. ###########: N@i r i=

ii. contain ###############: i r 9 M

iff i r M or ∃ → i r an( r 9

Miii. ########@########=:if i r 9 M → N @ M r 9 i=

♦ hierarchy re)ation "eans there are no ########## in the graph of the re)ation

(irecte( acyc)ic graph @D4=

vs. genera) graph @Oiger 5.1=

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*eneral *raph Directed Acyclic *raph#DA*%/evel

000

000

000

000

000

M1

M2M3

M4

M1,1 M1,2 M1,3

M1,2,1 M1,2,2

M1,2,1,1

M

M M

M M

M

1

2 3

4 5

6

a) b)

'igure 1.$ *raph representation of a relation among modules2

#a% *eneral graph2 #3% Direct acyclic graph #DA*%

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/evels in a 4ierarchy "elation

+ PEQEPG: Ii R ¬ ∃ M ∈ S → i r MJB #########################################################################################

#########################################

+ PEQEP91

: Ii R ∃

M∈ PEQEP

→

i r

M an( ∀

"

∈ S, i r "⇒ " ∈ PEQEP", " ∈ G,H, J

B #########################################################################################

#############################

+ "o()e i is Bhigher )eve) than "o()e M iff i ∈ PEQEPi and M ∈ PEQEP M and i ? M

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The 5SES "elation

+Oor i, M ∈ S, i USES M iff correcte0ection of M is necessary for i to *e

correct

i is a c)ient of M n o*vios USES e0a"p)e is when i an( its

correctness (epen( on a ca)) to a proce(re in"o()e M

+: 2s ################# e7iva)ent to ################## re)ationV

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5SES 6s 7ot E(uivalent to alls

a= proce(re ca))s are not the on)y way for "o()esto interact @!ot a)) USES are ca))s=

WE.g.1 in asse"*)y, a "o()e "ay "o(ify )oca)(ata or instrctions of another "o()e

WE.g.' #######################

) 00000000000000000 'ortran) 0000000000000

*eneral) 0000000000+aria3les

write read

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5SES 6s 7ot E(uivalent to alls

+ E.g. e0change of contro) infor"ation @#####= + E.g.6 in se7entia) environ"ent, "o()es "ay

co""nicate via para"eter passing throghs*progra"s

+ E.g.5 in concrrent environ"ent, "o()es "ayco""nicate via "essages passing throgh tass

*=!ot a)) ca))s are USES E.g. ca))ing for reporting e0ceptions

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5SES "elation

♦USES re)ation is static, i.e., in(epen(ent of thee0ection of the s/w:

in o()e :

Bif con( then proc1 e)se proc'

in 1 in ' 8 8 5SES

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5SES "elation

♦ Oor a goo( (esign, USES re)ation sho)( *e hierarchyi. easy to n(erstan(

W Bseparation of concerns >? se( co"ponents first, then theirc)ients

ii. easy to i"p)e"ent

W Bincre"enta)ity => otherwise, Bwe "ay en( p with a syste" inwhich nothing wors nti) everything wors.

iii. easy to (efine strctreW B)eve)s of a*straction => high-)eve) "o()es @c)ients= first, then

)ow-)eve) @se(= "o()es #iii% ⇒ 00000000000000000 design

#i%#ii% ⇒ 0000000000000000 implementation

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4ow to Build 4ierarchy "elations!

♦ &ey: (ecop)ing "o()es to avoi( recrsion a"ong"o()es.

1. recrsion within a "o()e (oes not affect there)ation a"ong "o()es

'. consi(er an a)ternative a)gorith" which (oes notre7ire recrsion

. if two "o()es have to USES each otherrecrsive)y, grop the" together into one )arge"o()e

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4ow to Build 4ierarchy "elations!

6. consi(er sp)itting one "o()e into two:, ,9

,

,9

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6S0,P7E7T0' "elation

Pet S *e a set of "o()es 1,',H,nfor any i, M ∈ S, i 2S#C3!E!T#O M "eans

B M is rea)i8e( *y severa) "o()es, one of which *eing i

⇒ M C32SES i

Pet s,i *e a s*set of S where

s,i > I R ∈ S an( 2S#C3!E!T#O iJ

then we say

i 2S#C3SED#O s,i or s,i 23PEE!TS i

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: ,; is component of 00000

: 0000000 comprises ,;

: 000000000000000 implements ,&

: ,& is composed of 0000000000000000000

M1

M M

M MM M M

2 4

5 67 8 9

M3

M MM M M

5 67 8 9

M2 M3 M4

M1

(IS_COMPONENT_OF) (COMPRISES)

'igure 1.& An e

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7otations for a Design

♦2n a (esign, once i is (eco"pose( into theset s,i, it is rep)ace( *y the" in the

i"p)e"entationX i *eco"es "ere)y an

a*straction for that i"p)e"entation

♦3hysica))y, the fina) i"p)e"entation on)ycontains the B)eaf "o()es in a C32SESre)ation graph

P d ' ili " i i d

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Product 'amilies "evisited

6s-composed-of

,929,92&,92$

,9

5ses

,;

,9

,1,=

,& ,>

,$

5ses

+ersion $

Design

Decision $

Design

Decision &

+ersion &

5ses

,$

0000000 ,>

0000000 0000000

,&

,$

0000000 ,>

0000000 0000000

,&

D i / l +i i3ili

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Design /evel +isi3ility

Data f)ow )eve)

Strctre chart )eve)

800000000000000?

A * d D i 4i h

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A *ood Design 4ierarchy

1. 3artition the (esign: ######## vs ########

'. there is "ore than one )eve)

. there arent too "any )eve)s6. for each i ∈ S, the set of "o()es

I M R i r M J to which it USES is s"a))

B)ow ######## + n"*er of otgoing e(ges of a"o()e

@ e0a"p)e =

A * d D i 4i h

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A *ood Design 4ierarchy

5. for each i ∈ S, the set of "o()es @c)ients=I M R M r iJ which USES i is )arge

Bhigh ####### + n"*er of inco"ing e(ges of a"o()e

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6nterface2 6mplementation2 and

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2 p 2

6nformation 4iding

♦ 2n the USES re)ation, the set of services that each"o()e provi(es to its c)ients is ca))e(

################

+ The services are e0porte( *y the se( "o()es an(

i"porte( *y the c)ients♦ The interface is an ############# of the "o()e

as viewe( *y its c)ients

♦ (esigner of "o()e on)y nee(s to now the

interfaces of other "o()es se( *y , an( "ayignore their ################.

6nterface2 6mplementation2 and

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p

6nformation 4iding

♦ 2nterface + #########################

+ #########################

+ #########################

♦ 2n s""ary, the c)ients of a "o()e now a*ot itsservices on)y throgh its interface, thei"p)e"entation is hi((en fro" the"

⇒ 2nfor"ation hi(ing, an i"portant concept forsoftware engineering princip)es

4ow to Design 6nterfaces 'acilitating

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g g

6nformation 4iding!

♦The interfaces sho)( *e as si"p)e aspossi*)e, *t not si"p)er

♦ i(entify changea*)e (esign (ecisions an(nchangea*)e "o()e infor"ation

i. nchangea*)e infor"ation⇒ ################ @sta*)e=

ii. changea*)e (esign (ecisions⇒

Bsecret @hi((en in the ################

=Le say sch infor"ation is ################ withinthe "o()e i"p)e"entation.

Typical Secrets

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Typical Secrets

1. The a)gorith" for carrying ot so"e operation, e.g.a)gorith"s for sorting rotine

'. The representation of so"e (ata strctre, e.g.a*stract (ata type

+ C)ients now how to operate it, *t (o not now how it

is i"p)e"ente(. The (etai)s of an interface to the a*stract "achine

n(er)ying the s/w

6. The po)icy for a))ocating so"e resorce or or(ering

certain operations @e.g., 32!T a sorte( )ist=5. *stract (ata type

A3stract Data Type

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A3stract Data Type

♦ *stract (ata type is an infor"ation hi(ing"o()e where the representations of (atastrctres are encaps)ate(.

+ e.g. Bstac co)( *e (efine( in on)y for operationsin its interface: #####,####,####, init

A 7ote A3out Architectural Design

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A 7ote A3out Architectural Design

♦ precise (efinition of the interface isnecessary for "o()e @re=sa*i)ity

+ %igh #########X %igh ##########

♦The interface "st contain a)) the infor"ationthat is nee(e( to characteri8e the "o()es*ehavior, an( nothing "ore

+ Pow ##########

Procedures for Architectural Design

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Procedures for Architectural Design

1. pp)y USES an( 2S#C3!E!T#O!otations

'. ;i)( hierarchy re)ations @avoi( recrsion=

. 2(entify "o()es with high cohesion an( )ow

cop)ing6. Design interface

5. %i(e infor"ation

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#&% Detailed Design

♦s/w (esign notations + for"a) in synta0

+ infor"a) in se"antics

1. TD! @Te0ta) Design !otation=

'. 4D! @4raphica) Design !otation=

TD7) Te

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TD7) Te

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'igure 1.9 A Sample ,odule Description

module Z

uses Y, [export

var : integerX

type ;: array @1..1G= of rea)X

procedure C@D: in out ;X E in integerX O: in rea)=

______________________________

Implementation

______________________________

is co"pose( of , T

end Z

'igure 1 9 A Sample ,odule Description

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module Z

uses Y, [export

var : integerX



Here is an optional natural language description of what A, B and C actuallyare, along with possible constraints or properties that clients need to know; forexample we might specify that objects of type B sent to procedure C should beinitialized by the client, and should neer contain all zeros!

Implementation

"f needed, here are general comments about the rationale of themodularization, hints on the implementation, etc!

is co"pose( of , T

end Z

'igure 1.9 A Sample ,odule Description

'igure 1 > Sample omponents of ,odule @

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'igure 1.> Sample omponents of ,odule @

module

uses Y

export

var &: record H endX



Implementation

H

end

module T

uses Y, [,

exports var : integerXimplementation

H

end T

'igure 1.1 An E

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Selective 6mport

module L

uses Z imports@;,C=,

ZZ

exports H

implementation

.

.

.

end L

@ e

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TD7

♦ TD! (esign taes so"e ti"e toco"prehen(

♦TD! can provi(e varios )eve)s of (etai)s

+ e.g., ############## in great (etai)

♦The (esigner nee(s to chec for consistencyan( co"p)eteness

♦The te(ios checing proce(re sho)( *e

ato"ate( if possi*)e♦ "ore co"p)icate( e0a"p)e fo))ows.

*D7 #*raphical Design 7otation%

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# p g %

♦a *o0 represents a ###########♦ inco"ing arrows represent a "o()es

##########, i.e., e0porte( ###########

♦not to *e confse( with DOD

♦can a)so show B2S#C3SED#O an(B2S#C3!E!T#O re)ations

'igure 1.= *D7 of ,odule @

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Oigre 5.< 4raphica) (escription of "o()e Z of Oigre 5.

gu e . * o odu e

X

Y

Z

A B

R TModuleModule

Module

Module

Module

C

'igure 1.; @s Decomposition

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g p

Oigre 5.A o()e Z is co"pose( of "o()es an( T

X

Y

ZBC

R TModuleModule

Module

Module

Module

A

K

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o()e

o()e P o()e !

o()e

o()e

o()e

o()e S

o()e % o()e 4

Oigre 5. o()e is a "e"*er of *oth P an( !

A

B

C

Module M

IS_COMPONENT_OF what?

_________________

IS_COMPOSED_OF what?

_________________

Exports what?

_________________

USES what?

_______ (which exports _______ o()e O

*D7 #*raphical Design 7otation%

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# p g %

♦2t provi(es Bs/w (esign visa)i8ation

♦2t is sef) in co"prehen(ing co"p)icate( s/[email protected]., concrrent s/w=

♦2t "ay tae too "ch space

♦2t is sef) for high-)eve) view of the s/w (esign

♦Detai)e( )eve)s nee( to *e ato"ate( @CSE=

+ E.g., State"ate, ationa), UP

ategories of ,odules

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g

1= 3roce(ra) a*stractions + prpose: to encaps)ate an ############ + e.g.: sorting "o()e, fast Oorier transfor"

"o()e

'= Pi*raries + prpose: to grop together re)ate(

###########################

+ e.g.: "athe"atica) rotines

graphica) rotines


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g

= Co""on poo) of (ata + prpose: to share ####### a"ong severa)"o()es

+ e.g.: syste" configration constants grop

+ note:


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6= *stract o*Mects + prpose: to hi(e the (etai)s of (ata ##########@change of (ata strctres is ######### of cost fortota) software "aintenance=

+ e.g.: a sy"*o)-ta*)e + note: e0hi*it a state


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5= *stract (ata type + prpose: to hi(e the ########### of a (ata typean( the a)gorith"s se( in ######## the o*Mects ofthat type

+ e.g.:

Stac (a - private type

o()e-' - opa7e type

+ note:

i= no stateii= can generate "any instances @ ########### =

Stac as an A3stract Data Type

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© Chinese University, CSE Dept. Software Engineering / 5 - i loop

if a(i) > a(j) then

interchange the elements at positions j and i ;end if ; j := j 1;

end loop;

i := i + 1;end loop;

Step !

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© Chinese University, CSE Dept. Software Engineering / 5 - i loop

if a(i) > a(j) then" := a(i);a(i) := a(j);a(j) := ";

end if ;

j := j 1;end loop;i := i + 1;

end loop;

Stepwise "efinement

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3'

3

31 3 5

3 ',1

3',1,1

3',1,'

C

C1

not C1

Oigre 6.15 4raphica) representation of stepwise refine"ent.

FWhile loop P&2$G

G

F 6f $ then P&2$2$

Else P&2$2&G

Step H

Step $

Step &

Step 7

Stepwise "efinement

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♦

2t is a "etho( that wors in the s"a)), *t fai)sin the )arge. %ere are the reasons:

1. s*-pro*)e"s ten( to *e ana)y8e( in iso)ation,re(cing ##############

'. !o attention is pai( to ############### . !o attention is pai( to ###############

6. The ######## fnction "ay not e0ist

5. pre"atre co""it"ent to the ############

strctres

A Short Summary A3out Design

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♦ stepwise refine"ent + top-(own (esign

♦ infor"ation hi(ing + *otto"-p (esign

♦ co"*ining *oth + yo-yo (esign

1. (esign sho)( se *oth sche"es

'. (escription of the res)ting (esign sho)( *e ##############

4andling Anomalies

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♦To achieve re)ia*)e so)tions

+ Syste"atic (esign approach

+ igoros an( (iscip)ine( i"p)e"entation

♦ne so)tion: e"p)oy ########## (esign

+ 3rpose: *i)( ro*st syste"s

+ The progra" sho)( contine to *ehavereasona*)y even in the case of ne0pecte( an(nforeseen circ"stances

4andling Anomalies

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♦ no"a)os + if a "o()e fai)s to provi(e aservice as e0pecte( an( specifie( in itsinterface

+ ######### + to *e associate( with a service,

(enoting the ano"a)ies that "ay occr whi)e thatservice is *eing perfor"e(

4andling Anomalies

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♦Defensive (esign re7ires that pon enteringan ano"a)os state, the "o()e sho)( signa)the ano"a)y *y raising an e0ception to thec)ient

♦The server "o()e ter"inates the serviceafter ######### an e0ceptionX the c)ientrespon(s *y sita*)y ######## the e0ception

Why an E

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© Chinese University, CSE Dept. Software Engineering / 5 - A<

1. s c)ient (oes not satisfy the re7ire(protoco) for invoing one of s service

'. Lhen provi(ing a service to its c)ient, (oes not invoe a service e0porte( *y

another "o()e proper)y. fai)s to provi(e its service *ecase of an

nforeseen con(ition

,s client,s client

A

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© Chinese University, CSE Dept. Software Engineering / 5 - AA

,s server

,

00

00

00

,s server

B

B

000000 an

e

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module /exports . . .

procedure 3 @Z: 2!TE4EX . . .=

raises Z#!!#!E4T2QE#EZ3ECTED,2!TE4E#QEOPLX

$ is to be positie; if not, exception $%&'&%&()A#"*(%($+(C#( is raised;"()(-%'*(-./'0 is raised if internal computation of + generates an oerflow

.

.

.

end /

,odule /

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© Chinese University, CSE Dept. Software Engineering / 5 - AF

module P uses / imports 3 @Z: 2!TE4EX . .=exports . . .X

procedure @ . . .=

raises 2!TE4E#QEOPLX . . .

implementation "f "()(-%'*(-./'0 is raised when + is inoked, the exception is propagated . . .

end P

oncurrent Software

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♦The case of a "o()e (efining share( (ata

♦ E.g., a*stract o*Mect ;UOOE + "o()e UEUE#O#C% is 4E!E2C#O2O#UEUE

@C%=

+ ;UOOE : UEUE#O#C%.UEUE

with operations + 3UT: inserts a character in ;UOOE

+ 4ET: e0tracts a character fro" ;UOOE

+ !T#OUPP: retrns tre if ;UOOE not f))

+ !T#E3TY: retrns tre if ;UOOE not e"pty

4ow to ontrol orrect Access toShared Data!

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♦

!ot sfficient that c)ients chec operationinvocations, sch asif UEUE#O#C%.!T#OUPP @;UOOE= then

UEUE#O#C%.3UT @Z, ;UOOE=X

en( ifX

♦Cons"er#1 an( Cons"er#' "ight (o thisconcrrent)y

if on)y one s)ot is )eft, *oth "ay fin( the *ffer not f)),

the first who writes fi))s it, an( the other writes in a f))*ffer

Enforcing Synchroniation

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♦Ensre that operations on *ffer are e0ecte(in mutual exclusion

♦Ensre that operations sch asif UEUE#O#C%.!T#OUPP @;UOOE= then

UEUE#O#C%.3UT @Z, ;UOOE=Xen( ifX

are e0ecte( as )ogica))y non-interrpti*)enits

,onitors

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♦ *stract o*Mects se( in a ############environ"ent

♦ vai)a*)e in the ]ava progra""ing )angage

,onitors) an E

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concurrent module C%#;UOOE

#his is a monitor, i!e!, an abstract object module in a concurrent enironment

uses . . . exports

procedure 3UT @C : in C%= reuires !T#OUPPX

procedure 4ET @C: out C%= reuires !T#E/3TYX &'#%(1+#2 and &'#%.3// are hidden Boolean functions yielding #-3( if the buffer is not empty and not full, respectiely! #hey are not exported as operations, because their purpose is only to delay the calls to +3# and )(# if they are issued when the buffer is in a state where it cannot accept them . . .

end C%#;UOOE

omments on ,onitors

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♦onitor operations are ass"e( to *ee0ecte( in #################

♦ requires c)ase "ay *e associate( with anoperation

+ it is ato"atica))y chece( when operation isca))e(

+ if the res)t is fa)se, the crrent process issspen(e( nti) it *eco"es tre @at that stage it*eco"es e)igi*)e for res"ption=

,onitor Types) an E

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!eneric concurrent module 4E!E2C#O2O#UEUE @EP= #his is a generic monitor type, i!e!, an abstract data type accessed in a concurrent enironment

uses . . . exports

type UEUE: VX procedure 3UT @1: in out UEUEX E1: in EP=

reuires !T#OUPP @1: UEUE=X procedure 4ET @': in out UEUEX E': out EP=

reuires !T#E/3TY@': UEUE=X . . .

end 4E!E2C#O2O#UEUE @EP=

*uardians and "ende-vous

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♦The (a sty)e of (esigning concrrentsyste"s

♦ 2n (a a share( o*Mect is ###########@whereas a "onitor is ############=

+ it is "anage( *y a guardian process which canaccept ren(e8-vos re7ests fro" tass wi))ing toaccess the o*Mect

A *uardian Tas

f

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loopselect

when NOT_FULLaccept PUT (C:in CHAR);This is the body of PUT; the client calls it as if itwere a normal procedure

end;orwhen NOT_EMPTYaccept GET (C:out CHAR);This is the body of GET; the client calls it as if itwere a normal procedure

end;end select;

end loop;

note _______________ a##eptan#e of

rende$%o&s re'&ests

A 'urther "elation) 6nheritance#*eneraliation I Specialiation%

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♦ The eywor( in @pre= o*Mect-oriente( (esign:

Binheritance - to for" a c)ass of o*Mects. + e.g., Bc)ass in C99 @p*)ic, private, protecte(=

+ e.g., Be0ten(s in ]ava creates Bs*c)asses

♦ DTs "ay *e organi8e( in a hierarchy

♦ C)ass ; "ay specia)i8e c)ass + ; inherits fro"

converse)y, genera)i8es ;

♦ is a sperc)ass of ;

♦ ; is a s*c)ass of

Cey oncept in - Design) 6nheritance

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© Chinese University, CSE Dept. Software Engineering / 5 - FG

♦ new re)ation: 2!%E2TS#O

♦ 2f 1 2!%E2TS#O ', then 1 has visi*i)ity into

the interna) strctre @the #######= of '

a hierarchy re)ation

1. ##################### '. #####################

. #####################

1 2!%E2TS#O '

+ ': parent "o()e + 1: heir "o()e

An 6nheritance E

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o()e E3PYEE

o()e

D2!STT2QE

STOO

o()e

TEC%!2CP

STOO

4ET#S&2PPDEO#S&2PP

D#T%2S

!E 4E

L%EEo()e S2TE

... to "o()es !EY

e

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♦ 2nheritance a))ows a hierarchica) c)assification

sche"e for a*stract (ata types throghgenera)i8ation-specia)i8ation re)ations

+ (istingish co""ona)ities an( (ifferences a"onga @potentia)= set of a*stract o*Mects

+ co""ona)ities are factore( ot in a ########c)ass

+ variations are sing)e( ot in the ###########

c)asses

Properties of 6nheritance

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♦2nheritance i"proves resa*i)ity - ########

c)ass

♦2nheritance is a way of *i)(ing software ##############

♦Disa(vantage of inheritance

Properties of 6nheritance

♦ s*c)ass (efines a s*type

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♦ s*c)ass (efines a s*type

+ s*type is substitutable for parent type

♦3o)y"orphis"

+ a varia*)e referring to type can refer to an o*Mect oftype ; if ; is a s*c)ass of

♦Dyna"ic *in(ing

+ the "etho( invoe( throgh a reference (epen(s onthe type of the o*Mect associate( with the reference

at rnti"e

Several #ontroversial% E

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♦ e(efinition: an heir pro(ct provi(es a (ifferent

i"p)e"entation for one of its parents services + e.g., change of the sorting a)gorith" regar(ing its i"p)e"entation

@no change to interface=

+ ####### an( ######### a))ow itX ######## (oes not

♦ e(efinition app)ie( to the (ata strctre hi((en in theparent "o()e

♦ )tip)e inheritance: (efine a new "o()e *y co"*ining thefeatre provi(e( *y two or "ore parent "o()es

+ e.g., O2O#UEUE, E3PYEE

+ ######## a))ows it, *t ######### an( ######### (o not

5sing 5,/ in Software Design

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♦UP @Unifie( o(e)ing Pangage= notation is

pop)ar in software engineering.♦UP is a co))ection of )angages that provi(e

specific notations to specify, ana)y8e, visa)i8e,constrct, an( ######## software.

♦UP is a wi(e)y a(opte( stan(ar( notation forrepresenting (esigns

♦Le intro(ce the UP c)ass (iagra"

+ c)asses are (escri*e( *y *o0es

5,/ "epresentation of 6nheritance

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© Chinese University, CSE Dept. Software Engineering / 5 - FF

E,P/EE

TE476A/0STA''AD,676ST"AT6+E0STA''

7ote) similar to 0000000000

5,/ Associations

♦ssociations are re)ations that the

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♦ ssociations are re)ations that the

i"p)e"entation is re7ire( to spport♦Can have ")tip)icity constraints

TE476A/

0STA''

,A7A*E"

P"KET L $

proMect0mem3er

$

$..L

manages

5,/ Aggregation

D fi 3T O ) ti

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♦Defines a 3T#O re)ation

Differs fro" 2S#C3SED#O

%ere T!4PE has its own "etho(s

2t i"p)icit)y ses 32!T to (efine

its (ata attri*tes

T"6A7*/E

P67T

$

9

,ore on 5,/

♦ UP evo)ves fro" TD!/4D!

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♦ UP evo)ves fro" TD!/4D!♦

USES re)ationship is refine( with se"antica))y richer re)ationship: inheritance,association, an( aggregation + 2f c)ass ; inherits fro" c)ass , ; USES >? ########### USES ######### + ssociation *etween c)asses i"p)icit)y (efine USES re)ation >? ########### USES

############ + 2f ; aggregates , ; USES >? ########## USES ##########

♦ epresentation of 2S#C3!E!T#O via the package notation

pacDage0name

lass $

lass &

lass 9

Software Architecture

♦D i* )) t i ti (

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♦Descri*es overa)) syste" organi8ation an(

strctre in ter"s of its "aMor constitents an(their interactions

♦Stan(ar( architectres can *e i(entifie(

+ pipe)ine + *)ac*oar(

+ event *ase( @p*)ish-s*scri*e=

Standard Architectures

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ipeline"a*ple: _________________

e%ent based"a*ple: _______________

_______________________

la#,board"a*ple: ____________ -

_________________

Domain Specific Architectures

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.*odel/%ie0/#ontroller. ar#hite#t&re for soft0arethat has a signi#ant a*o&nt of &ser intera#tion

,odel #store

data2 e.g.2 te

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♦Oro" two tiere( + C)ient-server

♦ to three tiere(

"e(uests

for service

#data3ase%

Web browser

(client)

Web server

#server%"e(uests

for service

#pages%

User interface

(client)

Decode

service

request

#&nd tier%

Application

server

#data3se%

Program 6mplementation Techni(ues

1 3rogra""ing Stan(ar(s an( 3roce(res

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© Chinese University, CSE Dept. Software Engineering / 5 - 1GA

1. 3rogra""ing Stan(ar(s an( 3roce(res

♦ !ee( for stan(ar(s an( proce(res nifor"e( goo( progra""ing sty)e he)psn(erstan(a*i)ity, consistency, correctness of a tea"proMect.

a= Stan(ar(s for Yo

Stan(ar(s an( proce(res he)p yo ############ yorthoghts an( avoi( "istaesX they a)so he)p in

############ (esign to co(e

*= Stan(ar(s for thers

2t is essentia) yo organi8e, for"at, an( (oc"ent yor

co(e to "ae it easy for others to n(erstan( what it(oes an( how it wors.


t hi ith

3333333333333333333333333333333333333333

3 5678 95 6 9S95 5 9?5 8S

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♦ atching ####### with ###############

+ Direct correspon(ence*etween the progra"(esign "o()es an( the

progra" co(e "o()es + &eep p with the goo(

(esign for tracea*i)ity an("aintaina*i)ity

+ Use hea(er fi)e to trace"o()e (esign

* MODULE NAME: FINDPT3 5AB: C7B D

3 ES5: 1FG (! BC 1H)

3

3 567 E5B95:

3 B88 69 (B1- 1- 1- B2- 2- 2- IS- DS- 8BA)

3

3 79 BB9S:3 79 8S B 5 9C 5

3 B13I + 13D + 1 = G B6

3 B23I + 23D + 2 = G

3 S5 79 S 59S B1- 1- 1 B6

3 B2- 2- 2

3

3 57979 BB9S:

3 8S B BB888- 8BA S9 95 1F

3 8S 8BA = G B6 59 5 9B95

3 S (IS- DS)F

33333333333333333333333333333333333333333


' 3rogra""ing 4i(e)ines

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© Chinese University, CSE Dept. Software Engineering / 5 - 1GF

'. 3rogra""ing 4i(e)ines

+ Contro) strctres

+ )gorith"s

+ Data strctres

+ 4enera) gi(e)ines

ontrol Structures

♦Using On(a"enta) Constrcts

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♦Using On(a"enta) Constrcts

ain ingre(ients for strctre( progra"s:

". ______________e.!.#___________________

$. ______________e.!.#___________________

%. ______________e.!.#___________________

######## ########

ontrol Structures

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##########

ontrol Structures

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000000000000 000000000000

ontrol Structures

♦Top-(own O)ow

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♦Top (own O)ow

3rogra"s sho)( *e rea(a*)e fro" the top (own

♦Use of S*"o()es

+ Oo))ow the (esign to *i)( s*"o()es @fnctions,

proce(res, "acros= for e)e"enta) fnctions + ;i)( genera) s*"o()es for ############

+ E0p)ain ######### of s*"o()es, *t not their(etai)s

Program Without Top-Down 'low

9 = 7

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9 7

(BA < JH) A5 95 B;9 = BI7;

A5 95 ;

(BA < KH) A5 95 ;

(BA < HH) A5 95 ;B: (BA < KH) A5 95 ;

9 = 9 3 1FH + 57S;

A5 95 ;

: (BA < HH) A5 95 ;

9 = 9 3 1FH;

:e"t state*ent

Program With Top-Down 'low

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(BA < HH) 9C 9 = 7;8S (BA < KH) 9C 9 = 7 + 57S;

8S (BA < JH) 9C 9 = 7 3 1FH +57S;

8S 9 = BI7;

Algorithms

♦3rogra" (esign often specifies a c)ass of

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g g p

a)gorith"s to *e se(♦Efficiency of co(e sho)( consi(er

1. ############ of co(e

'. ti"e to ###### the co(e. ti"e to ###### the co(e

6. ti"e for sers to ########### the co(e

5. ti"e to ###### the co(e, if necessary

Data Structures

♦&eeping the 3rogra" Si"p)e. estrctring (ata

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p g g p g

can si"p)ify a progra". + &eep 2t Si"p)e an( Straightforwar(: #########

♦Using the Strctre of Data to Deter"ine the

Strctre of the 3rogra"♦Poca)i8ing 2npt an( tpt in Separate o()es

*eneral *uidelines

♦Using 3se(oco(e

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g

♦evising an( ewriting 2nstea( of 3atching

E

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p g y

1. Oor the first ^1G,GGG of inco"e, the ta0 is 1G.'. Oor the ne0t ^1G,GGG a*ove ^1G,GGG, the ta0 is

1'.

. Oor the ne0t ^1G,GGG a*ove ^'G,GGG, the ta0 is

15.6. Oor the ne0t ^1G,GGG a*ove ^G,GGG, the ta0 is

1.

5. Oor any inco"e a*ove ^6G,GGG, the ta0 is 'G.

Program $

9BI = GF

9BIB8 5 = G- A5 95 I9

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9BIB8_5 G- A5 95 I9

9BIB8_5 > 1G-GGG- 9BI = 9BI + 1GGGF8S 9BI = 9BI + GF1G 3 9BIB8_5

A5 95 I9

9BIB8_5 > 2G-GGG- 9BI = 9BI + 12GGF

8S 9BI = 9BI + GF123(9BIB8_5 / 1GGGGF)

A5 95 I9

9BIB8_5 > !G-GGG- 9BI = 9BI + 1HGGF

8S 9BI = 9BI + GF1H3(9BIB8_5 / 2GGGGF)

A5 95 I9

9BIB8_5 < 4G-GGG- 9BI = 9BI + GF1L3(9BIB8_5 / !GGGGF)

A5 95 I9

8S 9BI=9BI+1LGGF+GF2G3(9BIB8_5/4GGGGF)

I9: 6

Program &

&uild a 'ample (ax (a)le *irst:

&rac+et &ase ,ercent

G G 1G

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G G 1G

1G,GGG 1GGG 1'

'G,GGG ''GG 15

G,GGG AGG 1

6G,GGG 55GG 'G

(he ,ro!ram:

8E8 = 1

5 = 1 95 4 65

______________________________

9C ___________________________

9BI = ______________________________________________________


. Doc"entation

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♦ 2nterna) Doc"entation @(oc"entationassociate( with the progra" co(e=

+ %ea(er Co""ent ;)oc

+ ther 3rogra" Co""ents

+ eaningf) Qaria*)e !a"es an( State"ent Pa*e)s

4eader omment Bloc

♦Specify < Ls

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1. ###### yor progra" is

'. ###### wrote the progra"

. ###### the progra" fits in the genera) syste"(esign

6. ###### the progra" was written an( revise(

5. ###### the progra" e0ists

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5AB: ?an- 8ai*an !M4! L4L1B88A SN7: B88 SB(8A9C-CB)

?here O8A9CP is the length of the line to be s#anned- OCBP isthe #hara#ter to be so&ght- line of te"t passed as array O9I9P

ES5 1: 0ritten 222G1K

ES5 1F1: !!2G1K to i*pro%e sear#hing algorith*F

75S: Aeneralp&rpose s#anning *od&le to be &sed for ea#hne0 line of te"t- no *atter the lengthF

6B9B S9797S: Eariable 8A9C / 9A

Eariable CB / CBB9

BBD 9I9 / CBB9 array of length O8A9CP

B8A59C: eads array 9I9 one #hara#ter at a ti*e;

if CB is fo&nd- position in 9I9 ret&rned in %ariable O8A9CP;else %ariable O8A9CP set to G

000000

000000

000000

000000


+ Oor"atting to Enhance Un(erstan(ing

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################################# #################################

+ Doc"enting Data

#################################


♦E0terna) Doc"entation

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© Chinese University, CSE Dept. Software Engineering / 5 - 1'<

+ Descri*ing ################# @what= + Descri*ing ################# @how=

+ Descri*ing ################# @how=

Topic 1 onclusion

♦ Software (esign activities an( "o()ari8ation techni7es

♦

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♦

vera)) strctre (esign + %ierarchica) re)ations, ses re)ation, is#co"ponent#of re)ation + 2nterface an( infor"ation hi(ing

♦ Detai)e( (esign + TD!, 4D!

+ Category of "o()es + Stepwise refine"ent

♦ %an()ing ano"a)ies

♦ 2nheritance

♦ UP in software (esign♦ 3rogra" i"p)e"entation techni7es

3100-topic5 (1)

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