Nhp mn Cng ngh phn mm

Bin tp bi:Phm Th Qunh

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Nhp mn Cng ngh phn mm

Bin tp bi:Phm Th Qunh

Cc tc gi:Phm Th Qunh

Phin bn trc tuyn:http://voer.edu.vn/c/fb584480

MC LC

1. Phn mm l g?2. Vn v tnh chuyn nghip v ng quy tc3. Mt s m hnh pht trin phn mm4. Cc hot ng trong quy trnh phn mm5. Qun l d n6. Mt s yu cu v nhp mn cng ngh phn mm7. Yu cu ca ngi s dng8. Ti liu c t yu cu9. Phn tch kh thi10. Pht hin v phn tch yu cu11. nh gi yu cu12. Lp k hoch qun l yu cu13. Cc m hnh Qun l14. M hnh ng x v my h thng15. M hnh d liu16. M hnh i tng,h thng,ng x v tha k17. Phng php hng cu trc18. Cc vn v thit k kin trc19. T chc h thng v cc m hnh20. Phn r h thng v phn r i tng21. Cc chin lc iu khin22. Cc kin trc tham chiu23. Thit k giao din ngi dng24. Quy trnh thit k giao din ngi dng25. Ci tin v bo tr phn mm26. Cc quy trnh ci tin phn mm27. Kim th phn mm v quy trinh28. Kim th h thng ,kim th tch hp v kim th c lp29. Cc phng php kim th30. Thit k cc trng hp kim th31. T ng kim thTham gia ng gp

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Phn mm l g?Khi nim

Phn mm l cc chng trnh my tnh v nhng ti liu lin quan n n nh: cc yucu, m hnh thit k, ti liu hng dn s dng Do , chng ta thy rng c imca phn mm l tru tng v v hnh.

Cc sn phm phn mm c chia thnh 2 loi:

- Sn phm i tr (Generic Product): c pht trin bn ra ngoi th trng, itng ngi s dng l tng i a dng v phong ph. Nhng sn phm phn mmthuc loi ny thng l nhng phn mm dnh cho my PC.

- Sn phm theo n t hng (Bespoke Product hoc Customised Product): c phttrin cho mt khch hng ring l theo yu cu. V d: Nhng h thng phn mmchuyn dng, h tr nghip v cho mt doanh nghip ring l

Mt phn mm mi c th c to ra bng cch pht trin cc chng trnh mi, thayi v iu chnh cc h thng phn mm i tr hoc ti s dng li cc phn mm tn ti.

Cng ngh phn mm l g?

Cng ngh phn mm l nhng quy tc cng ngh (engineering discipline) c lin quann tt c cc kha cnh ca qu trnh sn xut phn mm.

Cc k s phn mm nn tun theo mt phng php lun c h thng v c t chctrong cng vic ca h. ng thi, h nn s dng cc cng c v k thut thch hpvi vn cn gii quyt, cc rng buc v ti nguyn sn c.

S khc bit gia cng ngh phn mm v khoa hc my tnh?

Khoa hc my tnh cp ti l thuyt v nhng vn c bn; cn cng ngh phnmm cp ti cc hot ng xy dng v a ra mt phn mm hu ch.

Khi s pht trin ca phn mm tr ln mnh m th cc l thuyt ca khoa hc mytnh vn khng ng vai tr l nn tng hon thin cho cng ngh phn mm.

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S khc bit gia cng ngh phn mm v cng ngh h thng?

t vn

- Hc vin bao gi nghe nhc ti Cng ngh h thng hay cha?

- Hy trnh by mt s vn c lin quan n Cng ngh h thng.

- Cng ngh phn mm c phi l Cng ngh h thng khng?

Cng ngh h thng (hay cn gi l k ngh h thng) lin quan ti tt c cc kha cnhca qu trnh pht trin h thng da my tnh bao gm: phn cng, phn mm, v cngngh x l. Cng ngh phn mm ch l mt phn ca quy trnh ny, n c lin quan tivic pht trin h tng phn mm (software infrastructure), iu khin, cc ng dng vc s d liu trong h thng.

K s h thng phi thc hin vic c t h thng, thit k kin trc h thng, tch hpv trin khai.

Quy trnh phn mm l g?

t vn

- Hy cho bit sn xut mt phn mm, ngi ta phi thc hin nhng cng vic no?

Quy trnh phn mm l mt tp hp cc hnh ng m mc ch ca n l xy dng vpht trin phn mm. Nhng hnh ng thng c thc hin trong cc quy trnh phnmm bao gm

- c t: c t nhng g h thng phi lm v cc rng buc trong qu trnh xy dngh thng.

- Pht trin: xy dng h thng phn mm.

- Kim th: kim tra xem liu phn mm tho mn yu cu ca khch hng.

- M rng: iu chnh v thay i phn mm tng ng vi s thay i yu cu.

Nhng loi h thng khc nhau s cn nhng quy trnh pht trin khc nhau. V d, hthng thi gian thc yu cu phi hon thnh c t h thng trc khi chuyn sang giaion xy dng n. Nhng vi h thng thng mi in t, chng ta c th va c tva xy dng chng trnh mt cch ng thi.

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Tuy nhin, nu chng ta khng s dng mt quy trnh pht trin h thng thch hp thc th lm gim cht lng ca h thng v tng chi ph xy dng.

M hnh quy trnh pht trin phn mm l g?

M hnh quy trnh pht trin phn mm l mt th hin n gin ca mt quy trnh phnmm, v n c biu din t mt gc c th.

Sau y l mt s v d v m hnh quy trnh pht trin phn mm:

- M hnh lung cng vic (workflow): m t mt chui cc hnh ng cn phi thchin.

- M hnh lung d liu (data-flow): m t lung thng tin.

- M hnh Vai tr/Hnh ng (Role/action): ch ra vai tr ca nhng ngi lin quantrong quy trnh phn mm v nhim v ca tng ngi.

Ngoi ra, cn c mt s m hnh quy trnh chung cng c xut nh:

- M hnh thc nc (waterfall)

- M hnh pht trin lp li (Iterative development)

- M hnh cng ngh phn mm da thnh phn (Component-based softwareengineering).

Cc chi ph trong cng ngh phn mm

t vn

- xy dng mt h thng phn mm chng ta phi u t cho nhng hng mc no?

- Tt c cc h thng phn mm c cng cc hng mc chi ph hay khng? Ti sao?

xy dng mt h thng phn mm, chng ta thng phi u t mt khon ngn schkh ln. Theo thng k cho thy, chi ph cho vic xy dng phn mm chim mt phnng k ca GNP tt c cc nc pht trin.

Chi ph phn mm thng chim phn ln chi ph ca c h thng my tnh. Chi phphn mm trn my PC thng ln hn chi ph phn cng. Chi ph phn mm dnh chovic bo tr phn mm thng ln hn chi ph xy dng phn mm. i vi nhng hthng hot ng trong thi gian di, th chi ph bo tr thng ln gp nhiu ln so vichi ph xy dng.

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Xp x 60% chi ph l chi ph xy dng v 40% l chi ph kim th. i vi nhng phnmm lm theo yu cu ca khch hng, chi ph m rng thng vt qu chi ph xydng.

Chi ph bin i tu thuc vo tng loi h thng c xy dng v cc yu cu v cim ca h thng nh: hiu nng v tin cy ca h thng.

Vic phn b chi ph cng ph thuc vo m hnh pht trin h thng c s dng. Sauy l bng so snh chi ph ca 3 m hnh ph bin nht, thng c s dng:

M hnh thc nc:

Chi ph ca cc pha c t, thit k, ci t, tch hp v kim th c xc nh mtcch ring r.

M hnh pht trin lp li

Khng th phn bit r chi ph cho tng pha trong quy trnh.

Chi ph c t gim v y l c t bc cao.

Ti mi bc lp, cc pha trong quy trnh xy dng h thng c thc hin li nhmthc hin cc yu cu h thng khc nhau tng bc lp.

Sau khi thc hin ht cc bc lp, phi c chi ph kim th ton b h thng.

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M hnh cng ngh phn mm hng thnh phn

Chi ph ph thuc nhiu vo vic tch hp v kim th h thng.

Ngoi chi ph xy dng, chng ta cn phi mt phn ln chi ph phc v cho victhay i phn mm sau khi n c a vo s dng. Chi ph ci tin phn mm thayi ph thuc vo tng loi phn mm.

Cc phng php cng ngh phn mm l g?

Phng php cng ngh phn mm bao gm cc m hnh h thng, cc k php, quytc, hng dn thit k v quy trnh xy dng phn mm mt cch d dng, m bocht lng cao v chi ph hiu qu.

Mt s phng php cng ngh phn mm c xut nh: Phn tch hng cutrc - tp trung vo vic xc nh cc chc nng c bn ca h thng; phng phphng i tng - tp trung vo vic nh ngha cc i tng v s cng tc gia chng...

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CASE (Computer-Aided Software Engineering)

Cc h thng CASE thng c s dng h tr cc hot ng trong quy trnh xydng phn mm. C hai loi CASE:

- Upper-CASE: cng c h tr cc hot ng u tin nh c t yu cu v thit k.

- Lower-CASE: cng c h tr cc hot ng sau nh lp trnh, g li v kim th.

Th no l mt phn mm tt?

t vn

- Bn c thng xuyn s dng phn mm khng?

- Theo bn, th no l mt phn mm tt?

Phn mm phi p ng cc chc nng theo yu cu, c hiu nng tt, c kh nng botr, ng tin cy, v c ngi s dng chp nhn.

- Kh nng bo tr: phn mm phi c iu chnh v m rng tho mn nhng yucu thay i.

- Mc tin cy: phn mm phi c tin cy, bo mt v chnh xc.

- Hiu qu: phn mm khng nn s dng lng ph ti nguyn ca h thng.

- Kh nng c chp nhn: ngi s dng phi chp nhn phn mm. iu c nghal n phi d hiu, s dng c v tng thch vi cc h thng khc.

Thch thc i vi cng ngh phn mm?

t vn

- Nu quan tm n s pht trin ca cng ngh phn mm, bn hy cho bit nhngthch thc m cng ngh phn mm phi i mt.

Cng ngh phn mm trong th k 21 phi i mt vi rt nhiu thch thc to ln. Vimi thch thc ny, chng ta phi c nhng gii php c th.

- Khng ng nht: pht trin cc k thut xy dng phn mm gii quyt s khngng nht v mi trng thc hin v nn tng h tng.

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- Chuyn giao: pht trin cc k thut nhm dn ti vic chuyn giao phn mm tingi s dng nhanh hn.

- tin cy: pht trin cc k thut chng minh rng phn mm c ngi s dngn tin tng.

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Vn v tnh chuyn nghip v ng quytct vn

- Theo bn, p ng c cc yu cu cng vic mt k s phn mm phi tho mnc nhng yu cu g?

Quy trnh xy dng phn mm c thc hin trong mt mi trng chuyn nghip vi hi tun th cc nguyn tc mt cch chnh xc. Do , nhng k s phn mm phicoi cng vic ca h l trch nhim to ln, ch khng n thun ch l vic ng dngk thut.

K s phn mm phi ng x trung thc v cch lm ca h phi rt chuyn nghip vng quy tc. Trong phn ny, chng ta s trnh by mt s nguyn tc cn thit m mtk s phn mm phi thc hin.

- S tin cn: k s phn mm phi to c s tin cn t pha nhn vin v khch hng.

- Nng lc: k s phn mm khng nn trnh by sai kh nng ca mnh, khng nnnhn nhng cng vic vt qu kh nng ca mnh.

- Cc quyn v ti sn tr tu: k s phn mm nn quan tm v cc ti sn tr tu cbo h nh: bng sng ch, quyn tc gi m bo rng tt c ti sn tr tu canhn vin v khch hng u c bo h.

- Lm dng my tnh: k s phn mm khng nn s dng cc k nng ca mnh gy nh hng ti ngi khc. Lm dng my tnh c th c hiu l nhng vic tmthng (V d: chi in t trn my tnh ca ngi khc) n nhng vn nghimtrng (V d: pht tn virus).

Vn v tnh chuyn nghip v ng quy tc i vi k s phn mm quan trng timc mt s t chc M hp tc pht trin bn Code of Ethics gm 8 quy tclin quan n ng x v cch ra quyt nh ca cc k s phn mm chuyn nghip.

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Mt s m hnh pht trin phn mmMt s m hnh

Gii thiu

M hnh pht trin phn mm l mt th hin tru tng ca quy trnh phn mm. Nbiu din cc c t v quy trnh t nhng kha cnh c th; do , n ch cung cp mtphn thng tin v quy trnh phn mm.

Phn sau y s trnh by nm m hnh pht trin phn mm ph bin thng c sdng:

- M hnh thc nc

- M hnh xy dng tin trin

- Cng ngh phn mm da thnh phn

- M hnh pht trin lp li, tng thm

- M hnh xon c

Mc tiu

- Phi hiu r nm m hnh pht trin phn mm c bn.

- Phn bit c s khc nhau gia cc m hnh; u v nhc im ca tng m hnh.

- Bit r i vi loi h thng no th nn p dng m hnh pht trin no cho ph hp.

M hnh thc nc

Cc pha ca m hnh thc nc bao gm:

- Phn tch v xc nh cc yu cu

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- Thit k h thng v phn mm

- Ci t v kim th n v

- Tch hp v kim th h thng

- Vn hnh v bo tr.

Trong m hnh thc nc, nm pha trn phi c thc hin mt cch tun t; kt thcpha trc, ri mi c thc hin pha tip theo. Do , nhc im chnh ca m hnhthc nc l rt kh khn trong vic thay i cc pha c thc hin. Gi s, phaphn tch v xc nh yu cu hon tt v chuyn sang pha k tip, nhng lc ny lic s thay i yu cu ca ngi s dng; th ch cn cch l phi thc hin li t u.

Cho nn, m hnh ny ch thch hp khi cc yu cu c tm hiu r rng v nhngthay i s c gii hn mt cch r rng trong sut qu trnh thit k. Tuy nhin, trongthc t c rt t nhng h thng nghip v c cc yu cu n nh.

M hnh xy dng tin trin

M hnh xy dng tin trin da trn tng xy dng mt mu th ban u v acho ngi s dng xem xt; sau , tinh chnh mu th qua nhiu phin bn cho n khitho mn yu cu ca ngi s dng th dng li.

C hai phng php thc hin m hnh ny:

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- Pht trin thm d: mc ch ca n l lm vic vi khch hng v a ra hthng cui cng t nhng c t s b ban u. Phng php ny thng bt u thchin vi nhng yu cu c tm hiu r rng v sau , b sung nhng c im mic xut bi khch hng. Cui cng, khi cc yu cu ca ngi s dng c thomn th cng l lc chng ta xy dng xong h thng.

- Loi b mu th: mc ch l tm hiu cc yu cu ca h thng. Phng php nythng bt u vi nhng yu cu khng r rng v t thng tin. Cc mu th s cxy dng v chuyn giao ti cho ngi s dng. T , ta c th phn loi nhng yucu no l thc s cn thit v lc ny mu th khng cn cn thit na. Nh vy, muth ch c tc dng lm sng t yu cu ca ngi s dng.

Tuy nhin, nhc im ca m hnh xy dng tin trin l: thiu tm nhn ca c quytrnh; cc h thng thng hng cu trc ngho nn; yu cu cc k nng c bit (Vd: cc ngn ng to ra mu th nhanh chng).

M hnh xy dng tin trin ch nn p dng vi nhng h thng c tng tc mc nh hoc va; trn mt phn ca nhng h thng ln; hoc nhng h thng c thi gianchu k tn ti ngn.

Cng ngh phn mm da thnh phn

M hnh ny da trn k thut ti s dng mt cch c h thng; trong h thngc tch hp t nhiu thnh phn ang tn ti hoc cc thnh phn thng mi COTS(Commercial-off-the-shelf).

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Cc trng thi chnh ca quy trnh bao gm:

- Phn tch thnh phn sn c

- iu chnh yu cu

- Thit k h thng vi k thut ti s dng

- Xy dng v tch hp h thng

M hnh pht trin lp li, tng thm

M hnh ny c xut da trn tng thay v phi xy dng v chuyn giao hthng mt ln th s c chia thnh nhiu vng, tng dn. Mi vng l mt phn ktqu ca mt chc nng c yu cu.

Cc yu cu ca ngi s dng c nh th t u tin. Yu cu no c th t u tincng cao th cng trong nhng vng pht trin sm hn.

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T , chng ta c th thy r mt s u im ca m hnh pht trin tng vng:

- Sau mi ln tng vng th c th chuyn giao kt qu thc hin c cho khch hnhnn cc chc nng ca h thng c th nhn thy sm hn.

- Cc vng trc ng vai tr l mu th gip tm hiu thm cc yu cu nhngvng tip theo.

- Nhng chc nng ca h thng c th t u tin cng cao th s c kim th cngk.

M hnh xon c

Trong m hnh xon c, quy trnh pht trin phn mm c biu din nh mt vngxon c. Cc pha trong quy trnh pht trin xon c bao gm:

- Thit lp mc tiu: xc nh mc tiu cho tng pha ca d n.

- nh gi v gim thiu ri ro: ri ro c nh gi v thc hin cc hnh ng gimthiu ri ro.

- Pht trin v nh gi: sau khi nh gi ri ro, mt m hnh xy dng h thng s cla chn t nhng m hnh chung.

- Lp k hoch: nh gi d n v pha tip theo ca m hnh xon c s c lp khoch.

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Cc hot ng trong quy trnh phn mmCc hot ng

Gii thiu

Trong quy trnh phn mm gm 4 hot ng c bn. Nhng hot ng ny bao gm:

- c t: cc chc nng ca h thng v nhng rng buc khi vn hnh h thng cnphi c xc nh mt cch y v chi tit.

- Thit k v ci t: phn mm c xy dng phi tho mn c t ca n.

- nh gi: phn mm phi c nh gi v thm nh m bo rng n tho mntt c cc yu cu.

- Ci tin: phn mm cn phi ci tin v iu chnh ph hp vi nhng thay i vyu cu h thng.

Vi mi m hnh khc nhau th cc hot ng ny cng c t chc theo cc cchkhc nhau. V d, trong m hnh thc nc, chng c t chc mt cch tun t. Trongm hnh tin trin, cc hot ng ny c th gi ln nhau. Trong cc phn tip sau y,chng ta s nghin cu c th tng hot ng.

Mc tiu

- Xc nh r nhng cng vic no cn phi lm trong quy trnh pht trin phn mm.

- Tng cng vic c thc hin c th ra sao

- Phi nh mt iu rng: khi xy dng bt k phn mm no, chng ta u phi thchin bn cng vic trn. Tuy nhin, vi vic s dng cc m hnh pht trin phn mmkhc nhau th trnh t thc hin cc cng vic trn cng khc nhau.

c t phn mm

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t vn

- Cng vic u tin cn phi lm trong qu trnh xy dng phn mm l g?

- Tm quan trng ca vic c t phn mm.

c t phn mm (hay cn gi l k thut xc nh yu cu) l quy trnh tm hiu vnh ngha nhng dch v no c yu cu v cc rng buc trong qu trnh vn hnhv xy dng h thng.

Quy trnh xc nh yu cu bao gm bn pha chnh:

- Nghin cu kh thi: Nghin cu kh thi gip xc nh nhng yu cu ca ngi sdng c tho mn nhng cng ngh hin ti hay khng. V gc kinh doanh, nghincu kh thi nhm xc nh h thng a ra c mang li li nhun khng. Vic nghincu kh thi nn c thc hin mt cch nhanh chng v khng qu tn km. Kt quca vic nghin cu kh thi s xc nh c nn tip tc xy dng h thng na haykhng.

- Phn tch v rt ra cc yu cu: y l quy trnh a ra cc yu cu h thng thngqua mt s phng php nh: quan st h thng hin ti, phng vn v tho lun vingi s dng, phn tch nhim v, phn tch ti liu hoc h thng c Trong phany, chng ta c th phi xy dng mt hoc nhiu m hnh h thng v cc mu th.

- c t yu cu: Pha ny s t liu ho nhng thng tin thu thp c. C hai loi yucu cn c xc nh:

* Yu cu ca ngi s dng: l nhng yu cu bng ngn ng t nhin b sung thmcho cc biu ca cc dch v m h thng cung cp v cc rng buc vn hnh can. Kiu yu cu ny c vit bi ngi s dng.

* Yu cu h thng: l nhng ti liu c cu trc m t chi tit v cc chc nng, dchv v cc rng buc vn hnh ca h thng. Yu cu h thng s nh ngha nhng gcn phi xy dng, cho nn n c th tr thnh bn hp ng gia khch hng v nhthu.

- nh gi yu cu: pha ny s kim tra li cc yu cu xem chng c ng thc t haykhng, c thng nht khng, c y khng. Nu pht hin ra li th ta phi chnh sacc li ny.

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Thit k phn mm v ci t

t vn

- B qua giai on thit k, sau khi c t v phn tch yu cu, c th thc hin ci th thng ngay c khng?

- Vai tr ca bn thit k i vi giai on ci t l g?

Thit k phn mm l qu trnh thit k cu trc phn mm da trn nhng ti liu ct. Hot ng thit k bao gm nhng cng vic chnh sau:

- Thit k kin trc: Cc h thng con cu thnh ln h thng cn xy dng v mi quanh gia chng c xc nh v t liu ho.

- c t tru tng: vi mi h thng con, phi c mt bn c t v cc dch v ca nv nhng rng buc khi n vn hnh.

- Thit k giao din: vi mi h thng con, cc giao din ca n vi nhng h thng conkhc phi c thit k v t liu ho.

- Thit k thnh phn: cc dch v cung cp cho cc thnh phn khc v cc giao dintng tc vi chng phi c thit k.

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- Thit k cu trc d liu: cu trc d liu c s dng ci t h thng phi cthit k mt cch chi tit v c th.

- Thit k thut ton: Cc thut ton c s dng cung cp cc dch v phi cthit k chi tit v chnh xc.

Ci t l quy trnh chuyn i t ti liu c t h thng thnh mt h thng thc, cth vn hnh c v phi loi b cc li ca chng trnh.

Lp trnh l mt hnh ng c nhn, khng c quy trnh lp trnh chung. Ngi lp trnhphi thc hin mt s kim th pht hin ra li trong chng trnh v loi b n trongquy trnh g li.

nh gi phn mm

t vn

- Sau khi ci t phn mm, chng ta c th chuyn giao ngay cho ngi s dng ckhng?

- Vai tr ca vic nh gi phn mm l g?

nh gi phn mm hay cn gi l thm tra v nh gi (V&V - Verification andvalidation) c s dng ch ra rng h thng thc hin theo ng cc c t vtho mn mi yu cu ca khch hng.

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nh gi phn mm bao gm cc cng on: kim tra, xem xt li, v kim th h thng.Kim th h thng tc l cho h thng thc hin trn nhng trng hp c d liu thtc ly t ti liu c t h thng. Quy trnh kim th gm cc pha sau:

- Kim th thnh phn (n v): cc thnh phn c kim th mt cch c lp, thnhphn c th l mt chc nng hoc mt i tng hoc mt nhm cc thc th gn ktvi nhau.

- Kim th h thng: kim th ton b h thng.

- Kim th chp thun: kim th trn d liu ca khch hng kim tra h thng cp ng tt c cc yu cu ca khch hng hay khng.

Khi chuyn giao h thng cho khch hng th quy trnh kim th beta s c thc hin.Khch hng s thng bo cc li cho i d n. Nhng li ny s c chnh sa v tiptc kim th beta hoc chuyn giao thc s cho khch hng.

Ci tin phn mm

t vn

- Sau khi chuyn giao phn mm cho khch hng, th mi cng vic kt thc cha?

- Ci tin phn mm lm g?

- Ti sao khng xy dng h thng mi m li ci tin h thng c?

Khi cc yu cu h thng thay i theo s thay i ca cc yu cu nghip v th phnmm phi ci tin v thay i h tr khch hng. Thng thng chi ph bo tr vci tin thng t hn nhiu so vi chi ph xy dng phn mm.

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Qun l d nnh ngha v qun l d n

t vn

- xy dng c mt h thng phn mm thnh cng, cn thit phi qun l d n

- Da trn hiu bit ca mnh, hy cho bit qun l d n l g?

- Qun l d n phn mm c ging qun l cc d n khc khng?

Qun l d n phn mm l mt phn quan trng ca cng ngh phn mm. Nu qunl tt th cha chc d n thnh cng, nhng nu qun l ti th chc chn d n stht bi. D n tht bi khi phn mm chuyn giao chm hn so vi k hoch, chi phln hn d tnh, v khng tho mn cc yu cu ra.

Qun l d n phn mm c lin quan ti nhng hot ng nhm m bo chuyn giaophn mm ng thi hn, ng k hoch v ph hp vi cc yu cu ca t chc phttrin phn mm.

Qun l d n phn mm c mt s c trng khc bit so vi cc loi d n khc:

- Sn phm l v hnh. Sn phm c kh nng thay i linh ng.

- Cng ngh phn mm khng c tha nhn nh mt quy tc cng ngh c trng thichun mc nh cc ngnh cng ngh khc.

- Quy trnh pht trin phn mm khng c chun ho.

- Nhiu d n phn mm l nhng d n ch lm mt ln.

Qun l d n l mt yu cu cn thit v pht trin phn mm lun phi tho mn ccrng buc v k hoch v chi ph c xc nh bi t chc pht trin phn mm.Ngi qun l d n phi chu trch nhim lp k hoch v theo di qu trnh thc hind n.

Cc hot ng qun l

t vn

- Nhng cng vic phi lm trong Qun l d n l g?

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- Hy tho lun v nhng cng vic . Cho bit cng vic no l quan trng nht.

Cc hot ng qun l d n bao gm:

- Vit k hoch d kin: y l mt cng vic kh phc tp. N m t mc tiu ca dn, phng php thc hin, c lng thi gian v chi ph

- Lp k hoch d n: lin quan n vic xc nh cc hnh ng, cc mc thi gian vcc sn phm c to ra.

- Tnh chi ph d n

- iu hnh v xem xt li d n: ngi qun l phi gim st quy trnh thc hin d n,so snh quy trnh v chi ph thc t vi k hoch nh. Nu iu hnh tt, ngi qunl d n c th pht hin v khc phc c nhng ri ro tim tng.

- La chn v nh gi c nhn. Vic la chn nhn vin thch hp cho mt d n l rtkh khn. Khi la chn i d n, ngi qun l d n c th gp phi mt s vn sau: ngn sch ca d n khng tr cho nhng nhn vin c mc lng cao, khngc c nhng nhn vin c kinh nghim v trnh thch hp, t chc mun ch nhmt s nhn vin mi tham gia vo d n ...

- Vit bo co v trnh by.

Tuy nhin, ngy nay chng ta c rt nhiu k thut v cng c c s dng h trcho vic qun l d n phn mm.

Lp k hoch d n

Mc tiu

- Hiu r tm quan trng ca vic lp k hoch d n

- Phi bit rng ng vi mi hot ng trong qu trnh pht trin phn mm, chng ta sphi c mt bn k hoch ring.

- Nm c cu trc ca mt bn k hoch d n pht trin h thng phn mm.

Lp k hoch d n c th l hot ng tn nhiu thi gian nht trong qu trnh qun ld n. N lit k cc hnh ng t pha khi to cho n khi a ra c h thng. Khoch phi c theo di thng xuyn, nht l khi c nhng thng tin hoc nhng yucu mi xut hin.

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Trong qu trnh thc hin d n, chng ta c nhiu loi k hoch c xy dng htr cho k hoch chnh ca d n phn mm nh: k hoch cht lng, k hoch thmtra, k hoch qun l cu hnh, k hoch bo tr, k hoch pht trin nhn s

Cu trc ca bn k hoch d n gm:

- Phn gii thiu: m t cc mc tiu ca d n v cc rng buc gy nh hng ti vicqun l d n.

- T chc d n: m t cch t chc ca i d n, bao gm nhng ai v nhng nhimv g.

- Phn tch ri ro: m t nhng ri ro c th xy ra, d bo khi no chng xy ra v xut chin lc gim ri ro.

- Cc yu cu v ti nguyn phn cng v phn mm: xc nh nhng phn cng vphn mm no cn thit cho qu trnh thc hin d n.

- Bng thng k cng vic: xc nh cc cng vic, tng mc thi gian v kt qu catng cng vic.

- Lch biu ca d n: lch biu cho thy s ph thuc gia cc hnh ng, thi gian ctnh t ti mc v phn cng cng vic cho tng ngi. Mc l im cui ca mthnh ng trong quy trnh. V d, trong m hnh thc nc cho php ta nh ngha ccmc ca tin trnh mt cch r rng.

- Cc k thut iu hnh v bo co

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Lch biu ca d n

Mc tiu

- Phi hiu r lp lch biu d n l lm g?

- Nm c mt s quy tc v cc gi khi lp lch biu

- C kh nng p dng biu ct, s mng xy dng lch biu

- C th s dng mt s cng c h tr lp lch biu nh: M.Excel, M.Project

Lp lch biu d n l mt trong nhng cng vic kh khn nht i vi ngi qun ld n. Ngi qun l phi chia d n thnh nhiu nhim v, c lng thi gian v tinguyn cn thit hon thnh tng nhim v.

Khi lp lch biu, ngi qun l nn t chc cc cng vic song song s dng ti ulc lng lao ng v ti thiu ho s ph thuc ln nhau gia cc nhim v trnh schm tr khi mt nhim v phi i nhim v khc hon thnh.

Cht lng ca lch biu ph thuc vo hiu bit v kinh nghim ca ngi qun l. Tuynhin, khi lp lch biu chng ta phi ch ti cc vn sau:

- Vic c lng mc kh ca mt vn no v xc nh chi ph gii quytn l rt kh khn.

- Kh nng sn xut khng tng ng vi s lng ngi lm vic trong mt nhim v.

- B sung thm ngi vo d n s lm cho n chm hn v giao tip trong d n tr lnqu ti.

- Nhng s vic xy ra ngoi mong i.

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Chng ta s dng cc k php ho minh ho cho lch biu ca d n. S dng biu gip ta thy r cch chia d n thnh nhiu nhim v. Cc nhim v khng nn qunh, chng nn c thc hin trong vng mt hoc hai tun.

V d

Gi s c mt lot cc hot ng Ti, thi gian thc hin tng hot ng v s ph thucln nhau gia cc hot ng c lit k nh bng di y. Hy thc hin cc yu cusau:

1.Xy dng mng cc hot ng

2. Xy dng biu nhm biu din cc hot ng theo dng thi gian

3. Biu phn cng cng vic

Kt qu thc hin v d

Mnghot ng

Theothi gian

Theocng vic

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Qun l ri ro

Mc tiu

- Phi hiu c ri ro lun lun c th xy ra trong d n v khng th lng trcc

- Nm c mt s loi ri ro thng gp

- Bit c cc hot ng cn thc hin trong qun l ri ro.

Qun l ri ro lin quan ti vic xc nh ri ro v lp ra cc k hoch ti thiu honh hng ca chng ti d n.

Sau y l mt s loi ri ro thng gp trong qu trnh pht trin h thng phn mm:

- Ri ro ca d n c nh hng ti lch biu v ti nguyn ca d n

- Ri ro ca sn phm nh hng ti cht lng hoc hiu nng ca phn mm s cxy dng.

- Ri ro thng mi s nh hng ti t chc xy dng phn mm.

qun l ri ro, chng ta cn phi thc hin cc hot ng sau:

- Pht hin ri ro: Pht hin cc loi ri ro c lin quan n: cng ngh, con ngi, tchc, cc yu cu, c lng.

- Phn tch ri ro: nh gi cc kh nng xy ra ri ro v tnh nghim trng ca n nun xy ra.

- Lp k hoch ri ro: Xem xt tng ri ro v pht trin chin lc qun l n. Baogm cc chin lc nh: phng trnh - gim kh nng xy ra ri ro, ti thiu ho - gimnh hng ca ri ro, k hoch bt ng - k hoch ny dnh cho khi ri ro xy ra.

- Kim sot ri ro: nh gi tng ri ro c xc nh mt cch thng xuyn xcnh kh nng n c th xy ra hay khng v cng ng thi nh gi mc nh hngca n. Nhng ri ro chnh nn c tho lun ti cc cuc hp qun l tin trnh.

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Mt s yu cu v nhp mn cng nghphn mmYu cu h thng

Gii thiu

Cc yu cu ca h thng phn mm thng c chia thnh ba loi: yu cu chc nng,yu cu phi chc nng v yu cu min ng dng. Tuy nhin, trong thc t chng ta rtkh phn bit ba loi yu cu ny mt cch r rng.

Mc tiu

- Tm hiu v cc yu cu h thng v c im ca chng

- Phng php xc nh cc yu cu h thng

- Nm r cc k thut c t yu cu h thng v bit cch p dng nhng k thut nymt cch thch hp.

V d

Trong chng ny, chng ta s s dng mt v d v h thng th vin xc nh ccloi yu cu.

H thng th vin (LIBSYS) cung cp mt giao din n gin lu CSDL v cc bibo trn cc th vin khc nhau. Ngi s dng c th tm kim, download v in nhngti liu ny.

Yu cu chc nng

t vn

- xy dng mt h thng c th dng c thc s, trc ht n phi t c yucu g?

- Yu cu chc nng c phi l quan trng nht khng?

- Nu ta khng xc nh y , r rng cc yu cu chc nng th s xy ra chuyn g?

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Yu cu chc nng m t h thng s lm g. N m t cc chc nng hoc cc dch vca h thng mt cch chi tit.

c im ca yu cu chc nng:

- Tnh mp m, khng r rng ca cc yu cu: Vn ny xy ra khi cc yu cu khngc xc nh mt cch cn thn. Cc yu cu mp m c th c ngi xy dng vngi s dng hiu theo nhiu cch khc nhau.

- Tnh hon thin v nht qun: V nguyn tc, yu cu phi cha tt c cc m t chitit v khng c s xung t hoc i ngc gia cc yu cu. Tuy nhin, trong thc trt kh c th t c iu ny.

Xc nh cc yu cu chc nng ca LYBSYS

- Ngi s dng c th tm kim tt c CSDL hoc mt tp con ca CSDL.

- H thng s cung cp nhng giao din thch hp ngi s dng c ti liu.

- Tt c nhng ho n m ngi s dng ng k in sao ti liu c mt m duy nht.

Yu cu phi chc nng

t vn

- Nu h thng ch tho mn nhng yu cu chc nng th cha?

- V d h thng khng tin dng i vi ngi s dng th sao?

- Yu cu phi chc nng bao gm nhng vn g?

Yu cu phi chc nng khng cp trc tip ti cc chc nng c th ca h thng.Yu cu phi chc nng thng nh ngha cc thuc tnh nh: tin cy, thi gian png, cc yu cu v lu tr v cc rng buc ca h thng nh: kh nng ca thit bvo/ra, giao din

Mt s yu cu phi chc nng cn c lin quan n quy trnh xy dng h thng. V d:cc chun c s dng, cc cng c CASE, ngn ng lp trnh

Cc yu cu phi chc nng c th l hn ch hn nhng yu cu chc nng. Nhng nun khng c tho mn th h thng s khng s dng c.

Cc yu cu phi chc nng xut hin l do yu cu ca ngi s dng, rng buc vngn sch, cc chnh sch ca t chc s dng h thng, yu cu tng thch gia phn

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cng v phn mm v cc tc nhn ngoi khc. Do , chng ta c th phn loi cc yucu phi chc nng nh sau:

- Cc yu cu v sn phm xc nh ng x ca sn phm nh: hiu nng, kh nng sdng, tin cy ca sn phm

- Cc yu cu v t chc: cc yu cu ny c ly t nhng chnh sch v quy tc cakhch hng hoc t chc s dng h thng.

- Cc yu cu ngoi: c xc nh t cc tc nhn ngoi ca h thng.

Xc nh cc yu cu phi chc nng ca LIBSYS

- Yu cu v sn phm: LIBSYS phi c ci t bng HTML m khng c framehoc Java applets.

- Yu cu v mt t chc: Quy trnh xy dng h thng v cc ti liu chuyn giao phitho mn cc quy tc c nh ngha trong XYZCo-SP-STAN-95.

- Yu cu ngoi: H thng khng c l cc thng tin c nhn ca khch hng.

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Ni chung, chng ta rt kh xc nh chnh xc v rt kh thm tra nhng yu cu phichc nng mp m. Do , trong ti liu c t yu cu, ngi ta thng b sung ccmc tiu. Mc tiu rt hu ch i vi ngi pht trin h thng khi n truyn ti cnhng mong mun ca ngi s dng h thng. Cn vi nhng yu cu phi chc nngc th thm nh c l nhng yu cu c th kim th mt cch khch quan.

Tuy nhin, trong nhiu trng hp thng xy ra xung t gia cc yu cu phi chcnng i vi nhng h thng phc tp.

Cc mc tiu v yu cu phi chc nng c th thm nh c ca LIBSYS

- Mc tiu ca h thng l d s dng i vi nhng ngi s dng c kinh nghim vc t chc sao cho ti thiu ho c li.

- Cc yu cu phi chc nng c th thm nh c: Nhng ngi s dng c kinhnghim c th s dng c tt c cc chc nng ca h thng ch sau hai ting tphun. Sau kho hun luyn ny, s li chng trnh gy ra bi ngi s dng l khngqu hai li mt ngy.

Yu cu min ng dng

t vn

- Yu cu i vi i pht trin h thng?

- Cc yu cu v lnh vc ng dng ca h thng th thuc vo loi no trong hai loitrn trnh by?

Yu cu min ng dng c xc nh t min ng dng ca h thng v phn nh ccthuc tnh v rng buc ca min ng dng. N c th l yu cu chc nng hoc phichc nng.

Nu yu cu min ng dng khng c tho mn th c th h thng s khng lm vicc.

Sau y l mt s vn lin quan n yu cu min ng dng:

- Kh nng c th hiu c: cc yu cu c biu din di ngn ng ca lnh vcng dng.

- n : Cc chuyn gia c hiu bit v lnh vc ca h nhng h khng bit cch xydng nhng yu cu min ng dng mt cch r rng, mang tnh k thut.

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Yu cu v min ng dng ca LIBSYS

- Giao din ngi dng chun cho tt c cc CSDL u da trn chun Z39.50.

- V vn bn quyn nn mt s ti liu phi xo ngay khi va chuyn n.

- Ph thuc vo yu cu ca ngi s dng, nhng ti liu c th c in ngay trnserver v chuyn n cho ngi s dng hoc gi n cho my in mng.

Mt s k thut c t yu cu h thng

Gii thiu

Ni chung, ngn ng t nhin thng c s dng vit c t yu cu h thngcng nh yu cu ca ngi s dng. Tuy nhin, yu cu h thng thng chi tit hnyu cu ca ngi s dng nn c t bng ngn ng t nhin thng gp mt s vn sau:

- Khng r rng: Ngi c v ngi vit yu cu phi gii thch cc t theo cng mtngha. Ngn ng t nhin c bn cht l mp m nn t c yu cu trn l rt khkhn.

- Qu mm do: vi cng mt vn nhng c nhiu cch khc nhau c t.

- Thiu kh nng m-un ho: cu trc ca ngn ng t nhin khng tng xng vicu trc ca cc yu cu h thng.

V nhng l do ny m c t bng ngn ng t nhin thng gy kh hiu. Do ,chng ta c th s dng mt s phng php c trnh by trong cc phn sau ct yu cu.

c t bng ngn ng hng cu trc

S dng ngn ng hng cu trc s yu cu ngi vit c t tun theo nhng muc nh ngha trc. Tt c cc yu cu u c vit theo chun v cc thut ngc s dng c th b hn ch.

u im ca phng php ny l t c mc din t cao nht ca ngn ng tnhin nhng mc ng nht li b lm dng trong cc c t.

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c t da biu mu (Form-based)

c t da biu mu nh ngha cc chc nng hoc thc th, m t u vo v ni xutpht ca n, m t u ra v ni n s n. c t da biu mu ch r nhng thc thcn thit, cc iu kin trc v sau (nu thch hp), cc nh hng ca chc nng.

Biu trnh t

Biu trnh t biu din trnh t cc s kin xy ra khi ngi s dng tng tc vi hthng. Nu ta c biu ny t u n cui th ta s thy c th t ca cc hnhng c thc hin.

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Yu cu ca ngi s dngt vn

- Yu cu ca ngi s dng c c coi ging nh yu cu h thng hay khng?

- Yu cu ca ngi s dng l chc nng hay phi chc nng hay c hai?

Yu cu ca ngi s dng nn m t nhng yu cu chc nng v phi chc nng ngi s dng c th hiu c chng m khng cn phi c nhng kin thc v cngngh mt cch chi tit.

Yu cu ca ngi s dng c nh ngha bng cch s dng ngn ng t nhin, bnghoc biu n gin. Tuy nhin, chng ta s gp phi mt s kh khn khi s dngngn ng t nhin:

- Khng r rng: Tnh chnh xc rt kh t c nu ti liu kh c.

- Yu cu ln xn: cc yu cu chc nng v phi chc nng khng r rng.

- Ln ln gia cc yu cu: cc yu cu khc nhau c th c din t cng vi nhau.

Do , vit yu cu ca ngi s dng ta nn p dng mt s quy tc sau:

- a ra mt nh dng chun v p dng n cho tt c cc yu cu.

- Bt buc s dng ngn ng mt cch thng nht

- nh du nhng phn quan trng trong cc yu cu.

- Trnh s dng nhng t ng mang tnh chuyn mn, k thut.

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Ti liu c t yu cuTi liu

t vn

- Sau khi xc nh cc yu cu h thng v yu cu ca ngi s dng h thng thtip tc lm g?

- Cu trc ca mt ti liu c t yu cu h thng phi bao gm nhng ni dung g?

Ti liu c t yu cu l nhng yu cu chnh thc v nhng g cn phi thc hin bii pht trin h thng.

Ti liu c t yu cu nn bao gm c cc nh ngha v yu cu ca ngi s dng vc t yu cu h thng.

Ti liu c t yu cu khng phi l ti liu thit k h thng. N ch thit lp nhng gh thng phi lm, ch khng phi m t r lm nh th no.

Ti liu c t yu cu da theo chun IEEE

1. Gii thiu

1.1. Mc ch ca ti liu yu cu

1.2. Phm vi ca sn phm

1.3. Cc nh ngha, t vit tt

1.4. Cc tham chiu

1.5. Tng quan v ti liu yu cu

2. M t chung

2.1. Gii thiu chung v sn phm

2.2. Cc chc nng ca sn phm

2.3. c im ca ngi s dng

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2.4. Cc rng buc

2.5. Gi thit v cc ph thuc

3. c t yu cu: bao gm cc yu cu chc nng, phi chc nng, min ng dng vgiao din.

4. Ph lc

5. Ch mc

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Phn tch kh thiMc tiu

- Xc nh r vai tr ca phn tch kh thi

- phn tch kh thi, chng ta phi thc hin nhng cng vic g

- Nm c mt s gi khi phn tch kh thi

i vi tt c cc h thng mi, quy trnh xc nh yu cu thng bt u bng vicphn tch kh thi. Thng tin u vo phn tch kh thi l cc yu cu nghip v, mt s b v h thng, cch thc h thng h tr cc yu cu nghip v. Kt qu ca vicphn tch kh thi l mt bo co quyt nh c nn xy dng h thng xut haykhng.

Phn tch kh thi thng tp trung vo:

- Xc nh h thng c ng gp vo mc tiu ca t chc hay khng

- Kim tra xem h thng c th c xy dng bng cch s dng cng ngh hin ti vngn sch cho php.

- Kim tra xem liu h thng c c tch hp vi cc h thng khc ang s dng haykhng.

Thc hin phn tch kh thi da trn vic nh gi thng tin, la chn thng tin v vitbo co.

Nhng cu hi thng c t ra phn tch kh thi:

- Nu h thng khng c ci t th sao?

- Vn x l hin ti nh th no?

- H thng xut gip c g?

- Vn v tch hp l g?

- Cng ngh mi cn dng l g? Cn c nhng k nng g?

- Nhng li ch m h thng mang li?

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Pht hin v phn tch yu cuMc tiu

- Nhim v ca vic pht hin v phn tch yu cu l g?

- Hiu r m hnh xon c trong quy trnh pht hin v phn tch yu cu

- Cc k thut c s dng pht hin v phn tch yu cu

Trong pha pht hin v phn tch yu cu, nhn vin k thut v khch hng cng hptc xc nh min ng dng, cc dch v m h thng cung cp, hiu nng ca hthng, cc rng buc vn hnh ca h thng

y, chng ta c mt khi nim mi l stakeholder. Stakeholder l nhng ngi thamd vo d n xy dng h thng: ngi s dng cui, ngi qun l, k s, chuyn gialnh vc, V d, trong h thng ATM gm cc Stakeholder sau: khch hng ca ngnhng, i din ca cc ngn hng khc, ngi qun l ngn hng, nhn vin ngn hng,qun tr CSDL, qun l bo mt, phng marketing, k s bo tr phn cng v phnmm, ngi iu hnh ngn hng.

Tuy nhin, vic pht hin v tm hiu yu cu ca stakeholder, chng ta thng gp khkhn v nhng nguyn nhn sau:

- Stakeholder khng bit nhng g m h tht s mong mun.

- Stakeholder m t cc yu cu theo thut ng ca h.

- Nhng stakeholder khc nhau c th c cc yu cu xung t nhau

- Nhng yu t t chc v quyn lc c th nh hng ti cc yu cu h thng.

- Cc yu cu c th thay i trong sut qu trnh phn tch. Nhng stakeholder mi cth xut hin v mi trng nghip v c th thay i.

Do , ngi ta thng s dng m hnh xon c trong quy trnh pht hin v phn tchyu cu.

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Trong quy trnh ny bao gm cc hot ng sau:

- Pht hin yu cu: tip xc vi cc stakeholder pht hin ra cc yu cu ca h. Ccyu cu min ng dng cng c pht hin bc ny.

- Phn loi v sp xp yu cu: nhm cc yu cu c lin quan ln nhau v t chc chngthnh nhng nhm gn kt vi nhau.

- Sp th t u tin v iu chnh cc yu cu xung t: khi c nhiu stakeholder th ccyu cu ca h cng c nhiu xung t. Hot ng ny nhm nh th t u tin cacc yu cu, pht hin v gii quyt xung t gia cc yu cu.

- T liu ha yu cu: yu cu c t liu ho v l u vo ca vng k tip trong mhnh xon c.

Pht hin yu cu l quy trnh thu thp nhng thng tin v h thng c xut v hthng ang tn ti xc nh cc yu cu h thng v yu cu ca ngi s dng. Tac th ly thng tin ny t cc t liu, stakeholder, v bn c t ca nhng h thngtng t. Chng ta giao tip vi stakeholder thng qua phng vn hoc quan st v cth s dng kch bn v mu th gip pht hin yu cu.

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nh gi yu cuMc tiu

- Hiu r tm quan trng ca vic nh gi cc yu cu

- Nm c phi kim tra cc yu cu nhng kha cnh no

- Hiu c mt s k thut c s dng nh gi yu cu

nh gi yu cu c lin quan n vic gii thch cc yu cu c nh ngha trongh thng. V chi ph cho vic gii quyt cc li c lin quan ti yu cu s rt cao chonn vic nh gi yu cu l v cng quan trng.

Trong qu trnh nh gi yu cu, chng ta phi kim tra cc yu cu nhng kha cnhsau:

- Hp l: H thng c cung cp cc chc nng m h tr tt nht cho cc yu cu cangi s dng hay khng?

- Nht qun: c yu cu no xung t nhau hay khng?

- Hon thin: tt c cc yu cu ca khch hng c xc nh y cha?

- Hin thc: cc yu cu c th c ci t vi mt ngn sch v cng ngh cho trc?

- Xc thc: cc yu cu c th c kim tra hay khng?

Cc k thut nh gi yu cu sau y c th c s dng n l hoc hn hp:

- Xem xt li cc yu cu: phn tch cc yu cu mt cch h thng.

- Mu th: S dng cc m hnh h thng kim tra cc yu cu

- To ra cc trng hp kim th

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Lp k hoch qun l yu cuK hoch

Mc tiu

- Nm r quy trnh qun l yu cu

- Khi yu cu thay i, cn phi bit thc hin nhng thao tc g.

Qun l yu cu l quy trnh qun l s thay i ca cc yu cu trong qu trnh phthin yu cu v pht trin h thng.

Cc yu cu thng khng y v khng ng nht. l do mt s nguyn nhnsau:

- Nhng yu cu mi xut hin trong quy trnh khi cc yu cu nghip v thay i vkhi chng ta c hiu bit su hn v h thng s xy dng.

- cc khung nhn khc nhau s c cc yu cu khc nhau v do thng xut hincc mu thun.

- Th t u tin t cc khung nhn khc nhau cung thay i trong sut qu trnh phttrin h thng.

- Mi trng nghip v v mi trng k thut ca h thng cng thay i trong c trnhxy dng.

Cc yu cu lu di l nhng yu cu n nh k tha t nhng hnh ng chnh cakhch hng. V n c th k tha t nhiu m hnh min ng dng khc.

Cc yu cu thay i l nhng yu cu d b thay i trong qu trnh xy dng hoc khih thng c a vo s dng.

Quy trnh lp k hoch qun l yu cu:

- Xc nh yu cu: cch xc nh tng yu cu

- Qun l thay i: xc nh cc hot ng tip theo khi yu cu thay i.

- Cc chnh sch tm vt: lng thng tin v mi quan h gia cc yu cu cn phi clu gi. Thng thng, n cp ti quan h gia ti nguyn v bn thit k h thng.

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* Tm vt ngun: l nhng lin kt t cc yu cu ti stakeholder a ra nhng yu cu.

* Tm vt yu cu: l mi lin h gia cc yu cu c lp nhau.

* Tm vt thit k: l nhng lin kt t yu cu cho ti thit k.

- H tr CASE tool: s dng cc cng c h tr qun l yu cu thay i. CASE toolthng h tr nhng chc nng nh:

* Lu tr yu cu: cc yu cu c qun l mt cch bo mt v c lu trong khod liu.

* Qun l thay i: quy trnh qun l thay i l quy trnh lung cng vic m cc trngthi c th c nh ngha v lung thng tin gia cc trng thi l t ng.

* Qun l vt - t ng tm kim mi lin kt gia cc yu cu.

Chng ta nn p dng tt c cc kh nng thay i c th cho tt c cc yu cu. Ccpha chnh ca hot ng ny bao gm:

- Phn tch vn v c t thay i: tho lun v cc vn yu cu v nhng thay ic th xy ra.

- Phn tch thay i v chi ph: nh gi nh hng ca s thay i trn cc yu cukhc.

- Ci t thay i: iu chnh ti liu ca cc yu cu v nhng ti liu khc phnnh s thay i .

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Cc m hnh Qun lCc m hnh h thng

Gii thiu

Cc yu cu ca ngi s dng thng c vit bng ngn ng t nhin nhngngi khng c kin thc v mt k thut c th hiu c n. Tuy nhin, nhng yucu h thng chi tit phi c m hnh ho. M hnh ho h thng gip cho ngi phntch hiu r cc chc nng ca h thng.

Ta c th s dng cc m hnh khc nhau biu din h thng t nhiu kha cnh khcnhau.

Trong chng ny, chng ta s tm hiu v mt s m hnh ho h thng.

Mc tiu

- Hiu c m hnh ho h thng l g? V ti sao phi m hnh ho h thng.

- Phn bit c cc m hnh h thng.

- C kh nng la chn v ng dng cc m hnh h thng vo tng trng hp c th

M hnh ng cnh

t vn

- Khi xem xt mt vn , bao gi chng ta cng mun c ci nhn tng th v vn .

- M hnh ng cnh cho thy nhng thnh phn ct li ca h thng.

Trong qu trnh pht hin v phn tch yu cu, chng ta nn xc nh phm vi h thng,tc l phn bit ci g l h thng v ci g l mi trng ca h thng. iu ny s gipgim chi ph v thi gian phn tch.

Khi xc nh phm vi ca h thng, hot ng tip theo ca quy trnh phn tch lnh ngha ng cnh ca h thng v s ph thuc gia h thng vi mi trng ca n.

Thng thng, m hnh kin trc n gin ca h thng s c to ra trong bc ny.

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V d: m hnh ng cnh ca h thng ATM

M hnh kin trc m t mi trng ca h thng, nhng khng ch ra quan h gia cch thng khc nhau trong mt mi trng. V vy, ngi ta thng s dng thm mhnh tin trnh hoc m hnh lung d liuh b tr cho n.

M hnh tin trnh biu din tt c cc tin trnh c h thng h tr. M hnh lungd liu c th c s dng biu din cc tin trnh v lung thng tin i t tin trnhny ti tin trnh khc.

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M hnh ng x v my h thngM hnh ng x

Gii thiu

M hnh ng x c s dng m t ton b ng x ca h thng. C hai kiu mhnh ng x l:

- M hnh lung d liu: biu din cch x l d liu trong h thng v

- M hnh my trng thi: biu din cch p ng ca h thng vi cc s kin xy ra.

Hai m hnh ny biu din nhng gc nhn khc nhau, nhng c hai u cn thit mt ng x ca h thng.

M hnh lung d liu

M hnh lung d liu c s dng m hnh ho quy trnh x l d liu ca hthng. M hnh ny s biu din cc bc m lung d liu phi tri qua trong h thngt im u ti im cui.

M hnh lung d liu m hnh ho h thng t gc mt chc nng. Vic tm vt vt liu ho quan h gia d liu vi mt quy trnh rt c ch i vi vic tm hiu tonb h thng.

M hnh lung d liu l phn ct li ca rt nhiu phng php phn tch. N cha cck php rt d hiu i vi khch hng.

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V d: M hnh lung d liu ca chc nng x l n hng

M hnh my trng thi

M hnh my trng thi m t p ng ca h thng vi cc s kin bn trong v bnngoi ca n. M hnh my trng thi biu din cc trng thi ca h thng v cc skin gy ra s dch chuyn trng thi.

M hnh my trng thi biu din cc trng thi ca h thng l cc nt v s kin l cccung ni gia cc nt . Khi c mt s kin xy ra, h thng s dch chuyn t trngthi ny sang trng thi khc.

Biu trng thi l mt biu trong UML v c s dng biu din m hnh mytrng thi. Biu trng thi cho php phn tch mt m hnh thnh nhiu m hnh conv m t ngn gn v cc hnh ng cn thc hin ti mi trng thi. Ta c th v ccbng m t mi quan h gia trng thi v tc nhn kch hot.

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M hnh d liuGii thiu

M hnh d liu c s dng m t cu trc logic ca d liu c x l bi hthng. Thng thng, chng ta hay s dng m hnh thc th - quan h - thuc tnh(ERA) thit lp cc thc th ca h thng, quan h gia cc thc th v thuc tnh cacc thc th. M hnh ny c s dng trong thit k CSDL v thng c ci ttrong cc CSDL quan h.

V d m hnh d liu ca LIBSYS

Tuy nhin, m hnh d liu thng khng chi tit. Cho nn, chng ta c th s dng tin d liu lm cng c b tr. T in d liu l danh sch tt c cc tn gi c sdng trong cc m hnh h thng. c th l cc thc th, quan h v cc thuc tnh

u im ca t in d liu l: h tr qun l tn v trnh trng lp tn, lu tr kinthc mt cch c t chc kt ni pha phn tch, thit k v ci t.

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V d: t in d liu ca LIBSYS

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M hnh i tng,h thng,ng x v thakM hnh i tng

Gii thiu

S dng m hnh ng x hay m hnh d liu thng rt kh m t cc vn c linquan n th gii thc. M hnh i tng gii quyt c vn ny bng cch kthp ng x v d liu thnh i tng.

M hnh i tng c s dng biu din c d liu v quy trnh x l ca h thng.N m t h thng da theo thut ng cc lp i tng v cc quan h ca n. Mt lpi tng l s tru tng ho trn mt tp cc i tng c thuc tnh v phng thcchung.

M hnh i tng phn nh cc thc th trong th gii thc c vn dng trong hthng. Nu ta cng c nhiu thc th tru tng th vic m hnh ho cng kh khn.

Pht hin cc lp i tng l mt quy trnh rt kh khn khi tm hiu su v lnh vcca ng dng. Cc lp i tng thng phn nh cc thc th lin quan ti min ngdng ca h thng.

Cc m hnh i tng bao gm: m hnh tha k, m hnh kt hp v m hnh ng x.Trong phn tip theo, chng ta s tm hiu tng loi m hnh ny.

M hnh tha k

M hnh tha k t chc cc lp i tng theo mt cu trc phn cp. Cc lp nhca cu trc phn cp phn nh nhng c trng chung ca tt c cc lp. Cc lp itng tha k nhng thuc tnh v phng thc ca cc lp cha ca n n c th bsung nhng c im ca ring n.

Thit k lp phn cp l mt quy trnh kh phc tp, ta nn loi b s trng lp gia ccnhnh khc nhau.

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V d: cu trc phn cp ca lp Library trong LIBSYS

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V d: cu trc phn cp ca lp User trong LIBSYS

Cu trc a tha k: lp i tng c th tha k t mt hoc nhiu lp cha. Tuy nhin,iu ny c th dn ti s xung t v ng ngha khi cc thuc tnh/phng thc trngtn cc lp cha khc nhau c ng ngha khc nhau.

V d: lp Talking book tha k t hai lp Book v Voice recording.

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M hnh kt hp

M hnh kt hp biu din cch cu to ca mt lp t cc lp khc. M hnh kt hptng t nh quan h hp thnh (part-of).

V d: M hnh kt hp

i tng t c to thnh t nhiu i tng khc nh: ca, bnh xe ...

M hnh ng x

M hnh ng x m t tng tc gia cc i tng nhm to ra mt s ng x c thca h thng m c xc nh nh l mt ca s dng.

Biu trnh t hoc biu cng tc trong UML c s dng m hnh ho tngtc gia cc i tng.

V d

M t ca s dng Rt tin ca h thng ATM.

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Phng php hng cu trcGii thiu

Ngy nay, phng php hng cu trc rt t khi c s dng do khng cn ph hpvi cc h thng ln. Tuy nhin, trong gio trnh ny, chng ti vn trnh by phn ny hc vin c ci nhn mang tnh tng quan v vn ny.

Cc phng php hng cu trc u cung cp framework m hnh ho h thng mtcch chi tit. Chng thng c mt tp hp cc m hnh c nh ngha trc, quytrnh a ra cc m hnh v cc quy tc, hng dn c th p dng cho cc mhnh.

Tuy nhin, cc phng php hng cu trc thng c mt s nhc im sau:

- Khng m hnh ho c cc yu cu h thng phi chc nng

- Khng cha nhng thng tin xc nh liu mt phng thc c thch hp vi mtvn a ra hay khng.

- To ra qu nhiu ti liu

- M hnh ho h thng qu chi tit v kh hiu i vi ngi s dng.

CASE workbenches l tp hp cc cng c c thit k h tr cc quy trnh xydng h thng phn mm nh phn tch, thit k v kim th.

CASE tools h tr m hnh ho h thng l mt cng c quan trng ca phng phphng cu trc. Sau y l mt s CASE tool thng c s dng:

- Son tho biu

- Cng c phn tch m hnh v kim tra

- Ngn ng truy vn

- T in d liu

- Cng c to v nh ngha bo co

- Cng c nh ngha form

55/105

- B dch

- Cng c to m lnh t ng

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Cc vn v thit k kin trcThit k kin trc

Gii thiu

Sau khi xc nh v phn tch yu cu h thng, chng ta chuyn sang pha thit k v cit h thng. Thit k kin trc h thng l giai on sm nht trong quy trnh thit kh thng. Thit k kin trc cung cp cho chng ta bn c t v kin trc h thng, baogm nhng h thng con no, tng tc vi nhau ra sao, framework h tr iu khintng tc gia cc h thng con nh th no

Mc tiu

- Thit k kin trc l g v c im ca chng. ng thi, xem xt mt s m hnhkin trc h thng thng c s dng.

- Cc phng php t chc h thng

- Cc phng php phn r h thng con thnh cc m-un.

- Thy c mi quan h gia cc phng php t chc h thng v cc phng phpphn r h thng.

- Cc chin lc iu khin h thng

- Gii thiu mt s m hnh kin trc tham chiu

Thit k kin trc l g?

t vn

- Cng vic u tin ca giai on thit k h thng l g? Ti sao?

Quy trnh thit k nhm xc nh cc h thng con cu to ln h thng xut vframework gip iu khin cc h thng con v giao tip gia chng c gi l quytrnh thit k kin trc. Kt qu ca quy trnh thit k ny l bn c t v kin trc phnmm.

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Thit k kin trc l pha sm nht trong quy trnh thit k h thng. Thit k kin trcthng c thc hin song song vi mt s hnh ng c t. N bao gm c vic phthin cc thnh phn chnh ca h thng v giao tip gia chng.

Nu chng ta c c bn thit k kin trc r rng th ta s thy c cc u im can trong nhng hot ng sau:

- Giao tip gia cc stakeholder: kin trc h thng thng c s dng lm tm imca cc bui tho lun gia cc stakeholder.

- Phn tch h thng: tc l phn tch xc nh liu h thng c tho mn cc yu cuphi chc nng ca n hay khng.

- Ti s dng vi quy m ln: kin trc c th c ti s dng trong nhiu h thng.

Cc c im ca kin trc h thng:

- Hiu nng: hn ch cc thao tc phc tp v ti thiu ho giao tip.

- Bo mt: s dng kin trc phn lp vi nhiu kim sot cht ch cc lp su hn.

- An ton.

- Sn dng.

- C kh nng bo tr.

Tuy nhin, trong qu trnh thit k kin trc c th xy ra cc xung t v mt kin trcnh sau:

- S dng nhiu thnh phn ln s tng hiu nng nhng gim kh nng bo tr.

- Nu d liu b d tha th s ci thin tnh sn dng nhng lm cho vic bo mt khkhn hn.

- Hn ch cc thuc tnh c lin quan n tnh an ton c ngha l nu c nhiu giao tipth s lm gim hiu nng.

Thit k kin trc l mt quy trnh sng to cho nn s phc bit ca quy trnh ny phthuc vo tng loi h thng c xy dng. Tuy nhin, cc quy trnh thit k u datrn nhng quyt nh sau:

- Kin trc ng dng chung c c s dng li hay khng?

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- H thng s c phn tn nh th no?

- Nhng phong cch kin trc no l thch hp?

- H thng s c phn r thnh nhng m-un no?

- Chin lc iu khin no s c s dng?

- Cch nh gi thit k kin trc

- Kin trc s c t liu ho nh th no?

Hn na, cng cn phi ch rng cc h thng c cng min ng dng c th c cckin trc chung phn nh nhng khi nim lin quan n min ng dng . ngthi, cc dy chuyn sn xut phn mm c xy dng quanh kin trc nn tng cngvi cc bin i tu thuc vo yu cu ca khch hng. Do , kh nng ti s dng likin trc h thng l rt cao.

Sau y l cc m hnh kin trc c bn:

- M hnh cu trc tnh: m t cc thnh phn h thng chnh.

- M hnh quy trnh ng: biu din quy trnh cu trc ca h thng.

- M hnh giao din: nh ngha tp hp cc giao din ca h thng con

- M hnh quan h: biu din quan h gia cc h thng con.

- M hnh phn tn: biu din cch ci t cc h thng con trn my tnh.

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T chc h thng v cc m hnhT chc h thng

Gii thiu

T chc h thng phn nh chin lc c bn c s dng cu trc h thng. Trongqu trnh thit k kin trc h thng, hot ng u tin phi thc hin l xy dng mhnh t chc h thng. C 3 phng php t chc h thng thng c s dng:

- Kho d liu dng chung

- Server v cc dch v dng chung (client-server)

- Phn lp hoc my tru tng

cc phn tip theo, chng ta s tm hiu chi tit ba phng php t chc h thng ny.

Mc tiu

- Nm c ba phng php xy dng m hnh t chc h thng

- Tm hiu chi tit tng phng php v nh gi u/nhc im ca chng

- C kh nng vn dng trn h thng c th

Kho d liu dng chung

Cc h thng con phi trao i d liu v lm vic vi nhau mt cch hiu qu. Victrao i d liu c thc hin theo hai cch:

- D liu chia s c lu CSDL trung tm hoc kho d liu v c tt c cc hthng con truy nhp.

- Mi h thng con bo tr CSDL ca chnh n v truyn d liu mt cch tng minhcho cc h thng con khc.

Nu s lng d liu dng chung rt ln th m hnh kho d liu dng chung thngc s dng ph bin nht. u im ca m hnh ny l:

- y l phng php hiu qu chia s s lng ln d liu.

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- Cc h thng con khng cn quan tm ti nhng hot ng lin quan n d liu nh:sao lu, bo mt, v c b qun l trung tm thc hin nhim v ny.

Tuy nhin, vic s dng kho d liu dng chung cng c mt s nhc im sau:

- Tt c cc h thng con phi chp nhn m hnh kho d liu.

- Vic ci tin d liu rt phc tp v tn km

- Kh phn tn mt cch hiu qu

- Khng c gii hn cho cc chnh sch qun l c th.

M hnh client server

M hnh kin trc client-server l mt m hnh h thng trong h thng bao gm mttp hp cc server cung cp dch v v cc client truy nhp v s dng cc dch v .Cc thnh phn chnh ca m hnh ny bao gm:

- Tp hp cc server s cung cp nhng dch v c th nh: in n, qun l d liu

- Tp hp cc client truy nhp n server yu cu cung cp dch v.

- H thng mng cho php client truy cp ti dch v m server cung cp.

Client phi bit tn ca server v cc dch v m server cung cp. Nhng server thkhng cn xc nh r client v hin ti c bao nhiu client. Client to ra mt yu cuti server v ch server tr li.

u im ca m hnh client - server l:

- Phn tn d liu r rng

- S dng cc h thng c kt ni mng mt cch hiu qu v chi ph dnh cho phncng c th r hn.

- D dng b sung hoc nng cp server

Nhc im ca m hnh client - server l:

- Khng phi l m hnh d liu dng chung nn cc h thng con c th s dng cc tchc d liu khc nhau. Do , vic trao i d liu c th khng hiu qu.

- Qun l mi server khng thng nht, d tha.

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- Khng ng k tn v dch v tp trung. iu ny lm cho vic tm kim server hoccc dch v rt kh khn.

M hnh phn lp

M hnh phn lp t chc h thng thnh nhiu lp v mi lp cung cp mt tp ccdch v. Mi lp c th c coi nh mt my tru tng (abstract machine) m ngnng ca my c nh ngha bi cc dch v m lp cung cp. Do , m hnh nythng c s dng m hnh ho giao din (interface) ca h thng con.

M hnh phn lp h tr pht trin cc h thng con theo kiu tng vng nhiu lpkhc nhau. Khi giao din ca mt lp thay i th ch nhng lp lin k n mi b nhhng.

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Phn r h thng v phn r i tngPhn r h thng

Gii thiu

Sau khi cu trc h thng c la chn, ta cn phi xc nh phng php phn rcc h thng con thnh cc m-un.

H thng con l mt h thng c th vn hnh mt cch c lp, c th s dng mts dch v c cung cp bi cc h thng con khc hoc cung cp dch v cho cc hthng con khc s dng.

M-un l mt thnh phn h thng cung cp cc dch v cho cc thnh phn khc,nhng n thng khng c coi nh l mt h thng ring r, c lp.

C hai cch phn r cc h thng con thnh cc m-un:

- Phn r hng i tng: h thng c phn r thnh cc i tng tng tc vinhau.

- Pipeline hng chc nng hoc lung d liu: h thng c phn r thnh cc m-un chc nng chu trch nhim chuyn i thng tin u vo thnh kt qu u ra.

Mc tiu

- Phn bit c hai khi nim: h thng con v m-un

- Nm c hai phng php phn r h thng v nh gi u/nhc im ca tngphng php.

Phn r hng i tng

M hnh kin trc hng i tng cu trc h thng thnh mt tp hp cc i tnggn kt lng da trn cc giao din c nh ngha.

Phn r hng i tng lin quan ti vic xc nh lp i tng, cc thuc tnh vphng thc ca n. Khi ci t lp, cc i tng s c to ra t cc lp ny v cmt s m hnh iu khin c s dng kt hp cc phng thc ca i tng.

u im ca m hnh hng i tng:

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- i tng c gn kt lng nn khi thay i cch ci t chng c th khng nhhng ti cc i tng khc.

- i tng phn nh thc th trong th gii thc.

- Cc ngn ng lp trnh hng i tng c s dng rng ri.