TRNG I HC HNG HI VIT NAM KHOA CNG NGH THNG TIN B MN H THNG THNG TIN -----***----- BI GING NHP MN CNG NGH PHN MM TN HC PHN: CNG NGH PHN MM M HC PHN: 17404 TRNH O TO: I HC CHNH QUY DNG CHO SV NGNH: CNG NGH THNG TIN HI PHNG - 2011 2 MC LC Ni dung Trang Chng 1: Gii thiu 5 1.1. Khi nim phn mm 5 1.2. Cc c im ca phn mm 5 1.3. Cc ng dng ca phn mm 6 1.4. Gii thiu v Cng ngh phn mm (Software engineering) 8 Chng 2: Cc m hnh pht trin phn mm9 2.1. M hnh thc nc (Waterfall model) 9 2.2. M hnh nguyn mu (Prototyping model) 11 2.3. M hnh pht trin nhanh (RAD model) 13 2.4. M hnh tng trng (Incremental model) 13 2.5. M hnh xon c (Spiral model) 13 2.6. Cc m hnh hin i (Fourth generation techniques) 15 Chng 3: Kho st v phn tch yu cu 18 3.1. Thu thp yu cu (Requirements elicitation) 18 3.2. Phn tch yu cu (Requirements analysis) 28 3.3. c t yu cu (Requirements specification) 28 3.4. Xt duyt yu cu (Requirements validation) 35 Chng 4: M hnh ha h thng 37 4.1. M hnh ha d liu (Data modeling) 37 4.2. M hnh ha chc nng (Functional modeling) 37 4.3. M hnh ha lung thng tin (Information flow modeling) 38 Chng 5: Thit k h thng 40 5.1. Qu trnh thit k (Design process) 43 5.2. Cc nguyn tc thit k (Design principles) 46 Chng 6: Kim th phn mm 50 6.1. Mc ch (Testing objectives) 50 6.2. Nguyn tc kim th (Testing principles) 50 6.3. Kim th theo ng c bn (Basic path) 50 6.4. Kim th theo phn vng tng ng (Equivalence partitioning) 54 6.5. Kim th theo gi tr bin (Boundary value analysis) 56 6.6. Cc mc kim th (Testing strategy) 58 3 Tn hc phn: Nhp mn Cng ngh phn mmLoi hc phn: 1 B mn ph trch ging dy: H thng Thng tin Khoa ph trch: CNTT. M hc phn: 17404 Tng s TC: 2 Tng s titL thuytThc hnh/XeminaT hcBi tp ln n mn hc 303000khngkhng Hc phn hc trc: Khng yu cu. Hc phn tin quyt: Khng yu cu. Hc phn song song: Khng yu cu. Mc tiu ca hc phn: Cung cp cho sinh vin nhng kin thc c bn v cng ngh phn mm. Ni dung ch yu: Gii thiu v cng ngh phn mm; Cc m hnh pht trin phn mm; Lng gi d n phn mm; Kho st v phn tch yu cu; M hnh ha h thng; Thit k h thng; Kim th phn mm. Ni dung chi tit: TN CHNG MCPHN PHI S TIT TSLTTHBTKT Chng 1: Gii thiu22 1.1. Khi nim phn mm 1.2. Cc c im ca phn mm 1.3. Cc ng dng ca phn mm 1.4. Gii thiu v Cng ngh phn mm (Software engineering) Chng 2: Cc m hnh pht trin phn mm 66 2.1. M hnh thc nc (Waterfall model) 2.2. M hnh nguyn mu (Prototyping model) 2.3. M hnh pht trin nhanh (RAD model) 2.4. M hnh tng trng (Incremental model) 2.5. M hnh xon c (Spiral model) 2.6. Cc m hnh hin i (Fourth generation techniques) Chng 3: Kho st v phn tch yu cu44 3.1. Thu thp yu cu (Requirements elicitation) 3.2. Phn tch yu cu (Requirements analysis) 3.3. c t yu cu (Requirements specification) 3.4. Xt duyt yu cu (Requirements validation) Chng 4: M hnh ha h thng44 4.1. M hnh ha d liu (Data modeling) 4.2. M hnh ha chc nng (Functional modeling) 4.3. M hnh ha lung thng tin (Information flow modeling) Chng 5: Thit k h thng44 5.1. Qu trnh thit k (Design process) 5.2. Cc nguyn tc thit k (Design principles) 5.3. Cc khi nim trong thit k phn mm (Design concepts) Chng 6: Kim th phn mm66 6.1. Mc ch (Testing objectives) 6.2. Nguyn tc kim th (Testing principles) 6.3. Kim th theo ng c bn (Basic path) 6.4. Kim th theo phn vng tng ng (Equivalence partitioning) 4 TN CHNG MCPHN PHI S TIT TSLTTHBTKT 6.5. Kim th theo gi tr bin (Boundary value analysis) 6.6. Cc mc kim th (Testing strategy) Nhim v ca sinh vin: Tham d cc bui hc l thuyt v thc hnh, lm cc bi tp c giao, lm cc bi thi gia k v bi thi kt thc hc phn theo ng quy nh. Ti liu hc tp: 1.RogerS.Pressman,SoftwareEngineering-Apractitioner'sApproach,6thedition,McGraw-Hill. 2.Sommerville, Software Engineering, 7th edition, Pearson education. 3.Nguyn Xun Huy, Gio trnh cng ngh phn mm, NXB Trng HBK H Ni, 1996. Hnh thc v tiu chun nh gi sinh vin: - Hnh thc thi: t lun hoc trc nghim. - Tiu chun nh gi sinh vin: cn c vo s tham gia hc tp ca sinh vin trong cc bui hc l thuyt v thc hnh, kt qu lm cc bi tp c giao, kt qu ca cc bi thi gia hc phn v bi thi kt thc hc phn. Thang im: Thang im ch A, B, C, D, F. im nh gi hc phn:Z = 0,2X + 0,8Y. Bi ging ny l ti liu chnh thc v thng nht ca B mn H thng Thng tin, Khoa Cng ngh Thng tin v c dng ging dy cho sinh vin. Ngy ph duyt:// Trng B mn 5 Chng 1: Gii thiu 1.1. Khi nim phn mm Phn mm l mt tp hp bao gm: Cclnh(chngtrnhmytnh)khithchntharahotngvktqu mong mun. Cc cu trc d liu lm cho chng trnh thao tc thng tin thch hp. Cc ti liu m t thao tc v cch dng chng trnh. 1.2. Cc c im ca phn mm Phn mm l phn t ca h thng logic cha khng phi h thng vt l. Do vy, phn mm c mt s c trng khc bit ng k i vi c trng ca phn cng. c trng 1: Phn mm c pht trin hay c k ngh ho, n khng c ch to theo ngha c in. Mc du c mt s im tng ng gia pht trin phn mm v ch to phn cng, hai hot ngnyvcbnlkhcnhau.Trongchaihotngny,chtlngcaocttithng qua thit k tt, nhng giai on ch to phn cng c th a vo vn m cht lng khng tn ti (hay d c sa i) cho phn mm. C hai hot ng ny u ph thuc vo con ngi, nhng miquanhgiangicpdngvcngviccthchinhontonkhc.Chaihot ngnyihivicxydng"snphm",nhngcchtipcnlhontonkhc.Phnmm c ch to ra l hon ton mi, khng c tin l trc v n cng ch c to ra 1 ln duy nht. c trng 2: Phn mm khng hng i. Phn mm khngcm ng vi khim khuyt mi trng vngy cho phn cng mn c i. Phn mm nu c vi cc b d liu u vo hp l th n lun cho kt qu c ngha ging nhau, khng thay i theo thi gian, iu kin kh hu, Cht yu Mn c T l hng Thi gian ng cong hng hc ca phn cng Thi gian ng cong hng hc ca phn mm (l tng) Gi t l cho n khi lc hu T l hng 6 Thc t, phn mm s tri qua s thay i (bo tr). Khi thay i c thc hin, c th mt s khim khuyt s c thm vo, gy ra trong ng cong t l hng c du hiu nh hnh v di y. Trc khi ng cong c th tr v t l hng hc n nh ban u, th mt yu cu khc li c a vo, li gy ra ng cong pht sinh nh nhn mt ln na. Dn dn, mc t l hng ti thiu tng ln - phn mm b thoi ho do s thay i.Nhn xt: Phn cng hng c vt t thay th, nhng khng c phn mm thay th cho phn mm. Mi hng hc ca phn mm u ch ra li trong thit k hay trong tin trnh chuyn thit k thnh m ho lnh my thc hin c. Do , vic bo tr phn mm bao gm vic ph thm ng k so vi bo tr phn cng. c trng 3: Phn ln phn mm c xy dng theo n t hng, ch t khi c lp rp t cc thnh phn c sn. Cch thit k v xy dng phn cng iu khin cho mt sn phm da trn b vi x l: v s mch s => thc hin phn tch m bo chc nng ng => phn loi cc danh mc thnh phn => gn cho mi mch tch hp (thng gi l IC hay chip) mt s hiu mt chc nng nh trc v hp l; mt giao din xc nh r; mt tp cc hng dn tch hp chun ho. i vi phn mm: Khi xy dng ta khng c danh mc cc thnh phn. Phn mm c t hng vi n v hon chnh, khng phi l nhng thnh phn c th lp rp li thnh chng trnh mi. 1.3. Cc ng dng ca phn mm Sn phm phn mm l g? Snphmphnmmlmthocmtnhmccchngtrnhcxydnggiiquyt mt vn no . V d: chng trnh qun lhot ng ca my mcv cc chng trnh ng dng. Nhm cc sn phm hin c. Hin nay ngi ta phn chia thnh 7 nhm phn mm chnh. Nhm 1: Phn mm h thng. Thi gian Hnh 1: ng cong hng hc thc t ca phn mm T l hng Thay i ng cong l tng ng cong thc t 7 Lmttphpccchngtrnhcvitphcvchoccchngtrnhkhc.Chng trnhnyxlccthngtinphctpnhngxcnhcpthp,tomitrnghotng(trnh bin dch, trnh son tho, qun l tp tin, ). Cc chng trnh ny c trng bi tng tc ch yu vi phn cng my tnh, phc v nhiu ngi dng, c cu trc d liu phc tp v nhiu giao din ngoi. Nhm 2: Phn mm thi gian thc. Lphnmmiuphihocphntchhaykimsotccskinthgiithcngaykhi chng xut hin. Phn mm thi gian thc bao gm cc yu t: Mt thnh phn thu thp d liu thu v nh dng thng tin t bn ngoi. Mt thnh phn phn tch bin i thng tin theo yu cu ca ng dng. Mt thnh phn kim sot hoc a ra cc p ng cho mi trng ngoi. Mt thnh phn iu phi iu ho cc thnh phn khc sao cho c th duy tr vic p ng thi gian thc. H thng thi gian thc phi p ng c nhng rng buc thi gian cht ch. Nhm 3: Phn mm nghip v. Ngy nay, x l thng tin nghip v l lnh v ng dng phn mm ln nht. Phn mm loi ny phc v cho cc h thng ri rc: h thng tin qun l. Cc ng dng phn mm nghip v cn bao gm c tnh ton tng tc (nh x l cc giao tc cho cc im bn hng) ngoi ng dng x l d liu. Nhm 4: Phn mm khoa hc cng ngh. Phn mm ny c c trng bi cc thut ton. Phn mm to ra mt ng dng mi, thit kcmytnhtrgip(computeraidedofdesign-CAD),cchnccctrngthigian thc v phn mm h thng. Nhm 5: Phn mm nhng. Nm trong b nh ch c v c dng iu khin cc sn phm v h thng cho ngi dng v th trng cng nghip. C th thc hin cc chc nng n gin nhng mang tnh chuyn bit(huynb),vd:iukhinchcnngcholvisng;hayctharacckhnngiu khin v vn hnh (chc nng s ho -t, kim sot xng, biu th bng ng h, cc h thng phanh). Nhm 6: Phn mm my tnh c nhn. Loiphnmmnybngntronghnthpkvaqua(nhxlvnbn,trangtnh, ho, qun tr c s d liu). Hin nay c tip tc pht trin biu th giao din ngi my, to ra s thn thin, d s dng cho ngi dng. Nhm 7: Phn mm tr tu nhn to. 8 Dng cc thut ton phi s gii quyt cc vn phc tp m tnh ton hay phn tch trc tip u khng th qun l ni. Phn mm ny hot ng mnh h chuyn gia (h c s tri thc); trong lnh vc nhn dng v x l hnh nh v m thanh; chng minh cc nh l v chi tr chi. Hin nay pht trin mnh mng n-ron nhn to: m phng cu trc vic x l trong b no ca con ngi. 1.4. Gii thiu v Cng ngh phn mm (Software engineering) Cng ngh phn mm l mt lnh vc nghin cu ca tin hc nhm a ra cc nguyn l, phng php, cng c, phng tin gip cho vic thit k v ci t mt sn phm phn mm t c cc yu cu sau mt cch tt nht: Phi c tnh ng n v khoa hc. D tip cn v ci tin. Ph dng. c lp vi cc thit b. Bi tp: 1.Trnh by vai tr ca phn mm 2.Trnh by cc c im ca phn mm 3.Cc ng dng ca phn mm 9 Chng 2: Cc m hnh pht trin phn mm 2.1. M hnh thc nc (Waterfall model) i khi cn c gi l m hnh tun t tuyn tnh hay m hnh thc nc, m hnh ny gi mt cch tip cn tun t, c h thng ti vic pht trin phn mm vn bt u t mc h thng v tin dn qua phn tch, thit k, m ho, kim th v h tr. Di y minh ho m hnh thc nc cho k ngh phn mm. c m hnh ho theo chu k k ngh qui c, m hnh thc nc bao gm cc hot ng sau: Knghv mhnhhohthng/ thngtin. Bivphnmmbaogicnglmtphn ca mt h thng (hay nghip v) ln hn nn cng vic bt u t vic thit lp yu cu cho mi phn t h thng v ri cp pht mt tp con cc yu cu cho phn mm. Quan im h thng nyliubnchtkhiphnmmphitngtcviccthnhphnkhcnhphncng,con ngi v CSDL. K ngh v phn tch h thng bao gm vic thu thp yu cu mc h thng vi mt lng nh thit k v phn tch mc nh. K ngh thng tin bao gm vic thu thp yu cu ti mc nghip v chin lc v ti mc lnh vc nghip v. Phn tch yu cu phn mm. Tin trnh thu thp yu cu c tng cng v hi t c bit vo phn mm. hiu c bn cht ca cc chng trnh phi xy dng, k s phn mm ("nh phn tch") phi hiu v lnh vc thng tin (c m t trong phn sau) i vi phn mm cng nh chc nng cn c, hnh vi, hiu nng v giao din. Cc yu cu cho c h thng v phn mm cn phi c lp t liu v xt duyt cng vi khch hng. K ngh h thng Phn tch v nh r yu cu Thit k h thng v phn mm M ho Kim th n v v tch hp h thng Hnh 2: M hnh thc nc Vn hnh v bo tr 10 Thit k. Thit k phn mm thc t l mt tin trnh nhiu bc tp trung vo bn thuc tnh phn bit ca chng trnh: cu trc d liu, kin trc phn mm, biu din giao din v chi tit th tc (thut ton). Tin trnh thit k dch cc yu cu thnh mt biu din ca phn mm c th c nhgivchtlngtrckhigiaionmhobtu.Gingnhccyucu,victhitk phi c lp t liu v tr thnh mt phn ca cu hnh phn mm. Sinh m. Thit k phi c dch thnh dng my c c. Bc m ho thc hin nhim v ny. Nu thit k c thc hin theo mt cch chi tit th vic sinh m c th c thc hin mt cch my mc. Kim th. Mt khi m c sinh ra th vic kim th chng trnh bt u. Tin trnh kim th hi t vo ni b logic ca phn mm, m bo rng tt c cc cu lnh u c kim th, v vo bn ngoi chc nng; tc l tin hnh cc kim th lm l ra cc li v m bo nhng ci vo nh s to ra kt qu thng nht vi kt qu mun c. Vn hnh v bo tr. Phn mm chc chn s phi tri qua nhng thay i sau khi n c bn giao cho khch hng (mt ngoi l c th l nhng phn mm nhng). Thay i s xut hin bi v gp phi li, bi v phn mm phi thch ng vi nhng thay i trong mi trng bn ngoi (chng hn nh s thay i do h iu hnh mi hay thit b ngoi vi mi), hay bi v khch hng yu cu nng cao chc nng hay hiu nng. Vic bo tr phn mm phi p dng li cc bc vng i ni trn cho chng trnh hin ti ch khng phi chng trnh mi. M hnh tun t tuyn tnh l m hnh c nht v c s dng rng ri nht cho k ngh phn mm. Tuy nhin, nhng ch trch v m hnh ny lm cho nhng ngi ng h n tch cc phi t vn v tnh hiu qu ca n. Mt s cc vn thnh thong gp phi khi dng m hnh tun t tuyn tnh ny l: Ccdnthchimkhituntheodngchytuntmmhnhngh.Mcdum hnh tuyn tnh c th cho php lp, nhng iu ch lm gin tip. Kt qu l nhng thay i c th gy ra ln ln khi t d n tin hnh. Khchhngthngkhphtbiumiyucumtcchtngminh.Mhnhtunt tuyn tnh i hi iu ny v thng kh thch hp vi s bt trc t nhin tn ti vo lc u ca nhiu d n. Khch hng phi kin nhn. Bn lm vic c ca chng trnh ch c c vo lc cui ca thi gian d n. Mt sai lm ng ngn, nu n khi c chng trnh lm vic mi pht hin ra, c th s l mt thm ho. Trong mt phn tch th v v cc d n hin ti, Brada thy rng bn cht tuyn tnh ca vng i c in dn ti "cc trng thi nghn" m trong mt s thnh vin t d n phi i cho cc thnh vin khcca t hon thnh cc nhim vph thuc. Trong thc t, thi gian mt cho vic ch i c th vt qu thi gian dnh cho cng vic sn xut. Trng thi nghn c khuynh hng ph bin vo lc u v cui ca tin trnh tun t tuyn tnh. 11 Tng vn trn u l thc. Tuy nhin, m hnh vng i c in c mt v tr quan trng v xc nh trong cng vic v k ngh phn mm. N a ra mt tiu bn trong c th b tr cc phngphpchophntch,thitk,mho,kimthvbotr.Bncnh,vngicin vn cn l mt m hnh th tc c dng rng ri cho k ngh phn mm. Trong khi n qu thc cn im yu, n vn tt hn ng k nu so vi cch tip cn ngu nhin ti vic pht trin phn mm. 2.2. M hnh nguyn mu (Prototyping model) Thng thng khch hng xc nh mt tp cc mc tiu tng qut cho phn mm, nhng cn cha nh danh cc yu cu ci vo chi tit, hay x l ci ra. Trong cc trng hp khc, ngi pht trin c th khng chc v tnh hiu qu ca thut ton, vic thch nghi h iu hnh hay dng giao din ngi my cn c. Trong nhng trng hp ny v nhiu trng hp khcm hnh lm bn mu c th a ra cch tip cn tt nht. Mhnhlmbnmu(hnhdi)btuvivicthuthpyucu.Ngiphttrinv khch hng gp nhau v xc nh cc mc tiu tng th cho phn mm, xc nh cc yu cu no bit,vminnobtbucphixcnhthm. Rinvic"thitknhanh".Thitknhanhtp trung vo vic biu din cc kha cnh ca phn mm thy c i vi ngi dng (nh cch a vo v nh dng a ra). Thit k nhanh dn ti vic xy dng mt bn mu. Bn mu c khch hng / ngi dng nh gi v c dng lm mn cc yu cu i vi phn mm cn pht trin. Tin trnh lp i lp li xy ra cho bn mu c "vi chnh" tho mn nhu cu ca khch hng trong khi ng thi li lm cho ngi pht trin hiu c k hn cn phi thc hin nhu cu no. Mt cch l tng, bn mu phc v nh mt c ch xc nh cc yu cu phn mm. Nu mt bn mu lm vic c xy dng th ngi pht trin c th dng c cc on chng trnh BT U Tp hp yu cu v lm mn => xc nh mc tiu tng th, kho st thm nh r yu cu Thit k nhanh Xy dng bn mu nh gi ca khch hng v bn mu Sn phm Lm mn bn mu KT THC 12 c hay p dng cc cng c (nh b sinh bo co, b qun l ca s, v.v..) nhanh chng sinh ra chng trnh lm vic. Nhng chng ta ngh v bn mu th no khi n c dng cho mc ch c nu trn? Brook nu ra cu tr li: Trong hu ht cc d n, h thng u tin him khi s dng c. N c th l qu chm, qu ln, cng knh trong s dng hay tt c nhng nhc im ny. Khng c cch no khc l bt u li, au n nhng tinh khn hn, v xy dng mt phin bn c thit k li trong nhng vn nycgiiquyt...Khimtkhinimhthngmihaymtknghmicdng, ngi ta phi xy dng mt h thng ri vt i, cho d vic lp k hoch c thc hin chu o nhtthncngkhngthbaoquthtchyngcngaylnu.Docuhiqunl khng phi l liu chng ta c nn xy dng mt h thng th nghim v ri vt n i hay khng. Bn s lm nh vy. Cu hi duy nht l liu nn lp k hoch trc xy dng mt ci vt i hay ha hn bn giao ci vt i cho khch hng... Bnmucthphcvnh"hutin"-cimBrookluchngtannvti.Nhng iu ny c th l mt cch nhn l tng ho. Ging nh m hnh tuyntnh tun t (thc nc), vic lm bn mu ta nh mt m hnh cho k ngh phn mm c th tr thnh c vn bi nhng l do sau: 1.Khch hng thy c ci dng nh l phin bn lm vic ca phn mm m khng bit rng bn mu c gn li "bng ko cao su v dy gi hng", khng bit rng trong khi x y cho n lm vic th chng ai xem xt ti cht lng phn mm tng th hay tnh bo tr thi gian di.Khicthngborngsnphmphicxydnglichocthttimc cht lng cao, th khch hng ku tri v i hi rng "phi t sa cha" lm bn mu thnh sn phm lm vic. Rt thng l vic qun l pht trin phn mm b bung lng. 2.Ngiphttrinthnghaythohipcitccbnmulmvicnhanhchng.H iu hnh hay ngn ng lp trnh khng thch hp c th c dng n gin bi v n c sn v bit; mt thut ton khng hiu qu c th c ci t ngin chng t kh nng. Saumtthigian,ngiphttrinmic thtrnnquenthucvinhngchnlanyv qun mt mi l do ti sao chng li khng thch hp. Vic chn la khng c theo l tng by gi li tr thnh mt phn tch hp ca h thng. Mcduvncthxuthin,viclmbnmucthlmtmhnhhiuquchokngh phnmm.Chakholnhngharaccquitccatrchitngaylcbtu;tclkhch hng v ngi pht trin phi cng ng rng bn mu c xy dng phc v lm c ch xc nh yu cu. Th ri n phi b b i (t nht cng mt phn) v phn mm thc ti c a vo k ngh vi con mt hng v cht lng v tnh bo tr c. 13 2.3. M hnh pht trin nhanh (RAD model) M hnh pht trin nhanh (RAD Rapid Application Development) chnh l m hnh tng dnvichukphttrinccngn.tcmctiuny,RADdatrnphngphppht trin trn c s thnh phn ho h thng cng vi vic ti s dng cc thnh phn thch hp. RAD thch hp cho nhng h thng qun l thng tin. RAD - da vo phng php lun,iu chnh cc giai on SDLC to ra mt sphn ca hthng pht trin nhanh v vo cc thao tc th cng ca ngi s dng. PhnlnRAD-davophngphplunmngiphntchsdngcckthutcbitv cngcmytnhtngtcccgiaionphntch,thitk,vthchin,nhcngcCASE (computer-aided software engineering).2.4. M hnh tng trng (Incremental model) Thayvchuyngiaomtln,qutrnhphttrinvchuyngiaocchialmnhiuln,mi chuyn giao p ng mt phn chc nng. Yu cu ngi dng c phn loi u tin, mc cao s thuc phn chuyn giao sm Khi pht trin mt bn tng, yu cu tng ng l c nh, tuy nhin, yu cu cho bn tng sau vn pht trin. 2.5. M hnh xon c (Spiral model) M hnh xon c, ban u do Boehm xut, l m hnh tin trnh phn mm tin ho vn cp i bn cht lp ca lm bn mu vi cc kha cnh h thng v c kim sot ca m hnh trnh ttuyntnh.Ncungcptimnngchovicphttrinnhanhccphinbntngdncaphn mm. Dng m hnh xon c ny, phn mm c pht trin thnh tng chui cc ln a ra tng dn. Trong nhng ln lp u, vic a ra tng dn c th l m hnh trn giy hay bn mu. Trong cc ln lp sau, cc phin bn y tng dn ca h thng c k ngh ho s c to ra. Mhnhxonccchiathnhmtskhunkhhotng,cngcncgilvng nhim v. V c bn, c t ba ti su vng. Hnh sau m t cho m hnh xon c c cha su vng: 1.Trao i vi khch hng - nhim v i hi thit lp vic trao i c hiu qu gia ngi pht trin v khch hng. 2.Lp k hoch - nhim v i hi nh ngha cc ti nguyn, hn thi gian v cc thng tin lin quan ti d n. 3.Phn tch ri ro - nhim v i hi nh gi c nhng ri ro k thut v qun l 4.K ngh - nhim v i hi xy dng mt hay nhiu biu din cho ng dng 5.Xy dng v a ra - nhim v i hi xy dng, kim th, thit t v cung cp s h tr cho ngi dng (nh ti liu v hun luyn) 14 6.nh gi ca khnh hng - nhim v i hi thu c phn hi ca khch hng da trn nh gi v biu din phn mm c to ra trong giai on k ngh v c ci t trong giai on ci t. Mi mt trong cc vng u c t vo mt tp cc nhim v, c gi l tp nhim v, vn cthchngviccctrngcadnctinhnh.Viccsnnh,sccnhimv cngvicvtnhhnhthccachnglthp.Viccdnln,nhiucngthnghn,thmi vng nhim v li cha nhiu nhim v cng vic vn c xc nh t ti mc hnh thc cao hn. Trong mi trng hp, hot ng h tr (nh qun l cu hnh phn mm v m bo cht lng phn mm) - c nu trong phn sau - s c p dng. Khi tin trnh tin ho ny bt u, t k ngh phn mm i vng xon c theo chiu ngc kim ng h, bt u t trung tm. Mch u tin quanh xon c c th lm pht sinh vic pht trin c t sn phm; cc bc tip theo quanh xon c c th c dng pht trin bn mu v th ri cc phin bn phc tp dn thm. Mi bc qua vng lp k hoch li lm ny sinh vic iu chnh k hoch dn. Chi ph v lch biu c iu chnh da trn phn hi c suy t nhgi ca khch hng. Bn cnh , ngi qun l d n iu chnh s vic lp lp k hoch cn hon chnh phn mm. Khng ging nh m hnh tin trnh c in vn kt thc khi phn mm c chuyn giao, m hnh xon c c th c thch ng p dng trong ton b cuc i ca phn mm my tnh. Mt ci nhn khc c th c xem xt bng vic kim tra trc im vo d n, nh c v trong hnh trn. Mi hnh hp c t theo trc c th c dng biu din cho im bt u cho cc kiudnkhcnhau."Dnphttrinkhinim"btutictlicaxoncvstiptc (nhiu ln lp xut hin theo con ng xon c m vn gn vi vng t m trung tm) cho ti khi vic pht trin khi nim l y . Nu khi nim ny c pht trin thnh mt sn phm thc ti, D n bo tr sn phm D n nng cao sn phm D n pht trin sn phm miD n pht trin khi nim Xy dng v a ra K ngh Phn tch ri ro Lp k hoch Trao i vi khch hng Trc im vo d n nh gi ca khch hng 15 th tin trnh tin qua hnh hp tip (im vo d n pht trin sn phm mi) v mt "d n pht trin mi" c khi u. Sn phm mi s tin ho qua mt s ln lp quanh xon c, i theo con ng vn gn vng ct mu sng hn vng li. V bn cht, xon c, khi c c trng theo cchny,vncnlmvicchotikhiphnmmcchongh.Cnhnglctintrnhny ng, nhng bt k khi no mt thay i c khi u, th tin trnh ny li bt u ti im vo thch hp (tc l nng cao sn phm). M hnh xon c l cch tip cn thc t cho vic pht trin cho cc h thng v phn mm qui m ln. Bi v phn mm tin ho khi tin trnh tin ho, nn ngi pht trin v khch hng hiu r hn v phn ng vi ri ro ti tng mc tin ho. M hnh xon c dng cch lm bn mu nh mt c ch lm gim bt ri ro, nhng iu quantrng hn, lm cho ngi pht trin c kh nngp dng ccch tip cn lm bn mu ti mi giai on trong tin ho ca sn phm. N duytrcchtipcntngbcmtcchchthngdocchtipcnvngicingi, nhng t hp cch tip cn ny vo mt khun kh lp li, vn phn nh c st thc hn th gii thc. M hnh xon c i hi vic xem xt trc tip cc ri ro k thut ti mi giai on ca d n, v nu c p dng ng th n c th lm gim ri ro trc khi chng tr thnh vn thc s. Nhnggingnhccmhnhkhc,mhnhxonckhngphilmtliuthucbch bnh. C th kh thuyt phc nhng khch hng (c bit trong tnh hung c hp ng) rng cch tip cn tin ho l kim sot c. N i hi tri thc chuyn gia nh gi ri ro chnh xc v da trn tri thc chuyn gia ny m t c thnh cng. Nu mt ri ro chnh khng c pht hin v qun l th khng nghi ng g na vn s xut hin. Cui cng, chnh bn thn m hnh ny cng cnchacsdngrngrinhmhnhtrnhttuyntnhhoclmbnmu.Cnphic thm mt s nm na trc khi tnh hiu qu ca m hnh quan trng ny c th c xc nh vi s chc chn hon ton. 2.6. Cc m hnh hin i (Fourth generation techniques) Thut ng k thut th h th t (4GT) bao gm mt phm vi rng cc cng c phn mm c mt im chung: mi cng c u cho php ngi k s phn mm xc nh c trng no ca phnmmmccao.Ricngctngsinhramchngtrnhgcdatrnctca ngi pht trin. Ngi ta gn nh khng cn bn ci v vic phn mm c th c xc nh i vi mt my cng mc cao th chng trnh c th c xy dng cng nhanh hn. M hnh 4GT cho k ngh phn mm tp trung vo kh nng xc nh phn mm bng vic dng cc khun mu ngn ng c bit hay k php ho vn m t cho vn cn c gii quyt di dng khch hng c th hiu c. 16 Hin ti, mt mi trng pht trin phn mm h tr cho m hnh 4GT bao gm mt s hay tt c cc cng c sau: -Ngn ng phi th tc hi p c s d liu. -B sinh bo co. -B thao tc d liu. -B tng tc v xc nh mn hnh. -B sinh chng trnh. -Kh nng ho mc cao. -Kh nng lm trang tnh v vic sinh t ng HTML. -CcngnngtngtcdngchovictoratrangWebthngquavicdngcc cng c phn mm tin tin. Ban u nhiu trong nhng cng c c nhc ti c sn ch cho nhng lnh vc ng dng rt c th, nhng ngy nay mi trng 4GT c m rng cp ti hy ht cc loi ng dng phn mm. Ging nh cc m hnh khc, 4GT bt u t bc thu thp yu cu. Mt cch l tng, khch hng s m t ccyucu vccyu cu sc dch trc tip thnh mt bn mu vn hnh c. Nhng iu ny khng thc hin c. Khch hng c th khng chc chn mnh cn g, c th c s m h trong vic xc nh cc s kin bit, c th khng c kh nng hay khng sn lng xc nh thng tin theo cch thc m cng c 4GT c th gii quyt c. Bi l do ny, i thoi khch hng/ ngi pht trin c m t cho cc m hnh tin trnh khc vn cn l phn bn cht ca cch tip cn 4GT. Vi nhng ng dng nh, c th chuyn trc tip t bc thu thpyu cu sang ci t bng cch dng ngn ng sinh th h th t phi th tc (4GL) hay mt m hnh bao gm mt mng cc biu tng ho. Tuy nhin vi n lc ln hn, cn phi pht trin mt chin lc thit k cho h Tm hiu yu cu Phn tch Thit k Ci t Kim th Sn phm Cng c t ng hoc h tr Hnh 3: M hnh k ngh th 4 - 4GT 17 thng, ngay c nu c dng 4GL. Vic dng 4GT thiu thit k (vi cc d n ln) s gy ra cng nhng kh khn (cht lng km, kh bo tr, ngi dng kh chp nhn) m chng ta gp phi khi pht trin phn mm bng cch dng cc cch tip cn qui c. Vic ci t dng 4GL lm cho ngi pht trinphn mm biu din c cc kt qu mong mun theo cch l phtsinh t ng chng trnh tnh ra chng. Hin nhin, mt cu trc d liu vi nhng thng tin c lin quan cn phi c sn v sn sng cho 4GL truy nhp vo. bin i mt ci t 4GT thnh mt sn phm, ngi pht trin phi tin hnh vic kim th ton din, xy dng cc ti liu c ngha v thc hin mi hot ng tch hp gii php khc vn cntitrongccmhnhknghphnmmkhc.Bncnh,phnmmcphttrintheo 4GTphicxydngtheocchlmchovicbotrcthctinhnhmtcchchng vnh. Ging nh mi m hnh k ngh phn mm, m hnh 4GT c u im v nhc im. Nhng nginghchollmgimngkthigianphttrinphnmmvlmtngrtnhiuhiu sut ca ngi xy dng phn mm. Nhng ngi phn i cho l cc cng c 4GT hin ti khng phi tt c u d dng hn cc ngn ng lp trnh, rng chng trnh gc do cc cng c ny to ra l "khng hiu qu," v rng tnh bo tr cho cc h thng phn mm ln c pht trin bng cch dng 4GT vn cn l vn m. C i iu li ch trong cc lun im ca c hai pha v c th tm tt trng thi hin ti ca cch tip cn 4GT nh sau: 1.Vic dng 4GT l cch tip cn c th tn ti c cho nhiu lnh vc ng dng khc nhau. Gn vi cc cngc kngh phn mmc mytnh h tr v b sinh m, 4GT cungcp mt gii php tin cy c cho nhiu vn phn mm. 2.D liu c thu thp t cc cng ty c dng 4GT ch ra rng thi gian cn cho vic to ra phn mm c gim ng k i vi cc ng dng va v nh v rng khi lng thit k v phn tch cho cc ng dng nh cng c rt bt. 3.Tuy nhin, vic dng 4GT cho cc n lc pht trin phn mm ln i hi nhiu phn tch, thit k v kim th (cc hot ng k ngh phn mm) t ti vic tit kim thi gian vn ny sinh t vic xo b m ho. Tm li, cc k thut th h th t tr thnh mt phn quan trng ca k ngh phn mm. Khi i i vi cch tip cn da trn cu phn (s c trnh by mc tip theo), m hnh 4GT c th tr thnh cch tip cn thng tr cho vic pht trin phn mm\ Bi tp: 1.Trnh by m hnh thc nc 2.Phn bit m hnh bn mu vi m hnh thc nc 3.Phn bit m hnh tng trng vi m hnh thc nc 18 Chng 3: Kho st v phn tch yu cu 3.1. Thu thp yu cu (Requirements elicitation) Migiaionphttrinhthngihistraoigianhphttrinvngidng nhn c thng tin c ch. Mi giai on cn tm kim mt di rng cc cu hi v ng dng. V d: Khi phn tch tnh kh thi, cc cu hi tng i rng v tng qut: -u l phm vi ca vn ? -Cch tt nht t ng ho l g? -Cng ty c c gng pht trin ng dng ny hay khng? -Cng ty c th h tr vic pht trin ng dng khng? Khi phn tch yu cu chng ta tm hiu cc thng tin c lin quan n ng dng l g. V d: -Cc d liu cn thit l g? -Cc x l no c tin hnh v cc thng tin chi tit lin quan? Khi thit k chng ta pht trin thm: Lm th no thng tin c lin quan ti ng dng: -Lm th no chuyn ng dng vo mi trng chn? -Lm th no thit k d liu logic c chuyn vo thit k d liu vt l? -Cc module chng trnh c phi hp vi nhau nh th no? Cc thng tin khng xut pht t u khc ngoi chnh t yu cu ca ngi dng. Nhim vcanhphttrinlphinmbtcccthngtintrn.Cnhiucchthuthpdliu: Phng vn - hp nhm - quan st - gii thiu trc chng trnh sau xin kin- n nh cng vic tm thi- lm vicchung- xem xt ti liu ni b, ti liu ngoi Mi phng php c u, nhc im ring (chng ta s tho lun sau). Nh pht trin phn mm phi bit vn dng linh hot cc phng php trn thu c thng tin mt cch hiu qu nht. Cc tnh cht ca d liu. Cc d liu c phn bit theo mt vi kha cnh: -nh hng thi gian. -Cu trc. -Nhp nhng. -Ng ngha. - ln. Miyuttrnuquantrngtrongvicxcnhccctcangdngbivchng hng dn cho cng ngh phn mm bit s lng v kiu thng tin nn c chn. Cng vy, cc kiu d liu khc nhauc lin quan ti cc loing dng khc nhau vi hi cc k thut khai thc thng tin khc nhau. Khng ch ti cc c tnh ca d liu s dn ti li phn tch thit k. 19 Bn cnh vic thu thp thng tin, chng ta cng cn s dng cc k thut nh lng thng tin v bin dch v ng dng ra. Tnh cht 1: Hng thi gian. Tnh hng thi gian ca d liu cp ti qu kh, hin ti hoc cc i hi tng lai ca ng dng ra. Cc d liu qu kh, vd, c th m tcng vic c bin it th no qua thigian, cc quy nh nh hng th no ti nhim v, v tr ca n trong t chc v nhim v. Cc thng tin qu kh l chnh xc, y v xc ng. Cc thng tin hin ti l cc thng tin v ci g ang xy ra. V d thng tin ng dng hin ti lin quan ti qu trnh hot ng ca cng ty, s lng cc lnh c thc hin trong ngy hoc s lng cc hang ho c sn xut, cc chnh sch, sn phm, i hi nghip v, yu cu php quy hin ti hoc cc rang buc khc cng rt cn thit cho vic pht trin ng dng. Cc thng tin hin ti nn c chuyn thnh cc t liu cho ph hp vi i ng pht trin tng s hiu bit ca h v ng dng v phm vi ca bi ton Cc i hi trong tng lai lin quan n cc s thay i s din ra, chng khng chnh xc v rt kh kim tra. Cc d on kinh t, khuynh hng tip th, kinh doanh l cc v d. Tnh cht 2: Tnh c cu trc. Thng tin chng ta thu thp c l nhng thng tin c t chc theo mt cu trc (khun mu) nht nh; c nh vy mi th hin mt ngha phn nh mt i tng no , iu ny l hin nhin. Tuynhin, trong qu trnh thu thp d liu, chng ta c khi khng hiu c cu trc ca thng tin phn nh, m rt c th hiu theo hng khc (iu ny c cp phn cc li c th mc phi trong qu trnh pht trin h thng - Chng 2). Cu trc ca thng tin nh hng v phn m rng theo thng tin c th c phn loi theo mt cch no . Cu trc c th tham chiu ti cc hm, mi trng hoc dng d liu hy hnh thc x l. Cc thng tin thay i t phi cu trc cho ti cu trc m phn cu trc c xc nh bi cng ngh phn mm (SE). Mt v d thc t khi phn tch chc nng ca nghip v. Cc chc nng ca nghip v nu theongiqunlhthngthkhngthkrahtvlcccngviccatngbphn,ca tngnhnvin.Dovytachnmcnhngcitngquan(ctnhtrutngcao-khngr rng,cth).Cnccchcnngnghipvcatngbphn,tngnhnvinthrtnhl.V ng gia mt danh sch cc chc nng nh vy th kh c th thy c tnh cu trc ca n. Cc nh phn tch li phi "ngi li" vi nhau v t chc li cc chc nng nghip v . C nh vy th khi xy dng chng trnh, ta trnh phi lm i lm li cc chc nng ging nhau gia cc b phn trong thc t. M ta ch cn nu ra mt lin kt (link) t b phn (module) ny n b phn khc. Tnh "khng chun" ca d liu th hin r nht thng tin trong mt t "ho n". Ho n thanh ton th hin rt nhiu thng tin, nh: S HD, Tn H, Tn khch hng, a ch khch hng, 20 v sau l mt bng lit k chi tittn cc mt hng, n gi, s lng, thnh tin ... nhng trong thc t, khng mt bng d liu c khun dng ging nh mt ho n no c mt trong kho d liu ca h thng. iu ny l do lin kt d liu t cc bng khc m thnh, trnh lu tr trng lp qu nhiu thng tin. Do vy, cc nh thit k d liu t chc li cu trc ca d liu cn lu tr. Tnh cht 3: y . Hnlcnoht,khitmhiuvmtitnghaylnhvcno,taluncnthngtin phn nh v n mt cch y v chnh xc nht c th c. V mt l thuyt th khng bao gi ta c c ton b thng tin v i tng hay lnh vc m ta x l. Trong thc t cng nh vy, thng tin m ta c ch l tm ta c th x l m thi.Ccthngtincthxptheocptnhymcaonhtlmithngtincnthits c biu din. Mi kiu ng dng i hi mt mc y khc nhau. Cc h thng x l giao dch lun tipcncc thng tin y vchnhxc (v d h thng bnv my bay). Tuy nhin cc h thng xy dng theo kin trc h chuyn gia hay tr tu nhn to (AI) l minh ho tt nht vic x l thng tin khng y . Tnh cht 4: Nhp nhng. Tnh nhp nhng l mt thuc tnh ca d liu khng trong sng v ngha hoc c nhiu ngha mt cch hu (c ch nh). Tnh cht ny lin quan n mc ng ngha. V d, nhn thy mt ca hiu c th bin Git l hp, th mt cu b c th hi b mt cu hi nh sau: Ti sao gitlilhp?,vohoncnhny,ngbsphimtrtnhiucngscgiithchchocon hiu. Nh vy c hin tng ng ni g, b ho cuc. gii quyt vn nycn cn c vo ng cnh. Tnh cht 5: Ng ngha. Mingitrongmttchcucmttphpccnhnghacchiaschobitcc thut ng, chnh sch hoc cc hnh ng c biu hin nh th no. Ngnghartquantrngvivicphttrinngdngvvichnhbnthnngdng. Nu mi ngi dng chung mt thut ng m c cch hiu khc nhau th s dn n khng th trao i thng tin c. i vi ng dng th d liu s khng bao gi x l c cho n khi ngi s dng hiu c ng ngha ca d liu ny. Ccngdng sc nghaxc nh vi mc d liu c nh tnh thng qua vic o to v s dng lu di. Khi cc cn b ch cht chuyn cng tc, th kh nng chuyn ho ng ngha d mt. Vic nh mt ng ngha ca mt cng ty c th gy tn tht rt ln cho cng ty . Tnh cht 6: ln (volume). Volume l s lng cc s kin nghip v h thng phi tin hnh trong mt chu k no . Volume ca to mi hay thay i khch hng c tin hnh theo thng hoc nm, trong volume ca giao dch c tin hnh theo ngy gi hoc l theo peak volume (peak volume l s cc giao 21 dch hoc cc s kin c thc hin trong thi k bn nht). Thi k cao im c th l cui nm hoc cui cc qu, v d chun b cho bo co np thu. Volume ca d liu l mt ngun thng tin phc tp bi v s lng thi gian cn thit vi mt giao dch n l c th tr thnh rt quan trng i vi lng ln d liu cn x l sau ny. Cc k thut thu thp d liu. Cckthutthuthpdliucthkral:phngvn,hpnhm,quanstnnhcng vic tm thi, xem xt ti liu, xem xt phn mm. Mi k thut u c im mnh v hn ch v s lng v kiu d liu ta thu c khi s dng chng. Chng ta hy bn lun v cc k nng ny. Phng vn. Phngvnlvictphpmtnhmngislngttrongmtkhongthigiancnh vi mt mc ch c th. Phng vn thng c tin hnh vi 1 hoc 2 ngi hi i vi 1 ngi c phng vn. Trong qu trnh phng vn, cc cu hi c th c thay i. Bn c th nh gi c cm nhn ca h, ng c v thi quen vi cc b phn, qu trnh qun l hoc cc thng tin vthcthkhcngch.Kiucaphngvnlkiucathngtinyucu.Phngvnc dn dt sao cho c 2 bn tham gia u cm thy tho mn vi kt qu ca n. Cuc phng vn c chun b k ng ngha vi vic hiu c v ngi ang c phng vn. Do bn khng l cho h bi ri v bn c th hi vi cu ban u c chun b cho d khng phi l tt c. Mt cuc phng vn bao gi cng c bt u, on gia v kt thc. -Lcbtu,bntgiithiuvtcccuhingin.Nnbtuvicccuhi tngqutvkhngihicctrlimangtnhquanimcnhn.Hychnkt qu tr li tm ra mi cc cu hi tip theo v tnh trung thc, thi ca ngi c phng vn. -Vo gia bui, nn tp trung vo ch . Hy ly mi thng tin bn cn lu , s dng cc k thut m bn chn ban u. Nu thy mt vi thng tin qua trng, hy hi xem bn c th c tho lun sau ny. -Vo lc kt thc, hy tm tt cc th m bn nghe v ni nhng g s phng vn tip. Bn c th ghi chp v ngh ngi c hi xem xt li. Tt nht l trong thi gian 48 gi v c s chp nhn ca ngi dng theo ngy xc nh. Phng vn c th s dng 2 loi cu hi: -Cuhim:Lcuhicnhiucchtrlikhcnhau,cuhimthchhpchocc chcnngngdnghinticngnhangnghvchovicxcnhcmnhn kin, v mong i v ng dng c ra. Mt v d l: ng c th ni cho ti v , ng c th m t lm th no . -Cu hi ng: l cu hi m ch tr li c hoc khng hoc mt cu tr li c th. Cc cu hi ng tt cho khai thc thng tin thc t hoc bt ngi dng tp trung vo phng 22 vn. V d, cu hi c th l: Bn c dng cc bo co hng thng hay khng ?. Vi cc cu tr li C th c th c tip ni bng cu hi m: ng c th gii thch Cc bc tin hnh phng vn thnh cng Tin hnh t cuc hn ph hp vi thi gian ca phng vn. Chun b tt, tm hiu k v ngi c phng vn. ng gi. C k hoch m u Gii thiu bn thn, mc ch. S dng cu hi m bt u. Lun lu vo cu tr li. C k hoch cho ni dung chnh. Kt hp cu hi ng v m. Lun bm st cc cch trnh by v pht trin chi tit. Lun cung cp thng tin phn hi, v d: Cho php ti trnh l iu ng va ni . Hn ch ghi chp nu thy khng tin. C k hoch kt thc. Tm tt ni dung, yu cu hiu chnh. Yu cu xc thc li ni dung, nh gi li ghi chp. Cho bit ngy thng h s nhn c bo co. Thng nht ngy thng ly bn hiu chnh. Xc nhn li lch lm vic. Cc cu hi c th a ra theo kiu c cu trc hay phi cu trc. -Phng vn c cu trc l phng vn trong ngi c phng vn c danh sch cc mc cn duyt qua, cc cu hi xc nh v cc thng tin cn tm hiu c xc nh trc. -Phngvnkhngcutrclphngvncnhhngbicutrli.Cccuhi phn ln l cu hi m, khng c mt k hoch ban u. Do vy ngi i phng vn bit cc thng tin cn thit s dng t cc cu hi m pht trin chi tit hn v ch . Phng vn c cu trc thch hp khi bn bit v cc thng tin cn thit trc khi phng vn. Ngc li, phng vn phi cu trc thch hp khi bn khng th on trc c ch , hay cha c thng tin g v ngi c phng vn. Cc trng hp in hnh ca phng vn l ngi khch hng bt u vi phng vn phi cu trc cho hai bn nhn thc c v min ca bi ton (hiu s lc vn ). Sau , phng vn dn dn tr thnh c cu trc v tp trung vo cc thng tin bn cn hon chnh phn phn tch. 23 Cc kt qu phng vn ngi s dng ln c trao i li vi ngi c phng vn trong mt thi gian ngn. Ngi c phng vn phi c bo trc v thi hn i vi vic phng vn. Tuy nhin, c th xin b tr b sung phng vn trong trng hp cn nhiu iu cn hi hoc nhiu ngi cn gp. Bng sau so snh phng vn c cu trc v phng vn phi cu trc. Phng vn c cu trcPhng vn phi cu trc u im Dngdngchunchonhiu cu hi D qun l v nh gi nhgicnhiumc ch. Khng cn o to nhiu. Cktqutrongccphng vn. C kh nng mm do nht Cn chm ch nghe v c k nng m rng cu hi. C th bao c nhng thng tin cha bit i hi c thc hnh.Nhc imChi ph chun b ln. Tnhccutrccthkhng thch hp cho mi tnh hung. Gim tnh ch ng ca ngi i phng vn. Lng ph thi gian phng vn. Ngi c phng vn c th nh kin vi cc cu hi. Tn thi gian la chn v phn tch thng tin. Mt k nng tt l pht trin cc s nh l mt phn ca ti liu phng vn. Khi bt u mt cuc phng vn mi, nn bn bc v cc s v a cho h bn ghi chp h c th kim tra sau ny. Bn s nhn c ngay kin phn hi v tnh chnh xc ca s v hiu bit ca bn vngdng.Lichcacchtipcnnythhincmtknngvtml.Tkhacnhk thut, bn thng xuyn c kim tra li cc vn m bn c nghe. Cho ti khi thi gian phn tch kt thc, c bn v khch hng u tin chc rng qu trnh x l ng dng l y . T kha cnh tm l, bn lm tng nin tin ca khch hng vo kh nng phn tch bng cch trnh by cc hiu bit ca mnh. Mikhi bn ci thin s v i vo phn tch, bn cng tng c nim tin ca ngi s dng rng bn c th xy dng c ng dng p ng c nhu cu ca h. Phng vn thch hp cho vic nhn thng tin m bo c s lng ln cht lng: Cc kiu thng tin nh tnh l: cc kin, nim tin, thi quen, chnh sch v m t. Cckiuthngtinnhlngbaogm:tnsut,slng,nhlngccmccdng trong ng dng. Phng vn l mt dng khc ca thu thp d liu c th lm bn lc li, thiu chnh xc hoc thngtinkhngthchhp.Bncnhccchcngnngbngcch,thiquenquytinh c cc iu kin cn thit cho cng mt thng tin. 24 Trong khi phng vn, chng ta cn ch n hn ng c ngi c phng vn c cch ng x thch hp. Bng sau lit k mt vi tnh hung v kinh nghim x l. Hnh vi ca ngi c phng vn.p ng ca ngi i phng vn. oncccutrlichkhngthanhnl khng bit Sau phng vn, kim tra cho cc cu tr li. C ni nhng iu lt tai ngi i phng vn, sai s tht. Trnhcccuhidonccutrli, kim tra cho cc cu hi Cho thng tin khng y Kin tr hi t mc ch. Dngtrnhbykhingiiphngvnghi chp Ghinhanhnhtcth,chhicccuquan trng Vi v hay tr li ri rc, u oiNhanhchngktthc,nghbtrbui khc Thhinskhngquantm,trlit qung Ni chuyn vui sau chuyn ti khc Khng mun thay i mi trng hin ting vin ci thin mi trng hin ti v so snh 2 khuynh hng. Khng hp tc, t chi tr liLy ngun tin khc v hi: ng c quan tm vnhngiungikhcnivnghay khng?.NucutrlilKhngththi phng vn. Phn nn v v tr cng tc, lng, Tmramuchtvn.Cgngdndtv ch chnh, v d: Dng nh c quan ng c rt nhiu vn , c th ng dng mi m chng ti xut s gii quyt c cc vn trn. L ngi thch th v cng nghChn lc cc thng tin cn thit, khng b li cun vo cc vn cng ngh. Phngvnvgpgphhpvimiloikiudliudochngthngxuyncs dng. u im ca phng vn: -Nhn c c thng tin cht lng v s lng. -Nhn c c thng tin y v chi tit. -L phng php tt cho cc yu cu bn ngoi. Nhc im ca phng vn: -i hi c k nng giao tip. 25 -C th c kt qu thin v v mang tnh ch quan ca ngi c phng vn. -C th dn n cc thng tin sai lc, khng lin quan, thiu chnh xc. -i hi phi c 3 ngi kim tra kt qu. -Khng thch hp vi s lng ln ngi. Quan st. Quan st c th tin hnh th cng hoc t ng. -Theo cch th cng, ngi quan st ngi ti ch v ghi chp li cc hot ng, cc bc x l cng vic. Cc bng video i khi c th c dng. Ghi chp hoc bng ghi hnh c phn tch cho cc s kin, cc m t ng t chnh, hoc cc hot ng ch r l do, cng vic, hoc cc thng tin v cng vic. -Theocchtng,mytnhslutrchngtrnhthngtr,lulivtcaccchng trnhcsdng,emailvcchotngkhccxlbimy.Ccfilenhtkca my s c phn tch m t cng vic. u im ca quan st: -Bao trm c cc tiu chun quyt nh, quy trnh suy lun, cc th tc khp ni (mang tnh thc hnh). -Ksphnmmskhngbnhkin(khngbnhhngbingikhc)mhon ton tp trung vo vn ca mnh. -Quan st s khc phc ngn cch gia k s phn mm v ngi c phng vn. -Nhnccchiubitttvmitrngcngtchinti,vnvqutrnhxl thng qua quan st. Nhc im ca quan st: -Thi gian quan st c th khng biu din cho cc cong vic din ra thng thng. -Thi quen d thay i do bit mnh b quan st (ngi b quan st s mt t nhin, hnh ng c th b gh p). -Mt nhiu thi gian. Ngi i quan st nn xc nh ci g s c quan st. Nn xc nh thi gian cn thit cho vic quan st, hy xin s chp thun ca c ngi qun l v c nhn trc khi tin hnh quan st. n nh cng vic tm thi. Khng c g thay th c kinh nghim. Vi mt cng vic tm thi, bn c c nhn thc y hn v cc nhim v. Cng vy, u tin bn hc cc thut ng hon cnh s dng n. Thi giankodit2tunn1thngdibncthquenviphnlncccngvicthng thng v cc tnh hung ngoi l nhng khng c qu di tr thnh chuyn gia thc s i vi cng vic. 26 Cng vic tm thi cho bn c s hnh thc ho cc cu hi v chc nng no ca phng php hin thi ca cng vic s c gi li v ci no s b loi tr hoc thay i, nghin cu c ng cnh hin ti. C th bng cng vic thay th cho cc cu hi khng thc hin c. Bt li ca cng vic tm thi l tn thi gian v s la chn v thi gian c th lm ti thiu ho vn , khng bao ht c cc hot ng hoc thi gian. Mt nhc im khc na l k s phn mm c th thin kin ho v qu trnh x l cng vic (do t mnh lm), ni dung lm nh hng n cng vic thit k sau ny. Hp nhm (meeting) Meeting l vic tp trung t 3 ngi tr ln trong mt khong thi gian tho lun v mt ch nht nh. Meeting c th va b sung va thay th phng vn bng cch cho php cc thnh vin kim tra li cc kt qun phng vn c nhn. N c th thay th phng vn bng cch cung cp mt din n cho cc thnh vin cng tm ra cc yu cu v cc gii php cho ng dng. Meetingcthlmlngphthigian.Nichungnumeetingcnglnthcngtkin nht tr v thi gian i n quyt nh s ko di. Do vy ln c k hoch ban u cho meeting. Lch trnh nn cung cp trc cho cc thnh vin. S lng ch cn tho lun ch nn thp hn 5 ch . Meeting ln c thi gian c nh v c a im thng nht c th vi cc quyt nh cn thit.Meetingkhngnnkodiqu2gicthmbocstptrung,chcacc thnh vin. u im ca hp nhm : -C th ra quyt nh m cc thnh vin u phi tun theo (a s). -Nhn c c thng tin tng hp v chi tit. -L phng php tt cho cc yu cu bn ngoi. -Tp hp c nhiu ngi dng lin quan. Nhc im ca hp nhm: -Mt nhiu cng sc thi gian v tin bc chun b. -Nu s i biu nhiu s tn thi gian ra c quyt nh. -Cc ngt qung trong cuc hp d lm mi ngi phn tn. -D chuyn sang cc ch t lin quan nh : chnh tr, th thao, thi trang -Mi khng ng thnh vin dn n chm c kt qu. iu tra qua bn cu hi c ng dng khi cnly kin ca i a s ngi dng v mt s thng tin c th tp hp s liu thng k m khng c iu kin gp trc tip. Vi cch ny, ngi thu thp d liu s son trc mt bn cu hi, c th c sn cc phng n la chn ngi dng la chn nh du vo, sau thu li v thng k kt qu. V d, cc cu hi c th nh sau : 27 Bn thng ng dng my tnh vo cc lnh vc no sau y ? A. Gii tr.B. Cng vic.C. Do thch.D. Khng dng. Vi cch thc ny, ngi thu thp khng cn mt thi gian gp trc tip (nh phng vn hoc hpnhm)mvnthucthngtin,khngihiknnggiaotip.Cccuhitrongdanh schcthldngphngvntrngiyhocmytnh.uimchnhcacuhilnunh khng cn phi ch r tn ca ngi tr li th thng tin cc cu tr li s c tnh trung thc cao hn. Cng vy, cc cu hi chun xc cung cp cc d liu thc m theo cc quyt nh c th c da vo. Cc mc cu hi, nh l phng vn c th l cu hi m hoc ng. u im ca bn cu hi : -Ngichokincthkhngcnbittndovychoquanimvcmnhnctnh trung thc cao, c th da vo ra quyt nh. -C th tin hnh vi nhiu ngi. -Thch hp vi cc cu hi ng v hu hn. -Ph hp vi cng ty a chc nng v c th tu bin theo a phng. Nhc im ca bn cu hi : -Kh thc hin li c. -Cc cu hi khng c tr li khng c ngha l khng c thng tin. -Cc cu hi c th kh hiu do yu cu cn phi ngn gn -Thc hin nh gi c th chm. -Ngi dng t c kh nng a ra kin khc (do tnh ng ca cc cu hi). -Khng th b xung thm thng tin khi tin hnh cng b cc bn cu hi. Xem xt ti liu Khi nim ti liu m ch cc cm nang, quy nh, cc thao tc chun m t chc cung cp nh l hng dn cho cc nh qun l v nhn vin. Cc ti liu khng phi lun nm trong n v . Ti liu c th l ti liu ni b, c th l ccnphmkthut,ccboconghincu,Cctiliuthcscnghaviksphn mm tm hiu cc lnh vc m h cha tng c kinh nghim. N hu ch cho vic xc nh cc cu hi v qu trnh thao tc v sn xut. Ti liu a ra cc thng tin mang tnh khch quan. Ti liu ni b m t c ng cnh hin thi ; ph hp vi vic nghin cu c tnh lch s (qutrnhhotngludi).Tuynhinvicphicungcptiliuniblmchongidnge ngi, gy thnh kin ; kh c th nhn bit c quan im, ng c tin hnh cng vic. Ti liu ngoi cho ta xc nh c cc khuynh hng cng nghip, kin cc chuyn gia, cc kinh nghim ca cc cng ty khc v thng tin, k thut. Tuy nhin thng tin c th khng xc ng, thiu chnh xc v c th gy thnh kin. Xem xt phn mm 28 Mt cch thng xuyn, cc ng dng phi thay th cc phn mm c. H thng hin ti c th c phn mm h tr t trc. Nghin cu cc phn mm tn ti cung cp cho chng ta cc thng tin v qu trnh x l cng vic hin thi v cc m rng c rng buc bi thit k phn mm. Khim khuyt ca vic thu nhn thng tin t vic xem xt phn mm l ti liu c th khng chnh xc hoc kp thi, m c th khng c c v thi gian c th lng ph nu ng dng b xo b. Kt lun Thu thp d liu l bc khi u v cng quan trng trong qu trnh pht trin phn mm cho h thng. Nhng thng tin thu thp c s l cn c xy dng phn mm v l bng chng xc thc cc yu cu ca ngi dng c c cp v c c p ng hay khng ? Thu thp d liu c th c tin hnh trong mi giai on ca qu trnh pht trin ng dng nhng c cc mc ch khc nhau. Cc c tnh cn lu ca d liu cnthu thp l : tnh hng thi gian ; tnh c cu trc ; tnh y ; tnh khng nhm ln ; ng ngha v ln. Thuthpdliucththeonhiuknng :phngvn ;iutraquabncuhi ;quan st ; hi hp ; lm vic chung ; n nh cng vic tm thi ; xem xt ti liu v xem xt phn mm hin ti. Mi k nng c u im v nhc im ring. Tuy nhin u im ca k nng ny c th khcphcnhcimcaknngkia(vd :ccthngtinkhngthhichocdint khng r khi phng vnth c th thm c trong qu trnh lm vic chung). Tu tng iu kin hon cnh c th m ngi i thu thp ti liu c th p dng k nng cho ph hp. Mc ch chnh vn l thu thp c nhiu thng tin c tnh chn thc cao lm cn c cho cc cng vic sau ny. 3.2. Phn tch yu cu (Requirements analysis) Phn tch yu cu l cng vic bao gm cc tc v xc nh cc yu cu cho mt h thng mi hoc cthayi,datrncslccyucu(cthmuthun)mnhngngicvaitrquan trng i vi h thng, chng hn ngi s dng, a ra. Vic phn tchyucu c ngha quan trng i vi thnh cng ca mt d n. Vicphntchyucumtcchchthngcncgilknghyucu(requirements engineering). Thut ng "phn tch yu cu" cn c p dng c th cho cng vic thun ty phn tch (thay v cc vic khc chng hn nh lm r yu cu hay vit ti liu yu cu). 3.3. c t yu cu (Requirements specification)c t mt vn l m t (mt cch rt ring nh cc k thut th hin) cc c trng ca vn . Vn c th l i tng, khi nim, mt th tc no , Yu cu u tin ca c t l phi mang tnh chnh xc. 29 Phn tch v nh r yu cu l bc k thut u tin trong tin trnh k ngh phn mm. Hot ngphntchvnhryucuhngtictyucuphnmmocthhintrongcc khun cnh nh sau: Ccctthngmangtnhtrutnghocao.Dovyngitaphnchiathnhnhiu mc c t. Cng mc cao (nhng mc u tin ca qu trnh lm mn hoc chnh xc ho) c t cng tru tng. Cng xung cc mc thp hn, c t cng tin dn ti c th - tc l mt th hin trn mt my tnh c th vi mt ngn ng lp trnh c th - y chnh l qu trnh lm mn dn. Cc loi hnh c t. C hai kiu c t l c t hnh thc v c t phi hnh thc. cthnhthc:Lccctchnhxctclkhngthdntinhngcchhiukhc nhau. c t hnh thc s dng cng c ch yu l i s v logic. V d: c t mt ma trn:Cp ca ma trn n x n (n l s t nhin l). Phn t cui ca hng 1 bng phn t u ca hng cui. Phn t trung tm bng trung bnh cng ca cc phn t 4 gc. Hoc c th din t nh sau: A n x n = (a[i, j])n x n; n = 2k + 1, k e Z. a[1, n] = a[n, 1]. ( )1 1, [1,1] [1, ] [ ,1] [ , ] / 42 2n na a a n a n a n n+ +( = + + + ( 1. Thit lp cc nhu cu h thng 2. Nghin cu tnh kh thi 3. M hnh ho h thng 4. Xc nh yu cu 5. c t yu cu (c t tru tng) 6. c t thit k h thng vphn mm (m t tru tng cho phn mm) 1.1. Bo co nhu cu (ti liu quan nim cho phn mm) 2.1. Bo co kh thi3.1. M hnh h thng 4.1. Yu cu qua thm nh 4.2. T liu yu cu 6.1. Ti liu c t thit k (ti liu c t cc yu cu h thng v cc yu cu phn mm ) 5.1. Ti liu c t yu cu 30 c t phi hnh thc: Din t bng nhng ngn ng, tuy khng cht ch nhng c nhiu ngi bit v c th trao i vi nhau chnh xc ho cc im cha r rng, nhng khi nim cn m h. V d: C hai con hu trn bn c. Hai con hu s ng nu chng nm trn cng hng, cng ct hoc trn cng mt ng cho song song vi ng cho chnh hay ng cho ph. => R rng y c mt s khi nim m h. c t hn hp: Phi hp c hai kiu c t trn. Trong thc t, c nhiu loi hnh c t, v d nh: -c t cu trc d liu: Nu cc thnh phn ca d liu V d:c t mt phn s: Phn_s = { x/y , x e Z , y e N } S_phc = { a + b.i | a, b e R } -c t chc nng: M t thng qua vic nu ln cc tnh cht hay thuc tnh ca tn vo v tn ra. V d: -c t i tng: Bao gm c t cu trc d liu v m t cc chc nng. V d: c t i tng phn s. PS = { x/y , x e Z , y e N } Php cng: +: PS x PS PS -c t thao tc: Nu ln trnh t tin hnh cng vic. V d 1: x, y, z e PS. Cc bc cn thc hin i vi php cng (+) 2 phn s. z = x + y{Quy_ng_mu_s(x, y); z.t_s = x.t_s + y.t_s; z.mu_s = x.mu_s; }; V d 2: Quy trnh Bn hng: 1.Khch hng yu cu c mua hng. 2.Hng dn khch xem v la chn hng ho. 3.Tho thun hnh thc thanh ton: Tin mt, sc, chuyn khon, + a e PS b e PS c e PS UCLN a e N b e N c e N ;;a c b cc da d b d >`) 31 4.Ghi ho n cho khch. 5.Nhn tin v giao hng ho cho khch. -c t c php: Thc cht l cc nh ngha ctnh truy hi t tng thn c s. M t cch lp ghp cc k hiu, cc t vi nhau li to thnh chng trnh. V d: Trong ngn ng lp trnh PASCAL, tn (nh danh - identify) c khi qut nh sau: L dy cc k t bt u bng ch ci hoc du gch ni di, sau c th l ch s, ch ci hoc du gch ni di. = = = { A, B, C, , Z }{ a, b, , z } = { 0, 1, 2, , 9 } -c t qua s :V d: c t nh danh c t phn s g. c t thut ton: Cc bc thao tc gii quyt bi ton. Kiu c t phi ph hp vi gii php. Ccyu cu ca phn mm c th c phn tch theo mt s cch khc nhau. Cc k thut phn tch c th dn ti nhng c t trn giy hay trn my tnh (c xy dng nh CASE) c cha cc m t ngn ng ho v t nhin cho yu cu phn mm. Vic lm bn mu gip c t c th c trin khai, tc l bn mu s th hin nhng cng vic thc hin cc yu cu. Cc ngn ng c t hnh thc dn n biu din hnh thc. Cc nguyn l c t. ctcthxemnhmttintrnhbiudin.Mcchcuicngcactlccyu cu c biu th sao cho dn ti vic ci t phn mm thnh cng. Balzer v Goldman ngh 8 nguyn l c t tt. Nguyn l 1: Phn tch chc nng vi ci t. Trc ht, theo nh ngha, c t l mt m t v iu mong mun, ch khng phi l cch thc hin n (ci t). c t c th chp nhn 2 dng hon ton khc nhau. Dng th nht l dng ca cc hm ton hc: Vi mt tp d liu u vo cho, to ra mt tp d liu u ra c bit. Dng tng qut ca ct nh th l tm ra (mt hoc tt c nhng) ktqu ng vi P (u vo), vi P biu th mt tn t bt k. Trong c t nh th, kt qu thu c phi c din t mt cch A Z a z ;;a c b cc da d b d >`) A Z, a z 0 9 ;;a c b cc da d b d >`) + , - ;;a c b cc da d b d >`) 0 9 ;;a c b cc da d b d >`) / 0 9 1 9 32 y , ton vn, theo dng l ci g (khng phi l nh th no). Mt phn iu ny l v kt qu ca mt hm (ton hc) ca u vo (php ton c im bt u v im kt thc xc nh r) khng b nh hng bi mi trng bao quanh. Nguyn l 2: Cn ngn ng c t h thng hng tin trnh. Xt tnh hung trong mi trng l ng v s thay i ca n nh hng ti hnh vi ca thc th no tng tc vi mi trng (nh trong h thng my tnh nhng). Hnh vi ca n khng th biu din c dng hm (ton hc) ca u vo. Thay v th, cn phi s dng cch biu din khc - cch m t hng tin trnh, trong c t ci g t c bng cch xc nh mt m hnh cc thao tc mong mun t c ca h thng di dng cc cng vic p ng chc nng i vi kch thch khc nhau t mi trng. Nhng c t hng tin trnh nh vy, trnh by mt m hnhv hnh vi h thng, thng thng b loi ra khi cc ngn ng c t hnh thc, nhng chng li l bn cht nu nhiu tnh hung ng phc tp hn cn phi c c t. Trong thc t, cn phi tha nhn rng trong nhng tnh hung nh vy c tin trnh cn t ng ho ln mi trng tn ti ca n u phi c m t mt cch hnh thc. Tc l, ton b h thng cc b phn tng tc phi c c t ch khng ch mt thnh phn c c t. Nguyn l 3: c t phi bao gm h thng c phn mm l mt thnh phn trong Mththngbaogmccthnhphntngtcnhau.Chbntronghoncnhcah thng ton b v tng tc gia cc thnh phn ca n th hnh vi ca mt thnh phn ring mi c th c xc nh. Ni chung, mt h thng c th c m hnh ho nh mt tp hp cc s vt tch cc v th ng. Nhng s vt ny c lin quan ln nhau v qua thi gian th mi quan h gia cc s vt thay i. Mi quan h ng ny a ra s kch thch cho cc s vt tch cc, cn gi l cctcnhn,png.Spngcthgyranhngthayithmna,vdo,torathm kch thch cho cc tc nhn c th p ng li. Nguyn l 4: c t phi bao gm c mi trng m h thng vn hnh. Tngt,mitrngmtronghthngvnhnhvtngtcvicngphicxc nh. May mn l iu ny n thun ch cn s tha nhn rng bn thn mi trng cng l mt h thng bao gm cc s vt tng tc, c tch cc ln th ng, m trong h thng ch l mt tc nhn.Cctcnhnkhc,theonhnghalkhngthayibivchnglmtphncami trng, gii hn phm vi ca vic thit k v ci t v sau. Trong thc t, s khc nhau duy nht gia h thng v mi trng ca n l ch n lc thit k v ci t v sau s vn hnh ch trong c t cho h thng. c t mi trng lm cho giao din ca h thng c xc nh theo cng cch nh bn thn h thng ch khng a vo cch hnh thc khc. Cn phi ch rng bc tranh c t h thng c trnh by y chnh l bc tranh ca tp hp cc tc nhn xon xut nhau cao phn ng vi nhng kch thch trong mi trng (thay 33 i cc s vt) do cc tc nhn to ra. Ch c thng qua nhng hnh ng iu phi ca tc nhn m h thng mi t ti mc tiu ca n. S ph thuc ln nhau viphm vo nguyn l phn tch (c lp vi cc phn khc ca h thng v mi trng). Nhng y l mt nguyn l thit k, khng phi l nguyn l c t. Thit k tun theo c t, v quan tm ti vic phn r mt c t thnh cc mu gn tch bit chun b cho ci t. Tuy nhin c t phi v li chnh xc bc chn dung ca h thng v mi trng ca n nh cng ng ngi dng cm nhn theo mt cch thc nhiu chi tit nh cc giai on ci t v thit k cn ti. V mc chi tit cn thit ny l kh thy trc, nu khng ni l khng th, nn c t, thit k v ci t phi c tha nhn nh mt hot ng tng tc. Do iu mu cht l cng ngh cn c bao qut tht nhiu cho hot ng ny khi bn c t c son tho v thay i (trong c hai giai on pht trin khi u v bo tr v sau). Nguyn l 5: c t h thng phi l mt m hnh nhn thc. c t h thng phi l mt m hnh nhn thc ch khng phi l mt m hnh thit k hay ci t. N phi m t mt h thng nh cng ng ngi s dng cm nhn thy. Cc s vt m n thao tc phi tng ng vi cc s vt ca lnh vc ; cc tc nhn phi m hnh cho cc c nhn, tchcvtrangthitbtronglnhvc;cncchnhnghthchinthphimhnhcho nhng hot ng thc t xut hin trong lnh vc. ctphickhnngthpvotrongnnhngquitchaylutbaotrmccsvt thuc lnh vc. Mt s trong nhng trng hp l lut bi tr nhng trng thi no ca h thng (nh hai s vt khng th ng thi cng mt ch v vo cng mt lc), v do gii hn hnh vi ca cc tc nhn haych ra nhu cu son tho thm ngn cn nhng trng thi ny khi ny sinh. Cc lut khc m t cch cc s vt p ng li khi b kch thch (nh lut chuyn ng ca Newton).Nhnglutny,biuthchotnhvtlcalnhvc,lphnchucacth thng. Nguyn l 6: c t phi th hin tnh vn hnh. c t phi y v hnh thc c th c dng trong vic xc nh liu mt ci t c ngh c tho mn c t cho nhng trng hp kim th tu khng. Tc l,vi kt qu ca vic ci t trn mt tp d liu c chn mt cch tu , phi c th dng c t xc nh tnh hp l cho nhng kt qu . iu ny ko theo rng c t, mc du khng phi l mt c t hon ton v cch thc, vn c th hnh ng nh mt b sinh cc hnh vi c th trong s nhng hnhviphiccacitcngh.Do,theomtnghamrng,ctnyphilvn hnh ... Nguyn l 7: c t chp nhp dung sai v tnh khng y . Khngctnocthlyhonton.Mitrngtrongntntithngqu phc tp cho iu . Mt c t bao gi cng l mt m hnh- mt s tru tng ho- ca mt tnh hung thc (hay c mng tng) no . Do , n s khng y . Hn th na, nh c pht biu n s tn ti ti nhiu mc chi tit. Tnh vn hnh c yu cu trn khng nht 34 thit l cn thit. Cc cng c phn tch c s dng gip cho ngi c t v kim th c t phi c kh nng x l vi tnh khng y . Mt cch t nhin iu ny lm cho vic phn tch b yu i, khi c th c thc hin bng cch m rng phm vi cc hnh vi chp nhn c tha mn cho c t, nhng mt s suy gim nh vy phi phn nh cc mc bt trc cn li. Nguyn l 8: c t phi c cc b ho v c ghp lng lo. Cc nguyn l trc x l c t nh mt thc th tnh. Thc th ny ny sinh t ci ng ca c t. Cn phi tha nhn rng mc du mc tiu chnh ca mt c t l dng lm c s cho thit k v ci t mt h thng no , n khng phi l mt s vt tnh dng sn m l mt s vt ng ang tri qua thay i ng k. Vic thay i nh th xut hin trong ba hot ng chnh: pht biu, khi mt c t ban u ang c to ra, pht trin, khi c t c son tho trong qu trnh thit k lp phn nh mi trng thay i v / hoc cc yu cu chc nng ph. Vi nhiu thay i xut hin cho c t, iu mu cht l ni dung v cu trc ca n c chn lm ph hp hot ng ny. Yu cu chnh cho s ph hp l ch thng tin bn trong ctphicccbhosaochochmtphnnh(mtcchltng)cnphisaikhi thng tin thay i, v ch c t cn c cu trc (ghp) mt cch lng lo cho tng phn c th c thm vo hay loi b mt cch d dng, v cu trc c iu chnh mt cch t ng. Mc du cc nguyn l c Balzer v Goldman tn thnh tp trung vo tc ng ca c t trn nh ngha v ngn ng hnh thc, nhng li bnh lun ca h p dng c cho c mi dng c t. Tuy nhin, cc nguyn l cn phi c dch thnh s thc hin. Trong mc sau chng ta s xem xt mt tp cc hng dn to ra mt c t cc yu cu. Cc mc tru tng ca c t. Cc c t c th hin mt vi mc tru tng khc nhau cng vi mi tng lin gia cc mc y. Mi mc nhm n cc i tng c khc nhau m h c quyn quyt nh v vic da vo m thc hin nh gi bn thit k ca cc nh pht trin phn mm. Cc mc l: Mc 1: nh ra yu cu. c th hin bng ngn ng t nhin v cc dch v m h thng s phi cung cp. Phn nyphi c vit sao cho d hiu i vi khch hng v ngi qun l hp ng, ngi s mua sn phm phn mm vngi s s dng n. K thut c t phi hnh thc l thch hpcho mc c t ny. Mc 2: c t yu cu. Ti liu nu ra cc dch v mt cch chi tit hn. Ti liu ny i khi cn c gi l ti liu c t chc nng. Yu cu i vi c t mc ny l phi chnh xc n mc c th lm c s cho hp ng gia nh pht trin phn mm v khch hng. ng thi cngcn c vit sao cho d hiu i vi nhn vin k thut ca c ni mua phn mm v ni pht trin h thng. K thut c thnhthchnlthchhpchomcctnhvy,tuynhincngcntuthucvotrnh kin thc c bn ca khch hng. Tt hn c l ta c th dng loi hnh hn hp c t.35 Mc 3: c t phn mm / c t thit k (y l m t tru tng cho phn mm). Dng lm c s cho vic thit k v thc thi. Cn th hin mt quan h r rng gia t liu ny v ctyucu.Taphixcnhrng:itngcychyulccksphnmmch khng phi l ngi s dng hoc ngi qun l. K thut c t hnh hnh thc l hon ton ph hp cho mc c t ny. 3.4. Xt duyt yu cu (Requirements validation) Vic xt duyt bn c t yu cu phn mm (v/ hoc bn mu) do c ngi pht trin phn mm v khc hnh cng tin hnh. Bi v c t to nn nn tng cho giai on pht trin nn cn phi cc k cn thn trong khi tin hnh cuc hp xt duyt. Vicxtduyttrchtctinhnhmcvm.Timcny,ngixtduytcgng m bo rng bn c t c y , nht qun v chnh xc. Cn cp ti cc cu hi sau: 1.Ccmctiuvmcchcthitlpchophnmmcnhtqunvimctiuv mc ch ca h thng hay khng? 2.Nhng giao din quan trng vi mi phn t h thng c m t cha? 3.Lung v cu trc thng tin c m t thch hp cho lnh vc vn cha? 4.Ccbiucrrngkhng?Liumibiucthngringkhngligiithch khng? 5.Cc chc nng chnh c cn bn trong phm vi v c m t thch hp cha? 6.Liu hnh vi ca phn mm c nht qun vi thng tin n phi x l v chc nng n phi thc hin hay khng? 7.Cc rng buc thit k c hin thc khng? 8.Ri ro cng ngh pht trin l g? 9.Cc yu cu phn mm khc c xem xt n cha? 10. Cc tiu chun hp l c pht biu chi tit cha? Chng c thch hp m t mt h thng thnh cng khng? 11. Liu c s khng nht qun, b st hay d tha no khng? 12. Vic tip xc vi khch hng c y khng? 13. Ngi dng xt duyt bn Ti liu s b ca ngi dng hay bn mu cha? 14. Cc c lng v K hoch d n phn mm b nh hng th no? a ra cu tr li cho nhiu cu hi trn, vic xt duyt c th tp trung vo mc chi tit. Ti y, mi quan tm ca chng ta l vo t ng ca bn c t. Chng ta c gng lm l ra vn c th n nu bn trong ni dung c t. Nhng hng dn sau y l gi v vic xt duyt chi tit bn c t: -Phi quan st cc mi ni c sc thuyt phc (nh chc chn, do , r rng, hin nhin, t suy ra rng) v hi Ti sao chng li c ? 36 -Theo di nhng thut ng mng lung (nh mt s, i khi, thng, thng thng, bnh thng, phn ln, a s); yu cu lm sng t. -Khi c nu danh sch, nhng khng y , th phi m bo mi khon mc u c hiu r. Ch vo cc t nh vn vn, c nh th, c tip tc nh th, sao cho. -Phi chc chn pht biu phm vi khng cha nhng gi thit khng c ni r (nh m hp l trong khong 10 ti 100. l s nguyn, s thc hay s h 16? -Phinhnbitvccngtmhnhxl,loib,nhyqua,xobCthc nhiu cch hiu v n. -Phi nhn bit cc i t vu v (nh m un vo/ra lin lc vi m un kim tra tnh hp l d liu v t c bo kim sot ca n. C kim sot ca ai? ). -Tmcccucchaschcchn(nhbaogi,mi,ttc,khngmt,khngbao gi) ri yu cu bng chng. -Khi mt thut ng c nh ngha tng minh ti mt ch th hy th thay th nh ngha ny vo ch xut hin ca n. -Khi mt cu trc c m t theo li th hy v ra bc tranh gip hiu c n. -Khi mt tnh ton c xc nh th hy th vi t nht hai th d. Mtkhivicxtduythonttthbnbnctyucuphnmmscckhch hnglnngiphttrinktt.Bncttrthnhmthpngchovicphttrinphn mm. Nhng thay i trong yu cu c nu ra sau khi bn c t hon thnh s khng b hu b.Nhngkhchhngphilurngtngthayisaukhikulmtmrngcaphmvi phn mm v do c th lm tng thm chi ph v / hoc ko di lch biu (thi gian thc hin). Ngay c vi nhng th tc xt duyt tt nht ti ch th mt s vn c t thng thng vn cn li. Bn c t rt kh kim th theo mi cch c ngha, v do s khng nht qun hay b st c th b b qua khng ti. Trong khi xt duyt, ngi ta c th khuyn co nhng thay i cho bn c t. C th s cc k kh khn lng nh tc ng ton cc ca thay i; tc l, lm sao vic thay i trong mt chc nng li nh hng ti cc yu cu cho chc nng khc?Bi tp: 1.Trnh by cc k thut thu thp yu cu 2.Trnh by m hnh phn tch yu cu 3.Trnh by cc ti liu c t yu cu 37 Chng 4: M hnh ha h thng 4.1. M hnh ha d liu (Data modeling) M hnh ho d liu trong Cng ngh phn mm l qu trnh to ra m hnh dliu bng cch p dng cc m t m hnh d liu s dng cc k thut m hnh ho d liu. M hnh ho d liu xc nh v phn tch cc yu cu d liu cn thit cho qu trnh nghip v ca mttchc.Ccyucudliucbiudinbimhnhdliukhinimvccit trong m hnh d liu logic. Qu trnh m hnh ho d liu 4.2. M hnh ha chc nng (Functional modeling) M hnh chc nng l biu din c cu trc v cc chc nng, cc hot ng, v cc qu trnh bn trong h thng.Phn r chc nng l qu trnh phn r cc mi quan h c tnh chc nng thnh cc phn nh hn m da vo c th xy dng li h thng.V d v phn r chc nng: 38 Phng php: S dng biu khi lung chc nng S dng k thut phn tch v thit k hng cu trc 4.3. M hnh ha lung thng tin (Information flow modeling) Biu lung d liu l biu din ho ca lung d liu trong mt h thng thng tin.Mi mt s dng dliu thnggm cc thnh phnchc nng hoc tin trnh, dng d liu, kho d liu v cc i tng. - Chc nng: trong s dng d liu, chc nng hay tin trnh l mt qu trnh bin i thng tin. T thng tin u vo n bin i, t chc li thng tin, b sung thng tin hoc to ra thng tin mi, t chc thnh thng tin u ra, phc v cho hot ng ca h thng nh lu vo kho d liu hoc gi cho cc tin trnh hay i tng khc. 39 - Dng d liu: Dng d liu l dng chuyn di thng tin vo hoc ra khi mt tin trnh,mt chc nng, mt kho d liu hoc mt i tng no . Cc thnh phn ca dng d liu bao gm ng biu din dng, mi tn ch hng dch chuyn thng tin v tn ca dng. Cn ch l cc dng d liu khc nhau phi mang tn khc nhau, v cc thng tin tri qua thay i th phi c tn mi cho ph hp. - Kho d liu: Trong s dng d liu, kho d liu th hin cc thng tin cn lu tr. Di dng vt l, kho d liu ny c th l tp ti liu, cp h s hoc tp thng tin trn a. Trong s dng d liu, di tn kho d liu chng ta s ch quan tm ti cc thng tin c cha trong . Trong mt trang s dng d liu ta c th t mt kho d liu nhiu ch, nhm gip vic th hin cc dng d liu tr nn d dng hn. - Tc nhn ngoi: Tc nhn ngoi c th l mt ngi, mt nhm ngi hoc mt t chc bn ngoi h thng, nhng c mi lin h vi h thng. -Tcnhntrong:Tcnhntronglmtchcnnghocmttintrnhbntronghthng,c miu t trang khc ca s .- S ng cnh: S ng cnh(Context Diagrams) bao gm ba nhm thnh phn: + Thnh phn chnh l mt vng trn nm v tr trung tm va s , biu th cho ton b h thng ang c nghin cu. +Xungquanhvngtrntrungtmnylttcccphntbnngoi,cquanhvih thng (tc nhn ngoi). + Tt c cc ng truyn thng tin vo v ra khi h thng (ngha l ni h thng vi mi tc nhn ngoi ca n). V d v biu lung d liu: Bi tp: 1.Trnh by Biu Phn r chc nng 2.Trnh by biu lung d liu 40 Chng 5: Thit k h thng Trong i sng hng ngy, khi mt ngi no cn xy dng mt ngi nh, ngi mi mt k s xy dng n, yu cu thit k cho h ngi nh. Vi cc s liu v cn nh cn xy dng. Cn c vo , ngi k s s thit k ra m hnh ngi nh. y khng phi l ngi nh c c xy dng trong thc t, m ch l trn bn v. Nhng thng qua m hnh , cng vi s m t chi tit ca ngi k s, ch nh cng c th hnh dung ra ngi nh ca mnh. Bn thit k ny rt quan trng, ngip choch nh cng vi k s xy dng hiu v cng vic mnh cn lm, nu cyu cu chnh sa th thc hin ch trn bn v. Cn khi bt tay vo xy dng thc t th vic chnh sa lc ny s rt kh khn v tn km. Khi sn xut phn mm cng vy. R rng, yu cu ca khch hng cng khng khc g yu cu cn xy ngi nh ca ch nh n. Cng vic ca k s xy dng v k s phm mm theo tng giai on cng c nhiu im chung. Ta hy xem xt bng so snh sau: K s xy dngK s phn mm - Kho st a hnh, tm hiu nhu cu ca ch nh:cnxynhbaonhiutng,kchthc bao nhiu, trang tr nh th no, -Tmhiunhucukhchhng,khost h thng, ly s liu, - Thit k ngi nh trn bn v- Thit k phn mm, a ra m hnh - Tm hiu kin ch nh v bn thit k- Duyt li vi khch hng - Thc hin cc chnh sa nu cn- Thc hin cc chnh sa nu cn - Cho thi cng ngi nh- Tin hnh ci t chng trnh Thit k l bc u tin trong giai on pht trin cho bt k sn phm hay h thng cng ngh no. N c th c nh ngha l " tin trnh p dng nhiu k thut v nguyn l vi mc ch xc nh ra mt thit b, mt tin trnh hay mt h thng chi tit cho php thc hn n v mt vt l." Mctiucathitkl toramtmhnhhaybiudincamtthcth(svt:nginh, chic xe hi, ci cu, ) m sau ny c xy dng. Thit k l mt qu trnh sng to, i hi kinh nghim v s tinh nhanh ca ngi thit k.Thit k phi c thc hnh v hc bng kinh nghim, bng kho st cc h thng ang tn ti, khng th hc bng sch v (ni ng ra l khng ). Thitkphnmmlmtqutrnhchuynhoccyucuthnhmtbiudinphnmm. Bc u, biu din m t ton b v phn mm. Vic lm mn tip theo sau dn ti mt biu din thit k gn vi chng trnh gc. Thit k phn mm nm trung tm k thut ca tin trnh k ngh phn mm v c p dng btkkhuncnhknghcsdng(thcnc,xoyc,bnmu,thhth4-4GT,). 41 Mt khi cc yu cu v phn mm c phn tch v c t th thit k phn mm l mt trong bahotngkthut-thitk,lptrnh,kimth-nhnghotngcnxydngvkim chng phn mm. Tng hot ng ny bin i thng tin theo cch cui cng to ra phn mm my tnh hp l. Lung thng tin trong giai on k thut ny ca tin trnh k ngh phn mm c minh ho trong s sau: Ccyucuphnmm,cbiuthbiccmhnhthngtin,chcnngvhnhvilci vo cho bc thit k. Bng vic s dng mt trong s cc phng php thit k, bc thit k to ra thit k d liu, thit k kin trc v thit k th tc. -Thit k d liu: Chuyn m hnh lnh vc thng tin to ra trong bc phn tch thnh cu trc d liu s cn cho vic ci t phn mm. -Thit k kin trc: nhnghara mi quan hgia cc thnh phn cu trc chnh cachng trnh. "Hnh mu thit k" c th c dng t ti cc yu cu c xc nh cho h thng, v nhng rng buc nh hng ti cch m cc hnh mu thit k kin trc ny c th c p dng. Biu din thit k kin trc - khun kh ca h thng da trn my tnh - c th c suy ra t c t h thng, m hnh phn tch v tng tc ca cc h con c nh ngha bn trong m hnh phn tch. M hnh thng tin M hnh chc nng M hnh hnh vi Cc yu cu khc Thit k Lp trnh Kim th Thit k d liu (cu trc, cch lu tr, cch khai thc) Thit k kin trc (thnh phn, cu trc chng trnh, v mi quan h gia chng) Thit k th tc (m t th tc phn mm ng vi tng thnh phn cu trc) Module chng trnh Phn mm qua tch hp v kim th Thit k phn mm v k ngh phn mm Thit k giao din 42 - Thit k giao din: M t cho cch phn mm trao i vi chnh n, vi h thng lin tc vi n, v vi ngi dng n. Giao din bao gm mt lung thng tin (nh d liu v / hoc iu khin) v cc kiu hnh vi c bit. Do , cc biu lung d liu v iu khin cung cp nhiu thng tin cn cho thit k giao din. - Thit k th tc: Bin i cc thnh phncutrc ca kin trc phnmm thnh m t th tc chocccuphnphnmm.Chngtrnhgccsinhrarivickimthctinhnh tch hp v lm hp l. Trong khi thit k chng ta ra cc quyt nh m cui cng s nh hng ti s thnh cng ca vic xy dng phn mm v iu quan trng l nh hng ti s d dng bo tr n. Nhng ti sao thit k li quan trng? Tmquantrngcathitkphnmmcthcphtbiubngmtt-chtlng. Thitklnichtlngcnuidngtrongvicphttrinphnmm:cungcpcchbiu dinphnmmcthcxcnhnvchtlng,lcchduynhtmchngtacthchuyn ho mt cch chnh xc cc yu cu ca khch hng thnh sn phm hay h thng phn mm cui cng. Thit k phn mm phc v nh mt nn tng cho mi bc k ngh phn mm v bo tr: Tm quan trng ca thit k: - Khng c thit k, ta c nguy c dng ln mt h thng khng n nh - mt h thng s tht bi khi c mt thay i nh; mt h thng kh c th m th c; mt h thng khng th no xc nh c cht lng chng no cha n cui tin trnh kim th, khi thi gian cn rt ngn m khng t tin phi chi ra. - Thit k tt l cha kho cho cng trnh hu hiu, khng th hnh thc ho qu trnh thit k trong bt k mt cng trnh no. Ch rng RAISE ch l mt phng php nghim ngt vit ra thit k, pht trin n, kim tra n ch tuyt nhin khng phi l mt phng php hnh thc pht trin thit k. Thit k phn mm tri qua mt s giai on sau: Giai on 1: Nghin cu v hiu ra vn . Khng hiu r vn th khng c th thit k c phn mm hu hiu. Bo tr Kim th Ci t Thit k C thit k Khng thit k Ci t Kim th Bo tr 43 Giai on 2: Lm sng t cc c im ln ca mt hoc mt vi gii php c th. Vic chn gii phpphthucvokinhnghimcangithitk;phthucvoccthnhphncthtis dng v ph thuc vo s n gin ca cc gii php trc . Kinh nghim cho thy, nu cc nhn t l tng t th nn chn gii php n gin nht. Giai on 3: M t tng iu tru tng (cha r rng) trong gii php. Trc khi to ra cc t liu chnh thc, ngi thit k nn thy rng cn phi xy dng mt m t ban us khai ri chi tit hon.Ccsaistvkhimkhuyttrongmcthitkbanuscphthinvciu chnh cho ph hp ti cc mc chi tit thit k tip theo. Qutrnhkhcphckhimkhuytnysclplichotngphntrutngtmc thitkbanuchonkhimtctthitkchititchotngphntrutngktthc.Nn phn chia ra cc phn nh ng vi thit k ri t hp li, sao cho vic m t chi tit cc phn nh ch trong khong mt trang giy. 5.1. Qu trnh thit k (Design process) Qu trnh thit k l qu trnh tng cng hnh thc ho trong s tin trin ca thit k v phi lun quay tr li cc thit k ng n t hnh thc (t hnh thc y c ngha l mang tnh m t c h thng trong thc t) c trc y ca qu trnh . Nh thit k phi bt u vi mt bn phc tho ht sc khng hnh thc ri sau tinh ch n, thm vo cc thng tin l cho thit k tr nn hnh thc hn. Qu trnh thit k th hin nh sau: Quan h gia thit k v c t l rt cht ch. Mc du qu trnh a ra mt c t yu cu c xem nh l mt phn t c bn ca hp ng l mt hot ng ring bit, song vic hnh thc ho c t yu cu hn l mt phn ca qu trnh thit k. Thc t, ngi lm thit k s lp i lp li gia c t v thit k. Qu trnh thit k lin quan mt thit n vic m t h thng mt s mc tru tng khc nhau.Khimtthitkcphnchiathnhnhiuthnhphnthngitathngphthinra c nhng sai xt giai on trc. Do phi quay tr li tinh ch. Thng thng th ngi ta bt u giai on sau ngay trc khi giai on trc kt thc n gin l lui qu trnh tinh ch. Hnh v di y nu cc hot ng ca qu trnh thit k v cc sn phm ca n. Cc giai on l kh tu nhng n lm cho qu trnh thit k tr nn nhn thy c v t d qun l c. Phc tho thit k phi hnh thc Thit k phi hnh thc Thit k hnh thc Thit k kt thc 44 Thnh qu ca mi hot ng thit k l mt bn c t. c t ny c th l mt c t tru tng, hnh thc v c to ra lm r ccyu cu, n cng c th l mt c t v mt thnh phn no ca h thng phi c thc hin nh th no. khi qu trnh thit k tin trin th cc yucungycngcbsungvobnct.Ccktqucuicnglccctvthut ton v cc cu trc d liu c dng lm c s cho vic thc hin h thng. Thc t,cc hot ng thit k dinra song song vicc sn phm thit k khc nhau. Cc sn phm ny li c trin khai cc mc chi tit khc nhau trong din bin ca qu trnh thit k. Cc hot ng ct yu trong vic thit k mt h thng phn mm ln 1. Thit k kin trc: Cc h con to nn h tng th v cc quan h ca chng l c phn hoch r rng v ghi thnh ti liu. 2. c t tru tng: i vi mi h con, mt c t tru tng cc dch v m n cung cp v cc rng buc phi tun theo cng c h tr. 3. Thit k giao din: y bn c khng nn hiu giao din ch l nhng g hin th trn mn hnh, m phi hiurng c th l tng tcgia cc thnh phn trong h thng vi nhau. Giaodinvitnghconkhccngcthitkvghithnhtiliu.ctgiaodinkhng c m h v cho php s dng h con m khng cn bit n nhng g c din ra bn trong ca h con (theo kiu hp en). c t yu cuKin trc h thng c t phn mm c t giao din c t thnh phn c t cu trc d liu c t thut ton Thit k kin trc c t tru tng Thit k giao din Thit k thnh phn Thit k cu trc d liu Thit k thut ton c t cc yu cu c t cc yu cu Hot ngTi liu c to ra Cc hot ng thit k v sn phm ca thit k. 45 4. Thit k cc thnh phn: Cc dch v c cung cp bi h con c phn chia thnh cc thnh phn hp thnh ca h con . 5.Thitkcutrcd liu:Cccutrcdliucdngtrongvicthchinhthng c thit k chi tit v c c t y. 6.Thitkthut ton: Cccchthc(phngphpxl)cdngcungcpchocc dch v c thit k chi tit v c c t. Qu trnh ny c lp li cho mi h con sao cho n khi cc thnh phn hp thnh c xc nh mt cch r rng v u c th chuyn i (nh x) mt cch trc tip vo cc thnh phn ca ngnnglptrnh,chnghnnhccgi(packets),ccthtc(procedures)vcchm (functions). Phng php tip cn thng xuyn c khuyn khch s dng lphng php tip cn t trn xung (top down): Vn ln c phn chia mt cch quy thnh cc vn con cho n khi cc vn d gii quyt c xc nh r rng. Trong qu trnh ny ngi thit k khng nht thit phi phn r tt c cc thnh phn tru tng (ngha l vn ny cn phc tp m cch gii quyt l cha xc nh r) khi m bng kinh nghim h bit chc chn rng c th hon ton xy dng c. Do h c th tp trung sc lc vo cc thnh phn ng xt nht. Chrngkhimphngphphngitngcchpnhnthphngphpttrn xung s t hiu qu. Khi ngi thit k s dng cc i tng sn c lm khung thit k. Theo quan im qun l d n, thit k phn mm c tin hnh theo 2 bc: Bc 1- Thit k s b: Quan tm ti vic chuyn ho cc yu cu thnh kin trc d liu v cc thnh phn phn mm. Bc 2- Thit k chi tit: Tp trung vo vic lm mn biu din kin trc dn ti cu trc d liu chi tit v biu din cc quy trnh tnh ton v x l ca phn mm. Trongphmvithitksbvchitit,cxuthinmtshotngthitkkhcnhau. Bn cnh vic thit k d liu, kin trc v th tc, nhiu ng dng hin i c hot ng thit k giaodinphnbit.Thitkgiaodinlpracchbtrvcchtngtcngi-my(HCI humen computer interface). Mi quan h gia cc kha cnh k thut v qun l ca thit k c minh ho trong hnh v di y. 46 Vic m t thit k. Thit k phn mm l mt m hnh ca th gii thc m tcc thc th v cc mi quan h ca chng vi nhau. Thit k cn c m t sao cho t c mc sau: Lm c s cho vic thc hin chi tit. Lm phng tin lin lc gia cc nhm thit k cc h con. Cung cp y thng tin cho ngi bn tr h thng. Ngi ta thng dng cc khi nim th, ccngn ng m t chngtrnh hoc vn bn khng hnh thc to dng ti liu thit k. 5.2. Cc nguyn tc thit k (Design principles) Phng php cu trc c dng rng ri trong nhng nm u ca nhng nm 1980. N cdngthnhcngtrongnhiudnln,nlmgimgithnhmtcchngk,sdng c cc khi nim chun v m bo rng vic thit k tun theo mt chun nht nh. Cc cng c CASE (Computer Aided Software Engineering thit k phn mm c my tnh h tr) c dng tr gip cho phng php ny. Cc phng php thit k thng tr gip mt vi cch nhn nhn h thng nh sau: Nhn nhn cu trc: Cho ci nhn cu trc thng qua lc cu trc. Nhn nhn quan h thc th: M t cu trc d liu logic thng dng, cp n c t d liu quan h thc th. Nhn nhn dng d liu: V lc dng d liu. Ngi ta cn dng lc chuyn trng thi b sung cho phng php trn. m bo cht lng cho mt biu din thit k, cn c cc tiu chun cho thit k tt. Song v mt phng php, chng ta a ra cc hng dn sau: 1.Thit k nn a ra cch t chc theo cp bc dng cch kim sot thng minh trong s cc thnh phn phn mm. THIT K S B Thit k kin trc Thit k th tc Thit k giao din Thit k d liu THIT K CHI TIT KHA CNH QUN L KHA CNH K THUT Quan h gia kha cnh k thut v kha cnh qun l trong thit k 47 2.Thit k nn theo cc module, tc l phn mm nn c phn hoch mt cch logic thnh cc thnh phn thc hin chc nng hay cc chc nng con xc nh. 3.Thit k nn cha cch biu din phn bit v tch bit gia d liu v th tc. 4.Thitknndnticcmodule(nhchngtrnhconhaythtc)nuraccctrng chc nng c bit. 5.Thit k nn dn n giao din l rt gn phc tp ca vic ni ghp li gia cc module v vi mi trng bn ngoi. 6.Thitknnchngtheocchdngmtphngphplpliciukhinbi thng tin c trong phn tch cc yu cu phn mm. Cc c trng trn ca mt thit k tt c c khi thc hin ng tin trnh thit k k ngh phn mm thng qua vic p dng cc nguyn l thit k c bn, phng php lun h thng v xt duyt thu o. Nh vy, mi phng php thit k phn mm u a vo nhng phng php trc cm v l php duy nht, cng nh mt cch nhn thin cn th no v ci g c trng cho cht lng thit kTuy vy mi phng php u c nhng c trng sau: 1.Mt c ch chuyn ho t biu din min thng tin thnh biu din thit k 2.Mt k php biu din cc thnh phn chc nng v dao din ca chng3.Cc trc cm lm mn v phn hoch4.Cc hng dn v nh gi cht lng Bt k phng php lun thit k no c dng, cng trnh s phn mm phi p dng mt tp cc khi nim nn tng cho thit k d liu, kin trc v th tc: Tru tng Modul Kin trc phn mm. Cp bc iu khinCu trc d liuTh tc phn mm Che du thng tinThit k hng chc nng H thng c thit k theo quan im chc nng, bt u mc cao nht, sau tinh ch dn dn thnh thit k chi tit hn. Trng thi ca h thng l tp trung v c chia s cho cc chc nng thao tc trn trng thi . Ban u, ta coi yu cu mc cao nht ca h thng l mt chc nng duy nht cn phi thc hin. Sau , ta tr li cho cu hi thc hin chc nng trn th cn phi lm cc cng vic g? 48 t cng vic trong cu hi trn c coi l chc nng con ca chc nng trn. Thc hin xong cc chc nng con cng l thc hin xong chc nng cha. H thng c phn r dn dn, v c lm mn. Hnh nh ca h thng s c xy dng theo cc bc trn. Thit k hng i tng H thng c nhn nhn nh mt b cc i tng (ch khng phi l mt tp hp cc chc nng). H thng c phn tn, mi i tng c thng tin v trng thi ca ring n. i tng l mt b cc thuc tnh xc nh trng thi ca i tng v cc php ton thc hin trn . Mi i tng l mt khch th ca mt lp m lp c xc nh bi thuc tnh v cc php ton ca n. N c tha k t mt vi lp i tng cp cao hn, sao cho nh ngha n ch cn nu cc khc nhau gia n v cc lp cao hn n. Cc i tng lin lc vi nhau ch bng trao i cc thng bo. Trong thc t, hu ht cc lin lc c thc hin gia cc i tng bng cch ni i tng ny vi mt th tc, m th tc ny kt hp vi mt i tng khc. Thit k hng i tng da trn tng che du thng tin. Gn y theo cch thit k ny, ngitaphttrinnhiuhthngcutobinhiuthnhphnclpvctngtcvi nhau. S tht, cc h phn mm ln phc tp n mc m ngi ta dng cc phng php tip cnkhcnhautrongvicthitkccthnhphnkhcnhautronghthng.Chngcmtchin lc tt nht no cho cc d n ln. Cc cch tip cn hng chc nng v hng i tng l b sunghtrchonhauchkhngphilloibnhau.Ksphnmmschnracchtipcn thch hp nht trong tnggiai on thit k.Nhn mc tng th th hthng nh l mt b cc i tng (ch khng phi l mt b cc chc nng), cho nn mc tru tng cao th cch tip cn hng i tng l thch hp hn. n mc chi tit th mt cch t nhin hn nn xem chng l cc chc nng tng tc gia cc i tng. Sau mi i tng li c phn gii thnh cc thnh phn, tc l c th xem n nh l mt h con. Rtnhiuhthng,cbitlhthngthigianthccnhng(vomththitbvt cht c thc) c cu to nh mt h gm mt b cc qu trnh hot ng song song v c lin lc vi nhau. Cc h ny thng phi tun theo cc rng buc nghim ngt v thi gian, m cc phn cngthngphnngtngichm,chccchtipcnnhiubxlhotngsongsong mi c th hon thnh c yu cu v thi gian. Ccchngtrnhtuntldthitk,thchinvkimtravthnghimhnlcch thng song song. S ph thuc v thi gian gia cc qu trnh l kh hnh thc ho, kh khng ch v th nghim. Do , qu trnh thit k nn c xem nh l mt hot ng gm 2 giai on: Giai on 1: Minh nh cu trc thit k logic, c th l cc thnh phn ca h thng v cc mi quan h gia chng. C th dng cch nhn hng chc nng hoc cch nhn hng i tng. 49 Giai on 2: Thc hin cu trc trong dng c th thc hn c. Giai on ny i khi c gi l thit k chi tit v i khi l lp trnh. Chc rng s quyt nh v tnh song song nn l giai on ny ch khng phi l cc giai on sm hn trong qu trnh thit k. Bi tp: 1.Trnh by cc giai on thit k phn mm 2.Trnh by cc nguyn tc thit k phn mm 50 Chng 6: Kim th phn mm 6.1. Mc ch (Testing objectives) Kim th phn mm lhot ng kho st thctinsn phm hay dchv phn mm trong ng mi trng chng d nh s c trin khai nhm cung cp cho ngi c li ch lin quan nhng thng tin v cht lng ca sn phm hay dch v phn mm y. Mc ch ca kim th phn mm ltmracclihaykhimkhuytphnmmnhmmbohiuquhotngtiucaphn mm trong nhiu ngnh khc nhau. 6.2. Nguyn tc kim th (Testing principles) Kim th khng phi l g ri (Debugging) Kim th khng bao gi c th pht hin hon ton 100% li Mc ch ca kim th l tm ra li ch khng phi nguyn nhn gy ra chng 6.3. Kim th theo ng c bn (Basic path) Cc ng dn c xc nh bng vic xy dng th chng trnh. Mi trng hp kim th s tngngvimtngdn.Tacthgpvniviccngdnkhngththchin c. th chng trnh th chng trnh l mt th c hng trong : Cc nh ca th biu din cc cu lnh Cc cnh biu din lung iu khin Ngha l, c mt cnh t nh i n nh j nu cu lnh tng ng vi nh j c th c thc thi ngay lp tc sau cu lnh tng ng vi nh i th chng trnh ca bi ton tam gic: 51 Mt s nh ngha Chui: l mt ng dn m trong nh bt u v nh kt thc l khc nhau, v cc nh bn trong c bc vo =1 v bc ra =1 Cc bc thc hin: Xy dng th chng trnh/ th ng dn quyt nh t m ngun Tnh phc tp ca th 52 Xc nh mt tp hp cc ng dn c bn Thit k mt trng hp kim th tng ng vi mi ng dn c bn Thc thi cc trng hp kim th Mt ng dn c bn l ng dn ni t nh bt u n nh kt thc. S lng cc ng dn c lp cn c kim th bng gi tr V(G) = e-n+2*p . Trong : G l th ng dn quyt nhV(G) l phc tp ca th G e l s cnh, n l s nh, p l s thnh phn Cch xc nh cc ng dn c bn Chnmtngdncbnbanutngngvimtsthcthichngtrnhbnhthng (ng dn c bn ny nn c cng nhiu nh quyt nh cng tt) tm cc ng dn c bn khc, d tm ngc/xui trn ng dn ban u cho n khi gp mt nh quyt nh. Thay i quyt nh ti nh ny, v tip tc tm ng dn kh thi cho n nh kt thc Lp li bc trn cho n khi tt c cc quyt nh u c thay i vi nhnh ng v sai V d: 53 Cc ng dn c bn trong bi ton tam gic Cc ng dn c bn kh thi 54 KimththeongdncbndavophngphpcaTomMcCabe.Nsdngth chng trnh xc nh cc trng hp kim th. Kim th theo ng dn c bn c s dng cho cp kim th n v. N c nhc im l ngi kim th phi c k nng lp trnh tt c th hiu c m ngun v lung iu khin trong chng trnh 6.4. Kim th theo phn vng tng ng (Equivalence partitioning)Xem xt v min gi tr ca cc bin chia thnh cc phm vi tng ng Bao gm c min d liu khng ng Khng quan tm n s trng lp V d HyxemxtmthmFviccbinuvox1,x2cgitrcgiihnvnmtrongcc khong sau: a