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Hanoi University of Technology1 Dai Co Viet - Hanoi - Vietnam

Phn tch v thit khng i tng(Object Oriented System

Analysis and Design)

Ging vin: TS. Trn t

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Chng 5. Thit k h thng

5.1 Chuyn sang thit k

5.2 Thit k lp v phng thc

5.3 Thit k lp qun l d liu

5.4 Thit k lp tng tc ngi-my

5.5 Thit k lp kin trc vt l

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5.2.1 Gii thiu

5.2.2 Nhng vn c bn ca thit k HT.

5.2.3 Tiu ch thit k

5.2.4 Hot ng thit k i tng

5.2.5 Cc rng buc5.2.6 p dng trong CD Selection

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Bc quan trng nht trong pha thit k hng itng l thit k lp v phng thc (hnh vi).

Vic thit k hng i tng phi cung cp y thng tin cho vic hon thin v chnh sa nhng cngvic s c trin khai.

Cn phi hiu khi nim: coupling, cohesion and

connascence* restructure and optimise object designs

constraints and contracts

Create a method specification

5.2.1. Gii thiu

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Vi tt c cc tng, cc lp m c s dng to racc i tng th cn phi thit k.

Bt chp kh nng ca cc thnh phn phn mm

c pht trin (cc th vin), Thit k chi tit cc hthng con, cc h thng vn rt quan trng: Phn mm pht trin cn phi c hiu, c t chc

v c kt hp mt cch chnh xc vi phn mm khc. Mt s phn mm c pht trin theo theo phng php

hng mc ch ca nhm pht trin.

Pht trin v trin khai m khng cn vic thit k chnhxc v hon thin s dn n: Trin khai khng hiu qu: v phc tp ca nhng tng

tc gia cc thnh phn phn mm, thnh phn h thng. Trin khai khng chnh xc, n khng tha mn nhng thit

k v/hoc khng hot ng chnh xc/y nhng chc

nng d kin.

5.2.1. Gii thiu

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Trong cc HTHT, cc thay i c th din ra ti ccmc khc nhau ca s tru tng ha: bin (th hin),hnh vi (phng thc), lp v i tng, nhm, th vin,

ng dng. Cc thay i ti cc mc khc nhau ca vic tru tng

c th nh hng ti cc mc khc ca s tru tng. Cc thay i c th din ra ti cc mc khc nhau mt

cch ng thi. Nu ti pha phn tch cc tng tc gia cc i tng

ti tng min bi ton c thit k chun ( chi tit)th vic thit k chi tit s d dng v t gp kh khn.(tng t vi cc tng HCI, qun l d liu)

Do cc lp min bi ton khi to phi c thit kchnh xc v hon thin.

5.2.1. Gii thiu

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Cc mc tru tng

5.2.1. Gii thiu

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5.2.2. Nhng vn c bn ca thit k HT

Lp, i tng, phng thc thng ip: Khi c bn ca mt h thng phn mm hng i

tng l i tng Cc i tngl th hin ca cc lp. Lp l khun dng cho vic nh ngha i tng, n

nh ngha d liu(thuc tnh) v ccphng thcm

mi i tng trong lp cn phi c. Thuc tnh (Attributes): cha ng thng tin miu t v

i tng.

Phng thc (Methods, thao tc): thc thi hot ng cai tng.

Cc thng ip (messages): thng tin c gi ti cci tng kch hot cc phng thc

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Tm lc (ng gi) (Encapsulation) S kt hp ca c d liu v tin trnh trong

mt thc th. n thng tin (Information Hiding)

Ch c thng tin m n c yu cu s

dng mt m un phn mm c cng khaiti ngi s dng


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a hnh thi (Polymorphism) Mt thng ip c th c phin dch khc nhau bi cc

i tng khc nhau.

Kt ni ng (Dynamic Binding) Lm tr vic la chn cc phng thc cho mt i tng

cho ti thi im chy chng trnh.

V d: Bn tin c gi ti cc i tng: hnh trn,

hnh vung, hnh tam gic. Ty thuc i tng, phngthc v hnh s khc.

a hnh thi l con dao 2 li: Vic quyt nh c thc hin bi h thng.

C gp vn v thi gian chy nu i tng khng hiu

bn tin


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Tha k Cc lp s c sp xp theo mt cu trc phn cp,

cc lp trn, v cc lp di. Cc lp trn hay cc lp tng quan: nm trn nh h

thng phn cp lp Cc lp con hay cc lp c th: pha di ca h

thng. Cc lp con s tha k cc thuc tnh v v cc phng

thc ca cc lp cao hn trong h thng phn cp.

Tnh tha k lm cho vic nh ngha lp c n gin

Hai nh dng ca c ch k tha. Tha k n: lp con ch c mt lp cha. Tha k bi (phc): lp con c th c nhiu lp cha.


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Tha k Mt vi phng php, CSDL v ngn ng lp trnh cho php lp con

nh ngha li mt s thuc tnh v/hoc hnh v ca lp cha cachng

nh ngha li v Xung t tha k: Vic nh ngha li c th dn timt s xung t. Vd : mt thuc tnh hoc mt hnh vi ca lp contrng tn vi thuc tnh v hnh vi ca lp cha.

Doctor

+computePay()

Employee

+computePay()

+updateSchedule()

Is subclass of

a) Both have methods namedcomputePay()

+update schedule()b) If Employee, i.e. superclassis modified, all of its subclassesare affected

c) Subclass can cancelinheritance of methods fromits superclass by redefinitionof inherited method

+correctMethod()

+correctMethod()

Redefinesinheritedmethod, sosubclass of wrong

superclass


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Tha k: Rumbaughs Rules

Cc xung t tha k l do s phn lp khng tt

Cc cu trc a-kind-of tng qut ha b xm phm. Hoc c ch tha k vi phm nguyn tc ng gi. Vd cc

lp con truy cp trc tip vo cc thuc tnh v phngthc ca cc lp cha.

Cc hng dn ca Jim Rumbaugh

Query operations should not be redefined

Methods that redefine inherited ones should only restrict the

semantics of the inherited onesThe underlying semantics of the inherited method should neverbe changed

The signature (argument list) of the inherited method shouldnever be changed


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Tha k bi: mt lp con c th tha k nhiu lp chacc kiu xung t tha k tng.

Ba kiu xung t tha k: Hai phng thc hoc thuc tnh c tha k c cng tn v

ng ngha.

Hai phng thc hoc thuc tnh c tha k c tn khcnhau nhng cng ng ngha (ng ngha).

Hai phng thc hoc thuc tnh c tha k c cng tn

nhng ng ngha khc nhau (ng m).

V d:


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S kt ni: th hin s ph thuc v s lin quan bn trongca cc m un trong h thng ( lp, i tng, v hnh vi).

Kt ni tng tc gii quyt s kt ni bn trong gia ccphng thc v cc i tng thng qua trao i thng ip

5.2.3. Tiu ch thit k - S kt ni bn trong

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Kt ni tng tc: Law of Demeter: ti thiu ha s lng i tng c th

nhn cc thng ip t mt i tng cho trc. Mi i tng ch nn gi thng ip ti:

bn thn n i tng c cha ng trong mt thuc tnh ca n

hoc mt mi tng thuc lp cha ca n. mt i tng trao i nh l tham s i vi phng

thc. Mt i tng c to ra bi phng thc. Mt i tng c lu trong mt bin ton cc.

S kt ni s tng nu: Phng thc gi truyn cc thuc tnh cho phng thc b

gi. Phng thc gi ph thuc vo gi tr phn hi ca

phng thc b gi


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Kt ni tha k - Inheritance Coupling cp ti s cht ch trong s kt ni ca cc lp trong

mt h phn cp tha k. Kt ni tha k mc cao c th khng tt v c th gp

cc vn v xung t tha k, kh nng nh ngha liv kt ni ng.

Cc ngn ng lp trnh c cc kh nng khc nhau vmc kt ni tha k.

Cn phi tm hiu s cn bng gia nhng vn xung

t (ng gi v n thng tin) vi s kt ni mong mungia lp con v cha.

Nn s dng tha k khi cn phi h tr vic tng qutha.


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S gn kt: vic lm cch no gii quyt mt m un bntrong mt h thng. Gn kt phng thc:

5.2.3. Tiu ch thit k - S gn kt (cohesion)

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Gn kt lp: s gn kt gia cc thuc tnh v ccphng thc ca lp. (T chc mt lp ntn?).

Mt lp ch nn biu din cho mt vn (ngi lmthu, n t hng), cc thuc tnh, phng thctrong lp phi biu din cho vn .

Mt s gn kt lp l tng: Cha ng cc phng thc m c th nhn thy t bn

ngoi lp. Mi phng thc thc hin mt chc nng

C cc phng thc tham chiu cc thuc tnh hocphng thc khc c nh ngha vi lp hoc lp cha.

Khng c s kt ni dng iu khin no gia cc phngthc

5.2.3. Tiu ch thit k - S gn kt (cohesion)

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Hai m un (c to ra cng mt thi im) cth ph thuc ln nhau, do khi thay i mt

m un ny dn n phi thay i m un kia. Gim thiu s ng sinh tng qut bng vic

hn ch nhng s ng sinh khng cn thit.

Gim thiu s ng sinh xuyn qua cc ngbin ng gi

Tng s ng sinh trong cng mt ng bin

ca gi.

5.2.3. Tiu ch thit kConnascence - produced at the same time

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5.2.4. Hot ng thit k i tngAdditional Specification ch tiu b sung

m bo rng cc lp l cn thit v y cho vic giiquyt bi ton c bn

Cn phi hon thnh s nhn thy (n hay c th thy)ca cc thuc tnh hoc hnh vi trong mi lp.

Determine the signature of every method of each class Signature = name, (types of) formal parameters, type of

result Define constraints to be preserved by objects

Pre-conditions, post-conditions and invariants via contracts

Manage constraint violations, e.g. via exceptions

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5.2.4. Hot ng thit k i tngNhn din c hi s dng li.

Mu Pattern L mt s kt hp hu ch cc lp cng tc vi nhau nhm

cung cp mt gii php cho mt bi ton chung.

Cc mu phn tch: mc ch ch yu l th hin min biton Cc mu thit k: phc v cho mt bi ton thit k chung

trong mt ng cnh c th.

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Frameworks - Khung Tp hp cc lp c trin khai v c th c s dng li nh

l c s nn tng cho vic trin khai mt ng dng.

Hu ht cc framework cho php to ra cc lp con k tha cc lptrong framework. Cc lp con c to ra s c s ph thuc, kt ni tha k s tng

gia lp cha v lp con. Do s cn phi bin dch li khi mFramework b thay i bi ngi cung cp.

Th vin lp: Th vin lp ging nh l mt framework, vi n ta c mt tp hp

cc lp c trin khai c thit k cho vic s dng li.Framework hng vo min c th hn. Framework c th c

xy dng bi vic s dng mt th vin lp. Th vin c th dnh c h tr cho cc s l thng k, s hc,

qun l File, pht trin giao din ngi s dng.


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Thnh phn Component: L mu phn mm c ng gi c th c gn vi

h thng nhm cung cp mt chc nng c th. Hin nay c nhiu thnh phn kh dng, chng c

trin khai thng qua vic s dng cng ngh Active X.

Cc thnh phn c th c trin khai thng qua vics dng cc th vin hay framework, tuy nhin ncng c th c s dng xy dng Framework.


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Factoring Separate out shared aspects of a method or class into a

new method or class New class related to existing classes via inheritance,

aggregation or association

Normalization Identifies classes missing from the design All association and aggregation relationships converted to

attributes of the class

Challenge inheritance relationships to ensure they onlysupport a generalization/specialization semantics

5.2.4. Hot ng thit k i tngCu trc li thit k - Restructuring the Design

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Simple optimisations make an existing design moreefficient, but must not make optimised design significantlymore difficult to reason about, i.e. optimsation is a trade-

off between efficiencyand ease of understanding[1] access paths between objects A message from one object to another may go though many

intervening objects

If a) the path though the intervening objects is long and b) themessage is sent frequently consider a redundant path, i.e. anadditional attribute in the calling object that stores a directconnection to object at end of path

[2] attributes of each class If methods that use an attribute are only read and update

methods, and only instances of a single class send thosemessages then attribute may belong to calling class.

5.2.4. Hot ng thit k i tngTi u thit k - Optimizing the Design

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[3] direct and indirect fan-out of each method Fan-out = number of messages sent by a method Direct Fan-out = number of messages sent by given method

Indirect Fan-out includes number of messages sent bymethods called by other methods in a message tree If fan-out of a method significantly higher than other methods in

a system then should be optimised, e.g. add an index toattributes used to send messages to objects in message tree

[4] execution order of statements In frequently used methods, order of statements may be non-

optimal Changing order should not affect result of computation

Changing order can be more efficient, e.g. when searching, ifone attribute known to narrow search then search on thatattribute first

[5] unnecessary recomputation Derived attributes (or active values) need not be recomputed

until attributes that are involved in its computation change, e.g.

5.2.4. Hot ng thit k i tngOptimizing the Design

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OO designs assume class-based OO programminglanguage used to implement those designs

Need to resolve any conflicts between constructsassumed in the design to be available in programminglanguage but are not present in that language e.g. [1] design uses multiple inheritance, language has only

single inheritance [2] implementation language is object-basedand not

class-based, i.e. implementation language supportsobject creation but not implementation inheritance

[3] language is of another (less expressive) languageparadigm, e.g. C or Pascal are of the imperative-procedural paradigm

5.2.4. Hot ng thit k i tngMapping Problem Domain Classes to Implementation Languages

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[1] design uses multiple inheritance, language has onlysingle inheritance

A) Convert multiple inheritance relationships to superclass-subclassassociation relationships If additional superclasses are concrete (objects of the class can be

instantiated) then multiplicity from superclass to subclass is 0..1 Otherwise multiplicity is 1..1 Add an exclusive-OR constraint between associations Add appropriate methods to ensure all information remains available to

existing class

SuperClass1-attribute1

-attribute2


-attribute4


-attribute8

Class1-attribute5

-attribute6

Class2-attribute5

-attribute6

concrete

0..*

1..1

0..*

1..1

{XOR}[1]All classes preserved[2]Increases amountof message passing[3]Adds to processing

requirement due to XOR


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B) Copy ALL the attributes and methods of the additionalsuperclasses to ALL the subclassess and removeadditional superclass from the design


-attribute2


-attribute4


-attribute8

Class1

-attribute5-attribute6

Class2




PotentialInheritanceConflicts

abstract


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SuperClass1-attribute1-attribute2



Class1


Class2


-attribute3

-attribute4

-attribute3

-attribute4

If all superclasses are

abstract





PotentialInheritanceConflicts


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[3] language is of another (less expressive) languageparadigm, e.g. C or Pascal are of the imperative-procedural paradigm

Book suggests never attempt this! And says Beyond thescope of this text

In fact, it is possible to convert depending on the non-OO

language used, e.g. using pointers in C it is possible toemulate object-oriented language constructs

More difficult, but not impossible, in a modular variant ofan imperative-procedural language e.g. Pascal, but

inheritance must be factored-out


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Contract: formalises interactions between client and server objects

is a set of constraints and guarantees

Constraints may bepre-conditions,post-conditions orinvariants

Pre- and post-conditions model constraints on individual

methods, and contracts establish pre- and post-conditions for a method to execute correctly. Pre-condition is constraint which must be met for a method

to execute

Post-condition is constraint that must be met after methodexecutes. Otherwise effect of method execution must beundone

5.2.5. Cc rng buc v tha thun

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Invariants model constraints (that must always be true)for all instances of a class, e.g. Domains or types of attributes

Multiplicity of attributes

Legal values of attributes including attributes that modelassociation and aggregation and relationships

e.g. if association relationship is required, invariant is createdto enforce relationship to have valid value for instance to exist

Invariants usually attached to the class, e.g. CRC cardsor class diagrams as a set of assertions

5.2.5. Cc rng buc v tha thun

Attribute Constraint:

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5.2.5. continued

Example:-

Back:

Order Number (1:1) (unsigned long)Attributes:

Date (1..1) (Date)

Sub Total (0..1) (double)Tax (0..1) (double) {Sub Total = sum(Product Order.GetExtension())}Shipping (0..1) (double)Total (0..1) (double)Customer (1..1) (Customer)

Cust ID (1..1) (unsigned long) (Cust ID = Customer.GetCustID()}State (1..1) (State)StateName (String) {State Name = State.GetState()}

Relationships:Generalisation(a-kind-of):

Aggregation (has-parts):

Other Associations: Product{1..*} Customer(1..1} State{1..1}

Attribute Constraint:Order Number IS unsigned long

Attribute Constraint:Customer IS INSTANCE OFCustomer Class

Attribute Constraint:Cust ID IS unsigned

LongANDInvariantMUST HAVE one andONLY one value(1..1) =

GetCustID()Customer.

Constraint: Instance of Order EXISTSIF (instance of Customer class AND

instance of State class AND>=1 instance of Product class)

ASSOCIATED WITH order object

Product Order

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5.2.5. continuedInvariants On a Class Diagram(Not recommended Use CRC card for Invariants)

Order

-Order Number: unsigned long-Date[1..]: Date-Sub Total[0..1]: double-Tax[0..1]:double-Shipping[0..1]:double

-Total[0..1]double-Tax[0..1]: double-Customer[1..1]: Customer-Cust ID[1..1]: unsigned long-State[1..1] State-State Name[1..1: String

Customer

-Cust ID-Last Name-First Name

1..1 0..*

Product

-Product Number-Product Desc-Price0..* 1..*

State

-StateTax RateProduct Desc

0..* 1..1

Product Order

OrderProduct

QuantityExtension

{Cust ID=Customer.GetCustID()}

{State Name=State.GetState()}

{Tax=State.GetTaxRate()

*SubTotal}

{Sub Total=

Sum(Product Order.GetExtension())}}

5 2 5 Cc rng buc v tha thun

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Cc tha thun miu t thng dip trao i gia cc itng, v mi thng ip c to ra cho mi tng tc

Trn thc t, mi tha thun c to ra cho miphng thc m phng thc nhn cc thng ip tcc i tng khc.

Tha thun cha ng thng tin cn thit cho lp trnh

vin hiu phng thc lm g. Cc thng tin bao gm: Method name, class name, ID number, client objects,

associated use cases, description, arguments received,type of reurn value, pre- and post-conditions

Tha thun khng cha ng thng tin miu t thut tonca phng thc.

5.2.5. Cc rng buc v tha thunTha thun

5 2 5 C ti dUnique Contract ID

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5.2.5 Continued. Specific Method OF specific Classq

List of classes and methodsthat send a message to this

methodList of use cases containingthis method where method isused to realise implementationof the use case (from serverclasss CRC card and associated

use cases)

What the method does NOT how it does it

types of parameters passed

type of value returned to its clients

= method signature

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5.2.6. Method Specification

Bn ghi chi tit phng thc L mt ti liu vit bao gm cc ch dn tng mnh lm

th no vit lnh trin khai phng thc. Bn ghi chi tit cn phi r rng v d hiu lp trnh

vin c th da vo vit m lnh. Mt bn ghi gm 4 thnh phn;

Thng tin chung: cha ng cc thng tin tng qut v dtn ca phng thc, ten ca lp, Idnumber, Contract ID Cc s kin: Cc s kin kch hot phng thc (nhp

chut, n phm).

Thng ip trao i: miu t phng thc ti v i tphng thc. Chi tit thut ton: c vit theo kiu ting Anh c cu

trc hoc Cc lnh gi lp.

5.2.6. Continued General Information (for managing programming effort)

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5 6 Co t uedMethod Name Class Name ID:

Contract ID Programmer: Date Due:Programming Language: Visual Basic SmallTalk C++ Java

Triggers/Events

Arguments Received:Data Type:

Notes:

Messages Sent & Arguments PassedClassName.MethodName: Data Type: Notes:

Argument Returned:Data Type:

Notes:

Algorithithm Specification:

( g g p g g )

e.g. user initiated event(mouse event, keystroke event),system event or event initiated by another method

Message passing to and from method(c.f. sequence and collaboration diagrams)

Arguments = attributes and data structuresin implemented method

See next slide

5 2 6 Continued

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5.2.6. Continued Structured English will suffice for algorithm specification

Algorithm Specification:

Action Statement Examples: Profits = Revenues ExpensesGenerate Inventory-Report

IF Statement Examples: IF Customer NOT in Customer Object StoreTHENAdd Customer record to Customer Object StoreELSEAdd Current-Sale to Customers Total SalesUpdate Customer record in Customer Object Store

FOR Statement Examples: FOR all Customers in Customer Object Store DOGenerate a new line in Customer-Report

Add Customers Total-Sales to Report-Total

CASE Statement Examples: CASE

IF Income < 10,000: Marginal-tax-rate = 10 percentIF Income < 20,000: Marginal-tax-rate = 20 percentIF Income < 30,000: Marginal-tax-rate = 31 percentIF Income < 40,000: Marginal-tax-rate = 35 percentELSE Marginal-tax-rate = 38 percent

ENDCASE

Notes:

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CD S l ti

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Revised CD Selections Class Diagram

CD Selection

f C C C C

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Back of CD CRC Card

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Get Review Method Contract

R i d P k Di

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Revised Package Diagram

Ch 5 Thit k h th

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Chng 5. Thit k h thng

5.1 Chuyn sang thit k


5.3 Thit k lp qun l d liu5.4 Thit k lp tng tc ngi-my

5.5 Thit k lp kin trc vt l

5 3 Thit k lp q n l d li

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5.3 Thit k lp qun l d liu

5.3.1 Gii thiu

5.3.2 Cc nh dng lu tr d liu

5.3.3 nh x cc i tng ti cc nh dng lutr i tng.

5.3.4 Ti u ha lu tr i tng da trn

RDBMS5.3.5 Thit k lp qun l v truy cp d liu

5.3.6 CD Selection

5 3 1 Gii thiu

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5.3.1 Gii thiu

Design of data management layer: [1] Select format of storage; Alternatives are:

Files (Sequential and Random) Relational databases Object-relational databases Object-oriented databases

[2] Map problem domain classes to selected storageformat Problem domain objects drive object storage design

[3] Optimise storage for efficient performance

[4] Design appropriate data access classes andmanipulation classes to: Separate problem domain classes from storage format Handle all communication with the database

5 3 2 Cc nh dng lu tr d liu

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C 4 kiu nh dng lu tr i tng: Files (tp tin),CSDL hng i tng, CSDL quan h i tng vCSDL quan h.

File: tp tin (d liu in t phc v cho cng vic cth). CSDL la tp hp nhm cc thng tin m c quan h vi

nhau theo mt cch no .

H thng qun l CSDL (Database Management System:DBMS) l phn mm m n to ra v qun l CSDL


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Tp tin truy cp tun t: Ch cho php cc hot ng tp tin tun t c thc

hin (c, ghi v tm kim), khng hiu qu cho vic tm

kim v cp nht. Tp tin truy cp tun t ko theo th t.

Data is in sequence that it was written to the file, i.e. data isorganised serially.New data is added to end of file

Tp tin truy cp tun t theo th t. Data is in sorted order, e.g. ascending order of some

component in the dataTp tin truy cp ngu nhin. Cho php cc hot ng ngu nhin hoc trc tip. Hiu qu cho tm kim v cp nht mt i tng c th. Khng hiu qu cho vic vit cc bn bo co.

g Tp tin


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X l ngu nhin v tun t Sometimes need both sequential and random processing

Can use a sequential file with additional list of keys Key values are data items in which file is to kept in sorted

order

Actual data is kept in random access file

Minimises cost of additions and deletions to sequential file Allows random file to be processed in sequential order

Also allows fast random processing via random file alone

More effective if both sequential AND random processingto use a database

g Tp tin


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Cc kiu tp tin ng dng Master Files

Accumulate data, e.g. data from transaction files Maintained for long time periods and data for new entries is appended to

end of file Look-up files

Remain unchanged over time, usually used to validate data fromelsewhere against stored legal values

Transaction files Update masterfiles with transaction information May or may not be disposed of after masterfile has been updated

Audit file Contains data relating to changes in other data, e.g. data values before

and after each change in those values, the identity and authority of the

changer History file Archive of data from another file no longer needed by systems that

process the original file

gTp tin


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CSDL phn tn da trn mt b cc bng vi mi bngcha ng mt t kha chnh (trng), mi gi tr ca nch l duy nht ti mi hng.

Cc bng quan h vi nhau bi vic t cc t khachnh t bng ny ti bng c quan h nh l t khangoi (foreign key).

Cc h thng qun l CSDL u h tr s ton vn thamchiu (referential integrity), m bo cc gi tr lin ktcc bng vi nhau thng qua t kha chnh v khangoi l ng n v ng b.

C s d liu phn tn

5.3.2 Cc nh dng.. - C s d liu phn tnCust ID is p

rimary key

Payment Typeis primary

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Cust ID is primary keyof Customer table

Order Numberis primarykey of Ordertable

key of Payment

Type table

Order Numberis foreign

key in Order

Payment Typeis foreignkey in Order


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Tables related through Cust ID

All Payment Typevalues in Ordermust exist first inPayment Type table

All Cust ID

Values inOrder mustexist first inCustomerTable

Attempt to add order:

241 11/23/00 1111

OrderNumber

Cust ID

DBMS: Invalid Cust ID value

C s d liu phn tn

5.3.2 Cc nh dng lu tr d liuC d li h t

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Database Management System (DBMS) RDBMS is a DBMS for a Relational Database SQL (Structured Query Language) Ngn ng truy vn c

cu trc l ngn ng cho vi to, xa bng v truy cpd liu trong cc bng.

SQL hot ng trn ton b bng ch khng phi tnghng trong bng

Khi cc truy vn phi cha ng thng tin t nhiu bng,cc bng u tin c kt hp li vi nhau da trn ccmi quan h t kha chnh v t kha ngoi

Cc i tng cn phi c bin i mt cch ph hpcho vic lu tr trong bng.

C s d liu phn tn

5.3.2 Cc nh dng lu tr d liuC d li h t

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Object-Relational DBMSs ORDBMS: L H thng qun l CSDL quan h cng vi cc

m rng dnh cho vic x l lu tr i tng trong cu trcbng quan h. iu ny c thc hin thng qua cc kiuc nh ngha bi ngi dng. Example: Create a mapdata type.

Object-Oriented Database Management Systems(OODBMSs)

Xy dng c bng cch A) B sung cc m rng ti mt ngn ng lp trnh hng i

tng.

B) Xy dng mt h thng qun l d liu hon ton tch bit. The Object Data Management Group (ODMG) is standardising

process for defining Object Definition Language(ODL), ObjectManipulation Language (OML) and Object Query Language (OQL)

C s d liu phn tn

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5.3.2 Cc nh dng lu tr d liuLa chn nh dng lu tr d liu

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Cc tiu ch (Data) types to be supported Types of application systems to be constructed

(transaction processing, Decision Support System, ) Existing Storage Formats Future Needs

Other miscellaneous criteria (cost, concurrency control,)

La chn nh dng lu tr d liu

5.3.3. nh x cc i tng ti cc nh dng lu tri tng nh x i tng ti nh dng OODBMS

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i tng nh x i tng ti nh dng OODBMS

If OODBMS is to be used: Each concrete problem domain class has corresponding object persistence class Each object persistence class has a DAM (Data Access and Management) class that manages

interaction between object persistence class and problem domain layer

Unchanged fromanalysis phase

New Class

New Class

Dependent onMust be able to read fromand write to the OODBMS


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Nu s a tha k c s dng trong min bi tonnhng ko c h tr bi OODBMS Cc a tha k phi c phn mnh thnh cc lp

OODBMS. Lut phn mnh cho mi trng hp a tha k. Lut 1a. Thm thuc tnh ti lp OODBMS biu din

cc lp cha b sung. C s lin kt ca lin kt mi t lp con n lp cha l 1..1 Thm thuc tnh cha ng danh tnh i tng Object ID ca cc

th hin c lu tr trong lp OODBMS (biu din lp con) ti cclp OOBMDS biu din cc lp cha.

Nu lp cha l c th, c s lin kt t lp cha ti lp con l 0..*(trong trng hp khc l 1..1)

Thm rng buc exclusive OR (Xor) vo gia cc lin kt

Lut 1b. Lm phng h thng tha k. Copy cc thuc tnh ca cc lp cha ODBMS xung tt c cc lp

con. Loi b cc lp cha b sung

i tng nh x i tng ti nh dng OODBMS

Example:-

Assume

Attribute represents subclass that will contain an Object IDof instance stored in OODBMS class that representsadditional superclasses

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Assume

Superclass2is concrete

Add attribute toOODBMS class

additional superclasses

Add attribute toOODBMS class

Add pair of attributesTo represent associationWith Class1ODBMS &

Class2ODBMS

Add associations betweenClass2OODBMS and

Superclass2OODBMS,Class1OODBMS andSuperclass2ODBMSwith correct multiplicities

XOR

Shown XOR

constraintClass 1Inherits fromSuperclass1 andSUperclass2

By rule 1)b)


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u im ca Lut 1: lu gi c trong CSDL tt c cclp min bi ton c xc nh ti pha phn tch. iuny cho php s linh hot ln nht cho vic qun l (duytr) thit k ca tng qun l d liu. Tuy nhin Lut 1 lm tng s lng thng ip trao i v

cn phi x l thm quan h XOR (lm gim hiu qu cathit k)

Khi khi to cc i tng min bi ton t cc itng OODBMS, cc x l khc s cn n. Tin trnh x l b sung s l vic thu thp cc i tng

OODBM v a cc phn t ca n to i tng min

bi ton. khi lu tr i tng min bi ton, mt tin trnh b sung

c s dng chuyn i cc i tng OODBMS

g g g

5.3.3. nh x cc i tng ti cc nh dng lu tri tng nh x i tng ti nh dng ORDBMS

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vic nh x cc i tng min bi ton ti cc itng qun l d liu phc tp hn nhiu khi s dngnh dng lu tr ORDBMS.

Ph thuc vo mc h tr trong ORDBMS cho OOm cc lut nh x khc nhau s c s dng. Gi thit ORDBMS h tr :

Object ID.

Cc thuc tnh a gi tr (Multivalued attributes) Cc th tc lu tr (Stored procedures) NHNG khng h tr cho vic tha k

Rules for mapping from problem domain objects to

RDBMS-based data-access and management layertables

g g g

5.3.3. nh x cc i tng ti cc nh dng lu tri t

ng nh x i tng ti nh dng ORDBMS

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g g g

5.3.3. nh x cc i tng ti cc nh dng lu tr itng nh x i tng ti nh dng ORDBMS

6. Repeating groups

9. Patient Table hasP ib

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1. Concrete problem domainclasses mapped to tablesin ORDBMS

n.b. Person class is abstractbut has multiple direct

subclasses (in fulldiagram) so is also mapped

2. Single valued attributes mappedto columns in ORDBMS tables

Amount attribute ofPatient class included

in Patient Table class

3. Methods and derivedattributes mapped tostored procedures OR

program modules

4. Single-valued aggregationand association relationshipsmapped to a column storing

an Object ID

5. Multi-valuedattributesmapped to columns with

a set of values

p g g pused to create new table

7.Map multivaluedaggregation and

association relationshipsto columns storing setof Object IDs

Stores multipleObjectIDsTo Patient

Table objects

Stores multipleObjectIDsTo SymptomTable objects

8. Map one-to-many

and many-to-onerelationships

Multiple OIDsTo Appt. TableObjects

Single OIDTo Patient Table

Object

Person attribute,

Person Tablehas SubClassObjects

Single OIDTo Patient Table

Object

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5.3.3. nh x cc i tng ti cc nh dng lu tri tng nh x i tng ti nh dng RDBMS

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Rule 1: Map all concrete problem domain classes to the RDBMStables.

Rule 2: Map single valued attributes to columns of the tables. Rule 3: Map methods to stored procedures or to program modules.

Rule 4: Map single-valued aggregation and association relationshipsto a column that can store the key of the related table Rule 5: Map multi-valued attributes and repeating groups to new

tables and create a one-to-many association from the original table tothe new ones.

Rule 6: Map multi-valued aggregation and association relationshipsto a new associative table that relates the two original tablestogether. Copy the primary key from both original tables to the newassociative table

Rule 7: For aggregation and association relationships of mixed type,copy the primary key from the single-valued side (1..1 or 0..1) of therelationship to a new column in the table on the multi-valued side (1..*or 0..*) of the relationship that can store the key of the related table

Rule 8a: Ensure that the primary key of the subclass instance is thesame as the primary key of the superclass..OR

Rule 8b: Flatten the inheritance

2. Map single valued

5.3.3. nh x cc i tng ti cc nh dng lu tr i tng nh x i tng ti nh dng RDBMS

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1. Concrete problem domainClasses mapped to tables (also PDclass IF multiple directSubclasses)

2. Map single valued

attributes tocolumns

3. Apply Rule 3

4. Apply Rule 4

5. Apply Rule 5 6. etc

5.3.4. Ti u ha lu tr i tng da trn RDBMSTi u hiu qu lu tr

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2 chiu c bn cho vic ti u ha CSDL quan h: Hiu qu lu tr

v tc truy cp.

Bng d liu tt: Khng c d liu d tha

Lng ph khng gian b nh

Tng kh nng gp li.

t gi tr Null Mt gi tr trng trong bn c th c hiu thnh nhiu

ngha n s rt kh phin dch

5.3.4. Ti u ha lu tr i tng da trn RDBMSV d d liu khng chun ha

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Repeated customer information(name, state) for each order

Null values in product columnsif order < 3 items

If customer moves state,need program to update

ALL instances

Null = [1] 1 or 2 products only[2] Error: items missing

[3] Part of order cancelled

Problem is: Wasted storage space + data integrity threat

5.3.4. Ti u ha lu tr i tng da trn RDBMSChun ha d liu

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Chun ha d liu l qu trnh p dng mt chui cc nguyn tc ivi cc bng RDBMS nhm xc nh cc bng c cu trc tt ntn.

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Original Model Primary Key

for Order

5.3.4. Ti u ha lu tr i tng da trn RDBMSChun ha d liu -Create new Product Order Table

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g

Order

-Order Number: unsigned long-Date: Date-Cust ID: unsigned long

-Last Name: String-First name: String-State: String-Tax Rate: float-Product1 Number: unsigned long

-Product1 Desc.: String-Product1 Price: double-Product1Qty.: unsigned long-Product2 Number: unsigned long-Product2 Desc.: String

-Product2 Price: double-Product2 Qty.: unsigned long-Product3 Number: unsigned long-Product3 Desc.: String-Product3 Price: double

-Product3 Qty.: unsigned long

Revised ModelOrder

-Order Number: unsigned long-Date: Date-Cust ID: unsigned long-Last Name: String-First name: String-State: String-Tax Rate: float

Primary Key for Order

Product Order

-Order Number: unsigned long-Product Number: unsigned long-Product Desc.: String-Product Price: double-Product Qty.: unsigned long

0..*

1..*

Primary Key forProduct Order

Foreign Key inProduct Order

= 1NF

(zero tomany)


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Order TableOrder Date Cust Last First State TaxNumber ID Name Rate239 11/23/00 1035 Black John MD 0.05260 11/24/00 1035 Black John MD 0.05

273 11/27/00 1035 Black John MD 0.05241 11/23/00 1123 Williams Mary CA 0.08262 11/24/00 1123 Williams Mary CA 0.08287 11/27/00 1123 Williams Mary CA 0.08290 11/30/00 1123 Williams Mary CA 0.08234 11/23/00 2242 DeBerry Ann DC 0.065237 11/23/00 2242 DeBerry Ann DC 0.065

238 11/23/00 2242 DeBerry Ann DC 0.065245 11/24/00 2242 DeBerry Ann DC 0.065250 11/24/00 2242 DeBerry Ann DC 0.065252 11/24/00 2242 DeBerry Ann DC 0.065253 11/24/00 2242 DeBerry Ann DC 0.065297 11/30/00 2242 DeBerry Ann DC 0.065

243 11/23/00 4254 Bailey Ryan MD 0.05246 11/23/00 4254 Bailey Ryan MD 0.05248 11/24/00 4254 Bailey Ryan MD 0.05235 11/23/00 9500 Chin April KS 0.05242 11/23/00 9500 Chin April KS 0.05244 11/24/00 9500 Chin April KS 0.05251 11/24/00 9500 Chin April KS 0.05

? Products


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Product Order Table Order Product Product Product Product

Number Number Desc. Price Qty

339 555 Cheese Tray $45.00 2

260 444 Wine Gift Pack $60.00 1 273 222 Bottle Opener $12.00 1

241 444 Wine Gift Pack $60.00 2

262 222 Bottle Opener $12.00 2


290 555 Cheese Tray $45.00 3 234 555 Cheese Tray $45.00 2

237 111 Wine Guide $15.00 1

237 444 Wine Gift Pack $60.00 1

Order 237 has two products

New Design: [1] Eliminates nulls[2] Unlimited number of products per order


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2NF (Second Normal Form) M hnh d liu nh dng 1NF V Bng d liu cha ng cc trng m ch ph thuc vo mt kha

chnh hon chnh Gi tr kha chnh ca mi bn ghi c th xc nh gi tr ca tt c cc

trng khc trong bn ghi. Nu cc trng ph thuc ch mt phn ca kha chnh (ph thuc b phn),

nhng trng ny nn c t trong mt bng khc

Product Order Table Order Product Product Product Product

Number Number Desc. Price Qty

339 555 Cheese Tray $45.00 2 260 444 Wine Gift Pack $60.00 1


241 444 Wine Gift Pack $60.00 2



290 555 Cheese Tray $45.00 3

234 555 Cheese Tray $45.00 2 237 111 Wine Guide $15.00 1

237 444 Wine Gift Pack $60.00 1


248 333 Jams and Jellies $20.00 2

248 111 Wine Guide $15.00 1

Only depend on Product NumberPrimary Key

Need Order Number

+ Product Number

To find Qty

= 2NF5.3.4. Ti u ha lu tr i tng da trn RDBMSChun ha d liu

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Create new table to store product information

Order


Product Order


0..*

1..*Product

-Product Number: unsigned long-Product Desc.: String-Price: double

Order


0..*

1..*

-Order Number: unsigned long-Product Number: unsigned long-Qty.: unsigned long

First and Last name

Only dependOn Cust ID

NOT whole key

Customer

-Cust ID: unsigned long-Last Name: String-First name: String

1..1

0..*

-Order Number: unsigned long-Date: Date-Cust ID: unsigned long-State: String-Tax Rate: float


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Order


Product Order


0..*

1..*Product


Order


0..*

1..*

NOT whole key


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Product Order Product


Order


0..*

1..*


First and Last name


NOT whole key

Customer


1..1

0..*


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Product Order Product


Order

0..*

1..*



Customer


1..1

0..*

-Order Number: unsigned long-Date: Date-Cust ID: unsigned long-State: String-Tax Rate: float


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3NF (Third Normal Form) Model IS IN 1NF AND IS IN 2NF AND

tables in model do not have fields thatare dependent on non-primary key

fields = No Transitive Dependency

Order-Order Number: unsigned long-Date: Date

-Cust ID: unsigned long-State: String-Tax Rate: float

Depends on

5.3.4. Ti u ha lu tr i tng da trn RDBMSNhng vn vi RDBMS

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Creating new tables to optimise for minimum storage requirements= Separate access to tables

To access data in multiple tables, tables must bejoined This can result in many database operations and lead to very large tables

and slow processing

Customer

-Cust ID: unsigned long-Last Name: String

-First name: String

Order Number: unsigned long-Date: Date

-Cust ID: unsigned long-State: String

Order

To print out customers orders need to join CustomerTable with Order Table ON Cust ID field

Joins can be (computationally) expensive IF tables are large and/or manytables to be joined = slow processing

10,000 products, 25,000 customers, 100,000 orders X 3 products per order

Regional differences in music taste:QUERY = products ordered X state of customers = 300,000 row table

= no. products ordered X total no. columns in tables combined (11)

5.3.4. Ti u ha lu tr i tng da trn RDBMSTi u tc truy cp

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Denormalization Adds data from one table to another inorder to speed processing and eliminate a join operation

Example: Add customer last name to order table to avoidjoining order to customer to get just last name

5.3.4. Ti u ha lu tr i tng da trn RDBMSTi u tc truy cp -Denormalization Candidates

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[1] Lookup TablesTables of value, e.g. of product descriptions, payment types

Codes rarely change include in main table so query does not involve join

[3] Include a parent entitys attributes in its child entity on thephysical data model

Payment Type-Payment Type (PK): String-Paymment Description: String

Order-Order Number(PK): unsigned long-Date: Date-State(FK): String-Cust ID(FK): unsigned long

-Customer Last Name: String-Payment Type (FK): String-Paymment Description: String

Payment Description inPayment Type AND Order

[2] One-to-one relationships

If values from table often accessed together need join each timeCan combine tables (no join) or include some attributes

5.3.4. Ti u ha lu tr i tng da trn RDBMSTi u tc truy cp -Clustering and Indexing

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Clustering Interfile clustering

Arrange records on storage media so that similar recordsare stored close together

Indexing An indexin data storage is like an index in the back of a

textbook;

Index is minimised table containing values from one ormore columns in a table + location of the values withintable.

A query can use an index to find the locations of only those

records that are included in the query answerand A table can have an unlimited number of indexes (but too

many can add overhead)

5.3.4. Ti u ha lu tr i tng da trn RDBMSTi u tc truy cp Indexing example

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S th l f th idth f h l

5.3.4. Ti u ha lu tr i tng da trn RDBMSc lng kch thc khng gian b nh

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Sum the values of the average width of each column(field) to find total record size

Add overhead (vendor may provide an estimate)

Estimate the number of records you plan to have inthe database

5.3.4. Ti u ha lu tr i tng da trn RDBMSc lng kch thc khng gian b nh

V d

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V d

D i d t d i l ti l

5.3.5. Thit k cc lp qun l v truy cp d liu

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Design data access and manipulation classes

Prevent data management functionality from becomingpart of problem domain classes

Four Problem Domain Classes three are concrete

5.3.5. Thit k cc lp qun l v truy cp d liu

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Four Problem Domain Classes, three are concrete = three DAM classes supporting 1:1 translation between

concrete Problem Domain classes and ORDBMS tables

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