UNIVERSITI PUTRA MALAYSIA

A DESIGN AND IMPLEMENTATION OF VERSION MODEL IN OBJECT-ORIENTED DATABASES

ZULKIFLI BIN YAZID

FSAS 1997 23

A DESIGN AND IMPLEMENTATION OF VERSION MODEL

IN OBJECT-ORIENTED DATABASES

By

ZULKIFLI BIN YAZID

the Degree of Master of Science in the Faculty of Science and Environmental Studies

Universiti Putra Malaysia

July, 1997

Say Hay Amor Bliss Upon Day Dream

ii

ACKNOWLEDGEMENTS

The author w i she s to expre s s h i s deepe s t gra t i tude

to Dr.

Comm i t tee ,

Al i Mama t ,

for his

Cha irman o f the Supervisor y

gui dance , a s s i s tance and

encouragement dur ing the ent ire cour se o f s tudy.

The author a l so wi she s to expre s s his thanks to

member s o f the· Supervisor y Comm i t tee Pro f. Madya Dr.

Abu Ta l ib Othman and Dr. Ab dul Azim A. Ghani ,

Lec turer s , Depar tment o f Computer Sc ience , for the ir

kind a s s i s tance and scho lar l y guidance.

The author fur ther l i ke s to expre s s specia l thanks

to En. Ro s lan I sma i l and Mi s s Sha fida Herm y Ha lam y for

the ir va luab le a s s i s tance , mo tiva t ion and comments

dur ing the preparation of the the s i s.

The author a l so ac know ledge s the cooperat ion,

moral suppor t and encouragement from hi s love d o ne s and

fr iends .

iii

TABLE OF CONTENTS

Page

A CKN OWLEDGEMEN TS ........................... iii L IS T OF TABLES ............................. vii L IS T OF FIGU R ES ............................ ix L IS T O F ABBREV IA T IONS ...................... x ABS T R A C T ................................... x i ABS TRAK .................................... xiv

CHAPTER

I

I I

IN T R ODU C T I ON 1

Ba s ic Concept s and Te rm inolog ie s .. �... 3 The Objec t-o riente d Pa radigm . . . . . 3 Objec t-o riented Da taba se s ........ 6 Da taba se Suppo rt fo r Enginee ri ng De sign Applica tions .............. 8 The No tion of Objec t Ve rsions . . . . 9

Mo tiva t ions ........................... 11 Objec tive s of the S tu dy ... ............ 16 S ignificance of the S tu dy ............. 17 Organi sa tion of the The si s ...... . ..... 18

L I TERA TURE REV IEW .................... . 20

An Analysi s of Va riou s Ve rsion Mo del s .. ........... . .......... 21 Implementa tion A spects of Ve rsion Mo del . . . . . . . . . . . . . . . . . . . . . 25

Impo s ing S truc tu re on Ve rsions 26 Ba sic Re qu i rements fo r the Implementat i on of a Versi on

Control Management .. . .... . .... ... 28 Implementa tion of Gene ric Refe rence ........................ 30

A Surve y on the Imp lementa tion of Ve rsion Control Management i n OODBMS s ............................... 32

OR I ON .... ................... .. ... 33 IR IS ............................. 36 ODE .............................. 37 Ve rs ion Control Management I s sue s in OR I ON, IR IS and ODE .... 40

iv

I I I A GENERAL I SED VER S I ON MODEL ... . . . . . . .. 4 2

IV

v

VI

Intro duc tion . . . . ... .. . ..... . ..... . . ... 4 2 Charac teri stic s o f a Ver sion Model .... 4 3

Time Axi s .. . . . .... . ...... ... . .... 4 3 Variants . . . . . ... . . . . . . . . . ..... . .. 4 4 Ver sion Struc ture . . . . . . . . . . . . . . . . 4 4 Ver sion cla s si fica tion . . . . . . . . . . • 4 4

A Propo se d Ver sion Mo del . ............. 44 Advantage s of the Propo se d Mo del ...... 5 0

INCOR PORAT ING VER S I ONS INTO A DATA MODEL ........................... . 5 4

Intro duc tion . . . ... . . . .. . . . . . . ... . . . . .. 5 4 Core Fea ture s of an Objec t Ver sions Da ta Mo del . ... . . . . . ..... . .. . .... . . . . . . 5 5

Enti tie s and enti t y type . . . . .. . . . 5 5 At tribute s ... . ....... . . . . . . . . . . . . 5 5 Rela tion ship ... . . . . . . . ... . ... . . . . 5 6 Time ... . .... . .. . . . . . ...... . ... . .. 5 6

A Propo sed Da ta Model ....... .......... 5 7 Atomic Opera tions of the Schema . . . . ... 6 1

VERS ION C ONTROL MECHAN I SM . . . • . . . . . . . . . 6 4

Intro duc tion . . . . . . . . . . . . . . . . . ... . ..... 6 4 A Propo se d Ver sion Control Mechani sm .. . . .... . . . . . .. . . . . . . . ... . . . . 6 5

The Organi sa tion o f Da ta . ..... . . . 6 6 Re ference S tra tegie s . . . . . . . . . . . . . 6 9 Coor dina tion o f Ver sion Ac t i vi tie s ..... . ... . ... . . . .... . . . 7 2

Impac t o f the Propo sed Mec hani sm ... . . . 72

A PROTOTY PE OF V E R S I ONS MANAGEMENT .... 7 6

Requirements of the Pro to type ..... . . . . 76 Storage Area . . . . . ... . .. . ..... . . . . 7 7 Opera tio ns . . . ... . . . . . . . . . . ..... . . 7 9

Imp lementa tion ... . ... . . . ... . . . . . . . . ... 8 2 Tool to Develop the Pro to type . ... 8 2 Program o f the Pro to typ e .... . . .. . 8 2 Te s t Da ta . ... .. . . . . . . . . . .. . ...... 8 2

Te sting and Evaluation .... . . . . ..... . . . 8 4 Evaluate d Re sul t s o f the Te s t .... . . . . . 90 Guideline s to Manage and Control Object Ver sions in OODBMS . . . . ...... . .. 103

v

VII CONCLUSIONS AND RECOMMENDATION FOR FURTHER WORK . . . . . . . . . . . . . ...... ... 1 07

Conclu sion s . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Recommen da tion fo r Furthe r Wo r k . . . . . . . 110

T ran sac tion Prog ram s . . . . . . . . . . . . . 111 A Propo sed Vers ion Con trol Machani sm fo r T ran sac t ion Management . . . . . . . . . . . . . . . . . . . . . . . 1 1 5 Requiremen t s fo r Fu rthe r Re sea rch . . . . . . . . . . . . . . . . . . . . . . . . . 118

B IBL I OGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 V I TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

vi

LIST OF TABLES

Table

1 The Ver s io ns Management Operat ion Set .... ............. .

2 Propert ie s o f t he Fir st Data Set ...................... .

3 Propert ie s o f t he Se cond Data Set ...................... .

4 E f f i ciency Comparat ive

Page

80

8 3

8 3

Tab 1 e . . . . . . . . . . . . . . . . . . . . . . . . . . 90

5 E f f ic ie ncy to Coor dinate Object H i stor ie s and Integrate Di f ferent T ype s o f Deve lopment ( Data Set 1 ) . . . . . . . . . . . . . . . . . . . 9 3

6 E f ficiency to Coor dinate Obje ct H i stor ie s and Integrate Di f ferent T ype s o f Deve lopment ( Data Set 2 ) . . . . . . . . . . . . . . . . . . . 9 3

7 E f fi c ie ncy to T ie Loo se l y Re lated Ent it ie s ( Data Set 1 ) . . . 9 4

8 E f f i c iency to T ie Loo se l y Re late d Ent it ie s ( Data Set 2 ) . . . 95

9 E f fi c iency to Update Obje ct Re ference ( Data Set 1 ) ......... 96

10 E ff i c iency to Up date Obje ct Reference (Data set 2) . . . . . . . . . 96

11 E f f i ciency to Tr igger a Daemo n ( Data Set 1) . . . . . . . . . . . . 97

1 2 E f f i c ie ncy to Tr igger a Daemon ( Data Set 2) . . . . . . . . . . . . 98

1 3 E f f i c iency in Se le ct ing a Ver s ion A ccor ding to it s Obje ct' s Propert ie s ( Data Set 1 ) . . . . . . . . 99

vi i

1 4 Effi ci ency i n Sel ecting a V ers ion A ccording to its Obj ect' s Prop er ti es (Data Set 2 ) ..... . .. 9 9

15 Effici enc y to Coordinat e V er sion Activiti e s ( Data Set 1) ................... 100

16 Effi ci en cy to Coordinat e V er sion Activiti es (Data Set 2 ) ....... . .. . .. . ..... 101

17 Evaluation on th e V er sion s Manag em ent' s Effici ency ........ 101

viii

LIST OF F IGURES

Figure Page

1 D i f ferent V i ew s o f an Obj ec t on the T im e Ax i s .............. . 22

2 A Version Clus ter 23

3 A V er s ion Hierarc hy 27

4 The V i ew o f a G eneral i sed V er s i on Model . . .. . ............ . 46

5 V ersion Env i ronm ent o f a Program Dev elopm ent ................... . 49

6 Schem a o f Prog ram Dev elopm ent Datab a s e ..... . ...... .......... . 58

7 Org an i s at ion of Data ........ .. . 67

8 R epres entation o f Data in the V ers i ons Manag em ent ........... . 69

9 The S tr ateg y to Updat e R e ferenc e o f an Obj ec t ... .. ............. . 71

10 Prop o s ed Concu rrent Mechani sm . . 117

ix

AI

CAD

CAM

CASE

DBMS

GSM

I CE

IS

ODE

OlD

OODBMS

SEE

S PPD

LIST OF ABBREVIATIONS

Ar tifi cial In t e l lig en c e

C ompu ter Aid ed D e sign

C ompu ter Aid ed Manufa cturing

C ompu ter Aid ed Sof twar e Engin eering

Da taba s e Manag em en t Sys tem

Gen eric S eman ti c M od el

In tegra ted C ompu ter Environm en t

Informa ti on System

Obj ect Da taba s e and Environm en t

Obj ect Id en tifi er

Obj ect-ori en t ed Da taba se Manag emen t Sys t em

Sof twar e Engin eering Environm en t

Si stem Penguru san Pangkalan Da ta

x

Ab stract o f the t he s is submitted to the Sena te o f Unive r s i t i Put ra Malay s i a in ful f i lment o f the requiremen t s for the deg ree o f Ma ste r o f Science.

A DESIGN AND IMPLEMENTATION OF A VERSION MODEL IN OBJECT-ORIENTED DATABASES

By

ZULKIFLI BIN YAZID

July, 1 9 9 7

Chai rman Dr. Ali M amat

F aculty Science and Envi ronmen tal S tu die s

Due t o the a dvance s in c ompute r techn ol og y, new

applicati on s such as office aut omation, s oftw are

enginee ring and compute r aide d de sign ( CAD ) have

eme rged . The se new applic ation s n ot only demand fast

ret rieval and modi fication as t he e arlie r application s

but al so new requi rement s, for in s tance , the cap abili ty

t o rep re sent c omplex object. M an y app roache s have been

p ropo sed in orde r to meet the new requi remen t s. It i s

claimed th at Objec t-oriented Datab a se Management

System s (OODBMS s) o ffe r a g ood s oluti on . One of

OODBMS s' f acilitie s i s the ve rsi on c ont rol management.

With a ve rsi on c ont rol m anagement, the management and

x i

control o f ob j ect v er s ions can b e done in a sy s tema tic

way .

H ow ev er, obj ect v er sions hav e b e en plagu ed by the

la ck o f ad equa te knowl edg e for managing and contr olling

v er si on a cti vi ti es . A s tru ctur ed approa ch i s n eed ed

wi thin whi ch obj ect v er si on s can e f fectiv ely b e

appli ed sp eci fically in so f twar e engineering .

C on s equ en tly, the s tudy addr e s s es the d e sign and

impl em en ta ti on o f a v er si on m od el in obj ect- ori ented

da taba ses .

The s tudy ha s proposed a g eneral i s ed v er si on

m od el . The m od el can ov er com e som e drawba ck s o f som e

pr eviou s v er sion m od el s . The g en erali s ed v er si on m od el

i s then in corp ora ted in to a da ta m od el to provid e a

gl obal vi ew in d ev eloping a s tructur ed schema and

allow s the s eman ti c o f v ersion s to b e r epresented a t

the da ta m od el l ev el . El em en t s o f the da ta m od el ar e

then pr ogramm ed into v ersion con trol m echani sm s and

emb edd ed in to the prototyp e o f a v er si on s manag em en t.

The prin cipal ta sk o f the prototyp e i s to determin e

whether obj ect v er si ons ar e manag eabl e and

controllable. Evid ently , the protot yp e draw s a set o f

guid eline for managing and contr olling obj ect v er si ons .

xii

Indirect ly t he guid e line app rov e s t he e f f i cien cy o f the

p roposed g en e ra li s ed v ersi on m od e l to ov ercom e som e

d rawba ck s of s om e p reviou s v er si on m od e l s. M o reov er,

the guid e lin e p rovid es a direct i on in d ev e l oping a

st ru ctu red s chema and a l low s the s emantic of v ersi on s

t o b e rep re s ent ed at the da ta m od e l l ev e l.

The evid en ce whi ch ha s b e en summa ri s ed f rom the

stud y rev ea l s t hat t he noti on of obj ect v ersion s in IS

a cti vi ti es shou ld b e giv en att ention. T hi s, in tu rn,

can make t he int era ction with databa se sy st em s a more

p l ea sant exp eri en ce f o r end-u sers and at the sam e tim e

in crea ses thei r p rodu ctivit y.

xiii

Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia bagi memenuhi syarat untuk Ijazah Ma ster Sain s .

REKABENTUK DAN PERLAKSANAAN MODEL VERSI DI DALAM PANGKALAN DATA BERORIENTASIKAN OBJEK

Ol eh

ZULK I FL I B IN YAZ ID

Julai, 1997

Peng eru si Dr. Ali Mama t

Fakul ti Sain s dan Pengajian Alam S ek i tar

B eriku tan daripada k emajuan dalam tekn ologi

k omput er, banyak aplika si baru sep er ti au toma si

p ejaba t, k ejuru teraan p eri sian dan ban tuan k ompu ter

un tuk r ekab en tuk ( CAD) telah muncul. Aplika si-aplika si

baru ini bukan hanya m em erlukan capaian dan m odifika si

yang pan ta s s ep er ti aplika si seb elumnya tetapi

m em erlukan juga k ep erluan tambahan sep er ti k eupayaan

m ewakil obj ek k ompl ek s . Pelbagai p end eka tan telah

dicadangkan untuk m em enuhi k ep erluan baru ini. Salah

sa tu p eny el esaian yang baik ialah Si stem Penguru san

Pangkalan Data (SP PD ) B er ori en ta sikan Obj ek. Salah sa tu

k emudahannya ialah un tuk menguru skan p engawalan v er si .

xi v

D engan ini , p engurusan dan p engawa la n vers i obj e k boleh

dila ksana kan dengan l eb i h s i st emat i k.

Wa laubaga imanapun , p erla ksanaan v ersi obj e k

m engha dap i ma salah da ri seg i p eng etahuan m engurus dan

m engawal a kt iv it i versi. s uatu p endekatan b erst ruktur

dip erlukan supaya v ersi obj e k b ol eh dilak sanakan

s eca ra b erk e san khususnya di b i dang

kej urut e raan p eri s ian. Oleh it u kaj ian in i cuba

m eng enalpa st i sat u rekab entuk dan p e rla ksaan m odel

ver s i di dalam pang kalan data b erorienta s ikan obj e k .

Kaj ian in i m encadang kan suat u m odel v e r s i yang

m empunya i s ifat am. M odel-model in i b ol eh m emb eri

p enyel e sa ian k epada ma salah-ma salah yang diha dap i ol eh

m odel-model s eb elumnya. Model v e r s i in i d igabungkan

dengan model data untuk m emb e ri pandangan globa l

p embangunan s kima berst ruktur dan m emb ena rkan s emant ik

sesuatu versi diwa kil i di p ering kat m odel data . Un sur­

unsur m odel data akan dip rog ram k e dalam m ekan i sma

p engawalan versi dan dic erna k e dalam Protota ip

Pengurusan Versi. Tuga s utama p rot ota ip in i ialah untuk

m en entukan samada v ersi obj ek t erseb ut b ol eh diurus dan

dikawal. Terb ukt i , ha s il dari p rot ota ip dapat m emb eri

xv

sa tu garispanduan untuk mengurus dan mengawal versi

obj ek . S ecara tidak lang sung gari spanduan ini dapat

menunj ukkan k eberk e sanan mod el versi yang di cadangkan

untuk menyel esa ikan ma sa lah m od e l-mod e l s eb elumnya.

B egi tu juga ga ri spanduan ini m emb eri a rah di dalam

p embangunan skima b erst ruktu r dan m emb ena rkan s emantik

s esuatu v ersi diwakili di p e ringkat mod el data .

Bukti yang dib eri ol eh kajian ini m enunjukkan

bahawa versi obj ek di dalam aktiviti Si st em Mak lumat

( IS ) ha ru s dib eri p e rhatian . Ini b ol eh m emudahkan

int erak si di anta ra p engguna d engan si st em pangkalan

data , s ekaligu s dapat m eningkatkan pr oduktiviti.

xvi

CHAPTER I

INTRODUCTION

C onv en tional Da taba s e Manag em en t Sys tem s (DBMS s)

e sp ecially R elati onal DBMS, hav e l ong b een recogn i sed

a s p ow e rful and effic ien t tool s for manag ing

organi sa tion info rma t i on. Th e s e system s a re

pa rticu la rly sui ted f o r applica t i on a rea s such a s

bank ing, payroll, inv en tory and th e lik e. Du e t o th e

advanc es in c ompu ter technology, n ew appl icat i on s such

a s off ic e au toma t i on, sof twa re eng in eering and c ompu ter

aided design ( CAD) hav e em erged . Th e s e n ew application s

n ot only demand fa s t retrieval and m odifica t i on a s th e

ea rl i er applica tion s bu t al so n ew requi rem en t s, f or

in stance, th e capabil i ty to rep re s en t c ompl ex obj ec t.

Many app roach e s hav e b e en p rop o s ed in order to

m eet th e n ew requ irem en t s. It is claim ed tha t Obj ec t­

ori en t ed Databa s e Manag em ent Sys t em s ( OODBMS s ) offer a

good solu tion (Bertin o and Ma rtin o, 1991) . In OODBMS s

every ent i ty i s c on si dered a s an obj ec t . An objec t can

b e a s s impl e a s a s ingl e un i t da ta or a s compl ex a s w e

1

2

want. In add it ion , OODBMSs provide s ome facilities

which ar e not f ound in o ther types of da taba s e sy s tem s .

On e of such facili ti es i s the v er si on con trol m echani sm

and ther ef or e OODBMS s ar e v ery sui tabl e f or engin eering

d e sign applica tion s.

In applica tion s such a s comput er aid ed d e sign

( CAD ) , compu ter aid ed manufac turing ( CAM) or

compu ter aid ed sof twar e engin eer ing ( CASE) , the

sam e obj ect und erg oes mul tipl e c hang es , or s ta t e

tran si tion s. I t is d e sirabl e to acc e s s or inv e s tiga te

pr eviou s s ta t e s , or v er si on s , of the obj ec t . Wi th a

v er si on con tr ol m echani sm , the organi sa tion of v er si on s

can b e don e in a systema tic way. Whil e f ew commercia l

DBMS s app ear in the mar ket off ering v er si on facili ti es ,

som e i s sues p er taining to the obj ec t v er si on s r emain ed

to b e solv ed.

Thi s chap t er in tr oduc es

terminologies. Thi s chapt er

the ba sic conc ep t s

al so highlights

and

the

inher en t w eakn e s s that imp ed es the impl em en ta ti on of

obj ec t v er si on s and argue s f or a n e ed of r e search to

ov ercom e drawback s of obj ec t v er si on s.

al so presen t s obj ec ti v e s of the study.

Thi s chap ter

Finally , the

c hap t er pr esen t s the organi sa tion of the the s i s .

3

Basic Concepts and Terminologies

T h i s sect i on intr oduce s some a spect s o f ob j ect­

or ientat ion a s the backgroun d o f t he stu dy. The

intr o duct ion start s with the object-or iented feature s

and foll ow s b y a br ie f explanat ion on the emergence o f

object- or iente d databa se a s re source ful tool s for new

appl icat ion s.

T h i s sect i on al so highl ight s t he databa se supp ort

for eng ineer ing appl icat ion s which ha s caught the

attent ion o f m o st so ftware developer s .

The Object-oriented Paradigm

T he object- or iente d i s an approach pr imar ily

intr oduced in t he de s ign o f a dvanced pr ogramm ing

language s and environment s. The approach wa s f ir st

intro duced b y the language calle d S imula ( B irtw i stle et

al., 1973) , a language for pr ogramming c omputer

s imulat ion. Most recently the language o f c++ and

Smalltalk (Goldberg and R ob s on, 1983) have become t he

m o st w idely known object-or iented language s.

Several fundamental idea s have been pr op o se d in

underlying the object-or iented feature s. The se feature s

4

have been discus s ed extensively by authors such as

Bertino and Martino (1991), Coplien (1992), Joseph et

al. (1991) , Mart in (199 3) , Mat tos et al. (199 3) ,

Nierstrasz (1989) , Ozkarahan (1990) and, Unland and

Schalageter (1990). The object-oriented features are as

the following.

Objects and Classes

Each real-world entity is modelled by an obj ect.

Each obj ect is associated wit h a unique identifier

(OlD). An obj ect is an instance of an obj ect t ype. An

obj ect type is a category of obj ect. An obj ect is

concerned with bo th data and the me t hods with which the

data is manipulat ed. Each obj ect has a set of instance

at tributes and methods. The value of an at tribute can

be an obj ect or a set of obj ects. This charact eristic

perm i ts arbitrarily complex obj ects to be defined as an

aggre gation o f o ther obj ects. The se t o f attribut es o f

an object and the se t of methods represent the object

struct ure and behaviour, re spectively. The term class

refers to the implementation of an obj ect t ype. A class

can be de fined as a specialis a tion o f one or more

classes. A class defined as a specialisation is called

subclass, and inherits at tributes and methods from it s

superclass. A class

defining:

specified i t s ins tances by

5

( a) a structur e, that is, a s et o f inst anc e attr ib ut es

(b) a s et of m ess ag es t hat defines the ext er nal

int er fac e

(c) a s et o f m ethods that ar e invo ked by m ess ag es.

Method

Op er ati ons ar e us ed to m anipul at e the dat a

structure o f an obj ect typ e . An op er ati on wi l l b e s ent

as a m ess ag e to m anipulat e the dat a structur e o f an

obj ect o f an obj ect type. Onc e the op er ati ons ar e

encoded in s oftw ar e, they ar e usually r ef err ed to as

m ethod .

Message

To p er form op er ati ons on an object, w e n eed t o

s end a m ess ag e. The m ess ag e caus es an op er ati on t o b e

i nvoked but it does not indic at e how the op er ation

should b e p er form ed.

Inheritance

An obj ect typ e c an has s ubtyp es. Ther e is a

hier archy o f obj ect typ es, s ubtypes, and s o on . A c l ass

imp l em ents the obj ect typ e . A subc l ass inherits

6

prop erti es of it s par ent c la s s; sub- sub c la s s wi l l

inherit the pr op erty of the sub c la s s and s o on.

Encapsulation

The obj ect hid es i t s data from ot her obj ect s and

all ow s the data t o b e acce s s ed via it s op era tion s .

En cap sulation i s the r e sult of hiding the

impl em entation d etail s of an obj ect from it s u s er.

S om e oth er f eatur e s of obj ect-ori ent ed su ch a s

p olym orphi sm , p er si st en ce , obj e c t id enti ty , et c. , w er e

al so highlight ed by Andr ew (1990) , Ban cilhon et al .

(1988) , Martin (1993) , Ozkarahan (1990) , Unland and

S chalag et er (1990) . H owev er , the fiv e el em ent s whi ch

hav e b een d e s crib ed ar e the cor e of obj ect-ori enta tion .

Obj ect-oriented Databases

One of t oday' s m o s t burning databa se i s su e s is how

t o ad equa tely support n ew cla s s e s of appli ca tion s tha t

ar e n ot w ell s erv ed by conv entional da taba s e sy st em

(Unland and S chlag et er , 1990) . For exampl e CAD , CASE ,

data int en siv e Artifi cial Int ellig en ce (A I) application

or imag e and v oi ce processing pla ce d emand s on databa s e

sy st em s that ex ceed the capabiliti e s of conv enti onal

databa s e sy stem s by far . H ow ev er , r ec en t DBMS s such a s

7

Avanc e (Bjon er st edt an d Hult en , 1989 ) , G em stone ( Br e it l

et al . , 1989 ) , Iri s (Wi lkin son et al., 199 0 ) , 02

(Bancilhon et al ., 1988 ) , Orion (Kim et al., 1989 ) ,

P o stgr es ( R ow e and Ston ebrak er, 1987 ) an d Vba s e (Andr ew

et al., 199 0 ) have ta ken up t he c hall eng e by de signing

an arc hit ectur e which exc eeds the capabiliti es of

c onv entional databa se system s and supp orted the object­

ori ent ed f eatur es.

Ozkarahan ( 199 0 ) gives

t o the inf luenc e c ontribut ed

f eatur e s in the databa s e fi el d.

tw o rea s on s t hat

of obj ect-ori ented

Fir st , the databa s e

t echn ol ogy ha s evolved rapidly and widespr ead ov er

tim e. S ec on d , many ar ea s in the c omput er sci enc e have

bec om e m or e int egrat ed. T he ov eral l obj ective ,

ther ef or e , i s t o ext end the t ec hn ol ogy for capturing

m or e m eaningful inf ormation . T hi s imp li es t o the

s emantic and b ehavi oural a sp ect s of data into m odel ling

f orma li sm.

The fir st publici s ed semantic model app ear s in

197 4 (Abrial, 197 4 ) . The ar ea matur ed rapi dly in r ec ent

year s , and databa s e r es earcher s hav e turn ed their

att ention in incorp orating b ehavi oural a spect of data

into m odelling f orma li sm (King , 1988; Lock emann et al . ,

1990 ). Thus , the m odelling f ormali sm i s int egrated with

the obj ect-o:ti ented paradigm and paved the way for

8

resea rch direct ion s on obj ect-or ient ed dat a mode l l in g.

S ev era l att empt s (At kin son et a l . , 1989 ; St ein et

al. , 1989 ; Univ ersity of Cal if o rn ia , 1990) hav e been

ma de t o forg e a c ommon ag reem ent on the mode l ling

c onc ept but they hav e so fa r been un succ e s sf ul (Ling

an d T eo , 1993) . How ev e r , the c ore c onc ept of obj ect­

ori ent ed data m odel (K im et al. , 1989; Ozka rahan , 1990)

li es with t he usual f eatures of obj ect-o r i ent ed

languag es s uc h as the notion of cla s ses , obj ect s ,

encap sulation ,

abst racti on , etc .

inheritanc e , p ers i st enc e , data

Database Support for Engineering Design Applications

An eng in eering applicat i on p roc e s s inv olv es

numer ous typ e s of inf ormation and eno rm ous amount of

data . These data it em s can be mainta in ed in va ri ous

f ormat s and m edia . How ev e r , Liu and Horowitz (1991)

hav e sugg ested the use of databa s e supp o rt t o maintain

the data and imp rov e s the p roducti vi ty of softwa re

dev elopm ent. In addition to t hi s , the databa s e i s al so

us eful in softwa re ma int enanc e and rev erse engin eering

(K etabchi et al . , 1989) . A great deal of w o rk ha s been

tak ing plac e in dev elop ing n ew databa s e syst em ba s ed on

this app roach. Although there ha s been an inc rea s e

awar enes s among softwa re dev elop ers about the st rength