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Vlo1.9No.4Dec.2003

    ;UsngMiddlewaretoMigrateLegacySystem:ACaseStudy ;XingDahong(邢大红),LiuZongtian,XuDong,YangXuejun”

    ;(ResearchInstituteofIVli~puter,HdeiUniversityofTechnology,Hdei230009,P.R.China)

    ;(SchoolofComputer,shanghaiUniversity,hai200072,P.R.China) ;(“AnhuiBranchofChinaConstructionBank,Hefe230009,P.R.chi.~)

    ;Abstract

    ;erehasbeenanincreasingneedtomigratelegacysystemstonewhardwaretechnologies

    ;andsoftwaredevelopmentparadigmsbecausethelegacysystemspresentproblemssuchaslowef

    ;fectivenessandhighmaintenance.Iforganizationswanttoremaincompetitiveintoday’sfast

    ;changingbusinessandtechnologicalenvironment,theymustovercometheseproblems.Middle

    ;wareisflvaluabletechnologyinthatitprovidesconvenientmethodstoconstructsysteminfras

    ;tructure.soitcanbeusedtomigratethelegacysystems.Thispapergivesacasestudyonusing

    ;middlewaretechnologiesfortheimplementationofreengineeringdistributedaridheterogeneous

    ;banklegacysysteminAnhuibranchofChinaConstructionBank.Usingmiddlewaretomigrate

    ;legacysystemhasprovedtobegoodchoiceinpractice. ;Keywords:legacysystem,middleware,migrate ;0Introduction

    ;Therehasbeenanincreasingneedtoreplace

    ;legacysystemstonewhardwaretechnologiesand ;softwaredevelopmentparadigmsbecausethelegacy ;systemspresentproblemssuchasloweffectiveness ;andhighmaintenance.Iforganizationswanttore

    ;maincompetitiveintoday’sfastchangingbusiness

    ;andtechnologicalenvironment,theymustovercome ;theseproblems.Therearetwomainapproachestore

    ;placelegacysystemstonewplatformsandprogram

    ;mjngparadigms.(a)Redevelopment:Existinglega

    ;cysystemsarethoroughlyanalyzedandthentrans

    ;formedintocompletelynewsystems.Thisapproach ;ismorethanjustconvertingflcodefromonelanguage ;toanother.Itistheconversionofentiresystemarchi

    ;tectures,includinghardwareandsystemplatform. ;Thereareseveraladvantages.Specifications,design, ;andimplementationcanbestartedwithgoodprac

    ;tices.Therea1?alsoseveraldisadvantages,suchas

    ;highcost,timeconsumingandhighrisk.Itisinfea

    ;sibleformanyorganizationstoredeveloplargelegacy ;systemsfromscratchduetounaffordablecosts,time,

    ;andrisksofredevelopingflreplacementsystemgiven ;theknowledgeandexpertiserecordedintheexisting ;systems.(b)Migration:Becauseorganizationshave ;alreadymadesignificantinvestmentintheirlegacy ;systems,theyareusuallywillingtoretainthelegacy ;systemfunctionalityandcauselittledisruptiontothe ;ReceivedonMay6,2003

    ;existingoperationalandbusinessenvironmentaspo8

    ;sible.Migrationmovestheexistingoperationalsys

    ;temtoflnewplatform.Keepingthecompany’slegacy

    ;systemsoperational,preservingthelegacysystems, ;andfacilitatingthe?mpan,

    ;slegacysystemsevolu

    ;tionaI?majngoalsofthisapproach.Fromeconomical ;pointofview,migrationisthereforemorefeasible ;wayofmodernizingthelegacysystems.

    ;Therearefllotofwaystomigratelegacysystems ;tonewerparadigms.DeLuciaeta1.havedevelopedfl ;waytomigratelegacysystemstoobject-orientedplat..

    ;forms….Theyusereverse-engineeringtechniquesfor

    ;objectidentificationatfirstandthenencapsulatethe ;identifiedobjeetsintowrappers.Finally,theyfinish ;migrationbyperformingtheincrementaltranslation ;of”legacyobjects”toobject-orientedplatforms.Sneed

    ;andMajnarstudyonmigratinglegacysystemstoob

    ;jecttechnologiesandclient/serversystems.They

    ;usewrappingatdifferentlevelsofencapsulationsuch ;asjob,transaction,program,module,andproce

    ;dure.Inthispaper,wefirstlyintroducemiddleware ;intheSection1,andthengiveourstudyonusing ;mid~ewaretechnologytoachievemigrationinSec

    ;tion2.

    ;Thetermmiddlewareisusedtodescribeflframe

    ;workofgeneralservicesthatexistbetweentheappli

    ;cationandthenetwork.Middlewareisflvaluable ;

    ;91

    ;

    ;Vo1.9No.4Dec.20o3

    ;technologyinthatitprovidesageneralmechanismfor ;distributedapplicationstocooperateusingacommon ;poolofservices.Itprovidesfunctionsoutsidethe ;realmofanapplication.Throughtheuseofapplica- ;tionprogramminginterfaces(APIs),thedeveloper

    ;incorporatesthemiddlewareservicesinto811applica- ;tion.Each/niddleware~viceistranstkarenttothe ;applicationinthatthemiddlewareprovidesanab

    ;stractionfromitsfunctionality.Therefore,develop

    ;ersconcentrateonthespecificdetailsoftheapplica

    ;tionsfunctionality.reducesthecomplexityof ;building811applicationandthetimeofcreatinganap

    ;plication.Generallyspeaking,mid&ewareisaninte

    ;grallayerofsoftwareindistributedsystems.Ithides ;thedetailsoftheunderlyingfunctionsfromtheappli

    ;cation.asweftasendusers.Programmingabstrac

    ;tionsallowdeveloperstoseamlesslyblendmiddleware ;intotheirapplications.Middlewareprovidesasetof ;services,suchasidentification,authorization,direc

    ;tory,andsecurity.ThesecoInnlonandreusablefunc

    ;tionsassistthecooperationofdistributedapplications. ;Today,manydistributedsystemsexistina1-1en

    ;vironmentofmixedhardwareandsoftwarecompo

    ;nents.Moreover,themixischangingallthetimeas ;newhardwareinnovationsaremade.leitishigh

    ;lydesirablethatthedevelopersofanapplicationhave ;thefreedomtochoosethecomputingplatformson ;whichtorunit.itisalsodesirabletoshieldtheappli

    ;cationprogrmmnerfromthepeculiaritiesofparticular ;hardwareplatforms,andalsofromtheintricaciesof ;makingdifferentplatformsinteroperate.Middleware ;canmeettheserequirements,becauseitscomprehen

    ;slvecapabilitiessupportanintegratedi~rastructure ;thatearconnectlegacysystems.So.middlewarecan ;provideaneffectivewaytomigratethelegacys~tem ;smoothly,espedallyforaheterogeneousdistributed ;environment.

    ;2TheCaseofMigrationofLSystemUsing

    ;eware

    ;2.1Background

    ;TheAnhuibranchofChinaConstructionBank

    ;hasusedabusinessapplicationsystemforfiveyears ;since1995.There.are’16citiesintheAnhui

    ;province.Everycityformeditsdatapjro0沿section,

    ;whichwastwo-tierclient/serverarchitecture.e ;switchcenterconnected16dataprocesscentersfor ;dataexchangebetweendifferentdataprocesscenters. ;Businessdataweredistributedin16sectionsrespec

    ;tivelyandeachsectionhadadifferenthardwareplat

    ;form.Thelegacysystemwasdistributedandhetero.. ;

    ;92

    ;geneous.asshowninFig.1.Obviously,itwasdiffi

    ;cultfortheexistingsystemstobereadilyaccorflrllo

    ;datedtonewcircumstances.Themfom,theintegra

    ;tionandevolutionofexistingsystemsrepresentoneof ;themosturgentprioritiesofbankbusinesslegacysys

    ;tems.Integrating16sectionsandconcentratingtheir ;datatoformasingleprocesscentercanimprovethe ;systeminflexibility,scalability,maintainabilityand ;reliability.Wecallthismigrationactionthedatacon

    ;centrationproject.Mainobjectivesofthepectare ;keopingtheexistingsystemfunctions,makinguseof ;originalinvestmentincludinghardwareandsoftware, ;andreducingimplementingtime.

    ;Fig.1Legacysystemarchitecture

    ;2.2MigrationApproach

    ;2.2.1Decomposinglegacysystemfort’inhetero—

    ;geneousdistributedcomputingenvironments ;Weanalyzethoroughlythelegacys~temand ;takefldecomposingstrategytoutilizethelegacyre

    ;sources.Decomposingaprogramentailstheidentifi

    ;cationandreorganizationofdifferentprogramcompo

    ;nents.Inourproject,thesoftwaresystemisdecom

    ;pondintothreetypesofcomponents:userinterface ;components,applicationlogiccomponents,and ;databasecomponents.Userinterfacecomponentsin. ;eludestate~nentsthatdirectlyorindirectlycontrolthe ;executionofI/0controlstatements.Indeed.ina ;newdient/serversystem,theclientshouldmainly ;implementtheuserinterface.havecontrolofthesys. ;tern,andrequeststheservicesneeded(mainly ;databaseaccesses)fromtheserver.So,userinterface ;componentsaremigrat~totheclient.Adatabase ;componentmightbecomposedofanypieceofcode ;clusteringaroundI/0statementsonDISKfiles.in. ;eludingchunksofembeddedSQLor4GLcode.The ;databasecomponentsaremigratedtotheserver.Ap ;plicationlogiccomponentscorrespondtoaxlefrag

    ;mentsimplementingbusinessrules.eapplication

    ;logiccomponentsareindependentofeachotherand ;interact,ththedatabasecomponents.Theyarealso ;migratedtoth6server.

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    ;V0I.9No.4Dec.2003

    ;2.2.2Establishingthemiddle.re-basedstructtire ;,introducemiddlawaretotransformthelegacy ;systemintoathree-tierclient/serverarchitecturefls ;showninFig.2.Theopenarchitecture.basedonthe ;introductionoftheTlD(][Omiddlawarefromthe ;BEACompanyt4..notonlyreducestheeffortneoeS

    ;saryforallowingexistingsystemstointerwork,but ;alsoeffectivelyestablishesafunctionalandinforma- ;tionalbasiseotnnlontothewholeorganization.New ;applicationscanalsoberapidlydevelopedandnatively ;integratedwiththerestofthesystem.Threetypesof ;componentsdecomposedfromthelegacysystemare ;combinedwiththenewapplicationsystem. ;Nearly900frontendterminalsinstallTlDDO

    ;client.16citycommunicationserversinstallboth ;TIDDOclientandserver.Thecentralcenterin

    ;stallsTID)server.Onlycentralcenterbuysa ;newmainframe.Therestpartsofthenewsystemare ;ofiginalmachinel3].

    ;Fig.2Newsystemphysicalarchitecture

    ;Thefrontendinstallsapplicationsystemclient ;software,whichcombinesthelegacyuserinterface ;components.Thecentralcenterinstallssystemserver ;software,whichcombinesthelegacyapplicationlogic ;components,anddatabasecomponents.Newapplica

    ;tionsoftwareisdevelopedforthedtycommunication ;servers.Thenewsoftwareworksasserverforfront- ;endandclientforthecentralcenteratthesametime. ;Therestsurroundingthemainsystem.suchastele

    ;phonebanksystem,POS(PointOfSale)systemand ;ATM(AutomaticTellerMachine)system,remain ;thesameasbefore.Thesearealsothelegacysystems ;thatbelongtoeachcity.

    ;2.3EffectofMigration

    ;Ittookusnearlyoneyeartomigratealegacy ;system.Now,thenewsystemhasrunsmoothlyfor2 ;years.Thetotalcostoftheprojectwas$60million. ;Ifweconstructthenewsystemfromscratchwithout ;makinguseoflegacysystem,thetotalcostofthe ;proiectisestimatedtobe$200millionandwilltake ;2yearstoimplement.Obviously,migratingthelega

    ;cysystemusingmiddlawareiscost-effective.

;3Conclusion

    ;Fromourstudy,themiddlewarerepresentsthe ;keyelementforensuringtheopennessandmodularity ;ofaninformationsystem.aSwellasanoperationalin ;frastructuresuitablebothfortheintegrationoflegacy ;systemsandthedevelopmentofnewmodules.There ;fore,itisgoodchoicefororganizationstomigratethe ;legacysystem.

    ;References

    ;[1])eLuciaA,DiLuccaG,FasolinoA,eta1.Silverspring. ;I?,EComputerSocietyPress,1997.122129

    ;[2]SneedH,MajnarR.Silverspring.IE】旺ComputerSociety

    ;Press,1998.8693

    ;[3]xingDH,WangHC.F/nanc/a/computerofChina, ;2o02,(2):52

    ;[4]BEASystems,Inc.Openwhitepaper.http://www.bea. ;coin

    ;.

    ;rangDahong,hornin1966.Hereceivedhis

    ;Master’sdegreefromHefeiUniversityofTechnolo—

    ;gY.NowheisaPh.D.candidateinHefeiUniversity ;ofTechnology.Hisresearchinterestsincludesoft ;warearchitecture,softwareengineering,software ;processassessmentandimprovement.

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