199
Sum
mar
y
7.6.
3B
est
desi
gn p
ract
ices
Wh
en u
sin
g an
y pe
rsis
ten
ce s
olut
ion
wit
h R
estl
et, y
ou s
hou
ld t
ry lo
adin
g an
d st
orin
gth
e st
ate
of y
our
reso
urce
s ea
ch ti
me
a ServerResource in
stan
ce is
cre
ated
in o
rder
topr
oces
s a
new
cal
l. T
he
goal
is to
res
pect
the
stat
eles
s co
nst
rain
t of
RE
ST.
Th
is c
onst
rain
t do
esn
t m
ean
th
at y
our
appl
icat
ion
can
t h
ave
stat
e, b
ut t
hat
th
eco
nve
rsat
ion
bet
wee
n c
lien
ts a
nd
serv
ers
shou
ldn
t be
dri
ven
by
out-o
f-ban
d in
form
a-ti
on s
uch
as
cook
ie-b
ased
ses
sion
s pr
omot
ed in
the
Serv
let A
PI.
For
eff
icie
ncy
rea
son
s yo
u sh
ould
con
side
r pu
ttin
g in
pla
ce d
atab
ase
con
nec
tion
pool
s an
d da
ta c
ach
es i
n y
our
Res
tlet
app
licat
ion
sub
clas
ses,
acc
essi
ng
thos
e m
ech
a-ni
sms
by c
astin
g th
e re
sult
of th
e ServerResource#getApplication()
met
hod.
Ano
ther
opti
on t
o sh
are
stat
e be
twee
n s
ever
al r
esou
rce
inst
ance
s is
via
th
e pa
ren
t Context
inst
ance
, wh
ich
con
tain
s a
map
of a
ttri
bute
s. W
hen
dea
ling
wit
h t
ran
sien
t da
ta, s
uch
as
a sh
oppi
ng
cart
or
tran
sact
ion
s ru
nn
ing
acro
ss s
ever
al w
eb p
ages
, you
sh
ould
ret
hin
k yo
ur a
pplic
atio
n d
esig
n t
o tu
rn t
his
dat
ain
to r
esou
rces
, suc
h a
s a
shop
pin
g ca
rt r
esou
rce
wit
h a
spe
cifi
c U
RI.
Th
e st
ate
of th
ose
reso
urce
s m
igh
t be
stor
ed in
a d
atab
ase
like
oth
er r
esou
rces
, may
be w
ith
a s
hor
ter
life-
cycl
e bu
t wit
hou
t spe
cial
trea
tmen
t. F
ar fr
om b
ein
g a
back
war
d st
ep, t
his
sta
tele
ss c
onst
rain
t can
eve
n b
enef
it y
our
end
user
sth
ey w
ont
expe
rien
ce th
e ty
pica
l ses
sion
exp
irat
ion
issu
e w
hen
taki
ng
too
lon
gto
com
plet
e a
purc
has
e or
der,
for
exam
ple.
7.7
Sum
mar
yIn
th
is c
hap
ter
you
lear
ned
bes
t pr
actic
es t
hat
, ta
ken
tog
eth
er,
mak
e th
e di
ffer
ence
betw
een
a p
roto
type
Res
tlet a
pplic
atio
n a
nd
a m
ore
mat
ure
one
suita
ble
for
prod
uctio
n.
You
firs
t saw
how
to c
ompl
ete
an a
pplic
atio
n w
ith
the
usua
l web
ele
men
ts m
anip
u-la
ted
in m
ost
web
API
s an
d w
ebsi
tes,
suc
h a
s H
TM
L f
orm
s h
andl
ing,
sta
tic
file
ser
vin
g,an
d co
okie
man
ipul
atio
n. E
ach
feat
ure
has
bee
n c
aref
ully
illu
stra
ted
in th
e co
nte
xt o
fth
e on
goin
g m
ail s
erve
r ex
ampl
e. Y
ou a
lso
lear
ned
tw
o co
mpl
emen
tary
way
s to
han
dle
web
fee
ds i
n t
he
Ato
m a
nd
RSS
for
mat
s us
ing
two
Res
tlet
ext
ensi
ons,
com
pari
ng
the
adva
nta
ges
and
disa
dvan
-ta
ges
of e
ach
of
them
. Th
en y
ou le
arn
ed h
ow t
o re
dire
ct c
lien
t ca
lls, e
ith
er m
anua
llyby
set
tin
g th
e pr
oper
HT
TP
stat
uses
or
mor
e au
tom
atic
ally
an
d po
wer
fully
wit
h t
he
Redirector c
lass
. W
e al
so d
iscu
ssed
per
form
ance
an
d m
odul
ariz
atio
n a
spec
ts i
n o
rder
to
deal
wit
hap
plic
atio
ns
grow
ing
in s
ize
and
com
plex
ity.
We
look
ed a
t H
TT
P bu
ilt-in
feat
ures
suc
ha
con
diti
onal
met
hod
pro
cess
ing,
en
tity
com
pres
sion
, an
d ca
chin
g su
ppor
t. W
e al
soin
trod
uced
Res
tlet
-spe
cifi
c fe
atur
es s
uch
as
the
serv
er d
ispa
tch
er, t
he
inte
rnal
rou
ter,
and
the
RIA
P ps
eudo
prot
ocol
to c
omm
unic
ate
opti
mal
ly in
side
a R
estl
et c
ompo
nen
t. Y
oull
now
con
tin
ue e
xplo
rin
g fu
rth
er R
estl
et F
ram
ewor
k po
ssib
iliti
es,
such
as
depl
oym
ent
in c
loud
com
puti
ng,
web
bro
wse
rs,
and
smar
tph
ones
an
d in
nov
ativ
ese
man
tic
web
sup
port
.
