c t yu cu
Gio vin: Nguyn Dng
Email: [email protected]
Ni dung
Khi nim v tm quan trng
Phn loi cc yu cu
Phn tch v xc nh yu cu
c t yu cu
nh dng ti liu yu cu 2
Khi nim v tm quan trng
Xc nh v c t yu cu
L khu k thut u tin ca qu trnh pht trin phn mm. Thiu n khng th tip tc qu trnh
L s phi hp ca nh pht trin v khch hng
N quyt nh cht lng phn mm t c vi chi ph d kin v thi hn cho trc
3
Cc yu cu v mc tiu
Cc yu cu l cc m t tru tng n chi tit v dch v m h thng cung cp cng nh cc rng buc ln s pht trin v hot ng ca n
Mc ch ca cc yu cu:
Lm c s cho vic mi thu (cn c gii thch t pha ch u t)
Lm c s cho vic k hp ng thu (cn v chi tit)
Lm t liu u vo cho thit k v trin khai (cn , chnh xc v khng mu thun)
4
Cc loi yu cu Yu cu ngi s dng
n gin, d hiu Din t bng ngn ng t nhin v s v dch v h
thng cn cung cp v cc rng buc trong hot ng ca n
Dnh cho khch hng
Yu cu h thng
M t chi tit v cc dch v h thng cung cp
Cc c trng h thng cn c
Nh mt hp ng gia khch hng v ch u t
c t phn mm
chi tit lm c s cho vic thit k v trin khai
Dnh cho nh pht trin 5
Yu cu ngi s dng
Nn m t
Yu cu chc nng
Yu cu phi chc nng
D hiu i vi ngi s dng
Khng c kin thc chi tit v k thut/tin hc
Nn c m t bi:
Ngn ng t nhin
u im: D hiu, d s dng
Hn ch:
Khng r rng, thiu chnh xc, nhp nhng
Ln ln gia yu cu chc nng v phi chc nng
Qu mm do (trnh by nhiu cch)
Biu , bng biu 6
Yu cu h thng
L c t chi tit hn yu cu ngi s dng
Phc v c bn cho bc thit k
C th s dng lm mt phn ca hp ng
C th s dng cc m hnh m t
7
Ti liu c t
L cc pht biu chnh thc v h thng cn xy dng
Khng phi l ti liu thit k
Xc nh h thng cn lm g (What?)
Khng tr li cho cu hi nh th no (How?)
8
Ti liu c t
Cc yu cu i vi ti liu c t
c t hnh vi bn ngoi ca h thng
c t cc rng buc ci t
D dng thay i
S dng nh l cng c tham kho khi bo tr
D bo thi gian sng ca h thng
c t tr li cc s kin khng mong i 9
Nhng ngi c yu cu
Ngi dng h thng
Ngi qun l ca khch hng
K s ca khch hng
Nh kin trc h thng
Cc nh pht trin v bo tr phn mm
Yu cu vit ra cn p ng c cc i tng trn
10
Yu cu t nghip v
Cc yu cu chc nng (Function requirement):
M t cc chc nng hay cc dch v m h thng phn mm cn cung cp
Cc yu cu phi chc nng (Non-Function requirement):
M t cc rng buc t ln dch v v qu trnh pht trin h thng (v cht lng, v mi trng, chun s dng, qui trnh pht trin,)
Cc yu cu min/lnh vc ngoi:
Nhng yu cu t ra t min ng dng, phn nh nhng c trng min .
11
Cc yu cu chc nng
M t chc nng hay dch v ca h thng
Chng ph thuc vo:
Loi phn mm s c xy dng
S mong mun ca khch hng
Loi h thng m phn mm tr gip
Mc cc yu cu
Tru tng: h thng lm g?
Chi tit: nhim v c th ca h thng cn thc hin 12
V d
Ngi s dng c th tm kim ti liu da trn cc t kha c trong ti liu hoc tn ti liu
H thng phi c c cc nh dng khc nhau ca ti liu: vn bn (.txt), PDF, Word, Excel,
H thng cn cung cp phng tin hin th d dng cc ti liu t CSDL
13
Cc yu cu phi chc nng
nh ngha cc tnh cht v rng buc ca h thng
Yu cu tin trnh Phng php thit k
Ngn ng lp trnh
Cng c s dng
Thi gian tr li
tin cy
Yu cu v lu tr d liu
Yu cu phi chc nng c th quan trng hn yu cu chc nng. Nu yu cu phi chc nng khng c p ng h thng tr nn v dng 14
Cc yu cu phi chc nng
Yu cu v sn phm:
Tc , tin cy, b nh cn, giao din,
Yu cu v t chc/tin trnh pht trin:
Cc chun p dng, phng php thit k, ngn ng lp trnh, m trnh tin trnh,
Yu cu t bn ngoi:
V chi ph, thi gian, bn quyn, lin kt,
15
Cc loi yu cu phi chc nng
16
V d
Yu cu v sn phm
Ch s dng ti a 256 MB b nh
Yu cu v t chc
Tin trnh phi p ng chun DO178
Yu cu bn ngoi
H thng khng c l thng tin ca khch hng.
17
Tin trnh k ngh yu cu
Cc hot ng ca tin trnh k ngh
Nghin cu kh thi Bo co kh thi
Phn tch, xc nh yu cu M hnh h thng
c t yu cu Cc yu cu c c t
Thm nh yu cu Ti liu yu cu
18
Tin trnh k ngh yu cu
19
Nghin cu kh thi
Nhm tr li cu hi:
C nn pht trin h thng hay khng?
Ni dung nghin cu kh thi tp trung tr li cc cu hi:
H thng c xy dng s gip ch g cho t chc?
H thng s dng cng ngh no, kinh ph bao nhiu, thi gian bao nhiu?
H thng cn phi tch hp vi h thng no ang s dng?
20
Trin khai nghin cu kh thi
Bo co kh thi c vit da trn cc thng tin, bo co thu thp c, nhng nh gi ban u v h thng hin ti v phc tho cc phng n d kin
Cu hi t ra cho ngi ca t chc:
Ci g xy ra nu h thng khng c trin khai?
Nhng vn g cn gii quyt?
H thng c xut gip h nh th no?
Nhng tch hp g cn phi c?
Cng ngh mi l g, k nng g cn c?
Nhng tin ch g cn tr gip t h thng? 21
Phn tch v xc nh yu cu
Lm r:
Phm vi lnh vc ng dng
Cc dch v h thng cn cung cp
Cc rng buc t ln h thng
Bng cch xy dng cc m hnh phn tch (m hnh nghip v ca h thng) lm r cc yu cu trn 22
Nhng kh khn ca phn tch
Khch hng thng m h v yu cu, khng bit r mnh mun g, d ln ln gia yu cu v mong mun
H th hin yu cu theo thut ng ring
Khch hng a dng, cc yu cu c th mu thun nhau
Nhng yu t t chc v chnh sch c th nh hng n yu cu
Yu cu thng mang tnh c th, kh hiu, kh c chun chung.
Cc yu cu thay i trong qu trnh phn tch: mi trng nghip v thay i,
23
Mc tiu, mong mun v yu cu
Mc tiu, mong mun: l ci hng ti
Chng hn: xy dng giao din thn thin vi ngi dng
Yu cu: l ci c th, kim tra c
Chng hn: giao din ha, cc lnh c chn bng thc n hay biu tng
Nhim v ca ngi phn tch l gi m, xc nh ng, y , chnh xc cc yu cu
24
Tin trnh phn tch yu cu
Cc hot ng chnh: Tm hiu min ng dng
Pht hin, thu thp yu cu
Phn loi yu cu
Gii quyt xung t (nu c)
Sp xp u tin cc yu cu
Thm nh yu cu
25
Cc nguyn l
M hnh ha min thng tin:
Xc nh cc thc th d liu (i tng)
Xc nh cc thuc tnh ca chng
Thit lp mi quan h gia cc d liu
M hnh ha chc nng:
Bn cht ca phn mm l bin i thng tin
Xc nh cc chc nng (bin i thng tin)
Xc nh cch thc d liu (thng tin) di chuyn trong h thng (lung d liu)
Xc nh cc tc nhn to v nhn d liu 26
Cc nguyn l
M hnh ha hnh vi
Xc nh cc trng thi ca h thng
Xc nh cc d kin lm thay i hnh vi ca h thng
Phn hoch, lm mn: biu din cc m t cc mc chi tit khc nhau
Lm mn cc m hnh d liu
To cy (biu ) phn r chc nng
Biu din hnh vi cc mc chi tit khc nhau
27
c t yu cu
c t yu cu l m t yu cu mt cch c bit. Yu cu nn c biu din nhiu mc tru tng khc nhau: y , chnh xc dn, nhiu i tng c th c:
Ngi s dng
Nh qun l
Lp trnh vin
K s pht trin v bo tr
28
Cc mc tru tng ca yu cu
Xc nh yu cu:
M t cc dch v m phn mm cung cp
Vit bng ngn ng t nhin
Hng ngi dng
c t yu cu
Ti liu c cu trc (theo m hnh/phng php)
M t y , chnh xc v chi tit yu cu
Dng lm bn hp ng 29
V d: Chc nng kim tra chnh t
nh ra yu cu: Thng bo li chnh t ca vn bn
c t:
Cc li chnh t c gch bn di
Li son tho c gch xanh bn di
Li chnh t
T n khng c trong t in
Li son tho
Tha du cch
Khng vit hoa u cu 30
i hi c t yu cu
y : Mi yu cu ca ngi dng phi c m t
Khng mu thun vi nhau
Chnh xc: Yu cu khng c m h
Ch c hiu theo mt ngha duy nht
C th nh x c t vo chng trnh
Chi ph pht sinh do sa li t nht c th
D thay i:
Thay i c
t nh hng n cc chc nng khc
31
Cc phng php c t
C nhiu phng php:
c t hnh thc
c t bn hnh thc
c t phi hnh thc
c t phi hnh thc:
Bng ngn ng t nhin
Bng bng, s , hnh v ty chn
Khng cht ch, d hiu nhm
Nhiu cch biu din cho mt khi nim
Kh phn hoch, kh sa i 32
c t bn hnh thc
c t da trn m hnh
Khi nim
K php ha
Quy tc biu din
Cc bc xy dng
Gii thch
V d:
M hnh lung d liu
M hnh thc th - mi quan h (ERD)
M hnh d liu quan h
Cc m hnh nghip v, m hnh phn tch hng i tng vi UML 33
c t hnh thc
Biu din m hnh ton hc
Khi nim v k php ton hc
Quy tc khai bo v biu din biu thc
Cc lut biu din biu thc
C th t ng ha gii m hnh
S dng m hnh cho chng minh, kim chng
Kh hiu, kh s dng 34
Thm nh yu cu
Lin quan n vic kim tra tnh ng n, tnh y , tnh nht qun, tnh hin thc v kim tra c ca yu cu. C th tr li c cc cu hi:
Cn nhu cu no ca ngi dng cha k n?
C mu thun g gia cc yu cu?
Chc nng, rng buc g cha k?
C thc hin c khng?
C th kim tra n nh th no? 35
Cc k thut thm nh yu cu
Xem xt li yu cu:
Phn tch mt cch c h thng
Ly kin khch hng
Tin hnh thng xuyn
Lm bn mu
S dng m hnh kh dng
Kim tra tnh thc hin c
To ca kim th (test case)
S dng CASE: kim tra tnh nht qun 36
Phng php xc nh, c t yu cu
M hnh nghip v (Chc nng)
Biu phn r chc nng (FDD)
M hnh ca s dng (use case)
Biu hot ng (Activity Diagram)
Biu chuyn trng thi
M hnh lung d liu (DFD)
Biu thc th mi quan h (ERD) 37
Biu phn r chc nng
FDD Function Decomposition Diagram
Xc nh phm vi ca h thng
Phn hoch chc nng
To nn tng cho thit k kin trc h thng
38
V d:
39
Biu lung d liu
DFD Data Flow Diagram
M t qu trnh x l thng tin nghip v
Biu din cch thc d liu di chuyn, c x l, lu tr trong h thng v trao i vi mi trng
C nhiu mc tru tng khc nhau
Lm c s cu trc phn mm
40
Biu lung d liu
Khi nim
Tc nhn: ngi, t chc, h khc
i tng ngoi h thng
Pht sinh hoc tip nhn d liu/thng tin
Tin trnh: hot ng nghip v
Dy hot ng tc ng ln d liu
Lung d liu: d liu di chuyn
D liu di chuyn t ngun ti ch
Kho d liu: d liu c lu tr
D liu c lu tr mt v tr
41 Tn tc nhn Tn tin trnh
Tn lung d liu
Tn kho
V d: DFD mc 0 bn v tu
42
M hnh thc th mi quan h
43
Tm quan trng ca ERD
Phn tch d liu c lp vi lu tr v x l
Nghin cu phm vi min thng tin
To ra m hnh tru tng hng khch hng (m hnh khi nim), trc quan
Xc nh cc mi quan h mang tnh cu trc gia cc d liu. D dng chuyn sang m hnh thit k 44
Phng php thu thp yu cu
Phng vn
Quan st
iu tra bng bng hi
Nghin cu ti liu
45
Ti liu yu cu
Yu cu:
Ch m t chc nng, rng buc
Khng m t v phng thc ci t
Phi d thay i
Kh xc nh chnh xc, y ngay
Phi qua nhiu bc xt li
46
nh dng ti liu yu cu
Gii thiu: M t s cn thit ca h thng
Thut ng: nh ngha cc khi nim k thut c s dng trong ti liu ny
nh ngha yu cu ngi s dng: yu cu chc nng v phi chc nng
Kin trc h thng
c t yu cu h thng: M t yu cu c bn chi tit hn
M hnh h thng: M hnh i tng, m hnh lung d liu v ng ngha d liu,
Pht trin/thay i ca h thng: Cc gi thit, cc d on v pht trin phn cng, yu cu ngi dng
Ph lc
Ch mc: Ch mc theo ch ci, theo chng, theo chc nng 47
Question
48
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