I HC QUC GIA H NI TRNG I HC CNG NGH

Nguyn c Trung

XY DNG SERVICE PROXY KIM CHNG RNG BUC THI GIAN TRONG WEB SERVICE COMPOSITION

KHO LUN TT NGHIP I HC H CHNH QUY

Ngnh : Cng Ngh Thng Tin

H NI, 2009

I HC QUC GIA H NI TRNG I HC CNG NGH

Nguyn c Trung

XY DNG SERVICE PROXY KIM CHNG RNG BUC THI GIAN TRONG WEB SERVICE COMPOSITION

KHO LUN TT NGHIP I HC H CHNH QUY

Ngnh : Cng Ngh Thng Tin Cn b hng dn: TS. Trng Ninh Thun

H NI, 2009

i

LI CM N

Em xin gi li cm n su sc nht n TS. Trng Ninh Thun, ngi thy cho em nh hng, tn tnh ch bo em nhng kin qu bu v cng ngh Web Service, cc kin thc v cht lng dch v Web. Thy gip em rt nhiu v i cng em trong sut thi gian thc hin kho lun. Thy ch cho em cch tip cn, nghin cu mt cng ngh mi, cch tm ra nhng gii php cho vn mc phi. Em xin chn thnh cm n qu Thy C v cc bn gip em trong nhng nm hc qua. Em xin cm n B mn Cng ngh phn mm, Khoa Cng ngh thng tin, Trng i Hc Cng Ngh, i Hc Quc Gia H Ni to iu kin thun li cho em trong sut qu trnh hc tp v lm kho lun ny. ti Xy dng Service Proxy kim chng rng buc thi gian trong Web Service Composition l mt ti kh mi m, li c hon thnh trong qu thi gian hn hp nn kh trnh khi nhng khim khuyt. Em mong nhn c nhng gp chn thnh t thy c gio v cc bn ti c th c m rng v nghin cu k hn, a vo trong thc tin ngnh cng ngh thng tin hin nay.

H Ni, ngy 15 thng 05 nm 2009 Sinh vin: Nguyn c Trung

ii

TM TT KHO LUN

Ngy nay cng vi s pht trin mnh m ca mi trng Internet, cc ng dng trin khai trn nn Web ngy cng c pht trin rng ri v phong ph. ng thi i cng s pht trin mnh m ca nn kinh t th trng l nhu cu p dng cng ngh thng tin vo trong cc quy trnh thng mi ngy cng tr nn ph bin v l im mu cht cc t chc doanh nghip gii quyt cng vic ca mnh. S ra i ca Web Service c coi l mt cng ngh mang n cuc cch mng trong cch thc hot ng ca cc dch v B2B Business to Bussiness v B2C Bussiness to Customer. Gi tr c bn ca dch v Web da trn vic cung cp cc phng thc theo chun trong vic truy cp i vi h thng ng gi v k tha. Cc phn mm c vit bi nhng ngn ng lp trnh khc nhau v chy trn cc nn tng khc nhau c th s dng Web Service chuyn i d liu thng qua mng Internet. Ni dung ca kha lun a ra mt ci nhn tng qut v cng ngh Web Service, phn tch v tm hiu cc thnh phn chun c s dng trong cng ngh Web Service, i vo nghin cu kin trc v Web Service. T nhng kin thc thu c v cng ngh Web Service, kha lun i n mt hng tip cn mi l tm hiu v cht lng cc dch v Web QoS cho Web Service da trn m hnh tch hp Web Service vi cc Web Service Composition. T cc kin thc v cht lng cc dch v Web, kha lun s tm hiu v mt kha cnh cht lng dch v Web l kim chng rng buc thi gian p ng ca cc Web Service Composition v m hnh ha cc rng buc thi gian trn biu UML Timing Diagram. minh ha cho vic kim chng rng buc thi gian p ng ca cc Web Service Composition, chng ti tin hnh xy dng mt ng dng nh l Web Service Travel-Agent v tin hnh o lng thi gian p ng ca cc Service Composition hp thnh ln Web Service Travel-Agent .

iii

MC LCCHNG 1: T VN .....................................................................................................1 1.1. Bi cnh..........................................................................................................................1 1.2. Mc tiu kha lun.........................................................................................................2 1.3. Cu trc kha lun..........................................................................................................3 CHNG 2: CNG NGH WEB SERVICE..........................................................................5 2.1. Kin trc hng dch v SOA.......................................................................................5 2.1.1. Khi nim kin trc hng dch v SOA.................................................................5 2.1.2. Nguyn tc thit k ca SOA...................................................................................6 2.2. Cng ngh Web Service.................................................................................................7 2.2.1. Tng quan v Web Service.......................................................................................7 2.2.2. Kin trc Web Service.............................................................................................9 2.2.3. Cc cng ngh ca Web Service............................................................................13 CHNG 3: QoS CHO WEB SERVICE...............................................................................26 3.1. Cht lng dch v Web Service QoS cho Web Service..........................................26 3.2. Cc yu cu v cht lng dch v cho Web Service...................................................27 3.3. QoS cho cc dch v Web.............................................................................................29 3.4. iu chnh v thit lp rng buc QoS.........................................................................30 3.5. Hiu ng tht c chai trong qu trnh thc thi ca Web Service..................................30 3.6. nh gi hiu nng giao thc SOAP............................................................................32 3.7. Phng php tip cn cung cp cht lng dch v cho Web Service....................33 CHNG 4: BIU TIMING DIAGRAM.......................................................................35 4.1. Gii thiu UML............................................................................................................35 4.2. Tng quan v biu Timing Diagram........................................................................36 4.3. Mc ch ca biu Timing Diagram........................................................................37 4.4. Cc k hiu ca biu Timing Diagram.....................................................................37 4.5. Cc thnh phn ca biu Timing Diagram..............................................................39 4.5.1. Cc trng thi..........................................................................................................39 4.5.2. Cc s kin v cc thng ip................................................................................41 4.5.3. Thi gian.................................................................................................................42 4.5.4. Cc ng State-Line.............................................................................................43 4.5.5. Rng buc thi gian................................................................................................43 CHNG 5: BI TON NGHIN CU..............................................................................45 5.1. Tm hiu v Service Proxy...........................................................................................45 5.2. Tm hiu v Web Service Composition........................................................................48 5.3. Bi ton kim chng rng buc thi gian p ng ca cc Web Service Composition ..............................................................................................................................................52 5.3.1. Gii thiu bi ton..................................................................................................52 5.3.2. Mc tiu v yu cu ca bi ton..........................................................................53 5.3.3. Phn tch bi ton...................................................................................................54 CHNG 6: THC NGHIM...............................................................................................57 6.1. Phm vi ng dng.........................................................................................................57 iv

6.2. Thit k ng dng ........................................................................................................59 6.3. Ci t, xy dng v trin khai ng dng.....................................................................61 6.3.1. Ci t chng trnh...............................................................................................61 6.3.2. Xy dng v trin khai cc Web Services thnh phn..........................................64 6.3.3. Xy dng v trin khai Service Proxy....................................................................69 6.3.4. Pht trin chng trnh client v thc nghim.......................................................72 CHNG 7: KT LUN.......................................................................................................77

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DANH SCH CC THUT NG V KHI NIM

THUT NG

KHI NIM Service Oriented Architecture Kin trc hng dch v Cc Serivice c sn c th c dng tch hp ln mt Web Service ln hn. Hoc l mt Web Service thnh phn chuyn bit phc v cho mt nhim v

SOA Service Composition

Service Composite Service Provider Service Consumer

Web Service c tng hp ln t cc Service Composition Nh cung cp dch v Web Service. y chnh l cc ngun cung cp a ra cc dch v cho khch hng s dng y chnh l dch v pha ngi s dng, yu cu cc dch v a ra bi Service Provider Ni chp nhn cc yu cu a ra bi Service Consumer, lin h vi Service Provider ly dch v tr v cho Service Consumer Vit tt ca Word Wide Web Consortium l mt t chc lp ra cc chun cho cc cng ngh chy trn nn Internet, c bit l Word Wide Web Quality of Service - Cht lng dch v Thng ip yu cu Thng ip p ng

Service Broken

W3C

QoS Message request Message response

DANH SCH CC HNH VHnh 1:Web Service cho php truy cp ti cc code ng dng s dng chun cng ngh Internet........................................................................................................................................7 vi

Hnh 2:Web Service cung cp mt tng tru tng gia ng dng client v ng dng cn gi ti................................................................................................................................................8 Hnh 3:M t c ch hot ng ca Web Service......................................................................9 Hnh 4: Web Service technology stack.....................................................................................10 Hnh 5: TCP/IP network model................................................................................................11 Hnh 6:M t cu trc ca mt thng ip XML.....................................................................14 Hnh 7:M t cu trc ca mt thng ip SOAP....................................................................15 Hnh 8: M t thng ip SOAP faults....................................................................................16 Hnh 9:M t vic trao i thng ip SOAP thng qua giao thc HTTP...............................18 Hnh 10:M t thnh phn binding trong ti liu WSDL.........................................................20 Hnh 11:Minh ha v d ca mt ti liu WSDL.....................................................................21 Hnh 12:Minh ha cu trc d liu businessService................................................................23 Hnh 13:Biu Timing Diagram di dng Robus Diagram.............................................38 Hnh 14:Biu Timing Diagram di dng m rng............................................................39 Hnh 15:Minh ha cc trng thi c th hin trong biu Timing Diagram.....................40 Hnh 16:Minh ha cc s kin v thng ip trong biu Timing Diagram.........................41 Hnh 17:Minh ha th hin thi gian trong biu Timing Diagram......................................42 Hnh 18:Thi gian c lng trong biu Timing Diagram.................................................42 Hnh 19:Minh ha cc ng state-line trong biu Timing Diagram.................................43 Hnh 20:Minh ha cc rng buc thi gian trong biu Timing Diagram............................44 Hnh 21:Minh ho m hnh Web Service vi Service Proxy...................................................45 Hnh 22:Minh ha m hnh tch hp Web Service...................................................................49 Hnh 23:Minh ho m hnh tng quan bi ton Travel-Agent.................................................54 Hnh 24:Minh ho ng Lifeline cho SearchHotel Service...................................................55 Hnh 25:Minh ho ng Lifeline cho SearchFlight Service...................................................56 Hnh 26:Minh ha thit k tng th ca ng dng...................................................................59 Hnh 27:Biu tun t ca h thng......................................................................................60 Hnh 28:Minh ha giao din Admin ca apache soap trn Web Server ti cng 2417............62 Hnh 29:Minh ha giao din Admin ca apache soap trn Web Server ti cng 8080............63 Hnh 30:Minh ha trang Admin ca Apache Axis trn Web Server ti cng 8080.................63 Hnh 31:Code kt ni database trong file SearchHotel Service...............................................64 Hnh 32:Ni dung ca tp deploy.wsdl....................................................................................65 Hnh 33:Danh sch cc dch v lit k trn web site soap engine............................................66 Hnh 34:Ni dung file deploy.wsdd.........................................................................................67 Hnh 35:Cc dch v c lit k trn trang qun tr ca Axis................................................68 Hnh 36:Ni dung file WSDL ca dch v SearchFlightService..............................................69 Hnh 37:Code Service Proxy goi ti SearchFlightService.......................................................70 Hnh 38:Minh ha o lng thi gian p ng........................................................................71 Hnh 39:Minh ha test chng trnh.........................................................................................73 Hnh 40:Biu Timing Diagram m t rng buc thi gian ca WSComposition...............74 Hnh 41:Minh ho m hnh kim chng rng buc thi gian p ng....................................75

vii

CHNG 1: T VN

1.1. Bi cnhS pht trin ca cng ngh thng tin cho php ng dng hiu qu vo cc hot ng kinh doanh, gii tr, qun l cng nh mt s lnh vc khoa hc x hi khc. S bng n ca Internet tr thnh mt iu kin ht sc thun li, em li hiu sut cao trong cng vic ng thi gim thiu chi ph cho cc doanh nghip. Tuy nhin cc yu cu v nghip v phc tp trong h thng ny dn n cc h thng phn mm tng ng cng ngy cng tr nn phc tp, cng knh v kh kim sot. Rt nhiu yu cu nghip v i hi x l cc vn lin quan n d liu phn tn, x l cc thng tin khc nhau do nhiu t chc nm gi. c nhiu kin trc phn mm c a ra nhng cha mnh gii quyt c vn ny. S ra i ca kin trc phn mm hng dch v m ra mt hng i mi trong vic gii quyt cc loi bi ton ny. Kin trc SOA nh ngha mt kiu kin trc cho vic xy dng cc h thng phn tn theo hng dch v, tc l h thng c phn tch thnh cc module chng trnh, v cc module ny c pht trin c lp, cc module s dng cc cng ngh khc nhau nhng vn c th giao tip c vi nhau. Mt cng ngh tiu biu nht cho kin trc hng dch v l cng ngh Web Service. Vi cng ngh Web Service, mi Service y l mt module c th thc hin cc cng vic khc nhau, ta c th tng hp cc Service thnh phn li cng thc hin mt cng vic ln, c gi l cng ngh tch hp Web Service, khi mi Service thnh phn c gi l mt Service Composition. S ra i ca cng ngh Web Service em li rt nhiu li th cho vic chia s ti nguyn qua mng, tr gip xy dng cc h thng phn tn ng thi p ng c tnh mm do cn thit, h thng c th d dng chp nhn nhng thay i ln so vi thit k ban u m vn m bo cho vn nng cp v bo tr sau ny. Web Service em n y s

1

p ng cn thit cho cc quy trnh B2B Bussiness to Bussiness v B2C Bussiness to Customer, chnh v th Web Service hin ti ang l mt thut ng ang c nhc n rt nhiu v ngy cng c s dng rng ri. Tuy nhin Web Service l mt cng ngh trin khai thng qua mi trng Internet cho nn vn v cht lng cc dch v Web cng l mt vn ng lu tm, chnh v th xut hin cc tiu chun cht lng dch v cho Web Service QoS cho Web Service. Mt kha cnh v QoS cho Web Service l thi gian p ng ca cc dch v Web, y l mt vn rt ng quan tm v Web Service l mt kin trc phn mm phn tn, cho nn thng c mt s lin kt gia cc dch v vi nhau. Khi thi gian p ng ca mt dch v qu lu c th dn n nh hng ti cc dch v khc. Mt khc khi c nhiu nh cung cp dch v Web th khi s c nhiu s la chn ca khch hng trong vic tm v s dng dch v Web tt nht cho mnh. Trn mi trng Internet, ngi s dng trc tin s quan tm nht n vn thi gian, thi gian p ng ca mt dch v Web nhanh hay chm s quyt nh n s thnh cng hay khng ca nh cung cp dch v Web . Vic kim sot thi gian p ng ca cc dch v Web l mt kha cnh rt rng, cho nn phm vi kha lun ny chng ti cp n vic kim chng rng buc thi gian p ng ca vic tch hp cc Web Services c p ng c vi tiu chun QoS v thi gian hay khng.

1.2. Mc tiu kha lun thc hin cc vn nu ra nh trn, kho lun s ln lt trnh by nhng kin thc cn thit gii quyt yu cu ca bi ton t ra. Kha lun s tp trung vo mt s cc vn sau:

Tm hiu khi qut v kin trc hng dch v SOA, i su tm hiu cng ngh Web Service, kin trc v cc thnh phn s dng cho Web Service.

Tm hiu Service Proxy, mt dng Web Service c bit c trin khai pha ngi s dng dch v.

2

Tip cn n vn v cht lng cc dch v Web, cc yu t nh hng n hiu nng hot ng ca Web Service. i vo tm hiu vic o lng thi gian p ng ca cc Web Service Composition s dng Service Proxy.

Nghin cu v biu UML Timing Diagram, m hnh ha cc rng buc thi gian p ng ca Web Service Composition trn biu UML Timing Diagram.

xut phng php kim chng t ng thi gian p ng ca cc Web Services trong mt ng dng s dng s tch hp cc Web Services vi cc rng buc m biu UML Timing Diagram m t.

1.3. Cu trc kha lunCc phn cn li ca kha lun bao gm cc phn sau: Chng 2 a ra ci nhn tng qut v cng ngh Web Service, tm hiu v cc thnh phn chun c s dng trong cng ngh Web Service, kin trc Web Service v quy trnh hot ng ca mt Web Service. Chng 3 tip cn n vn cht lng dch v Web. Xem xt cc yu cu v cht lng cho Web Service, cc yu t nh hng n hiu nng hot ng ca Web Service v mt vi phng php n gin cung cp cht lng dch v Web. Chng 4 trnh by v biu mi c thm vo trong UML 2.0 l biu Timing Diagram. Tm hiu v mc ch biu , cc thnh phn s dng trong biu Timing Diagram v t s dng biu Timing Diagram c t cho cc rng buc thi gian ca cc Web Service Composition. Chng 5 phn tch bi ton Xy dng Service Proxy kim chng rng buc thi gian p ng trong Web Service Composition, nghin cu v Service Proxy, Service Composition v cng ngh tch hp Web Service.

3

Chng 6 xy dng mt v d minh ho cho bi ton kim chng, da vo cc kt qu thu c t v d minh ho thc hin mc tiu ca kha lun l kim chng xem cc kt qu thu c c p ng c tiu chun ra hay khng. Chng 7 nh gi kt qu kha lun t c v nu ra hng pht trin trong tng lai cho ti ny.

4

CHNG 2: CNG NGH WEB SERVICEChng 2 cp n cng ngh Web Service, a ra khi nim cn bn v kin trc hng dch v SOA, i su vo tm hiu cng ngh Web Service, cc cng ngh c s dng cho Web Service, kin trc ca Web Service v cc li ch khi s dng cng ngh ny.

2.1. Kin trc hng dch v SOA2.1.1.Khi nim kin trc hng dch v SOA SOA - vit tt ca thut ng Service Oriented Architecture (kin trc hng dch v) l Khi nim v h thng trong mi ng dng c xem nh mt ngun cung cp dch v [9]. Dch v l yu t then cht trong SOA. C th hiu dch v nh l hm chc nng (module phn mm) thc hin quy trnh nghip v no , mt cch c bn, SOA l tp hp cc dch v kt ni mm do vi nhau (ngha l mt ng dng c th ni chuyn vi mt ng dng khc m khng cn bit cc chi tit k thut bn trong), c giao tip (dng gi hm dch v) c nh ngha r rng v c lp vi nn tng h thng, v c th ti s dng. SOA l cp cao hn ca pht trin ng dng, ch trng n quy trnh nghip v v dng giao tip chun gip che i s phc tp ca k thut bn di. Thit k SOA tch ring phn thc hin dch v (phn mm) vi giao tip gi dch v. iu ny to nn mt giao tip nht qun cho ng dng khch s dng dch v bt chp cng ngh thc hin dch v. Thay v xy dng cc ng dng n l v s, nh pht trin s xy dng cc dch v c tnh linh hot c th trin khai v ti s dng trong ton b quy trnh nghip v. iu ny cho php ti s dng phn mm tt hn, cng nh tng s linh hot v nh pht trin c th ci tin dch v m khng lm nh hng n Client s dng dch v.

5

Thc ra khi nim SOA khng hon ton mi, DCOM v CORBA cng c kin trc tng t. Tuy nhin cc kin trc c rng buc cc thnh phn vi nhau qu cht, v d cc ng dng phn tn mun lm vic vi nhau phi t uc tho thun v chi tit tp hm API, mt thay i m lnh trong thnh phn COM s yu cu nhng thay i tng ng i vi m lnh truy cp thnh phn COM ny. u im quan trng nht ca SOA l kh nng kt ni mm do (nh s chun ho giao tip) v ti s dng. Cc dch v c th c s dng vi trnh Client chy trn nn tng bt k v c vit bi ngn ng bt k. 2.1.2.Nguyn tc thit k ca SOA SOA da trn hai nguyn tc thit k quan trng [17]: M-un: l tch cc vn ln thnh nhiu vn nh hn ng gi : Che i d liu v l-gic trong tng m-un i vi cc truy cp t bn ngoi. Hai tnh cht ny s dn n c im thit k ca kin trc SOA l cc dch v tng tc vi nhau qua cc thnh phn giao tip, tuy nhin cc dch v vn hot ng c lp vi nhau, chia s cc lc d liu cho nhau v tun th cc chnh sch ca kin trc chung nht.

6

2.2. Cng ngh Web Service2.2.1.Tng quan v Web Service Web Service l g: Web Service l mt giao din truy cp mng n cc ng dng chc nng, c xy dng t vic s dng cc cng ngh chun Internet [1][4]. c minh ho trong hnh di y.

Hnh 1: Web Service cho php truy cp ti cc code ng dng s dng chun cng ngh Internet

Thut ng Web Service din t mt cch thc tch hp cc ng dng trn nn web li vi nhau bng cch s dng cc cng ngh XML, SOAP, WSDL, v UDDI trn nn tng cc giao thc Internet vi mc tiu tch hp ng dng v truyn thng ip. XML c s dng nh du d liu, SOAP c dng truyn d liu, WSDL c s dng m t cc dch v c sn v UDDI c s dng lit k nhng dch v no hin ti ang c sn c th s dng. Web Service cho php cc t chc c th trao i d liu vi nhau m khng cn phi c kin thc hiu bit v h thng thng tin ng sau Firewall kia [1]. Khng ging nh m hnh Client/Server truyn thng, chng hn nh h thng Webserver/webpage, Web Service khng cung cp cho ngi dng mt giao din ho no, Web Service n thun ch l vic chia s cc d liu logic v x l cc d liu thng qua mt giao din chng trnh ng dng c ci t xuyn sut trn mng my tnh. Tuy nhin ngui pht trin Web Service hon ton c th a Web Service vo mt giao din ho ngi dng (chng hn nh l mt trang web hoc mt chng trnh thc thi no ) c th cung cp thm cc chc nng c bit cho ngi dng.

7

Web Service cho php cc ng dng khc nhau t cc ngun khc nhau c th giao tip vi cc ng dng khc m khng i hi nhiu thi gian coding, do tt c cc qu trnh giao tip u tun theo nh dng XML, cho nn Web Service khng b ph thuc vo bt k h iu hnh hay ngn ng lp trnh no. V d, chng trnh vit bng ngn ng Java cng c th trao i d liu vi cc chng trnh vit bng Perl, cc ng dng chy trn nn Windows cng c th trao i d liu vi cc ng dng chy trn nn Linux. Cng ngh Web Service khng yu cu phi s dng trnh duyt v ngn ng HTML, i khi Web Service cn c gi l Application Services. Xt theo mt kha cnh khc, nu cc ng dng c th truy cp thng qua mng my tnh bng vic s dng cc giao thc nh HTTP, XML, SMTP hoc Jabber th chnh l Web Service. Nh Hnh 1 v Hnh 2 minh ha , Web Service l mt Application Interface c t gia Application Code v ngi s dng cc code . N c th c v nh mt tng tru tng, phn tch gia platform v ngn ng lp trnh, n m t cch thc m cc application code c triu gi nh th no. iu ny c ngha nu bt k mt ngn ng lp trnh no h tr Web Service u c th truy cp cc ng dng chc nng ca nhau.

Hnh 2: Web Service cung cp mt tng tru tng gia ng dng client v ng dng cn gi ti.

Ngy ny, Web Service c th c trin khai trn Internet di dng mt Website HTML, chnh v th, cc Application Service cn phi c mt c th cho vic cng b, qun l, tm kim v phc hi ni dung c ngi s dng truy cp thng qua giao thc chun HTTP v nh dng d liu HTML. Cc ng dng Client ( nh Web Browser) cn phi hiu cc chun m Web Service h tr c th tng tc vi cc service nhm thc thi mt nhim v nh vic t mua sch, gi thip mng hoc l c bn tin v..v.8

Web Service cung cp tnh tru tng cho cc giao din chun, cho nn s khng ny sinh ra bt k vn g trong qu trnh tng tc khi cc service c vit trn java v trnh duyt c vit bng C++, hoc cc service c trin khai trn Unix trong khi cc trnh duyt li c trin khai trn Windows. Web Service cho php giao tip gia cc platform khc nhau c th hot ng cng nhau theo nguyn tc to ra mt platform trung gian c lin quan. Tnh tng thch (Inteoperability) l mt li th v cng mnh m ca Web Service, thng thng, cc cng ngh Java v cng ngh ca Microsoft rt kh c th tch hp c vi nhau , nhng vi Web Service th cc Application v Client s dng 2 cng ngh trn hon ton c kh nng tng tc vi nhau thng qua Web Service. Rt nhiu nh cung cp ng dng nh IBM v Microsoft u h tr Web Service trong cc sn phm ca h. IBM h tr Web Service thng qua gi WebSphere, Tivoli, Lotus v DB2 v Microsoft vi .NET cng h tr Web Service. 2.2.2. Kin trc Web Service 2.2.2.1. M t c ch hot ng ca Web Service

Hnh 3: M t c ch hot ng ca Web Service.

C ch hot ng ca Web Service yu cu phi c 3 thao tc l : Find, Public, Bind[1].

9

Trong kin trc Web Service, Service Provider cng b cc m t v cc service thng qua Service Registry. Service Consumer tm kim trong cc Service Registry tm ra cc service m h cn s dng. Service Consumer c th l mt ngi hoc cng c th l mt chng trnh. K thut m t dch v l mt trong nhng thnh phn ch cht ca kin trc Web Service. Cc thng tin m t y nht v kin trc Web Service c th hin trong hai ti liu ring bit, l NASSL Network Accessible Service Specification Language v WDS Web-Defined Service. NASSL l mt ti liu di dng chun ca XML cho cc service chy trn nn Network, n c s dng ch ra cc thng tin hot ng ca Web Service, chng hn nh danh sch cc service, cc m t v service, ngy ht hn ca service v cc thng tin lin quan n cc Service Provider, nh tn, a ch. Ti liu WDS l mt ti liu mang tnh p ng y cho ti liu NASSL. Khi ta kt hp hai ti liu ny vi nhau ta s c c s m t mt cch y v cc dch v cho pha yu cu dch v c th d dng tm kim v gi cc dch v . 2.2.2.2.Kin trc phn tng ca Web Service

Hnh 4:

Web Service technology stack

10

M hnh kin trc phn tng ca Web Service tng t vi m hnh TCP/IP c s dng m t kin trc Internet.

Hnh 5:

TCP/IP network model

Cc tng truyn thng nh Packaging, Description, v Discovery trong m hnh Web Service Stack l nhng tng cung cp kh nng tch hp v cn thit cho m hnh ngn ng lp trnh trung lp.

Tng Discovery : Tng Discovery cung cp c ch cho ngi dng kh nng ly cc thng tin m t v cc Service Provider. Cng ngh c s dng ti tng ny chnh l UDDI Universal Description, Discovery and Integration.

Tng Desciption : Khi Web Service c thc thi, n cn phi a ra cc quyt nh v cc giao thc trn cc tng Network, Transport, Packaging m n s h tr trong qu trnh thc thi. Cc m t v dch v s a ra phng php lm th no m cc Service Consumer c th lin kt v s dng cc service . Ti tng Description, cng ngh c s dng y chnh l WSDL (Web Service Desciption Language) Ngn ng m t Web Service. Ngoi ra, t ph bin hn, chng ta cn c 2 ngn ng khc c nh ngha bi t chc W3C l ngn ng mt t ti nguyn - W3Cs Resource Desciption Framework (RDF) v ngn ng nh du s kin DARPA. C hai ngn ng ny u c kh nng cung cp vic m t Web Service mnh hn ngn ng WSDL tuy nhin do tnh phc tp ca chng nn khng c pht trin rng ri. Chng ti s cp n ngn ng WSDL mt cch c th hn trong phn Cc cng ngh ca Web Service ti chng 2 ca kha lun ny.

11

Tng Packaging: Vic thc hin vn chuyn cc d liu Web Service c thc hin bi tng Transport, tuy nhin trc khi c vn chuyn, cc d liu cn phi c ng gi li theo cc nh dng nh trc cc thnh phn tham gia vo m hnh Web Service c th hiu c, vic ng gi d liu c thi bi tng Packaging. Vic ng gi d liu bao gm cc cng vic nh dng d liu, m ha cc gi tr i km d liu v cc cng vic khc. Cc d liu c th c ng gi di dng cc ti liu HTML, tuy nhin vi cc ti liu HTML thng khng thun tin cho yu cu ny bi v HTML ch c u im trong vic th hin d liu hn l trnh by ngha d liu . XML l mt nh dng c bn nht cho vic trnh by d liu, bi v XML c th c s dng trnh by ngha d liu c vn chuyn, v hn th na, hin ti a s cc ng dng chy trn nn Web-Base u h tr cc b phn tch c php XML. SOAP l cng ngh ch yu c s dng ti tng ny, n l mt giao thc ng gi d liu ph bin da trn nn tng XML. Chng ta s cp su hn n giao thc ng gi d liu SOAP trong phn Cc cng ngh ca Web Service trong chng 2 ca kha lun ny.

Tng Transport : Tng Transport c vai tr m nhim vic vn chuyn cc Web Service Message, ti y bao gm mt vi dng cng ngh khc nhau cho php cc giao tip trc tip gia cc Application to Application da trn tng Network. Mi cng ngh bao gm cc giao thc nh tcp, http, smtp v jabber ..v.v. Vic la chn giao thc vn chuyn c da trn mi nhu cu giao tip ca cc Web Service. v d: vi giao thc HTTP l mt giao thc vn chuyn kh ph bin c s dng cho cc ng dng Web-Base, nhng n khng cung cp c ch giao tip bt i xng. Jabber, xt trn phng din khc, n khng phi l mt chun nhng c kh nng cung cp tt cc knh giao tip bt i xng.

12

Tng Network : Tng Network trong cng ngh Web Service chnh xc ging tng Network trong m hnh giao thc TCP/IP. N cung cp kh nng giao tip c bn, nh a ch v nh tuyn.

2.2.3.Cc cng ngh ca Web Service 2.2.3.1.Ngn ng XML RPC

XML : c vit tt ca cm t Extensible Markup Language Ngn ng nh du d liu[1][3].

RPC c vit tt ca cm t Remote Procedure Call Th tc gi t xa. RPC cung cp cho ngi pht trin k thut nh ngha ra mt giao din m c th c gi t xa thng qua mi trng mng my tnh. Giao din ny c th l mt hm n gin nhng cng c th l mt th vin API khng l[1][3].

XML RPC l mt hng tip cn d v r rng nht cho Web Service, n cung cp phng thc gi mt ng dng t mt my tnh local n mt my tnh t xa thng qua mi trng mng. XML RPC cho php chng trnh c kh nng to ra cc hm hoc cc th tc gi hm thng qua mng my tnh.

XML RPC s dng giao thc HTTP vn chuyn thng tin t Client n Server.

XML RPC s dng ngn ng XML m t cc thng ip yu cu v cc thng ip p ng gn gi vi ngn ng t nhin.

XML RPC Client ch ra c th cc thng tin v tn th tc, cc tham bin trong thng ip XML request, v Server tr v li hoc tr v thng ip response trong thng ip XML response.

Cc tham s ca XML-RPC n gin ch l kiu d liu v ni dung tuy nhin cc cu trc d liu phc tp nh struct, array cng c h tr bi XML RPC.13

2.2.3.2.Giao thc truyn thng ip SOAP SOAP vit tt cho cm t - Simple Object Access Protocol. Trong kin trc phn tng ca Web Service, SOAP nm tng Packaging, SOAP l mt giao thc ng gi cho cc d liu chia s gia cc ng dng. Xt v c bn, SOAP l XML, chnh v th SOAP l mt ng dng c th ca XML. SOAP c xy dng ln t cc chun XML nh XML Schema v XML Namespaces dng cho vic nh ngha SOAP v cc chc nng ca n[14]. Cc thnh phn chun ca SOAP a) Thng ip XML Thng ip XML l cc ti liu XML c dng trao i thng tin gia cc ng dng. N cung cp tnh mm do cho cc ng dng trong qu trnh giao tip vi nhau v l mt dng c bn ca SOAP. Cc thng ip ny c th l bt c th g: Ha n thanh ton, yu cu v gi c phiu, mt truy vn ti mt cng c tm kim hoc c th l bt k thng tin no c quan h ti tng thnh phn ca ng dng.

Hnh 6: M t cu trc ca mt thng ip XML

Bi v XML khng ph thuc vo mt ng dng c th, h iu hnh hay ngn ng lp trnh no, cho nn cc thng ip XML c th s dng trong tt c cc mi trng. Mt chng trnh Windows Perl c th to ra mt thng ip XML, trnh by thng ip v gi n cho mt chng trnh ci t bng ngn ng Java c trin khai trn nn Unix.

14

b) RPC v EDI S dng thng ip XML, ng nhin SOAP c 2 ng dng lin quan: RPC v EDI. Th tc gi hm t xa RPC - Remote Procedure Call l mt dng tnh ton phn tn c bn, m t cch thc mt chng trnh to ra mt th tc gi hm hoc phng thc ti mt my tnh khc, truyn i s v ly gi tr tr v. Trao i ti liu in t EDI Electronic Document Interchange l mt dng transaction c bn cho quy trnh thng mi , n nh ngha cc chun nh dng v thng dch ca cc ti liu, thng ip ti chnh v thng mi. Nu bn s dng SOAP cho EDI, khi thng ip XML c th l cc ha n thanh ton, tr tin thu, hoc cc ti liu tng t. Nu bn s dng SOAP cho RPC khi thng ip XML c th trnh by cc i s hoc cc gi tr tr v. c) Thng ip SOAP Thng ip SOAP bao gm phn t gc envelope bao trm ton b ni dung thng ip SOAP, v cc phn t header v body. Phn t header cha cc khi thng tin c lin quan n cch thc cc thng ip c x l nh th no. N bao gm vic nh tuyn v cc thit lp cho vic phn phi cc thng ip. Ngoi ra phn t Header cn c th cha cc thng tin v vic thm nh quyn, xc minh v cc ng cnh cho cc transaction. Cc d liu thc s c lu tr ti phn t body. Bt c th g c th trnh by c php XML u nm trong phn t body ca mt thng ip SOAP[3].

Hnh 7: M t cu trc ca mt thng ip SOAP

15

Tt c cc phn t envelope u cha chnh xc mt phn t body. Thn t body c th cha cc nt con theo yu cu. Ni dung ca phn t body l cc thng ip. Nu phn t envelope m cha phn t header, n ch cha khng nhiu hn mt phn t header v phn t header ny bt buc phi l phn t con u tin ca phn t envelope. Mi mt phn t cha header u c gi l header block. Mc ch ca header block cung cp giao tip cc thng tin theo ng cnh c lin quan n quy trnh x l cc thng ip SOAP. d) SOAP Faults SOAP faults l mt dng thng ip SOAP c bit c dng thng bo li trong qu trnh trao i thng tin, SOAP faults c th xut hin trong qu trnh x l cc thng ip SOAP[1].

Hnh 8:

M t thng ip SOAP faults

Cc thng tin v SOAP faults c din t di y:-

Fault code: Cc thut ton pht hin li s t sinh ra cc gi tr dng phn bit cc kiu li xut hin. Cc gi tr ny phi l l cc XML Qualified Name, iu c ngha l cc tn ca cc m li ch c ngha duy nht trong vng nh ngha XML Namespace.

-

Fault string: Din t cc li m ngi dng c th c hiu c.

16

-

Fault actor: y l du hiu nhn dng duy nht ca cc nt x l cc thng ip ni m cc li c kh nng xut hin.

-

Fault details: c s dng trnh by cc thng tin c th ca ng dng v li m n xut hin. N phi c trnh by nu c li xut hin trc tip c lin quan n cc vn v phn thn ca thng ip. Fault details c th khng cn s dng, tuy nhin s cn thit khi ta cn trnh by c th v thng tin li xut hin trong mi quan h ti cc phn cn li ca quy trnh x l cc thng ip SOAP.

e) Vn chuyn SOAP Nh chng ti trnh by trn, SOAP c t tng Packaging trong kin trc phn tng ca Web Service, SOAP ng pha trn tng Network v tng Transport. V th SOAP khng quan tm n vic giao thc vn chuyn no c s dng trong qu trnh trao i cc thng ip, iu lm cho giao thc thc s mm do ti bt k mi trng SOAP c trin khai no. Tnh mm do ca SOAP c th hin qua vic SOAP c th s dng cc giao thc vn chuyn khc nhau trao i cc thng ip, nh HTTP, FTP, SMTP, POP3, MQUERY v Jabber. Hin nay, HTTP c s dng ph bin trn Internet, chnh v tnh ph bin ca n, cho nn HTTP hin ti ang l giao thc vn chuyn ph bin nht cho vic vn chuyn cc thng ip SOAP. SOAP thng qua HTTP rt thun tin cho SOAP RPC trong vic gi yu cu v nhn cc thng ip p ng bi v bn cht HTTP chnh l giao thc da trn nn tng gi cc yu cu v nhn cc p ng (request-response-base protocol). Cc SOAP request c gi ti HTTP server thng qua phng thc POST v HTTP Server tr li gi tr SOAP response thng qua cc HTTP response.17

Hnh 9: M t vic trao i thng ip SOAP thng qua giao thc HTTP

2.2.3.3.Ngn ng m t Web Service - WSDL Tng quan v WSDL

WSDL vit tt ca cm t Web Service Description Language Ngn ng m t Web Service. WSDL ra i di s pht trin ca IBM v Microsoft[15].

WSDL da trn giao thc XML trao i thng tin trong mi trng tp trung hoc phn tn.

WSDL m t cch thc truy cp ti Web Service v cc hnh ng thc thi trn Web Service .

WSDL l ngn ng cho vic m t cc giao din Web Service da trn nn tng XML.

WSDL l ngn ng m UDDI S dng.

Cc thnh phn ca WSDL Mt ti liu WSDL thng bao gm cc thnh phn chnh sau y: Thnh phn M t nh ngha kiu d liu c dng trong Web Service Cc thng ip c s dng trong Web Service Cc thao tc c thc thi bi Web Service Cc giao thc giao tip dng cho Web Service18

Gii thch ngha cc thnh phn[15]

Type : Thnh phn type nh ngha kiu d liu c s dng cho Web Service m bo tnh khng ph thuc vo platform, WSDL s dng cu trc ca lc XML nh ngha kiu d liu.

Message : Thnh phn message dng nh ngha cc thnh phn d liu v cc thng ip m n c gi ti. Mi thng ip c th bao gm mt hoc nhiu phn, cc thnh phn ny c th so snh vi cc cu lnh ca cc li gi hm trong cc ngn ng lp trnh truyn thng.

Port Type : y l thnh phn quan trng nht trong mt ti liu WSDL. N c s dng m t Web Service, cc thao tc c thc thi v cc li gi thng ip. Thnh phn port type c th c so snh vi cc th vin hm (hoc cc module, cc lp ) trong cc ngn ng lp trnh. Trong thnh phn , ta thng gp 4 kiu thao tc c WSDL nh ngha di y: Kiu thao tc One-way M t Thao tc ny th hin rng n ch nhn cc li gi thng ip nhng khng tr li thng

19

ip p ng Requestresponse Solicit-response Notification Thao tc ny bao gm vic nhn cc thng ip yu cu v tr v cc thng ip p ng Thao tc ny s gi i cc yu cu v i cc p ng Thao tc ny s gi i cc yu cu nhng khng i nhn cc p ng

Binding: Thnh phn ny nh ngha cc nh dng thng ip, cc m t c th v cc giao thc cho mi port.

Hnh 10: M t thnh phn binding trong ti liu WSDL

Mt thnh phn binding thng thng bao gm 2 thuc tnh: name v type.

20

Thuc tnh name glossaryTerms.

nh ngha tn ca binding, v thuc tnh

type tr n port ca binding, trong v d ny port ca binding l

Thnh phn soap:binding c 2 thuc tnh l style v transport. Thuc tnh style c th l rpc hoc document. Trong v d trn chng ta s dng document. Thuc tnh transport nh ngha giao thc vn chuyn thng ip SOAP. Trong v d trn s dng giao thc HTTP.

Hnh 11: Minh ha v d ca mt ti liu WSDL

Trong thao tc. Thao

v

d

trn,

thnh

phn

nh

ngha

glossaryTerm nh l tn ca mt Port, v getTerm nh tn ca mt

tc

getTerm

c

thng

ip

nhp

vo

gi

l

getTermRequest v c thng ip xut ra gi l getTermResponse. Thnh phn nh ngha cc phn ca mi thng ip v kiu d liu kt hp vi cc thng ip . Nu so snh vi cc ngn ng lp trnh truyn thng, glossaryTerm c th c coi nh l mt th vin hm, getTerm l mt hm vi i s truyn vo l getTermRequest v tr li li kt qu l getTermResponse.21

2.2.3.4.ng k dch v UDDI Tng quan v UDDI UDDI l mt chun da trn XML dng cho vic m t, cng b v tm kim Web Service.

UDDI c vit tt ca Universal Description, Discovery and Integration.

UDDI l th mc dng cho vic lu tr cc thng tin v Web Service.

UDDI l th mc ca mt giao din Web Service c m t bi WSDL.

UDDI giao tip thng qua SOAP. UDDI cng vi SOAP v WSDL c xem l 3 chun ca Web Service.

UDDI l mt k thut m u tin cho php cc quy trnh thng mi in t c th khm ph ln nhau v nh ngha cch thc tng tc vi nhau qua Internet. UDDI c 2 phn

Phn ng k ca tt c cc Web Services metadata, bao gm c vic tr n ti liu WSDL m t dch v[16].

Phn thit lp WSDL Port type nh ngha cho cc thao tc v tm kim thng tin ng k. UDDI xy dng da trn cc giao thc chun Internet c cng b bi W3C v IETF nh XML, HTTP, v DNS. UDDI s dng WSDL m t

22

giao din ca Web Service. Thm na tnh nng c lp vi nn tng ngn ng lp trnh c iu hp cng vi giao thc SOAP. M hnh d liu ca UDDI UDDI bao gm lc XML, m t bn kiu cu trc d liu di y: BusinessEntity BusinessService BindingTemplate tModel publisherAssertion a) Cu trc d liu businessEntity Cu trc d liu businessEntity trnh by nh cung cp Web Service. Cu trc ny cha cc thng tin v cng ty, bao gm danh sch lin lc, thng tin, phn bit cc t chc thng mi, v danh sch cc nh cung cp dch v web. b) Cu trc d liu businessService Cu trc d liu business service trnh by mt Web Service c lp c cung cp bi business entity. N m t cc thng tin v cch thc gn kt vi Web Service, nh ngha kiu Web Service v phn loi danh mc c lit k trong .

Hnh 12: Minh ha cu trc d liu businessService

23

Ch rng s dng du hiu nhn dng duy nht Universally Unique Identifiers trong thuc tnh BusinessKey v serviceKey. Tt c cc business entity v business service u l du hiu nhn dng duy nht trong UDDI registries thng qua vic ch nh UUID bi vic ng k khi thng tin c nhp vo ln u. c) Cu trc d liu bindingTemplate BindingTemplate l k thut m t ca Web Service c trnh by bi cu trc d liu Business Service. Binding template trnh by s hot ng thc t ca Web Service, m t cng ngh s dng giao tip vi Web Service. Mt Business Service c th c th c nhiu binding template, cho nn dch v phi ch r cc hnh ng c th khc nhau trong cng mt dch v. d) Cu trc d liu tModel tModel l li trong cng ca kiu d liu, nhng rt kh c kh nng c th nm bt c ht. tModel l chun cho m hnh k thut tModel l phng php m t mt vi quy trnh thng mi, dch v v cc cu trc mu lu tr trong UDDI registry. Bt k mt khi nim tru tng no u c th c ng k trong UDDI nh l mt tModel. V d: chng ta c th nh ngha ra mt kiu cng (port type) WSDL mi, v ng ngha vi ta c th nh ngha ra mt tModel mi m trnh by kiu cng trong UDDI. Sau , ta c th ch nh ra dch v thng mi m thc thi kiu cng bng vic kt hp vi tModel vi mt business services binding template. e) Cu trc d liu publisherAssertion

24

y l mt cu trc d liu quan h m n t s kt hp gia hai hoc nhiu cu trc d liu businessEntity theo mt kiu quan h c th, chng hn nh mt cng ty con hoc mt phng ban. Cu trc d liu pubisherAssertion bao gm ba thnh phn chnh: fromkey (BusinessKey u tin), toKey (bussinesskey th hai) v keyedReference. KeyReference thit k ra kiu mi quan h kt hp trong cp thut ng keyName, keyValue trong tModel. Tham chiu duy nht bi tModelkey.

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CHNG 3: QoS CHO WEB SERVICETrong chng 2 chng ti trnh by cc khi nim c bn v cng ngh Web Service. Vi s pht trin mnh m ca Internet v cng ngh Web Service, cht lng cc dch v Web tr thnh mt vn ht sc cn thit. Trong chng 3 ny, chng ti s cp n hng tip cn kh mi v s tr thnh mt xu hng tt yu cho cc dch v web trong tng lai gn, l Cht lng dch v Web.

3.1. Cht lng dch v Web Service QoS cho Web ServiceVi s pht trin nhanh phng v ph bin ca cng ngh Web Service, Cht lng cc dch v Web Service (QoS Quality of Service) s tr thnh mt yu t quan trng trong vic nh gi s thnh cng ca cc nh cung cp dch v web. QoS s quyt nh n kh nng s dng v tnh hu ch ca dch v, c hai yu t ny u nh hng n tnh ph bin ca mt dch v web. Trong phn ny, chng ti s trnh by mt vi yu cu khc nhau ca QoS cho Web Serivce, nh hng ca hiu ng tht c chai n hiu nng hot ng ca mt Web Service, tip cn ti cc phng php cung cp cht lng dch v cho Web Service v mt phng php n gin o lng thi gian p ng ca Web Services s dng Service Proxy[6]. Trong thi i hin nay, vi s pht trin mnh m ca thng mi in t, mt yu cu t ra l phi lm sao c th tch hp lin mch cc quy trnh thng mi, cc ng dng thng mi in t v cc Web Service thng qua mi trng Internet. Vic nh gi cht lng mt dch v web l mt thch thc ln, v mi trng Internet cng cc ng dng WebBase ngy cng pht trin mnh m, cng chnh v th nn cc yu cu v cht lng dch v cng lun thay i v khng th d26

on theo cch t nhin c. Cc ng dng vi cc c im v yu cu ring bit s cnh tranh nhau v ti nguyn mng vn rt hn ch. S thay i lu lng thng tin trn mng, tn cng t chi dch v, nh hng ca c s h tng cng ngh thng tin yu km v vn an ninh cho cc ng dng Web-Base to ra s cn thit ca vic a ra cc chun cht lng cho cc dch v trn Internet. Thng thng, khi khng p ng c cc yu cu QoS l mt nguyn nhn then cht dn ti cc giao tc c hiu sut hot ng rt thp. Vi cc chun nh SOAP, UDDI v WSDL c thng nht s dng bi cc lnh vc s dng cng ngh Web Service bao gm cc dch v ti chnh, cng ngh cao, a phng tin v gii tr. Tt c cc Web Service ang cn phi c gn kt vi nhau tr thnh chun, QoS s l mt yu t then cht nh gi s thnh cng cng nh s khc nhau v cht lng phc v ca cc dch v Web.

3.2. Cc yu cu v cht lng dch v cho Web ServiceCc yu cu v cht lng dch v cho Web Service phi p ng c cc yu cu di y[6]

Tnh c sn : Tnh c sn th hin mt kha cnh cht lng ca dch v, tnh c sn trnh by dch v c sn dng ti mt thi im c th hay khng. Tnh c sn m t xc sut m dch v sn sng phc v. Trong tnh c sn, mt gi tr thi gian c dng m t liu mt dch v c sn sng phc v hay khng. Gi tr ln hn ch ra rng dch v lun sn sng s dng trong khi gi tr nh hn ch ra khng th d on c liu dch v c sn trong khong thi gian c th hin ti hay khng. Thng thng, ngi ta thng s dng mt i lung thi gian

27

kt hp vi tnh c sn ca mt dch v, i lng thi gian c gi l TTR (Time to Repair ) - Thi gian phc hi. TTR m t khong thi gian c dng phc hi mt dch v web nu c li xy ra. Thi gian phc hi l tng v c mong i l thi gian phc hi c gi tr nh.

Tnh truy cp c : Tnh truy cp c th hin kha cnh cht lng dch v qua mc , kh nng phc v cc yu cu Web Service. N din t kh nng c lng bao gm tc thnh cng hoc s thay i thnh cng ca mt dch v c th trong mt thi im. Tnh truy cp c cn c th hin thng qua tnh c sn ca dch v Web. Mt Web Service c tnh truy cp cao khi h thng trin khai Web Service c mm do cao. mm do tham chiu ti kh nng phc v cc yu cu mt cch nht qun mc d c th c nhiu yu cu khc nhau cng tn ti trong mt tp hp cc yu cu.

Tnh ton vn : Tnh ton vn th hin cht lng dch v cch thc m Web Service m bo s ng n chnh xc trong cc tng tc theo tng kha cnh c th ca ti nguyn. S thc thi ng n ca cc giao tc Web Service s cung cp tnh ng n trong cc tung tc. Mt giao tc s tham chiu ti trnh t lm vic ca cc thao tc c x l nh mt n v cng vic c lp. Tt c cc hot ng c hon thnh to s thnh cng cho mt giao tc. Khi mt giao tc khng c thc hin thnh cng, tt c cc thay i s c phc hi li trng thi ban u.

Kh nng hot ng : Kh nng hot ng th hin cht lng dch v kha cnh o lng gii hn ca thng lng v tr. Gi tr thng lng cao hn v tr thp th hin mt Web

28

Service hot ng tt. Thng lng trnh by s lng yu cu Web Service phc v ti mt n v thi gian nh k. tr l thi gian xoay vng gia vic gi yu cu v nhn cc p ng.

Tnh tin cy : Tnh tin cy th hin kh nng m bo dch v v cht lng dch v. Tnh tin cy c tnh qua s lng li trn mt thng hay mt nm. Theo hng tip cn khc tnh tin cy tham chiu n vic phn pht ng n v m bo cc thng ip s c gi v nhn bi cc dch v yu cu v cc dch v p ng.

Tnh linh ng : Tnh linh ng th hin cht lng dch v kha cnh Web Service c th thch ng vi cc lut, cc quy tc v kh nng kt hp chun v thit lp cc dch v mc cao hn. Web Service s dng mt s chun nh SOAP, UDDI, WSDL. S tun th ngt ngho cc chun m bo tnh ng n ca cc phin bn (VD SOAP V1.2) bi cc nh cung cp dch v web l mt yu t cn thit cho cc yu cu ng n ca Web Service bi cc Web Service request.

Tnh an ton : Tnh an ton ca Web Service th hin c ch bo mt, thm nh quyn, m ho thng ip v cung cp quyn truy cp. Cc nh cung cp dch v Web c th c cc hng tip cn khc nhau m bo an ton cho cc dch v web.

3.3. QoS cho cc dch v WebQoS cho cc dch v web yu cu mt vi ngn ng QoS tr li mt s cc cu hi sau[2]:

Thi gian tr mong ch l bao nhiu

Khong thi gian roundtrip-time chp nhn c l bao nhiu29

Lp trnh vin cn phi c kh nng hiu c cc c im QoS ca Web Service trong qu trnh pht trin cc ng dng gi dch v web. Trn l tng, th QoS cho Web Service phi c kh nng h tr nhiu kiu ng dng khc nhau vi cc yu cu QoS khc nhau, cc quy tc giao tip khc nhau v ti nguyn my tnh khc nhau.

3.4. iu chnh v thit lp rng buc QoSDi y l cc bc m cc Web Service phi thc hin trong qu trnh thit lp rng buc QoS[2][6]:a) Service Requestor a ra yu cu thit lp lin kt rng buc bng cch thit lp

tham chiu ti mt Web Service Interface. Nhng yu cu ny ch cha cc quy nh v QoS.b) QoS broker tm kim cc service cung cp dch v trong th mc UDDI. c) Sau , QoS broker thc thi vic thng lng cht lng dch v nh cc m t

di y:- Web Service QoS broker so snh cc QoS ca cc Service Provider vi cc yu

cu QoS m n t ra, v s dng yu cu quyt nh chp nhn QoS m cc Service Provider a ra hay khng. Qu trnh ny c gi l thng lng QoS.- Nu qu trnh thng lng cht lng dch v thnh cng, cc Service

Requestor v Service Provider s c thng bo rng qu trnh thng lng thnh cng v rng buc QoS gia 2 pha c thit lp. T lc ny tr i, cc i tng ny c th tng tc vi nhau thng qua lin kt .

3.5. Hiu ng tht c chai trong qu trnh thc thi ca Web ServiceWeb Service c th gp phi hiu ng tht c chai trong qu trnh thc thi, nguyn nhn do gii hn ca cc giao thc vn chuyn v s lng thng ip qu ln. Vic tin30

tng vo cc giao thc c chp nhn rng ri nh HTTP, SOAP tuy nhin chng vn tn ti cc gii hn, chnh v th rt quan trng c th hiu v lm vic trn cc gii hn ca cc giao thc . HTTP l giao thc theo hng c gng ti mc ti a. Hai vn chnh thng gp phi trong c ch chuyn tip d liu ca HTTP l:

Khng c c ch m bo gi tin c phn pht ti ch. Khng c c ch m bo th t n ca cc gi tin.

Nu khng c bng thng c sn, cc gi tin s b loi b. Bng thng s b gim st khi ngi dng v s lng d liu trong mng gia tng. Mt s ng dng ch nh tr bng khng v bng thng bng v cng. Theo truyn thng, ng dng thng s dng cc thng ip ng b. Thng ip ng b s tt khi ng dng chy trn mt my tnh n, khi cc thnh phn tham gia truyn thng ip c tr o bng n v micro giy. Tuy nhin vi Web Service, chng giao tip thng qua Internet, iu c ngha tr c th o bng 10, 100 hoc thm ch 1000 mili giy. Di y l mt s phng php tng kh nng hot ng ca Web Service S dng hng i thng ip bt ng b. ng dng da trn cc dch v web c th s dng hng i thng ip tng tin cy nhng li tn thi gian p ng. Cc ng dng v Web Service c th s dng hng i thng ip nh Java Messaging Service JMS hoc IBM MQSerier cho li gi thng ip. Hng i thng ip cung cp 2 im thun li chnh sau:- C ch bt ng b: cc Service Provider c th phn pht cc thng ip ti cc

requestor v khng yu cu pha requestor gi li thng ip xc nhn vic nhn thng ip t Service Provider. tin cy: m bo cho cc thng ip c th phn pht mt ln v ch mt m thi.

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S dng private Wan v mng Web Service S dng mng ring Wan v mng Web Service c th l mt gii php thch hp cho cc doanh nghip s dng Web Service cho cc nghip v quan trng. Mng wan ring cung cp tr mng thp, t ng v m bo vic phn pht cc thng ip. Tuy nhin c c mt mng wan ring th chi ph cng rt tn km.

3.6. nh gi hiu nng giao thc SOAPSOAP l mt giao thc ch yu c dng cho Web Service. Tuy nhin hiu nng ca giao thc SOAP li b gim thiu i v cc nguyn nhn sau y: Vic tch b thnh phn Soap Envelope t mt gi tin SOAP tn nhiu thi gian.

Phn tch cc thng tin XML trong thnh phn SOAP envelope s dng b phn tch c php XML tn nhiu thi gian.

Kh nng ti u ho d liu XML khng cao. Cc quy tc m ho thng ip SOAP phi c thc hin c pha gi v pha nhn thng ip.

Tn thm ti nguyn my tnh x l cc thng ip XML c m ho di dng nh phn bao gm vic m ho v gii m. B x l XML phi c np ra v vn chuyn i cng vi cc d liu XML. iu ny s tn thm ti nguyn thc thi SOAP.

gii quyt cc vn gp phi khi s dng giao thc SOAP, chng ta c mt phng php nn d liu XML. D liu XML c vn chuyn bi giao thc SOAP . iu g s xy ra nu hng trm thng ip SOAP c vn chuyn qua web, khi s dn n tnh trng bng thng mng b tng ti gii hn. Phng php trnh by d liu di dng XML thng em li hiu qu ng k khi mt lng ln d liu c nn di dng nh phn , trung bnh hiu

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sut lm vic c th l 400% hoc cao hn. Tuy nhin khi d liu c trnh by di dng nh phn s lm tng kch thc cc thng ip dn ti thi gian vn chuyn cc thng ip s b tng ln ng k . Mt s ng dng c thit k nhm hng n k thut tn dng hiu qu ca vic th hin d liu. Mt phng php c th gii quyt vn trn l nn d liu XML - c bit l khi ti nguyn CPU yu cu cho vic nn phi nh hn tr mng. Mt s yu t nh hng n kh nng hot ng ca Web Service y l mt s yu t nh hng n kh nng hot ng ca Web Service m n nm ngoi quyn iu khin ca ng dng Web Service, chng hn nh:

thi gian p ng v tnh sn sng ca Web Server

Thi gian thc thi ng dng nh EJB/serverlet trong my ch ng dng web. Back-end c s d liu v vt qu kh nng hot ng ca h thng.

3.7. Phng php tip cn cung cp cht lng dch v cho Web ServiceCc nh cung cp dch v trn nn web c th tu vo nhu cu v tng loi dch v m c phng php cung cp cht lng dch v web khc nhau. Hin ti hai phng php m bo cht lng dch v ang c s dng rng ri l cn bng ti v s dng b nh m. Hai phng php ny u c kh nng thc thi tt ti c mc l Web Server v cc ng dng ca Web server. Phng php cn bng ti th hin qua mc u tin ca lu lng v m bo mi yu cu u c gii quyt mt cch thch hp tu vo mc ti nguyn i vi yu cu [6]. Cc nh cung cp dch v web c th da vo m hnh top-down nhn dng cc lung yu cu c gi n, t phn loi cc loi Web Service traffic bng label ca cc traffic , bao gm cc traffic cho cc dch v ng dng khc nhau xut pht t cc ngun khc nhau. Da trn cc lung traffic m cc nh cung cp dch v web a ra yu cu QoS cho tng loi traffic. iu ny s gip cho vic hiu c kh nng yu cu cung cp mt cht lng dch v tt cho cc lung traffic ng thi c th xy dng33

c mt k hoch cung cp cht lng dch v trong tng lai, v d nh xc nh chui cc yu cu lin tip phn cm ra cc server phc v. Mi mt yu cu nghip v khc nhau cng s c cc yu cu v QoS khc nhau cho tng loi nghip v, vic da trn kh nng m hnh ho ca QoS c th m bo tip cn v mc QoS cho cc ng dng v khch hng khc nhau. Ly v d : mt Web Service cung cp cc dch v a phng tin th thng yu cu QoS thin v thng lng tt, tuy nhin vi cc Web Service cung cp cc dch v ngn hng th yu cu QoS thng thin v m bo an ton cho cc transaction.

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CHNG 4: BIU TIMING DIAGRAMTrong cc chng trc, chng ti cp n cng ngh Web Service v phng php tip cn cung cp cht lng dch v cho cc Web Service. Trong chng ny, chng ti s trnh by v mt loi biu UML dng c t rng buc thi gian p ng ca cc i tng l biu UML 2.0 Timing Diagram.

4.1. Gii thiu UMLUML Unified Modeling Language l ngn ng dnh cho vic c t, hin th, xy dng v lm ti liu ca cc h thng phn mm. UML to c hi vit thit k h thng, bao gm nhng khi nim nh tin trnh nghip v v chc nng h thng. C th n hu dng cho nhng ngn ng khai bo, gin c s d liu, thnh phn phn mm c kh nng ti s dng[10]. UML l mt Ngn ng c t hnh thc (formal specification language). Chng ta cn ch n thut ng ngn ng. Ngn ng y khng phi l ngn ng ging vi ngn ng t nhin ca con ngi hay ngn ng lp trnh. Tuy nhin, n cng c mt tp cc quy lut xc nh cch s dng. Cc ngn ng lp trnh c mt tp cc phn t v mt tp cc quy lut cho php chng ta t hp cc phn t li vi nhau to ra cc chng trnh hp l. Cc ngn ng c t hnh thc ging nh UML cng c mt tp cc phn t v mt tp cc quy lut ring. Vi UML, hu ht cc phn t ca n l cc i tng ho nh ng thng, hnh ch nht, hnh oval, Chng thng c t nhn cung cp thm thng tin. Tuy nhin, cc phn t ho ca UML ch biu din cc phn cn m hnh di dng hnh nh, ta cng c th to ra mt m hnh UML di dng thun d liu (Ging nh CORBA v XMI DTD ). Tuy nhin, cch biu din bng hnh nh vn gip m hnh d hiu v trc quan hn. Cc quy lut trong UML c m t trong c t UML. C ba loi quy lut: C php tru tng, lut well-formedness (Lut hnh thc) v ng ngha. Trong c php35

tru tng c biu din nh cc biu v ngn ng t nhin, lut well-formedness nm trong ngn ng rng buc i tng OCL (Object Constraint Language). Lut c biu din nh biu s dng mt tp cc k hiu con ca UML xc nh cch kt hp gia cc phn t. UML c pht trin bi Rational Rose v mt s nhm cng tc, n nhanh chng tr thnh mt trong nhng ngn ng chun xy dng h thng phn mm hng i tng nh cc li ch sau:

UML cung cp kh nng m rng v chuyn mn ho m rng nhng khi nim ct li.

c lp vi ngn ng lp trnh chuyn bit, v cc tin trnh pht trin. Cung cp nn tng v s biu bit ngn ng m hnh ho. Khuyn khch v h tr s pht trin cc cng c hng i tng. H tr nhng khi nim pht trin cp cao nh collaboration, framework, pattern and component.

Tch hp mt cch tt nht vi thc tin.

4.2. Tng quan v biu Timing DiagramBiu Timing Diaram l mt biu c thm vo cho UML 2.0, l mt trong cc dng ca mu biu tng tc. N c dng khm ph hnh vi ca mt hoc nhiu i tng trong sut mt khong thi gian c cung cp nh k. Biu Timing Diagram thng xuyn c s dng trong vic thit k cc h thng nhng, chng hn phn mm iu khin cho h thng t thm nhin liu trong xe t, v i khi biu Timing Diagram c s dng m t phn tch thit k cho cc phn mm thng mi. Nhn chung, biu Timing Diagram tng t nh biu khi ta phn tch mt mch in t logic. Biu phn tch mch in t ghi li trnh t xut hin ca cc thnh phn trn mch in t. Kt qu a ra ca vic phn tch logic s hin th thi gian m

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ti cc thnh phn ca mch in t trong cc trng thi ring bit v cc tn hiu in t s thay i tc th trong cc trng thi . Biu Timing Diagram thc thi cng vic tng t cho cc thnh phn trong h thng. Trong biu Timing Diagram, cc s kin ging nh cc tn hiu in, v trng thi l cc trng thi m cc thnh phn c t trong n khi n nhn mt s kin[10][11].

4.3. Mc ch ca biu Timing DiagramBiu Timing Diagram c pht trin cho cc h thng thi gian thc: l h thng phi tun th theo mt rng buc thi gian trong qu trnh m h thng thc thi. Biu Timing Diagram c u thch hn biu tun t im n c mt rng buc thi gian bt buc cc i tng phi tun th cht ch. Mc ch ca biu Timing Diagram c tng hp thnh cc chnh sau: Biu Timing Diagram c s dng tr gip qu trnh phn tch cc hnh vi c lin quan n thi gian thc hin ca cc i tng, cc h thng con. N dng ch r rng buc thi gian ca cc hnh vi ca i tng v cc h thng con. Thng c s dng m hnh ho mi quan h gia cc ng lifeline trong ton b qu trnh tng tc m ph thuc vo s tham gia ca cc rng buc v thi gian

4.4. Cc k hiu ca biu Timing DiagramBiu Timing Diagrams l mt dng ca biu tng tc, n c th hin trong cc khung vi cc t kho sd v tn ca cc tng tc trong phn tiu trn pha gc bn tri ca khung . Tn ca cc ng lifelines c vit bn tri ca khung v c th chy xuyn sut t tri qua phi pha bn trn ca khung v . Chng ta c th th hin y mt biu Timing Diagram ch bng mt ng lifeline, nhm th hin mc ch ca biu ny chnh l trnh by cc nguyn nhn nh hng n cc tng tc

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ca cc ng lifelines xuyn sut qua mt khong thi gian hn l hin th vic vn chuyn cc thng ip gia cc ng lifeline. Khi c nhiu hn mt ng lifeline trong biu Timing Diagram, chng ta c th phn tch chng ra bi cc ng nm ngang nhm th hin vic chuyn tng tc ca cc ng linelife [10]. Biu Timing Diagram c th c th hin di 2 dng. Biu Timing Diagram c th c th hin di dng Robust Diagram, dng ny cc trng thi c th hin bng cc ng thng, hnh di minh ho biu Timing Diagram c th hin di dng robust diagram.

Hnh 13: Biu Timing Diagram di dng Robus Diagram

Trong dng th hin ny, cc ng lifeline th hin cc trng thi tng ng nhau mt cch trc quan. N khng thm c bt k ngha g cho biu , cch th hin ny ch n gin l thay i vic iu phi cc thnh thnh phn c s dng cho biu timing diagram. Trong dng th hin ny ca cc ng lifeline, cc trng thi c lit k xuyn sut trc y ca biu v thi gian c th hin trn trc x, chng ta cn ch rng trong biu Timing Diagram khng c mt n v thi gian c th no cho cc trng thi, tt c vic o lng thi gian cho cc qu trnh tng tc u c o tru tng trong mt khong thi gian xc nh c th no . Cc ng ni tip nhau trnh by cc trng thi ca cc trng hp trong tng thi im thi gian.

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Biu Timing Diagram c th c th hin di dng cc trng thi c trnh by bng cc vng ring bit nh Hnh 14.

Hnh 14: Biu Timing Diagram di dng m rng

Trong dng th hin ny, cc ng lifeline c th hin bng 2 ng bao quanh cc trng thi. Trng hp ny cc ng lifeline c gi l cc ng gi tr tng quan, khi cc ng lifeline giao nhau n ch ra rng im l im chuyn tip gia cc trng thi. Di cc ng lifeline l cc rng buc thi gian thc hin cho cc trng thi c chy xuyn sut t tri qua phi. Trong qu trnh m hnh ho, ph thuc vo mc ch m hnh ho v s lng cc trng thi c s dng chng ta quyt nh xem nn dng dng biu no. Nu ch c mt mt ng lifeline hoc s lng trng thi qu ln th biu dng th 2 l thch hp cn nu s lng ng lifeline ln th biu dng 1 nn c la chn.

4.5. Cc thnh phn ca biu Timing Diagram4.5.1.Cc trng thi Trong qu trnh tng tc, cc thnh phn c th tn ti trong bt c s lng trng thi no. Cc thnh phn c th gi l trong mt trng thi ring bit khi n tip nhn

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cc s kin (chng hn cc thng ip). T thnh phn c ni trong trng thi cho n khi mt s kin khc xut hin (chng hn nh s tr v ca mt thng ip). Cc trng thi v cc iu kin cn phi c phn bit vi cc trng thi v iu kin trong biu tun t mc d chng c cng mt thao tc, chng ta cn phi da trn biu trng thi quyt nh cc i tng no c th c trnh by bi cc ng lifeline. Ta c th khng cn th hin y tn ca cc trng thi thnh phn c th gi cho kch thc ca biu trong phm vi qun l c, mc d ta hon ton c th tn y cc trng thi thnh phn theo nh dng :. Mt s cc trng thi thnh phn ta thy xut hin trong biu tun t nhng li khng c a vo biu Timing Diagram l do n c to ra v hy trong vng i ca qu trnh tng tc, cc thnh phn ny n khng c lin h n cc trng thi c thay i v chng khng th thm c bt k thng tin no cho cc thnh phn. Trong sut qu trnh m hnh ha, chng ta cn phi quyt nh nhng g nn v khng nn t vo trong biu bng cch tr li cu hi : Nhng thng tin c th c quan trng hiu nhng g ta ang m hnh ha hay khng v Liu thm cc thng tin vo c lm cho biu ca ta tr nn trong sng hn hay khng, nu cu tr li l c th ta hy a cc thng tin vo trong biu , cn khng th khng a cc thng tin vo gi biu trong phm vi kim sot n gin nht.

Hnh 15: Minh ha cc trng thi c th hin trong biu Timing Diagram

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4.5.2.Cc s kin v cc thng ip Trong biu timing diagram, cc thnh phn thay i trng thi p ng mt s kin. Cc s kin c th l cc li gi thng ip hoc c th l bt c th g, chng hn nh s tr v ca mt thng ip sau khi n c gi. Trong biu timing diagram, ta khng cn phn bit r s khc nhau gia cc thng ip v cc s kin nh trong biu tun t. iu quan trng nht cn phi nh y chnh l s kin xy ra nh th no, v cch thc n hin th trn biu timing diagram th hin r s thay i trng thi ca cc thnh phn[10][11]. Hnh di minh ho cc s kin v cc thng ip c t vo biu Timing Diagram th hin s thay i ca cc trng thi di s tc ng ca cc s kin .

Hnh 16: Minh ha cc s kin v thng ip trong biu Timing Diagram

Trong v d trn ta thy, s kin 1 c thc thi trong 1 n v thi gian, v c gi bi thnh phn p1 v c nhn bi thnh phn p2. Cc thng ip y c th l cc thng ip yu cu v cc thng ip tr v. Cc thng ip yu cu c th hin bng cc ng nt lin, v cc thng ip tr v c th hin bng cc ng nt t. Cc thng ip th hin cc giao tip gia cc ng lifeline.

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4.5.3.Thi gian Thi gian c th hin theo chiu t bn tri qua phi dc theo trc x ca biu nh hnh 17.

Hnh 17: Minh ha th hin thi gian trong biu Timing Diagram

o lng thi gian c th thc hin theo hai cch khc nhau: chng ta c th s dng thi gian chnh xc nh hnh minh ha trn nhng ta cng c th s dng thi gian c lng nh hnh 18.

Hnh 18: Thi gian c lng trong biu Timing Diagram

Trong biu timing diagram, thi gian t trnh by mt khong thi gian c lng khi m ta khng bit chnh xc khi no mt s kin xy ra, n c th xy ra mt cch ngu nhin p ng mt thng ip hoc mt s kin, nhng thi gian t l mt phng

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php tham chiu ti khong thi gian m ta khng bit chnh xc khi no xy ra. Vi thi gian tham chiu t, ta c th ch ra rng buc thi gian ti thi im t. 4.5.4.Cc ng State-Line Sau khi thm thi gian vo biu Timing Diagram, chng ta cn phi hin th trng thi ca cc thnh phn theo cc n v thi gian c cung cp. Trong biu Timing Diagram, cc ng state-line l cc ng c t thng hng vi mi trng thi thnh phn th hin rng buc thi gian thc hin cho cc trng thi thnh phn [13]. Hnh di minh ho cc ng state-line trong biu Timing Diagram

Hnh 19: Minh ha cc ng state-line trong biu Timing Diagram

Trong v d trn, ng state-line thnh phn p1 ch ra rng trng thi 1 thc thi trong 1 n v thi gian, trng thi 2 trong 3 n v thi gian, v trng thi 3 thc hin trong 5 n v thi gian (trc khi tr v trng thi 1 kt thc qu trnh tng tc). 4.5.5.Rng buc thi gian Rng buc thi gian m t mt cch chi tit yu cu: cn bao nhiu thi gian qu trnh tng tc c thc thi. Cc hnh ng cn mt s lng thi gian nht nh cc trng thi thnh phn cn thc thi cc li gi v li tr v thng ip. Vic a cc rng buc thi gian vo biu Timing diagram c th hin nh hnh 20 [10].

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Hnh 20: Minh ha cc rng buc thi gian trong biu Timing Diagram

Trong v d minh ho trn, khong thi gian thc thi s kin 1 phi nh hn 1 gi tr thi gian c lng t, v thi gian thnh phn p2 bc vo trng thi 4 phi din ra trong vng 5s. Cc nh dng v rng buc thi gian Rng buc thi gian trong biu timing diagram c th c th hin bng nhiu cch khc nhau, bng di y th hin cc nh dng c th ca rng buc thi gian cho cc s kin, trng thi trong cc thnh phn[10].

nh dng {tt+5s} {5s, t th khng tho mn tiu chun QoS. chnh l tng v l mc tiu cn t c ca kho lun.

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CHNG 6: THC NGHIMChng 6 xy dng mt ng dng c th cho bi ton Travel-Agent kim tra rng buc thi gian p ng ca cc Web Service Composition, v dng kt qu t c bng thc nghim m hnh ho rng buc thi gian trn biu UML Timing Diagram.

6.1. Phm vi ng dngTrong phm vi kho lun ny, chng ti ch chn mt ng dng nh lm v d minh ho kim chng rng buc thi gian p ng ca trong Web Service Composition. ng dng c chia thnh cc nhim v chnh nh sau:

Xy dng hai Web Services, mt Web Service tm kim khch sn da vo tn ca thnh ph ch n Tn Web Service ny l SearchHotel Service, mt Web Service tm kim cc chuyn bay da trn tn ca thnh ph xut pht v tn ca thnh ph ch n. C 2 Web Service ny u c pht trin bng ngn ng lp trnh Java, qu trnh pht trin hai Web Service hon ton th cng, khng dng bt c mt cng c h tr no. C s d liu c dng cho hai Web Service c trin khai trn h qun tr c s d liu MySQL hon ton min ph.

Xy dng Service Proxy triu gi ti hai Web Services kia. Trn Service Proxy cha hai phng thc triu gi ti hai Service Composition. Thng thng Service Proxy khng cn phi c vit ra bi ngi lp trnh vin m thng c t sinh t file WSDL ca SearchFlight Service v SearchHotel Service. Tuy nhin v vn bn quyn, chng ti s dng cng c t sinh min ph trn Internet ti trang http://nsoftware.com, y vic t sinh ra Service Proxy cng b gii hn v cc chc nng ca Service, Service Proxy c th thc hin c bng cch sinh t website trn bt buc cn phi c cc th vin API i km c cung cp bi nsoftware.com. V th chng ti ch s dng website http://nsoftware.com sinh ra cc lp v phng thc tru tng ca Service57

Proxy, cn qu trnh pht trin li bn trong triu gi ti cc Service Composition v o lng thi gian p ng u c code th cng. Service Proxy cng c pht trin trn ngn ng java. Chng trnh Client triu gi ti Service Proxy l mt chng trnh giao din GUI. Cho php ngi dng chn la tn thnh ph n v tn thnh ph xut pht. T chng trnh s triu gi ti Service Proxy ly kt qu tr v bao gm danh sch cc chuyn bay, danh sch cc khch sn v kt qu thi gian p ng ca hai Web Service Composition. th hin tnh c lp vi platform, y chng ti c 3 Web Service tuy nhin do iu kin c hn nn chng ti s trin khai tt c cc Web Service ny trn mi trng localhost ti 2 Web Server khc nhau.

Service SearchHotel c trin khai bng th vin Apache-Soap, ci t trn mi trng J2EE Java 2 Platform, Enterprise Edition. Web Server thc hin trn cng 2417 y chng ti s dng th vin Soap nh km vo trong mi trng J2EE. Trang Admin ca SOAP c th c truy cp qua URL : http://localhost:2417/soap/admin

Service SearchFlight c trin khai bng th vin Apache-Axis ci t trn Web Server Apache TomCat ti cng 8080. Trang Admin ca Axis c th c truy cp qua URL : http://localhost:8080/axis/

Service Proxy c trin khai bng th vin Apache-Soap, ci t trn Web Server Apache TomCat ti cng 8080. Trang Admin ca Soap trn Apache TomCat c th truy cp qua URL : http://localhost:8080/soap/admin

Ta thy mc d c hai web server, nhng chng ti b tr tt c cc Service u c thc thi trn cc nn Platform khc nhau. Service SearchFlight v Service Proxy cng c trin khai trn Apache Tomcat ti cng 8080 nhng chng li dng 2 th vin API khc nhau trin khai l Axis v Apache Soap. Cn Service SearchHotel th

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c trin khai hon ton trn mt Web Server khc v s dng cng ngh khc l J2EE. Qua thy c tnh c lp vi nn ca cng ngh Web Service.

6.2. Thit k ng dngTa c m hnh thit k tng th ca ng dng nh sau:

Hnh 26: Minh ha thit k tng th ca ng dng

Ngi s dng ti Client s la chn thnh ph xut pht v thnh ph ch n. Ti y Soap engine lm nhim v to ra cc thng ip SOAP request gi n Service Proxy. Ti Service Proxy s phn ra lm 2 lung SOAP request tip tc gi n hai Web Service SearchFlight v SearchHotel. Sau khi gi i cc thng ip Soap request, Service Proxy bt u bt ng h m thi gian o thi gian p ng ca hai Web Service thnh phn. Ti hai Web Service thnh phn tip nhn cc Soap request x l v tr li cc thng ip Soap response cho Service Proxy. Sau khi nhn c thng ip Soap response ca cc Service Composition, Service Proxy dng ng h o thi gian. ng gi kt qu o lng thi gian p ng vo cng thng ip Soap response v gi tr li kt qu cho Client bao gm kt qu tm kim chuyn bay, tm kim khch sn v km theo thi gian p ng ca tng dch v.

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Do ng dng kh n gin nn chng ti khng s dng cc biu phn r chc nng, biu lp, biu tng tc. M ch s dng biu tun t thy c th t lm vic ca cc thnh phn trong h thng.

Hnh 27: Biu tun t ca h thng

Da vo biu tun t ta thy ti chng trnh Client s c cc i tng ApplicationGUI, CallService1, CallService2. i tng ServiceProxy i din cho Web Service Proxy v hai i tng cn li i din cho cc Web Service Composition. Khi ngi s dng nhp thng tin v click submit, d liu s c gi i ln lt bng 2 i tng CallService1, CallService2. Trong v d ny chng ti gi CallService1 trc, sau khi d liu c tr v cho CallService1 s tip tc gi n CallService2. Sau khi c tt c cc d liu cn thit tr v mi tr li kt qu cho User.

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6.3. Ci t, xy dng v trin khai ng dng6.3.1.Ci t chng trnh Bi ton c xy dng da trn ngn ng Java, c th thc hin vic xy dng v trin khai bi ton chng ta cn phi ci mt s chng trnh sau[8][12]: Ci t mi trng chy cho Java: Ci t JDK -1.5 v thit lp bin mi trng JAVA_HOME l : C:\Program Files\Java\jdk1.5.0_07.

Ci t mi trng Web Server. y chng ta s dng 2 Web Server. Trc tin ci t b cng c J2EE Java 2 platform, Enterprise Edition. B cng c J2EE sau khi ci t s c ng dn C:\Sun. Sau ci Web Server Apache Tomcat theo ng dn C:\ Webservice\tomcat.

Ci t h qun tr c s d liu MySQL v thit lp bin mi trng cho b kt ni MySQL connector. Ta cn phi thit lp bin mi trng CLASSPATH tr n th mc cha file mysql-connector-java-5.0.5.jar. Ci t Soap engine: y chng ti s dng Soap engine l Apache Soap c ci t trn 2 Web Server, mt Web Server c trin khai ti cng 2417, mt Web Server chy ti cng 8080. Soap engine th hai l Apache Axis. Lu tt c cc Soap Engine u c mc nh ci t trong th mc C:\Webservice. Mt iu rt quan trng khi chng ta ci t cc Soap engine cn phi ch y l cc Soap engine ny c th thc hin c cn phi cha danh sch cch th vin cn thit l th vin Java Mail vi file mail.jar, th vin activation.jar, th vin xerces vi 2 file xercesImpl.jar v xml-apis.jar c s dng cho b phn tch c php XML. Sau khi c y tt c cc th vin trn chng ta chp 2 file mail.jar v activation.jar vo th mc tomcat/common/lib. Sau chng ta cn phi cp nht li bin mi trng CLASSPATH, y l bc rt quan trng v khng cho php c b qua. Di y l cu hnh CLASSPATH km theo.

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WEBSERVICE_HOME=C:\WebService JAVA_HOME=: C:\Program Files\Java\jdk1.5.0_07 CATALINA_HOME=%WEBSERVICE_HOME%\tomcat CATALINA_LIB=%CATALINA_HOME%\common\lib XERCES_HOME=%WEBSERVICE_HOME%\xerces SOAP_HOME=%WEBSERVICE_HOME%\soap CLASSPATH=%CLASSPATH%;%SOAP_HOME%\lib\soap.jar CLASSPATH=.;%CATALINA_LIB%\mail.jar;%CATALINA_LIB%\activation.jar; CLASSPATH=%CLASSPATH%;%XERCES_HOME%\xercesImpl.jar;

%XERCES_HOME%\xml-apis.jarPATH=%PATH%;%CATALINA_HOME%\bin;%JAVA_HOME%\bin

Sau khi thit lp bin mi trng cho Apache SOAP chng ta phi tin hnh thit lp cc bin mi trng cho Apache Axis.. Nu qu trnh ci t Apache Soap v Apache Axis thnh cng th mn hnh my tnh s hin th nh sau khi ta gi n trang admin ca cc Soap engine ny.

Hnh 28: Minh ha giao din Admin ca apache soap trn Web Server ti cng 2417

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Hnh 29: Minh ha giao din Admin ca apache soap trn Web Server ti cng 8080

Nu ci t Apache Axis thnh cng ta c th nhn thy giao din trang Admin ca Apache Axis nh hnh di y:

Hnh 30: Minh ha trang Admin ca Apache Axis trn Web Server ti cng 8080

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Sau khi cc Soap Engine sn sng phc v, chng ta hon ton c th trin khai cc Web Service thc hin mc tiu bi ton. 6.3.2. Xy dng v trin khai cc Web Services thnh phn Sau khi ci t thnh cng cc Soap engine, chng ti s tin hnh ci t cc Service Composition trn cc Web Server va c ci t ln. Ci t Service SearchHotel Trc tin tin hnh ci t Web Service SearchHotel chy trn mi trng J2EE ti cng 2417. Tp ci t cho Web Service SearchHotel c chng ti vit trong file SearchHotelService.java, trong file ny c cha mt phng thc SearchHotel vi i s truyn vo l mt String v kt qu tr v cng l mt String. Khi Service Proxy gi ti SearchHotel Service, th xu cha tn ca thnh ph ch n c ng gi vo thng ip SOAP, ti SearchHotel Service, s dng xu cha tn thnh ph ch n lm i s truyn vo, thc hin thao tc tm kim trong database xem c kt qu khch sn no tng ng vi thnh ph ch n hay khng.

Hnh 31: Code kt ni database trong file SearchHotel Service

Sau chng ti tin hnh bin dch file SearchHotelService.java thnh file HTService.SearchHotelService.class, copy file ny v t vo trong th mc Wapp ca J2EE theo ng dn sau C:\Sun\SDK\domains\domain1\applications\j2eemodulees\soap\WEB-INF\classes.

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Tip theo trin khai dch v ny trn Web Server, ta cn phi vit mt tp deploy.wsdl trin khai tp ln web server, ni dung ca file deploy.wsdl c th hin qua Hnh 32:

Hnh 32: Ni dung ca tp deploy.wsdl

Nhn vo ni dung ca tp deploy.wsdl ta thy mt s cc c im sau:

id = urn:HTService : y chnh l tn ca Web Service m ta trin khai, s c dng gi trong code ca Service Proxy.

methods=SearchHotel : y chnh l phng thc m Web Service s s dng thc hin cc thao tc tnh ton nh tm kim database, tr v kt qu.

dd:java class=HTService.SearchHotelService : y l ng dn web server c th tm kim c file SearchHotelService.class thc thi cng vic.

Sau chng ti copy file deploy.wsdl ny vo th mc C:\Webservice. M mt console, chuyn th mc lm vic ti th mc C:\WebService v g lnh sau trin khai dch v ln Web Server : C:\Webservice > java org.apache.soap.Server.ServiceManagerClient http://localhost:2417/soap/servlet/rpcrouter deploy deploy.xml. Lnh ny nhn ba tham s truyn vo l URL n my ch SOAP, lnh deploy v tp tin hp l trin khai dch v trn my ch SOAP. Nu qu trnh65

trin khai thnh cng th s khng c thng bo li no xut hin, sau ta c th dng lnh C:\webservice > java org.apache.soap.Server.ServiceManagerClient http://localhost:2417/soap/servlet/rcprouter list lit k danh sch cc service c trin khai trn my ch SOAP. Nu ta thy danh sch dch v c xut hin tn urn:HTService l qu trnh trin khai ca ta thnh cng. Ngoi ra nu mun g b dch v SearchHotel Serviece, ta hon ton c th dng lnh g b dch v bng lnh C:\Webservice > java org.apache.soap.Server.ServiceManagerClient http://localhost:8080/soap/servlet/rpcrouter undeploy urn:HTService. Ngoi vic s dng cng c dng lnh trin khai, g b, lit k danh sch cc dch v, chng ta cn c th s dng cng c trin khai trc quan c truy cp thng qua a ch

http://localhost:8080/soap/admin

Hnh 33: Danh sch cc dch v lit k trn web site soap engine

Nhn vo hnh minh ha trn ta c th thy c danh sch cc dch v c trin khai trn my ch SOAP ca chng ta. D thy dch v SearchHotel Service c trin khai, th hin ca SearchHotel Service chnh l urn:HTService.66

Ci t Service SearchFlight SearchHotel Service c ci t trn nn J2EE, vi my ch Soap engine chy trn cng 2417 s dng th vin API Apache Soap. Gi chng ta s tin hnh ci t dch v SearchFlight trn Web Server Apache TomCat, ti cng 8080, s dng th vin API Apache Axis. y l mt th vin hon ton khc so vi Apache Soap, iu cng minh ha r hn cho cng ngh Web Service l mt cng ngh khng ph thuc vo mi trng ci t, ta hon ton c th s dng cc cng ngh khc nhau nhng vn lm cho cc Service giao tip c vi nhau. Tng t nh dch v SearchHotel, dch v SearchFlight cng c vit trong mt file SearchFlightService.java. V file ny c dch ra file SearchFlightService.SearchFlightService.class. Sau ta cn phi copy file ny vo th mc C:\Webservice\tomcat\webapps\axis\WEB-INF\classes. V trin khai dch v ny, chng ta cn phi vit mt file deploy.wsdd trin khai dch v. Ni dung ca tp deploy.wsdd c minh ha trong hnh di y :

Hnh 34: Ni dung file deploy.wsdd

Trong file deploy.wsdd trn ta cn lu :

Thuc tnh service name = SearchFlightService : y chnh l tn ca Service c dng triu gi, n tng ng vi thuc tnh id=urn:HTService trong file deploy.wsdl dng trin khai dch v trn Apache Soap.

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Thuc tnh parameter = value=SearchFlightService.SearchFlightService : tr n v tr ca file SearchFlightService.class my ch Axis tm kim v s dng. N tng ng vi thuc tnh dd:java class=HTService.SearchHotelService trn Apache Soap.

Sau chng ti copy file deploy.wsdd ny vo th mc C:\Webservice. M mt console, chuyn th mc lm vic ti th mc C:\WebService v g lnh sau trin khai dch v ln Web Server: C:\Webservice > java org.apache.axis.Client.AdminClient deploy.wsdd trin khai dch v. Thc cht lnh ny s dng th vin trong axis nhn tham s truyn vo l file deploy.wsdd trin khai dch v. Khi chy lnh thnh cng s c thng bo Processing file deploy.wsdd. Nu mun hy b dch v, chng ta ch cn i tn file deploy.wsdd thnh undeploy.wsdd v sa ni dung 2 th ng m trong file undeploy.wsdd thnh v thc hin lnh java org.apache.axis.Client.AdminClient undeploy.wsdd hy b dch v. Sau khi trin khai thnh cng Web Service SearchFlight sn sng phc v. Ta c th nhn thy danh sch cc dch v c trin khai trong trang qun tr ca Apache Axis nh hnh di y:

Hnh 35: Cc dch v c lit k trn trang qun tr ca Axis

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6.3.3.Xy dng v trin khai Service Proxy y l ni dung quan trng v l vn ch cht gii quyt bi ton t ra trong kha lun ny. Chng ti s trin khai Service Proxy trn web server Apache-Tomcat ti cng 8080 s dng Soap engine l Apache Soap. Thng thng th Service Proxy thng khng phi code cng bi ngi lp trnh, m n thng c t sinh ra t file WSDL ca cc Web Services m Service Proxy triu gi n. Tuy nhin, v vn bn quyn nn y chng ti ch tn dng c mt tnh nng rt nh trong vic t sinh ra Service Proxy t file WSDL, y ch sinh ra tn lp v tn phng thc sao cho Service Proxy c th triu gi ti cc Service Composition. File m ngun Service Proxy c vit trong mt file Proxy.java, trong file ny chng ti nh ngha ra hai lp, mt lp dng triu gi cc Web Service Composition, v mt lp khc dng ly kt qu tr v khi triu gi tun t hai Web Service Composition . Tng ng vi hai Web Services SearchHotel v SearchFlight, ln lt trong mi lp chng ta u c 2 phng thc tng ng triu gi ti hai Web Services . Di y chng ti s trnh by phng php to ra Service Proxy t file WSDL ca dch v SearchFlightService, vi dch v SearchHotelService cch lm cng tng t. Hnh di minh ha file WSDL ca Web Service SearchFlight:

Hnh 36: Ni dung file WSDL ca dch v SearchFlightService

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sinh ra Service Proxy ta ch cn copy ni dung file WSDL a vo chng trnh t sinh, ta s c Service Proxy cn thit gi ti cc Service Composition. Chng ti s dng chng trnh t sinh ca web-site http://nsoftware.com , sau khi a ni dung file WSDL vo chng trnh t sinh ca website , ta c phng thc cn triu gi n Service Composition l phng thc Search_Flight trong dch v SearchFlight. Phng thc Search_Flight ny cn phi c triu gi trong li gi dch v c code trong m ngun ca Service Proxy. Sau khi t sinh ra cc lp v phng thc tru tng cho Service Proxy, chng ta cn phi hiu chnh li Service Proxy c th s dng trn th vin API apache Soap.

Hnh 37: Code Service Proxy goi ti SearchFlightService

Nhn vo hnh trn ta c th thy, do Service Proxy chuyn tip yu cu ti 2 Web Services phc v mc ch tht, cho nn phng thc Flight ca Service Proxy cng phi c kiu tr v l mt String v nhn i s truyn vo l mt String nh mc ch yu cu ca Service Proxy chng ti trnh by trong phn tm hiu bi ton. D thy trong hnh trn, Service Proxy gi ti dch v SearchFlight ti a ch http://localhost:8080/axis/servlet/AxisServlet bng vic khi to ra mt i tng url.

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V gi ti phng thc Search_Flight ca dch v SearchFlight bng li gi call.setMethodname(SearchFlight). Mc tiu bi ton ca chng ta chnh l xy dng Service Proxy kim tra rng buc thi gian p ng ca cc Web Service Composition, cho nn khng th thiu c phn o lng thi gian trong code Service Proxy. Mt phng php n gin o lng thi giap p ng cc Web Service Composition l ta ch cn s dng mt ng h m thi gian trong khong thi gian thc hin li gi dch v. Hnh di y minh ha phng php o lng thi gian p ng:

Hnh 38: Minh ha o lng thi gian p ng

Ta c th thy li gi n cc Service Composition c thc hin qua phng thc Response resp = call.invoke(url,); tng thut ton o lng thi gian p ng trong Web Service Composition c m t nh sau:

Trc khi thc hin li gi ti cc Services thnh phn, ta bt ng h m thi gian thng qua phng thc timer.start();

Sau khi gi phng thc v ly kt qu tr v ta dng ng h m thi gian thng qua li gi phng thc timer.stop();

Sau khi ta c thi gian bt u, thi gian kt thc, ta hon ton c th tnh ra c thi gian p ng l bao nhiu thng qua phng thc getDifference() = timer.stop() timer.start();

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Nh vy vi cc Web Services khc ta u c phng php o lng thi gian tng t nh o lng thi gian p dng vi SearchFlight Service. Vic o lng thi gian p ng i vi SearchHotel Service cng c thc hin vi cch tng t nh p dng vi dch v SearchFlight. Nh vy chng ta c y mt Service Proxy o lng thi gian p ng ca hai Web Services SearchHotel Service v SearchFlight Service. V vic ci t Service Proxy c chng ti vit trong 2 file. File ServiceProxy.java cha 2 lp, mt lp Service cha hai phng thc gi dch v ti hai Web Services thnh phn, mt lp ServiceProxy cha hai phng thc gi ln lt ti hai phng thc trong lp Service. File Timer.java l file chuyn bit dng o lng thi gian p ng ca cc Web Services. Trong code ca file ServiceProxy chng ta phi import file Timer.class c th thc hin vic o thi gian p ng. Chng ti bin dch hai File ny ra thnh 3 lp, l lp mytimer.Timer.class, test.ServiceProxy.class, test.Service.Class, copy 3 file ny vo th mc C:\Webservice\tomcat\webapps\soap\WEB-INF\classes. Service Proxy c ci t s dng Soap engine Apache Soap nn qu trnh ci t hon ton tng t nh khi chng ta ci t dch v SearchHotel. im khc bit duy nht y l a ch ca ServiceProxy lc ny s l http://localhost:8080/soap/ ch khng phi http://localhost:2417/soap/ nh i vi SearchHotel Service. 6.3.4.Pht trin chng trnh client v thc nghim Sau khi c tt c c Web Services thnh phn v Service Proxy, chng ti s pht trin mt chng trnh client n gin c th nhn thy kt qu p ng thi gian ca cc Service Composition. ly kt qu tr v, chng ta ch vic chn thnh ph xut pht ti th Source, thnh ph n ti th Destination v sau nhn nt Search c kt qu tr v. Chng trnh Client c pht trin minh ha qua Hnh 39:

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Hnh 39: Minh ha test chng trnh

Ta thy sau khi nhn nt Search, kt qu ca SearchHotel Service s c hin th trong TextField 1, kt qu tm kim my bay s hin th trong TextField 2. ng thi Service Proxy cng tr v thi gian p ng cho SearchHotel Service l 33ms, thi gian p ng ca SearchFlight Service l 32ms. Chng trnh ca chng ta o lng c thi gian p ng ca cc Web Service Composition, gi chng ta s kim chng xem thi gian p ng c p ng c tiu chun QoS t ra v thi gian hay khng ?

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Gi s ta t ra quy c v thi gian p ng khi gi tun t c hai dch v trong mi trng localhost ti a mt 60 micro giy. Ta c biu Timing Diagram cho vic c t rng buc thi gian p ng trong Web Service Compostion nh sau:

Hnh 40: Biu Timing Diagram m t rng buc thi gian ca WSComposition

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Nhn vo biu trn ta thy, ton b qu trnh thc hin hai Web Service Composition mt cch tun t c gii hn trong vng 60micro giy, nu thi gian vt qu 60micro giy th coi nh khng p ng c yu cu QoS v thi gian t ra. Cc thao tc ti hai Web Services nh tm kim c s d liu, tr li kt qu tr v u c xc nh bng cc khong thi gian tru tng minh ha bng thi gian t v y ta khng th bit chnh xc rng mt bao lu thc thi cc thao tc , ta ch c th c lng c mt bao lu mt thao tc nh vy c th hon thnh. y chng ta ch kim chng thi gian p ng ca cc Web Service Composition cho nn cc thao tc c thc hin ti Client nh nhp thng tin, gi n Service Proxy hay Service Proxy tr li kt qu cho Client s khng lin quan n cc rng buc thi gian ca chng ta. Ta c m hnh kim chng c minh ho nh sau:

Hnh 41: Minh ho m hnh kim chng rng buc thi gian p ng

Vi kt qu tr v bi Service Proxy khi thc hin qu trnh triu gi n hai Web Services, ta c thi gian thc hin tm kim kt qu ca SearchHotel Service l 33 micro75

giy, SearchFlight Service l 32 micro giy, do vic gi 2 dch v ny c thc hin tun t nn tng thi gian gi dch v l 65 micro giy. Trong khi rng buc QoS cho thi gian p ng ca chng ta t ra l ti a cho php 2 dch v ny gi trong mi trng localhost l 60 micro giy. p dng ln m hnh km chng minh ho hnh 41 ta thy rng t1+t2 > t (33ms + 32ms > 60ms) nn ta dn n kt lun l thi gian p ng ca hai Web Service Composition ny cha p ng c tiu chun ra. Nh vy chng ta xy dng c nn mt Service Proxy kim tra rng buc thi gian p ng trong Web Service Composition, c t rng buc thi gian trn biu UML Timing Diagram. Ta hon ton c th m rng bi ton vi mt tp hp rt nhiu cc Web Service Composition khc vi phng php p dng nh trn, y mc tiu ca kha lun ch l kim tra xem thi gian p ng c tun th thi gian QoS ra hay khng. Ta mi kim tra mt trng hp, ty vo tng ng cnh m ta c th kt lun liu cc dch v c p ng c vi tiu chun QoS v thi gian khng. Tuy nhin trong thc nghim khi chng ti kim tra cc p ng vi nhiu truy vn chng ti thy thi gian p ng cng gim i ng k, v hu ht cc Service Composition u p ng c vi yu cu v rng buc thi gian a ra. Tuy nhin th hin y th cn phi c cc phng php, iu kin ng cnh khc nhau mi c th c kt lun chnh xc. Do iu kin hn hp nn chng ti mi ch th hin phng php bi ton, chnh xc vi thc t cn phi th hin bi ton trn mi trng Internet, ni m c rt nhiu yu t nh hng ti cht lng p ng ca cc dch v.

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CHNG 7: KT LUNCng ngh Web Service ngy cng c s dng rng ri trong vic gii quyt cc bi ton lin quan n d liu phn tn. Vi cc u im ca mnh, Web Service chng t c kh nng p ng mnh m i vi cc quy trnh nghip v ngy cng phc tp ca cc t chc doanh nghip. S pht trin ca Web Service s dn n nhu cu nh gi cht lng dch v Web no tt nht cho ngi s dng, ngi s dng c th la chn dch v thch hp cho mnh. Vic nh gi cht lng cc dch v Web l mt ti rt mi m v ang nhn c s quan tm su sc ca gii chuyn mn. p ng vi mc tiu nh gi cht lng phc v ca cc dch v Web, kha lun xut ra mt phng php kim chng rng buc thi gian p ng trong Web Service Composition thng qua cc rng buc QoS v thi gian c c t bng biu UML Timing Diagram. Sau mt thi gian nghin cu v hc hi, n nay chng ti hon thnh kha lun v thu c cc kt qu sau y: Kha lun trnh by mt cch tng qut v m hnh h phn tn qua vic tip cn kin trc hng dch v SOA, a ra ci nhn r rng hn v cng ngh Web Service, cch xy dng v trin khai cc Web Services. Nm c cc cng ngh chun c s dng cho Web Service nh SOAP, WSDL, UDDI, v cng ngh dng tch hp cc Web Services. Da trn cc kin thc nn tng v cng ngh Web Service, kha lun tip cn n mt hng nghin cu mi l tm hiu v cht lng cc dch v Web hay cn gi l QoS cho Web Services. Kha lun trnh by mt dng biu UML mi c thm vo cho UML 2.0 l biu UML Timing Diagram. Mt biu dng c t rng buc thi gian p ng ca cc i tng trong mt qu trnh tng tc di s tc ng ca cc s kin hay thng ip.

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Thng qua v d minh ha trong chng Thc nghim, kha lun xy dng thnh cng Service Proxy, c dng o lng thi gian p ng ca cc Web Services. T da trn cc rng buc v thi gian c c t bng biu Timing Diagram dn n kt lun cc Web Services c p ng c tiu chun QoS hay khng.

Tuy nhin do qu thi gian nghin cu hn hp cng nh iu kin k thut b gii hn, kha lun khng trnh khi cc hn ch sau:

Mi ch thc hin vic kim chng i vi cc Web Services c trin khai trn mi trng localhost. gn vi thc t, bi ton cn phi c p dng trn mi trng Internet, ni c rt nhiu yu t nh hng n cht lng phc v ca cc dch v Web.

Vic kim chng thc hin mc tng quan i vi mt tp hp cc Web Services. Cha kim chng rng buc c th i vi tng thao tc trong tng Web Service nh thao tc truy cp c s d liu, thao tc tr v kt qu v..v Trong tng lai chng ti s tip tc m rng ti ny theo hng nghin cu v a ra cc gii php khc phc khi cc dch v Web cha p ng c cc tiu chun QoS, ng thi pht trin bi ton p ng y cho cc yu cu v cht lng dch v Web nh p ng c tnh c sn, tnh an ton, tnh tin cy ca Web Services. s l mt hng i kh cn thit sau ny khi s dng cng ngh Web Service ngy cng l mt la chn hon ho cho cc doanh nghip thc hin cc nhu cu nghip v ca mnh.

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TI LIU THAM KHO[1] Doug Tidwell, James Snell, Paval Kulchelko Programing Web Services With

Soap, December 2001. [2] Daniela Malfatti - A Meta-Model for QoS-Aware Service Composition, December 2007. [3] Prentice Hall PTR Web Service Platform Architechture: SOAP, WSDL, WSPolicy, WS-Addressing, WS-BPEL, WS-Reliable Messaging, and More, Marth 2005. [4] Robert Englander - Java and Soap, May 2002. [5] Ethan Cerami Web Service Essentials Distributed Application with RPC, SOAP, UDDI &WSDL, February 2002. [6] Anbazhagan Mani, Arun Nagarajan Understanding quality of service for Web Service, January -2002. [7] W3C Working Group QoS for Web Service: Requirements and Possible Approaches, November 2003. [8] Javavietnam.org Web Service ci t v s dng, 2007. [9] Jamers P.Lawler, H.Howell-Baber, Service Oriented Architecture SOA strategy, Methodology and Technology, January- 2008. [10] Kim Hamilton, Russell Miles Learning UML 2.0, April- 2006. [11] Simon Bennett, John Skelton, Kelunn UML Second Edition, May - 2006 [12] Axis Users Guide, http://ws.apache.org/axis/java , April- 2009. [13] Marcus Cobden, Ben Humphrays, Kathryn Macarthur Timing Diagram Plugin Support for RODIN/UML-B, December 2007. [14] W3C School Soap Tutorial , http://www.w3schools.com/soap , April - 2009. [15] W3C School WSDL Tutorial , http://www.w3schools.com/WSDL , April - 2009. [16] W3C School UDDI Tutorial , http://www.w3schools.com/UDDI , April - 2009. [17] Gerhard Wiehler Web Service and Service Oriented Architecture, February2004.

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