Object Oriented Development (OOD) is one of the extremely few software development methods actually designed for modern Ada language, real-time, embedded applications. OOD is a significant improvement over more traditional functional decomposition and modeling methods in that ODD: Better manages the size, complexity, and concurrancy of today's systems; Better addresses important software engineering principles such as abstract data types, levels of abstraction, and information hiding; Produces a better design that more closely matches reality; Produces more maintainable software by better localizing data and thus limiting the impact of requirements changes; and Specifically exploits the power of Ada. OOD is further explored in detail

Firesmith, Donald G.

English

NASA Technical Reports Server

OBJECT-ORIENTED DEVELOPHENT 
by 
Donald G. Firesmith 
Software Hethodologiet 
Hagnavox Electronic Syeteme Company 
Advanced Software Syetems Division 
1313 Production Road 
Fort Uayne. IN 46808 
( 2 1 9 )  429-4327 
1 )  WHY IS OBJECT-ORIENTED DEVELOPMENT (OOD) IMPORTANT? 
O O D  ie one of the extremely feu eoftuare development methode 
actually deeigned for modern Ada ( * I  language. real-time. 
embedded appllcatione. 
O O D  is a eigniflcant improvement over more traditional functional 
decomposition and modeling methode in that OOD: 
a) Better managee the eize. complexity. and concurrancy 
b) Better addreeeee important eottuare engineering 
of today’s syeteme. 
princlplee euch as abetract data types. levele of 
abstractionr and information hiding. 
real i ty. 
data end thue limiting the impact of requlremente changes. 
c) Producee a better deelgn that more closely matchee 
d )  Producee more maintainable eoftuare by better localizing 
e) Specifically exploite the pouer of Ada. 
2) VHAT IS OOD? 
OOD ie a eyetematic. etep-by-etep eoftuere development method that: 
a) Hae an optimal domain of application -- the development of 
b) Covere alle or a m a j o r  portion. of the eoftuare life-cycle. 
c) Supporte exteneive parallel development. 
d )  Henagee the complexity of large development efforte. 
e) le supported by detailed etandarde and proceduree. 
f )  Requtree training and eupport to be effective. 
modern Ada appllcatione (e.~.. real-time. embedded eoftuare). 
O O D  ie: 
a ) 
b) Ada-oriented. 
Obj ec t-or i ented. 
( i t )  Ada ie a regietered trademark of t h e  U . S .  Government (AJPO). a 
D . 4 . 1 . 1  
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E N T I T Y - A T T R I B U T E  R E L A T I O N S H I P  
D a t a b a s e  T e c h n o l o g y  ( 1 9 6 0 ' s )  - 
c )  Based upon modern aoftuaro engineering. 
d) Recursive. globally top-down, hierarchical COHPOSITION 
e) Revolutionary in approach. 
f )  A "grab and go" method. 
gl Relatively eaey to learn. 
h) Being aucceeefully used by several companlee. 
i )  Still evolving (Bee figure 1 ) .  
method. 
. 
L E V E L S  OF ADBSTRACTION 
D t j k s t r a  (1968) 
ABSTRACT DATA TYPES 
L ( s k o v ,  G u t t o g ,  Show (1970's) 
FORMAL TECHNIOUES 
R o b t n s o n ,  L e o v l t t  (19771 
INFORMATION H I D I N G  
P a r n a s  (19721 
r 
NOUNS AND VERBS 
A b b o t t  (19811 
Figure 1 :  The evolution of OOD 
D . 4 . 1 . 2  
1 
AFATDS EXPERIENCE 
M o g n a v o x  (1985) 
OBJECT-ORIENTED DEVELOPMENT 
F t r e s m t t h ,  e t .  a l .  (1985) 
OOD ia NOT: 
A functional, hierarchical DECOHPOSlTlOW method. 
A modeling method. 
Easily mated with much methode. 
Effective without adequate training. 
Conetrained to the claaeical muaterfall" lifecycle. 
Consietent with DOD-STD-2167 and related pre-Ada etandarde. 
Standardized acroer the indumtry. 
Yet adequately eupported by commercially available eoftWare 
tools. 
3) OOD IS OBJECT-ORIENTED. 
An OBJECT ie an entity that: 
a) Hae a value (e.g. . data) or state (e.g. Ada taek). 
b) Suffere and/or caueee operatione. 
OOD producee: 
a) Ada objecte that correepond to objecte in the real world. 
b) Ada typee (i.e.. object templatee). 
c) Operatione that operate on theme objecte. 
OOD emphaeizee the implementation of objecte in terme of 
ABSTRACT DATA TYPES. OOD groupe. in the eame Ada package: 
a) A mingle type and 
b) A l l  operatione that operate upon euch objecte. 
OOD producee a eubetantially different eoftuare architecture 
than traditional functional decompoeition method8 euch am 
Structured Deeign which generate untts. each of which implements 
eome FUNCTION of the requirement8 epecification. 
4) OOD IS ADA-ORIENTED. 
Ada ie an object-oriented high-level language. 
Packagee. which are the main building blocke of properly designed 
Ada eoftuare. are ale0 the main building blockm produced by OOD. 
The physical design produced by OOD ie top-down in terme of Ada: 
a) Neeting and 
b) Context (i.e.. the Ada "uith" etatement). 
OOD eeparately develope Ada epecificatione and bodies. 
O O D * e  low-level teeting naturally accounte for Ada compilation 
order conetra 1 nte. 
D . 4 . 1 . 3  
OOD Diaqrame clearly identify the vmrious Ada programming iinite. 
Ad8 PDL ir an intogral part o f  OOD'r  dorign 8nd coding rtope- 
The Object8 produced by OOD aro implemented in Ada ae: 
a) Constants and variables 
b) Abetract data typor 
0 )  T a s k r  
The operatione producmd by OOD mro implemented i r i  Ada primarily 
a) Subprograms 
b) Taek entries 
5 )  OOD IS BASED UPON HODERN SOFTVARE ENGINEERING. 
OOD specifically addresses each of the following eoftuare 
engineering principlee or concepts: 
a) ABSTRACT DATA TYPES. i ) HODULAR ITY. 
b) ABSTRACTION LEVELS. j )  Organizational Independence. 
c) Coheeion. k) Readabi 1 i ty. 
d )  Concurrency. 1 )  Reusability. 
e) Coupling. m )  Structuro. 
f 1 INFORHATION HIDING. n) Teatability 
g )  Localization. 0 )  Verifiability. 
h )  HAINTAINABILITY. 0 
6) O O D  IS RECURSIVE, GLOBALLY TOP-DOVN, HIERARCHIAL COHPOSITION METHOD. 
Traditional software development methods are reetricted to the 
claeeic wuaterfall* life-cycle (eee Figure 2 )  in which: 
a) The eoftuare requiremente are analyzed firet. 
b) The preliminary deeign ie developed eecond. 
c )  The detailed deeign followe. 
d )  And eo on. 
csc I 
lES l I f f i  1 
Figure 2: The claeeic "uaterfall" life-cycle 
D.4.1.4 
Bocauoe tho eoftw8ro 1. dmvoloped in 8 top-down manner only within 
the boundrier of 08oh lif~-cycIm phmre, theme aethode are at beet 
only locally top-down. 
OOD 1. a rocurrlve~ globrlly top-doun. hierarchial compoeition 
method. Itr roftumre lifo-cyclm (om. Figure 3) diftors eignificantlY 
from the cl8eeio “uaterfalla life-cycle becauee rt le baeed upon 
reCUr0iOn and tWO concepte unique to OOD: tha Booth and SubbOOCh. 
A BOOCH is t h e  collection of a11 eottuare reeulting from the 
recursive application of O O D  to o mpecific met of coherent 
eottuare requiresente -- roquirernnte that rpecify a mingle 
well-defined problem. 
A SUBBOOCH ie a emall. onnagable eubset of a booch that ie 
identilied and developed during a eingle recureion of OOD. 
See Figure 4. 
Note that theme two concepte have no obvioue natural relationehip to 
the DoD hierarchical decompoeition entitiee CSCI. TLCSC. and LLCSC. 
Beginning with the higheet abetraction level and progreeeing 
steadily dounuarde in terme of nesting and *uithingw. the booch 
le deeignedr coded. and tested in incremente of a eubbooch. Thug. 
the eoftwere groue top-down. eubbooch by eubbooch. via the 
recureive application of ODD until the entire softuare tree 
ie completed. 
Locally. however. OOD employe the appropriate technique 
(top-down or bottom-up) depending upon the epecific requirement8 
of each individual development activity. 
This alloue very significant parallel development baoed upon the 
“Deeign a little. code a little. teat a little“ concept. 
7 )  AESPONS I B I L I T I ES. 
The follouing pereonnel have OOD reeponeiblitiee (eee Figure 5 ) :  
a )  Hanagement 
b )  Softuare Development Teams. each coneistino of a: 
- Designer 
- Programmer 
- Teeter 
c )  Hetrice Collectore 
d )  Softuare Puality Evaluation 
e) Softuare Syetem Engineering 
8 )  SUBBOOCH DEVELOPHENT 
The eubbooche that compriee each booch are recureively developed 
in a globally top-down fashion. The development of each eubbooch 
coneiete of the following three EUbph86ee: 
D.4.1.5 
0 
0B.ECT- W T W A R E  SYSTEM 
OAIENTED 
DEVELOPrENT AN0 TEST AND TEST 
INTEGRATION INTEiFAlIm I BUILD L 1 BUILD L 1 BUILD L 
Figure 3: Tho OOD eoftuare life-cycle 
D . 4 . 1 . 6  
I I 
I I 
I I 
I I 
I I 
I 
TERTIARY SUBBOOCH 
RESULTING FROM 
THE USE OF 
RECURSION 
WHEREI 0 REPREKNTS A SUBPWXRAM A N 0  REPRESENTS A MPENDENCY I 
REPRESENTS A PACKAGE 
Figure 4: Sample Booch structure 
D . 4 . 1 . 7  
I H I Softwmrm I 
Objmot-Orlmntmd Dmvmlopmmnt Proammm I G I Dmv. Tmmm I I s 
Step I Tit 10 I T l D l P l T l C l E  
= = = = = = = = = = ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ - = = = - - = - ~ = - = - = - - - = - = - - -  
- - - - - - - - g - o ~ ~ g ~ g ~ ~ ~ g ~ ~ ~ ~ ~ o ~ g ~ ~ ~ ~ ~ ~ ~ ~ o ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~  n I----------- I H I Q  
1 I INITIATION OF BOOCH DEVELOPXENT 1 1 1  I l l  1 4  
2 I SUBBOOCH DEVELOPHENT I---------------------" 
2 - 1  I SUBBOOCH REQUIREHENTS SUBPHASE I----------------------- 
2.1.1 I Inltimtlon of Subboooh Dmvmlopmmnt 1 1 1  I 1 1 1 4  
2.1.2 I Inltimtlon of tho SDF 1 3 1 1 1  1 I 1 4  
2.1.3 I Problmm Statmmont 1 3 1 1 1 2 1 2 1  1 4  
2.1.4 I Rrpuirmmsntm Analymim 1 3 1 1 1 2 1 2 1  1 4  
2.1.5 I Subbooch Roquirmmmntm lnmpmction 1 1 1 2 1 2 1 2 1  1 4  
2.2 I SUBBOOCH DESIGN SUBPHASE I----------------------- 
2.2.1 I Loglcml Dmmign 1 3 1 1 3 2 1 2 1  1 4  
2.2.2 t Object Anmlymim 1 3 : 1 1 2 1 2 1  1 4  
2.2.3 1 Opmrmtion An8lyrir 1 3 1 1 1 2 1 2 1  1 4  
2.2.4 I Unit Id., 0rg.r and Dependonciom 1 3 1 1 1 2 1 2 1  1 4  
2.2.5 1 Subboooh Prmliminmry Deoign Inmpmction I 3 I 2 1 1 I 1 I 1 4  
2.2.6 I Dmoign Analymim 1 3 1 1 1 2 1 2 1  I 4  
2.2.7 1 Coding of Unit Speoificmtione 1 3 1 1 1 2 1 2 1  1 4  
2 .2 .8  I Subbooch Dmt8iled Dmmign Inmpmction 1 3 1 2 1 1 1 2 1 1 1 4  
2.3.1 I Coding of Unit Bodire 1 3 1 3 1 1 1 2 1  1 4  
2.3.2 1 Subbooch Tmrt Plan 1 3 1 2 1 2 1 1 1  1 4  
2.3 .3  I Subbooch Tmmt Software 1 3 1 2 1 2 1 1 1  1 4  
2.3.4 I Subbooch Tmmt Procrduras 1 3 3 2 3 2 1 1 :  : 4  
2.3.5 : Subbuoch Code Inrpection 1 3 1 1 1 2 : 2 : 1 : 4  
2.3.6 1 Initial Subbooch Teeting 1 3 1 2 1 2 1 1 1  1 4  
3 1 BOOCH INTEGRATION AND TESTING I----------------------- 
3.1 I BOOCH INTEGRATION 1 3 1  I I 1 1  : 4  
3.2 I BOOCH FUNCTIONAL TESTING 1 3 1  I 1 1 1  1 4  
3 .3  1 BOOCH DELIVERABLE DOCUHENTATION 1 2 1 1 1 1 1 1 :  1 4  
3.4 1 BOOCH REVIEV 1 1 : 2 1 2 : 2 1 1 : 1  
---------------o-------g-----o------g----------------------------------- 
- - _ - - - o - - _ o - - - - - - - - - - - - - - - - - - - - - - - - -  
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
@ 2 .3  1 SUBBOOCH CODE AND TEST SUBPHASE I----------------------- 
---------------------------------------------.--------------------------- 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
........................................................................ 
HGHT - Hanagement 1 - Primmrv or major rmmponolbility 
D = Deeigner(e) 2 = SrOond8ry rrrponmibility 
P = Programmer(e) 3 m tlanageriml reeponeibility 
T = Teeter(e) 4 = Indmpmndmnt mudit responeibility 
NC = Hetrice Collector(0) 
SPE = Software Puelity Evaluation 
FIGURE 5: OOD Reeponeibilitiee 
D.4.1.8 
‘ m  
a )  Subboooh Rmquirmmmntm. 
b) Subbooah Dmmigtz.  
a )  Subbooah Cod. and Tmmt. 
Thm SUBBOOCH REOUIREHENTS SUBPHASE h8m tho following rtope: 
INITIATION OF SUBBOOCH DEVELOPHENT - Tho Hmnager initimtoe 
mubboooh dmvolopmmnt by idmntifying the mombere of the 
8eSOt~iated Softw8rm Devolopment Toam and t8mking them to 
meet an 8mrigned oahmdulm 0 2  mubbooch milmstonee. 
INITIATION OF SOFTWARE DEVELOPHENT FILE (SDF) - The Deeigner 
initfatom thm aeoooiatmd SDF by obtmining an ompty SDF 
binder 8nd inmorting tho initial Soitw8re Engineering Form. 
( S E F S )  that make up the covmrp8ges. 
PROBLER STATEHENT - Tho Softuoro Dovolopmont Te8m jointly 
atate in a eingle eentrnce the problam to be eolved during 
the current recureion. 
REQUIRERENTS ANALYSIS - The Softuare Development Team jointly 
col lect. analyze. clari iy. organize. and identify the eubbooch 
requi rrmente. 
SUBBOOCH REQUlRE?fENTS INSPECTION - The Deeigner prepares the 
SDF f o r  inepoction. Tho Hanager echeduleo the apreocioted 
meeting. The Hanager. the Programmer* and the Teeter perform 
the inepection. The Software Development Team takee any 
8ppropriate corrective action. 
The SUBBOOCH DESIGN SUBPHASE has the following mtepe: 
LOGICAL DESIGN - The Software Development Team (under the 
leaderehip of the Deeigner) devralope in a eingle paragraph 
a logical design that properly eolvoe the problmm of the 
current recureion and identifiee the relevant object6 and 
operatione. 
OBJECT ANALYSIS - The Software Development Team (under the 
leadarehip of the Deetgner) anrlyzee a11 relevant ObjeCte 
in the logical deeign perrgrrph. determinee and documente 
their relevancy. and providee the relevant objecte uith 
valid Ada identifiere- brief deecriptione, and a liet ot 
aeeociated ottributee. 
OPERATION ANALYSIS - The Software Development Team (under the 
leaderehip of the Doeigner) 8nmlyzeo all relevant operatione 
in the logical deeign paragraph. determines and documente 
their relevancy* and providee the rrlevent operatione uith 
valid Ada identifiers. brief dercriptiono. and a liet of 
aeeociated at t ri butee. 
HODULE IDENTIFICATION. ORGANIZATION. AND DEPENDENCIES - The 
Software Development Team (under the leaderehip of the 
Deeigner) organizee all relevant objecte and operatione 
D . 4 . 1 . 9  
by typm8r idontifimm thm non-nmmtmd unitm for  maoh muoh 
Or98niz8tionr nmmtm thm orgmniamd objmctm and OpmratiOnm 
within thmro unitr. 8nd dmtmrminom tho vimiblo dmpmndmnoimo 
bmtuoen thmmo unitm. 
SUBBOOCH PRELIHINARY DESIGN INSPECTION - Thm Dmmignmr prmparmm 
the SDF for inmpmotion. Thm Progrmmmmr and Tmrtmr pmrform 
thm Inmpmotion. Thm Softuarm Dmvmlopmmnt Imam takmm m y  
approprimtm oorrmotivm action. 
DESIGN ANALYSIS - Tho Softuarm Dmvmlopment T m 8 m  (undmr thm 
lmadmrmhip of thm Dmsignmr) analy~oe tho dmmignr idmntifiom 
the typm of thm nemtmd unitm. oommon moftuarm* and nertmd 
unite requiring rmureion. mto. 
CODING OF UNIT SPECIFICATIONS - The Softwaro Development Te8m 
tundor tho 1madarsl.ip of the Demignor) implmmmntm and 
compiler. in bottom-up manner in t e r m m  of unit dmpondenciomt 
the Ada epeoiticatione of all unite. Thim includmm the 
development of epecification hmadere. PDL. commantm. and 
code from ekoleton unit epooificatione. 
SUBBOOCH DETAILED DESIGN INSPECTiON - The Derigner prepmrem 
the SDF for inepmction. The tlotriar Collootor colleotm. 
eummarizee. and reportm the eubbooch design motrice. 
The Programmer end Teeter perform thm Inmpmction. Thm 
Softuere Development Team takes any rppropri8tm oorrrctivm 
action. 
The SUBBOOCH CODE AND TEST SUBPHASE ham the following stepe: 
CODING OF UNIT BODIES - The Software Development Team (under 
the leaderehip of the Programmer) implement. and compilom* 
in a top-down manner in terme of unit dependenciem. thm 
Ada bodiem of all unite to be implementod during thm currmnt 
build. Thio tncludee the development of body hemderm~ PDL. 
cornmente. and code from ekeleton unit bodiee ueing the 
technique ot etep-uiee retinement. 
SUBBOOCH TEST PLAN - The Software Development Team (under 
the leaderehip o f  the Teeter) develope the teet plan by 
determining. creating file0 of. and documenting the tset 
input and expected teet output date required f o r  all 
aubbooch teeting end documenting the allocetion of theme 
teat camem to specific eubbooch teeto. 
SUBBOOCH TEST SOFTVARE - The Software Development Team (under 
the leadership of the Teeter) demignm. implemrnts. rnd 
cornpilee all teet eOftWare program8 required f o r  subbooch 
teeting echeduled for the, current build. 
S I J B B O O C H  TEST PROCEDURES - The Softuare Development Team (under 
the leaderehip of the Teeter) develope the detailed stmp-by- 
etep proceduree f o r  performing 011 eubboooh tmmtr moheduled 
Zor the current bui Id. 
D.4.1.10 
SUBBOOCH CODE INSPECTION - Tho Progrmmmer proparen tho SDF for 
inrpootion. Tho Hotrior Colloator oollootml mummarizom~ 
mnd rmportr tho rubboooh oodo motriam. Tho Softuaro 
Dovmlopmont Trmm porform tho inmpootion. Thm Softuare 
Devolopmont Tomm tmkor mny approprieto corrootive action. 
INITIAL SUBBOOCH TESTING - The Softuarm Development Team 
(undor tho lomder~hip of tho To~tor) perform and document 
tho rorultr of a11 initial rubboooh torte. 
9)  PRACTICAL EXPERIENCE. 
The uee of O O D  at Hognavox on the AFATDS Project (over 50K 
linea of Ada code eo f e r )  hee rmsultad in the follouinQ leoeone 
1 earned : 
Avoid overe:mcrfying the requirementfa uith cexplicit or 
implicit deeign information of a functional decompoeltion 
nature. 
I f  e functional decompoeition method ie ueed to produce the 
top-level deeign. It uill be incompatible uith the deelgn 
produced by O O D  at the lower-levele and numeroum interface 
problem6 wi 1 1  roeul t. 
Replacing the previoue functional decompoeition mindeet isa 
difficult. primarily among the more experienced deeignere. 
The concept of  recureion re fairly difficult to meeter. 
OOD training and eupport in t1.e method need.e to continue 
beyond the c 1 aeeroom. 
000 needs to be further refined. primarily in the area of 
object-oriented requirement@ analyeie. 
Ada-oriented teet traininn le as necemsary ae training 
in Ada-oriented deeign mntl programming. 
O O D  improves deeigne due to: 
- Proper abetraction levele. 
- Proper information hiding. 
- High modularity. 
- Improved interfacee. 
- Good eupport f o r  etrong typing. 
- Good correepondonce to the, real uorld. 
OOD improvee productivity due to: 
- Fnhanced parnllel development. 
- Reliee of code. 
- Eaey coding from deeigri intormation. 
- Eoey modification Of deeion and code. 
D . 4 .  1. 1 1  


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