1. No category

TheUni
v
e
r
s
i
t
yofI
o
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CS:2820 (22C:22)
Object-Oriented Software Development
S
pr
i
ng2
01
5
TheDomai
nMode
l
by
Mauricio Monsalve
De
s
i
g
nr
oad
●
●
●
●
Be
g
i
nni
ngt
hede
s
i
g
n
Domai
nMode
l
de
s
c
r
i
be
st
he
domai
n(
c
ont
e
x
t
)
I
ti
sf
ol
l
owe
db
yt
he
S
y
s
t
e
mS
y
s
t
e
m
Di
ag
r
am(
s
)
The
nf
ol
l
owst
heOO
De
s
i
g
nMode
l
(
s
)
Domai
nMode
l
Vi
s
ualr
epr
es
ent
at
i
onofc
onc
ept
ual
c
l
as
s
esorr
eal
s
i
t
uat
i
onobj
ec
t
si
na
domai
n
●
●
Theobj
e
c
t
s(
c
onc
e
pt
ual
c
l
as
s
e
s
)oft
he
domai
nar
enots
of
t
war
eobj
e
c
t
s(
c
l
as
s
e
s
)
I
nUML,t
heDomai
nMode
li
si
l
l
us
t
r
a
t
e
dwi
t
ha
s
etofc
l
as
sdi
ag
r
amswi
t
houtmet
hods
●
Al
s
oknownasVi
s
u
a
lDi
c
t
i
o
n
a
r
y
●
P
e
r
hapsmos
te
s
s
e
nt
i
al
di
ag
r
am
Domai
nMode
l
●
●
Conc
ept
ualc
l
as
s
:i
de
a,t
hi
ng
,obj
e
c
t
I
tma
ybec
ons
i
de
r
e
di
nt
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r
msof
– S
ymbol
—wor
dsori
mag
e
sr
e
pr
e
s
e
nt
i
ngt
he
c
onc
e
pt
ual
c
l
as
s
●
–
I
nt
ens
i
on—t
hede
ni
t
i
onoft
hec
onc
e
pt
ual
c
l
as
s
●
–
Vi
s
u
a
ld
e
pi
c
t
i
o
n
,d
i
a
g
r
a
m
Co
mpr
e
h
e
n
s
i
v
ed
e
⇠
n
i
t
i
o
n
Ext
ens
i
on—t
hes
e
tofe
x
ampl
e
st
owhi
c
ht
he
c
onc
e
pt
ual
c
l
as
sappl
i
e
s
●
Ex
t
e
n
s
i
v
ed
e
⇠
n
i
t
i
o
n
Domai
nMode
l
Domai
nMode
l
●
●
Conc
ept
ualc
l
as
s
esonl
y!
Noti
ndomai
nmode
l
– S
of
t
war
ear
t
i
f
ac
t
s
–
●
Wi
n
d
o
ws
,d
a
t
a
b
a
s
e
s
,e
t
c
.
●
Un
l
e
s
sd
o
ma
i
ni
ss
o
f
t
wa
r
e
Re
s
pons
i
bi
l
i
t
i
e
sorme
t
hods
●
Th
e
ya
r
epa
r
to
ft
h
ed
e
s
i
g
na
n
dt
h
es
o
f
t
wa
r
e
Dr
a
wi
ngt
heDM
Conc
ept
shave
namesand
at
t
r
i
but
es
(
s
omet
i
mes
)
,but
notmet
hods
Dr
a
wi
ngt
heDM
Dr
a
wi
ngt
heDM
*
1..*
1..40
5
3, 5, 8
T
zero or more;
"many"
T
one or more
T
one to 40
T
exactly 5
T
exactly 3, 5, or 8
As
s
oc
i
at
i
onss
houl
dhave
s
pec
i
$cnames
—ands
oc
l
as
s
es
“
h
a
s
”i
sab
a
dn
a
me
!
Mul
t
i
pl
i
c
i
t
ys
houl
dbekept
s
i
mpl
eatt
hi
ss
t
ag
et
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c
onc
ept
ualmodel
i
ngdœsnot
needt
obeaspr
ec
i
s
e
Dr
a
wi
ngt
heDM
Cl
as
s
esal
s
oi
nc
l
udeat
t
r
i
but
esr
el
evantt
ot
hedomai
n
At
t
r
i
but
eds
houl
dha
ves
i
mpl
et
ypes(
number
s
,t
ext
,bool
eans
,et
c
.
)
—t
h
i
si
sn
o
ts
or
e
l
e
v
a
n
ta
tt
h
i
ss
t
a
g
e
,t
h
o
u
g
h
Theys
omet
i
mesc
anbe“
der
i
ved”
,meani
ngt
hatt
heyc
anbei
nf
er
r
ed,by
meansofaf
or
mul
a,f
r
om ot
herat
t
r
i
but
esoras
s
oc
i
at
i
ons
Sale
- dateTime : Date
- / total : Money
Private visibility
attributes
Math
+ pi : Real = 3.14 {readOnly}
Public visibility readonly
attribute with initialization
Person
firstName
middleName : [0..1]
lastName
Optional value
Dr
a
wi
ngt
heDM
Exampl
eofas
s
oc
i
at
i
onandder
i
vedat
t
r
i
but
e
SalesLineItem
SalesLineItem
SalesLineItem
Item
Each line item records a
separate item sale.
For example, 1 tofu package.
1..*
Item
Each line item can record a
group of the same kind of items.
For example, 6 tofu packages.
1..*
Item
0..1
Records-sale-of
1
0..1
Records-sale-of
0..1
Records-sale-of
/quantity
derived attribute from
the multiplicity value
Dr
a
wi
ngt
heDM
●
Pi
c
kex
ac
t
,s
pe
c
i
cnamesf
orobj
ec
t
s
,as
s
oc
i
a
t
i
ons
,e
t
c
●
At
t
r
i
but
ess
houl
dha
v
et
r
i
v
i
al
t
y
pes(
number
s
,t
e
x
t
,e
t
c
)
●
Kee
pt
hemos
tr
el
e
v
antas
s
oc
i
a
t
i
onsi
nt
heDM
●
Enc
aps
ul
at
i
on—don'
tc
onne
c
te
v
er
y
t
hi
ngt
o
e
v
e
r
y
t
hi
ng
!
– Ob
j
ec
t
ss
houl
dha
v
es
t
r
ongi
nt
er
nal
c
ohes
i
on
(
a
t
t
r
i
but
e
s
)
–
●
Obj
ec
t
ss
houl
dbeas
s
oc
i
a
t
edt
of
e
wot
herobj
e
c
t
s
(
l
o
wc
oupl
i
ng
)
Pr
obl
em:wher
edoweg
etourobj
ec
t
sf
r
om?
Ge
t
t
i
ngt
hec
onc
e
pt
s
●
Re
us
ee
x
i
s
t
i
ngmode
l
s
– C
op
yoradapte
x
i
s
t
i
ng
,we
l
lac
c
e
pt
e
dmode
l
s
–
●
●
Us
ee
x
i
s
t
i
ngDM whe
nmodi
f
y
i
ngas
y
s
t
e
m
Ca
t
e
g
or
yl
i
s
t
s
– T
abl
e9.
1i
nbook
I
de
nt
i
f
ynounphr
as
e
s(
e
as
y
!
)
– P
i
c
knouns
,e
v
e
nt
s
–
F
ul
l
ydr
e
s
s
e
dus
ec
as
e
sar
eg
r
e
a
ts
our
c
e
–
Bewar
e:na
t
ur
all
ang
uag
ei
si
mpr
ec
i
s
e
Ge
t
t
i
ngt
hec
onc
e
pt
s
Cl
as
sl
i
s
t
sc
ons
i
s
tof
c
ommont
ax
onomi
e
s
Thebookhasone
,but
t
he
r
ear
eot
he
rl
i
s
t
s
—
a
r
et
h
e
yf
o
rt
h
eDM?
●
Bus
i
ne
s
st
r
ans
ac
t
i
ons
●
Phy
s
i
c
alobj
e
c
t
s
●
De
s
c
r
i
pt
i
onsoft
hi
ng
s
●
Ca
t
al
og
s
●
Cont
ai
ne
r
soft
hi
ng
s
●
Thi
ng
si
nac
ont
ai
ne
r
●
Ot
he
rr
e
l
a
t
e
ds
y
s
t
e
ms
●
●
T
r
ans
ac
t
i
onl
i
nei
t
e
ms
●
Pr
oduc
t
s
,s
e
r
v
i
c
e
s
●
●
Pl
ac
eoft
r
a
ns
ac
t
i
on
●
●
Not
e
wor
t
h
ye
v
e
nt
s
F
i
duc
i
ar
yr
e
c
or
ds(
wor
k,
c
ont
r
ac
t
s
,nanc
e
s
,e
t
c
)
F
i
nanc
i
ali
ns
t
r
ume
nt
s
Re
f
e
r
e
nc
edoc
ume
nt
s
(
s
c
he
dul
e
s
,manual
s
,e
t
c
)
Ge
t
t
i
ngt
hec
onc
e
pt
s
Mai
nS
uc
c
e
s
sS
c
e
nar
i
o(
orBas
i
cF
l
o
w)
:
1
)Cus
t
ome
rar
r
i
v
e
sa
taPOSc
he
c
k
outwi
t
hg
oodsand/
ors
e
r
v
i
c
e
st
opur
c
has
e
.
2
)Cas
hi
e
rs
t
ar
t
sane
ws
al
e
.
3
)Cas
hi
e
re
nt
e
r
si
t
e
mi
de
nt
i
e
r
.
4)S
y
s
t
e
mr
e
c
or
dss
al
el
i
nei
t
e
m andpr
e
s
e
nt
si
t
e
m de
s
c
r
i
pt
i
on,pr
i
c
e
,andr
unni
ngt
ot
al
.
Pr
i
c
ec
al
c
ul
a
t
e
df
r
om as
e
tofpr
i
c
er
ul
e
s
.
Ca
s
h
i
e
rr
e
pe
a
t
ss
t
e
ps2
3u
n
t
i
li
n
d
i
c
a
t
e
sd
o
n
e
.
5
)S
y
s
t
e
m pr
e
s
e
nt
st
ot
alwi
t
ht
ax
e
sc
al
c
ul
a
t
e
d.
6)Cas
hi
e
rt
e
l
l
sCus
t
ome
rt
het
ot
al
,andas
ksf
orpa
y
me
nt
.
7
)Cus
t
ome
rpa
y
sandS
y
s
t
e
m handl
e
spa
y
me
nt
.
8)S
y
s
t
e
ml
og
st
hec
ompl
e
t
e
ds
al
eands
e
ndss
al
eandpa
y
me
nti
nf
or
ma
t
i
ont
ot
he
e
x
t
e
r
nalAc
c
ount
i
ng(
f
orac
c
ount
i
ngandc
ommi
s
s
i
ons
)andI
n
v
e
nt
or
ys
y
s
t
e
ms(
t
o
upda
t
ei
n
v
e
nt
or
y
)
.
9)S
y
s
t
e
m pr
e
s
e
nt
sr
e
c
e
i
pt
.
1
0)Cus
t
ome
rl
e
a
v
e
swi
t
hr
e
c
e
i
ptandg
oods(
i
fan
y
)
.
Ge
t
t
i
ngt
hec
onc
e
pt
s
Mai
nS
uc
c
e
s
sS
c
e
nar
i
o(
orBas
i
cF
l
o
w)
:
1
)Cus
t
ome
rar
r
i
v
e
sa
taPOSc
he
c
k
outwi
t
hg
oodsand/
ors
e
r
v
i
c
e
st
opur
c
has
e
.
2
)Cas
hi
e
rs
t
ar
t
sane
ws
al
e.
3
)Cas
hi
e
re
nt
e
r
si
t
e
mi
de
nt
i
e
r
.
4)S
y
s
t
e
mr
e
c
or
dss
al
el
i
nei
t
e
m andpr
e
s
e
nt
si
t
e
m de
s
c
r
i
pt
i
on,pr
i
c
e,andr
unni
ngt
ot
al
.
Pr
i
c
ec
al
c
ul
a
t
e
df
r
om as
e
tofpr
i
c
er
ul
e
s
.
Ca
s
h
i
e
rr
e
pe
a
t
ss
t
e
ps2
3u
n
t
i
li
n
d
i
c
a
t
e
sd
o
n
e
.
5
)S
y
s
t
e
m pr
e
s
e
nt
st
ot
alwi
t
ht
ax
e
sc
al
c
ul
a
t
e
d.
6)Cas
hi
e
rt
e
l
l
sCus
t
ome
rt
het
ot
al
,andas
ksf
orpa
y
me
nt
.
7
)Cus
t
ome
rpa
y
sandS
y
s
t
e
m handl
e
spa
y
me
nt
.
8)S
y
s
t
e
ml
og
st
hec
ompl
e
t
e
ds
al
eands
e
ndss
al
eandpa
y
me
nti
nf
or
ma
t
i
ont
ot
he
e
x
t
e
r
nalAc
c
ount
i
ng(
f
orac
c
ount
i
ngandc
ommi
s
s
i
ons
)andI
n
v
e
nt
or
ys
y
s
t
e
ms(
t
o
upda
t
ei
n
v
e
nt
or
y
)
.
9)S
y
s
t
e
m pr
e
s
e
nt
sr
e
c
e
i
pt
.
1
0)Cus
t
ome
rl
e
a
v
e
swi
t
hr
e
c
e
i
ptandg
oods(
i
fan
y
)
.
Ge
t
t
i
ngt
hec
onc
e
pt
s
●
●
●
●
Us
i
ngnounsornounphr
as
eshas[
al
mos
t
]no
l
ear
ni
ngc
ur
v
e(
eas
y
!
)
Ver
bsof
t
eni
mpl
yas
s
oc
i
a
t
i
ons
Thi
sme
t
hodi
sasi
mper
f
ec
tasna
t
ur
all
ang
uag
e
– Al
s
os
er
v
est
oc
hec
kus
ec
as
esandr
equi
r
ement
s
t
houg
h
S
ol
ut
i
ons
– R
ef
ert
oc
l
as
sl
i
s
t
–
●
T
al
kt
odomai
nex
per
t
Butwec
anpat
c
hourappr
oxi
mat
i
ons
!
Ge
t
t
i
ngmor
ec
onc
e
pt
s
Wema
yi
nf
ermor
ec
onc
ept
sf
r
om wha
tweha
v
e
●
Pat
c
ht
hehol
es
—ar
et
her
eh
o
l
e
si
nt
hede
s
i
g
n?
●
S
pec
i
al
i
z
e—ar
et
he
r
ei
nt
er
es
t
i
ngs
ubc
l
as
s
es
?
●
Gener
al
i
z
e—ar
et
he
r
ei
nt
e
r
e
s
t
i
ngs
upe
r
c
l
as
s
e
s
?
●
●
●
Dec
ompos
e—c
ananobj
e
c
tbede
s
c
r
i
be
di
nt
er
ms
ofot
he
r
,c
ont
ai
ne
dobj
ec
t
s
?(
Ma
n
yme
a
n
i
n
g
st
ot
h
i
s
)
Compos
e—i
sac
ol
l
e
c
t
i
onofg
i
v
e
nobj
ec
t
s
r
e
l
e
v
ant
?
Fi
xi
mper
f
ec
t
i
ons
—nex
ts
l
i
de
s
Ge
t
t
i
ngmor
ec
onc
e
pt
s
Cashier
Worse
a "simple" attribute, but being
used as a foreign key to relate to
another object
name
currentRegisterNumber
Cashier
Better
name
1
Works-on
1
Register
number
“
F
or
ei
g
nk
eys
”i
dent
i
f
yot
herc
onc
ept
s
.“
Keys
”ar
ei
dent
i
$er
s
;t
heyhol
da
1
t
o1r
el
at
i
onwi
t
hanobj
ec
t
Ge
t
t
i
ngmor
ec
onc
e
pt
s
Item
Worse
description
price
serial number
itemID
Anot
herf
or
ei
g
nkeyexampl
e
ProductDescription
description
price
itemID
Item
Describes
1
*
serial number
Better
Ge
t
t
i
ngmor
ec
onc
e
pt
s
Flight
date
number
time
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