ck metrics

7/26/2019 Ck Metrics

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Chidamber & KemererChidamber & Kemerer

Suite of MetricsSuite of Metrics

Camargo Cruz Ana Erika

Supervisor: Ochimizu Koichiro

May 2008

Japan Avance !ns"i"u"e o# Science an $echno%ogyJapan Avance !ns"i"u"e o# Science an $echno%ogy

Schoo% o# !n#orma"ion ScienceSchoo% o# !n#orma"ion Science


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CK Metrics: Outline

& O'(ec"ive

& )e#ini"ion * +uie%ines

& $hresho%s

& CK in "he %i"era"ure ,o"her uses-


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CK Metrics: Objective

CK me"rics /ere esigne 1:

& $o measureuniue aspec"s o# "he OO approach3

& $o measure comp%e4i"yo# "he esign3

& $o improve"heeve%opmen" o# "he so#"/are

HOW?


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CK Metrics: ObjectiveSW development Improvement

Managers can improve the development of the SW'y :

& Ana%ysing CKme"rics "hrough "he ien"i#ica"iono#outlying va%ues ,e4"reme evia"ions-6 /hich may 'e a

signa% o#:7 high comp%e4i"y anor

7 possi'%e design violations

& $aking managerial decisions6 such as:

9eesigning anor assigning e4"ra or higherski%%e resources ,"o eve%op6 "o "es" an "o

main"ain "he S;-3


5/22

um'er o# Me"hos ,>OM-6 /hen a%% me"ho?s comp%e4i"y

are consiere @>!$3

& Bie/poin"s

7 ;MC is a preic"or o# ho/ much TIMEanEFFORTis reuire todevelopan to!int!in"he c%ass3

7 $he %arger >OM "he grea"er "he impac" on chi%ren3

7 C%asses /i"h %arge >OM are %ike%y "o 'e more app%ica"ion speci#ic6limiting"he possi'i%i"y o# RE"#$Ean making "heEFFORTe4pene one-shot investment3

& O'(ec"ive: %o&


6/22

CK Metrics: DefinitionI! (epth of Inheritance !ree)

& )e#ini"ion$he ma4imum %eng"h #rom "he noe "o "he roo" o# "he "ree

& Bie/poin"s

$he grea"er va%ues o# )!$ :7 $he grea"er "he >OM i" is %ike%y "o inheri"6 making more COM'%E("o preic" i"s 'ehaviour

7 $he grea"er "he po"en"ia% RE"#$Eo# inheri"e me"hos

Sma%% va%ues o# )!$ in mos" o# "he sys"em?s c%asses may 'e aninica"or "ha" esigners are #orsaking RE"#$)*I%IT+#or simp%ici"yo# #,DER$T),DI,-3

& O'(ec"ive: Tr!de"off


7/22

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CK Metrics: Definition"#C ("umber of Children)

& )e#ini"ion>um'er o# immeia"e su'c%asses su'orina"e "o a c%ass in "he c%asshierarchy

& Bie/poin"s

$he grea"er "he >OC is:7 "he grea"er is "heRE"#$E

7 "he grea"er is "he pro'a'i%i"y o# iproper !bstr!ctiono# "he paren"c%ass6

7 "he grea"er "he reuiremen"s o# me"hos TE$TI,-in "ha" c%ass3

Sma%% va%ues o# >OC6 may 'e an inica"or o# %ack o# communica"ion'e"/een i##eren" c%ass esigners3

& O'(ec"ive: Tr!de"off


8/22

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CK Metrics: DefinitionC$# (Coupling $et%een #bects)

& )e#ini"ion!" is a coun" o# "he num'er o# o"her c%asses "o /hich i" is coup%e

& Bie/poin"s

Sma%% va%ues o# CFO :

7 !mprove MOD#%)RIT+an promo"e E,C)'$#%)TIO,

7 !nica"es inepenence in "he c%ass6 making easier i"sRE"#$E

7Makes easier "o M)I,T)I,an "o TE$Ta c%ass3

& O'(ec"ive: %o&


9/22

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CK Metrics: Definition'C ('esponse for Class)

& )e#ini"ion!" is "he num'er o# me"hos o# "he c%ass p%us "he num'er o# me"hos

ca%%e 'y any o# "hose me"hos3

& Bie/poin"s

!# a %arge num'ers o# me"hos are invoke #rom a c%ass ,9HC ishigh-:

7 TE$TI,-an M)I,T),)CEo# "he C%ass 'ecomes more

COM'%E(3

& O'(ec"ive:%o&


10/22

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CK Metrics: DefinitionC#M (ac* of Cohesion of Methods)

& )e#ini"ion

Measures "he issimi%ari"y o# me"hos in a c%ass via ins"ancevaria'%es3

& Bie/poin"s

+rea" va%ues o# ICOM:

7 !ncreases COM'%E(IT+

7 )oes no" promo"es E,C)'$#%)TIO, an imp%ies c%asses

shou% pro'a'%y 'e sp%i" in"o "/o or more su'c%asses7 e%ps "o ien"i#ie %o/ua%i"y esign

& O'(ec"ive: %o&


11/22

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CK Metrics: -uidelines

Fu" o/ much is Io/ an igh

METRIC GOAL LEVEL COMPLEXITY

(To develop, to testand to maintain)

RE-!A"ILITY E#CAP!LATIO#,

MO$LARITY

%MC Lo&

$IT T'ade-o

#OC T'ade-o

C"O Lo&

RC Lo&

LCOM Lo&


12/22

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CK Metrics: T.res.olds

$hresho%s o# "he CK me"rics 26.65:

& Can no" 'e e"ermine 'e#ore "heir use

& Shou% 'e erive an use %oca%%y #or each a"ase"

& 80"han 20"hpercen"i%es o# "he is"ri'u"ions can 'euse "o e"ermine high an %o/ va%ues o# "he me"rics3

& Are no" inica"ors o# L'aness 'u" inica"ors o#i##erence "ha" nees "o 'e inves"iga"e3


13/22

1.

CK in t.e %iter!tureCK Metrics & other Managerial performance indicators

Chiam'er * Kemerer s"uy "he re%a"ion o# CK

me"rics /i"h 2:

& Nrouc"ivi"y

S!E IOC EHHO9$ o# )eve%opmen"

ours

& 9e/ork E##or" #or reusing c%asses

& E##or" "o speci#y high%eve% esign o# c%asses


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CK in t.e %iter!tureCK Metrics & Maintenance effort

Ii an enry ,1GG.- use CK me"rics ,among o"hers-

"o preic"


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8 Kanmani6 S36 an @"hariara( B3 9ymen6 O'(ec" orien"e so#"/are ua%i"y preic"ion usinggenera% regression neura% ne"/orks6 S!+SOH$ So#"3 Eng3 >o"es6 >e/ ork >6 @SA6

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inprocess "es"ing me"rics: a con"ro%%e case s"uy 6 Nroceeings o# "he "hir /orkshop

on So#"/are ua%i"y6 S"3 Iouis6 Missouri6 @SA3 ,200

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