基于Web的在线问题解答系统-外文翻译

0外文资料DevelopWebapplicationprogramusingASPthearchitecturethatmustfirstestablishWebapplication.Nowinapplicationfrequentlywithtohavetwo:ThearchitectureofC/SandthearchitectureofB/S.Client/serverandcustomerend/serverholdthearchitectureofC/S.Thecustomer/serverstructureoftwofloor.Customer/server(Client/Server)modelisakindofgoodsoftwarearchitecture,itistheoneofbestapplicationpatternofnetwork.Fromtechnology,seethatitisalogicconcept,denotewillaapplicationmanytasksofdecomposingdifferencecarryout,commoncompletionisentiretoapplythefunctionoftask.Oneachnetworkmaincomputerofwebsite,resource(hardware,softwareanddata)divideintostep,isnotbalanced,undercustomer/serverstructure,withouttheclientcomputerofresourcethroughsendingrequesttotheserverthathasresource,getresourcerequest,someettheresourcedistributioninnetworknotbalancedness.Withthiskindofstructure,cansynthesizevariouscomputerstocooperatewithwork,letiteachcan,realizethescaleforthesystemofcomputeroptimization(Rightsizing)withscalereducetomelt(Downsizing).Pictureisasfollows:Itismostoftodivideintocomputernetworkapplicationintotwo,inwhichtheresourceandfunctionthatpartsupportsmanyuserstoshare,itisrealizedbyserver;Anotherpartfaceseveryuser,isrealizedbyclientcomputer,alsonamely,clientcomputerisusualtocarryoutprosceniumfunction,realizesman-machineinteractionthroughuserinterface,oristheapplicationprogramofspecificconducteduser.Andserverusuallycarriesoutthefunctionofbackstagesupporter,managestheoutsiderequestconcerningsetingup,accepting1andreplyinguserthatshared.Foracomputer,itcanhavedoublefunction,isbeingcertainandmomentarytocarvetoactasserver,andagainbecomesclientcomputerinanothertime.Customer/servertypecomputerdivideintotwokinds,onesidewhooffersserviceiscalledasserver,asksonesideofservicetobecalledascustomer.Tobeabletoofferservice,serveronesidemusthavecertainhardwareandcorrespondingserversoftware;Also,customeronesidemustalsohavecertainhardwareandcorrespondingcustomersoftware.Theremustbeaagreementbetweenserverandcustomer,bothsidescommunicateaccordingtothisagreement.Applycustomer/servermodelinInternetservice,therelationbetweencustomerandserverisnotimmutable.SomeInternetnodeoffersserviceontheonehand,alsogetsserviceontheotherhandfromothernode;Itiseveninonetimedialoguecourse,mutualrolealsoexchangesprobably.Asincarryoutfiletransmission,ifbecalledasonesidewhooffersfileserver,iscalledasonesidewhogetsfilecustomer,whenusinggetormgetordersinceanothernodetakesfile,canthinkthatwhatselfuseanditisclientcomputer,isusingputormputordertoanothernodedispatchfilecanagainthinkthemachinethatusedselfisserver.Multilayercustomer/serverstructureAlongwiththedevelopmentofenterpriseapplication,recently,haveagainarisenakindofnewmultilayerarchitecture,itappliescustomerendtodivideintotwominutes:Customerapplicationandserverapply.Customerapplicationisthepartoforiginalcustomerapplication,isanotherandpartialtohavebeentransferedtoservertoapply.Newcustomerapplicationtakestheresponsibilityforuserinterfaceandsimpleregularbusinesslogicandnewserverapplicationresidentcore,changeablebusinesslogic.Thereforeitsstructurehasbecomenew(Clientapplication+Serverapplication)/Serverstructure.Followingpictureshows:2ThiskindofstructurehassolvedtraditionalClient/Servercanexpandproblem,havereducedcustomerendbusinesslogic,andhavereducedtherequirementofcustomerendforhardware.Atthesametimebecauseofalotofbusinesslogicconcentrationshavegonetounitaryapplicationserveron,themaintenanceworkofapplicationsystemhadbeenalsoconcentratedtogether,haveeliminatedtheprobleminthetraditionalstructureofClient/Serverthatsoftwaredistributes.ThiskindofstructureiscalledasthearchitectureofB/S.Browser/Serverandbrowser/serverholdthearchitectureofB/S.Onessence,Browser/ServerisalsoakindofstructureofClient/Server,itisakindoffromthetraditionaltwolevelsofstructuraldevelopmentofClient/Servercometothethree-layerstructuralspecialcaseofClient/ServerthatappliedonWeb.InthesystemofBrowser/Server,usercanpassthroughbrowsertoalotofserversthatspreadonnetworktosendrequest.ThestructureofBrowser/Serverismaximumtohavesimplifiedtheworkofclientcomputer,onclientcomputer,needtoinstallanddeployfewcustomerendsoftwareonly,serverwillbearmorework,fordatabasevisitandapplyprogramcarryoutwillinserverfinish.Underthethree-layerarchitectureofBrowser/Server,expresslayer(Presentatioon),functionlayer(BusinessLogic),datalayer(DataService)havebeencuttheunitof3relativeindependences:Itisthefirstlayeroftoexpresslayer:Webbrowser.Inexpressinglayercontainsystemshowlogic,locateincustomerend.Itstaskisto3suggestbyWebbrowsertothecertainaWebserveronnetworkthatserviceisasked,afterverifyingforuseridentity,WebserverdeliversneededhomepagewithHTTPagreementtocustomerend,clientcomputeracceptthehomepagefilethatpassed,andshowitinWebbrowseron.Secondlayerfunctionlayer:HavetheWebserveroftheapplicationfunctionofprogramextension.Infunctionlayercontainthesystematichandlingofgeneralaffairslogic,locateinWebserverend.Itstaskistherequestconcerningacceptinguser,needtobefirstconductedandcorrespondingtoexpandapplicationprogramanddatabasetocarryoutconnection,passesthroughthewaiessuchasSQLtodatabaseservertoputforwarddatahandlingtoapplyfor,thenetc.databaseservertheresultofhandlingdatasubmittoWebserver,deliveragainbyWebservertoreturncustomerend.Thenumberofpliesof3thaccordingtolayer:Databaseserver.Indatalayercontainsystematicdatahandlinglogic,locateindatabaseserverend.ItstaskistoaccepttherequestthatWebservercontrolsfordatabase,realizationisinquiredandmodifiedfordatabase,updateetc.function,submitoperationresulttoWebserver.Carefulanalysisisbeeneasytosee,thearchitectureofBrowser/Serverofthree-layeristhehandlingofgeneralaffairsofthetwolevelsofstructureofClient/Serverlogicmodularfromthetaskofclientcomputerinsplit,fromthefirstfloorofindividualcompositionbearthepressureofitstaskandsuchclientcomputerhavealleviatedgreatly,distributeloadbalancedlyandhavegivenWebserver,sofromthestructuralchangeofClient/serveroforiginaltwofloorthestructureofBrowser/Serverofthree-layer.Thiskindofthree-layerarchitecturefollowingpictureshows.Thiskindofstructurenotonlyclientcomputerfromheavyburdenandtherequirementofperformancethatrisescontinuouslyforitinliberationcomeout,alsodefendtechnologypeoplefromheavymaintenanceupgradingworkinfreeoneself.Sinceclientcomputerhandlesgeneralaffairs,logicpartialminuteshavegivenfunctionserver,makeclientcomputerrightoffslenderalotof,donottaketheresponsibilityforhandlingcomplexcalculationanddataagainvisitetc.crucialgeneralaffairs,isresponsibletoshowpart,so,4maintenancepeopledonotrushaboutagainforthemaintenanceworkofprogrambetweeneveryclientcomputer,andputmajorenergyintheprogramonfunctionserverupdatework.Betweenthiskindofthree-layerstructurallayerandlayer,themutuallyindependentchangeofanyfirstfloordoesnotaffectthefunctionofotherlayer.IthaschangedthedefectofthetwolevelsofarchitectureofClient/Serveroftraditionfromfoundation,itisthetransformwithdeeponceinapplicationsystematicarchitecture.ThecontrastoftwoarchitecturesThearchitectureofBrowser/ServerandthearchitectureofClient/ServercomparewithalladvantagesthatnotonlyhavethearchitectureofClient/ServerandalsohavethearchitectureofClinet/Servertheuniqueadvantagethatplacedoesnothave:Openstandard:ThestandardadoptedbyClient/Serveronlyindepartmentunificationforbut,itsapplicationisoftenforspecialpurpose.Itislowertodevelopanddefendcost:ItneedtobeimplementedonallclientcomputersthattheapplicationofClient/Servermustdevelopthecustomerendsoftwareforspecialpurpose,nomatterinstallationanddispositionescalatestill,havewastedmanpowerandmaterialresourcesmaximumly.TheapplicationofBrowser/Serverneedincustomerendhavegeneralbrowser,defendandescalatetoworkinserverendgoon,neednotcarryoutanychangeascustomerholds,havereducedthecostofdevelopmentandmaintenancesogreatly.Itissimpletouse,interfacefriendly:TheinterfaceoftheuserofClient/Serverisdecidedbycustomerendsoftware,interfaceandthemethodofitsusearenotidenticaleach,perpopularizeasystemofClient/Serveraskuserstudyfromthebeginning,ishardtouse.TheinterfaceoftheuserofBrowser/Serverisunifiedonbrowser,browseriseasytouse,interfacefriendly,mustnotstudyuseagainothersoftware,theuseofaLaoYongYithathassolveduserproblem.Customerenddetumescence:ThecustomerendofClient/Serverhasthefunctionthatshowsandhandlesdata,astherequirementofcustomerendisaclientcomputeritisfatveryhigh.ThecustomerofBrowser/Serverholdstheaccessthatnottakestheresponsibilityfordatabaseagainandtheetc.taskofcomplexdatacalculation,needitonlyshow,the5powerfulrolethathasplayedserverfullyissolargetohavereducedtherequirementforcustomerend,customerendbecomeverythin.Systemisflexible:The3minutesofthesystemofClient/Server,inmodular,havethepartthatneedtochangetowantrelationtothechangeofothermodular,makesystemverydifficultupgrading.The3minutesofthesystemofBrowser/Servermodularrelativeindependence,inwhichapartofmodularchange,othermodulardoesnotgetinfluence,itisveryeasythatsystemimprovetobecome,andcanformthesystemwithmuchbetterperformancewiththeproductofdifferentmanufacturer.Ensuresystematicsafety:InthesystemofClient/Server,directlyjoinwithdatabaseserverbecauseofclientcomputer,usercanveryeasilychangethedataonserver,cannotguaranteesystematicsafety.ThesystemofBrowser/ServerhasincreasedalevelofWebserverbetweenclientcomputeranddatabaseserver,makestwonottobedirectlylinkedagain,clientcomputercannotbedirectlycontroledfordatabase,preventuserefficientlyinvadeillegally.ThearchitectureofBrowser/Serverofthree-layerhastheadvantagethatalotoftraditionalarchitecturesofClient/Serverdoesnothave,andisclosetohavecombinedthetechnologyofInternet/Intranet,isthatthetendencyoftechnicaldevelopmenttendsto,itapplicationsystemtapeintoonebrand-newdeveloptimes.FromthisusoptiontheconfigurationofB/Sthearchitecturethatdevelopsassystem.whatareC/SwithB/SForC/SwiththetechnologyofB/Sdevelopchangeknow,first,mustmakeitclearthat3problems.(1)WhatisthestructureofC/S.C/S(Client/Server)structure,theserverstructureandclientcomputerthatallknowwell.Itissoftwaresystematicarchitecture,throughitcanholdhardwareenvironmentfullyusingtwoadvantage,realizetaskreasonabledistributiontoClientendandServerend,havereducedsystematiccommunicationexpense.Now,themostsystemsofapplicationsoftwarearethetwolevelsofstructureoftheformofClient/Server,aredevelopingtotheWebapplicationofdistributiontypesincecurrentsoftwareapplicationissystematic,Webandthe6applicationofClient/Servercancarryoutsamebusinesshandling,applydifferentmodulartosharelogicassembly;Thereforeitissystematicthatbuilt-inandexternalusercanvisitnewandexistingapplication,throughthelogicinexistingapplicationsystem,canexpandnewapplicationsystem.Thisisalsopresentapplicationsystemdevelopdirection.TraditionalCSarchitecturethoughadoptingisopenpattern,butthisistheopennessthatsystemdevelopsalevel,inspecificapplicationnomatterClientendorServerendthesoftwarethatneedtostillspecifysupport.BecauseofthesoftwaresoftwarethatneedtodevelopdifferenteditionaccordingtothedifferentsystemofoperatingsystemthatcannotofferthestructureofC/Sandtheopenenvironmentofusergenuineexpectation,besides,therenovationofproductisveryrapid,isnearlyimpossibletoalreadymeetthe100computeraboveusersoflocalareanetworkatthesametimeuse.Pricehaslowefficiencyhigh.Ifmycourtyarduses,ShanghaiexceedtheorchidcompanysmanagementsoftwarestatisticsoflawcaseistypicalCSarchitecturemanagementsoftware.(2)WhatisthestructureofB/S.B/S(Browser/Server)structurebrowserandserverstructure.ItisalongwiththetechnologyofInternetspringup,itisforthestructureofimprovementorakindofchangeofthestructureofC/S.Underthiskindofstructure,userworkinginterfaceistorealizethroughWWWbrowser,losethelogicofgeneralaffairsverymuchinfront(Browser)realization,butthemajorlogicofgeneralaffairsinserverend(Server)realization,formthethree-layerclaimed3-tierstructure.So,havesimplifiedcustomerendcomputerloadgreatly,havealleviatedsystemtodefendworkloadandthecostwithupgrading,havereducedtheoverallcostofuser(TCO).Withpresenttechnologysee,localareanetworkthenetworkapplicationthatestablishesthestructureofB/S,andunderthepatternofInternet/Intranet,databaseapplicationiseasytoholdrelatively,costalsoislower.Itisthatonenessgoestothedevelopmentofposition,canrealizedifferentpeople,neversameplace,withdifferencereceivethewayofentering(forexampleLAN,WAN,Internet/Intranetetc.)visitandoperatecommondatabase;Itcanprotectdataplatformefficientlywithmanagementvisitlimitsofauthority,serverdatabaseisalsosafe.Nowinmycourtyard,net(Intranet),outernet(Internet)withBeijingeasternclearbigcompanylawcaseandthemanagement7softwareofofficialbusinessisthestructuralmanagementsoftwareofB/S,policemeneachworkingstationinlocalareanetworkpassthroughWWWbrowsercanrealizeworkingbusiness.EspeciallyinJAVAstepplatformlanguageappearanceafter,theconfigurationmanagementsoftwareofB/Sismorefacilitated,isshortcut,efficient.(3)Themanagementsoftwaretechnologyofmainstream.Thetechnologyofmainstreamofmanagementsoftwaretechnologyisasmanagementthought,havealsogonethrough3developperiod.First,interfacetechnologygoestoWindowsgraphinterface(orgraphuserinterfaceGUI)fromlastcenturyDOScharacterinterface,tillBrowserbrowserinterface3differencesdevelopperiod.Secondly,todayownthebrowserinterfaceofcomputer,isnotonlyvisualandiseasytouse,whatismoremajoristhatanyitsstyleofapplicationsoftwarebasedonbrowserplatformisas,maketherequirementofchoosingapersonforthejobforoperatingtrainingnothighandsoftwareoperabilityisstrong,iseasytodistinguish;Moreoverplatformarchitecturethefilethatalsogoestotodayfrompastsingleuserdevelopmentserver(FS)systemandclientcomputerserver(CS)systemandbrowserserver(BS)system.ThecomparisonofC/SandB/SC/SandB/Sisthenowworldtwotechnologiesofmainstreamofdevelopingpatterntechnicalconfiguration.C/SisthatAmericanBorlandcompanyresearchesanddevelopmostearly,B/SisthatAmericanMicrosoftresearchesanddevelop.Nowthistwotechnologieswithquiltworldcountriesgrasp,itismanythatdomesticcompanyproducearticlewithC/SandthetechnicaldevelopmentofB/S.Thistwotechnologieshavethecertainmarketshareofself,iswithcustomercrowd,eachdomesticenterprisesaysthatownmanagementsoftwareconfigurationtechnicalfunctionispowerful,advanced,convenient,thecustomergroupthatcanlift,haveacrowdscholarinkguesttoshakeflagselfcryout,advertisementfliesalloverthesky,maybecalledbenevolenttoseekernel,sageseeswisdomC/Sconfiguresinferiorpositionandtheadvantageofsoftware(1)Applicationserveroperationdataloadislightcomparatively.8ThedatabaseapplicationofthemostsimplearchitectureofC/Sisbecomebytwopartialgroups,customerappliesprogramanddatabaseserverprogram.Bothcanbecalledasprosceniumprogramandtheprogramofbackstagesupporterrespectively.Themachineofoperationdatabaseserverprogramisalsocalledasapplicationserver.Onceserverprogramhadbeenstarted,waitstherequestconcerningrespondingcustomerprogramhairatanytime;Customerapplicationprogramoperationcanbecalledascustomercomputerontheowncomputerofuser,incorrespondencewithdatabaseserver,whenneedscarryoutanyoperationforthedataindatabase,customerprogramseeksserverprogramvoluntarily,andsendsrequesttoit,serverprogramisregularasbasisintendstomaketoreply,sendtoreturnresult,applicationserveroperationdataloadislighter.(2)Datastoremanagementfunctionrelativelytransparent.Indatabaseapplicationdatastoremanagementfunction,iscarriedoutrespectivelyindependentlybyserverprogramandcustomerapplicationprogram,isregularasprosceniumapplicationcanviolate,andusuallythosedifferent(nomatterishaveknownstillunknown)operationsdata,inserverprogram,donotconcentraterealization,forinstancevisitlimitsofauthority,serialnumbercanberepeated,musthavecustomertalentestablishmenttheruleorder.Itisthesetoown,forthelastuserthatworksonprosceniumprogramistransparent,theyneednotbeinterestin(cannotusuallyalsointerfere)thecourseofbehind,cancompleteownallwork.Intheapplicationofcustomerserverconfigurationprosceniumprogramnotisverythin,troublesomematterisdeliveredtoserverandnetwork.InthesystemofC/Stakeoff,databasecannotbecomepublicreally,professionallymorecompetentstorehouse,itgetsindependentspecialmanagement.(3)TheinferiorpositionoftheconfigurationofC/Sishighmaintenancecostmakeinvestmentjustbig.First,withtheconfigurationofC/S,willselectproperdatabaseplatformtorealizethegenuineunificationofdatabasedata,makethedatasynchronismthatspreadsintwolandscompletedeliverbydatabasesystemgotomanage,butthelogicallytwooperatorsoflandwilldirectlyvisitasamedatabasetorealizeefficiently,havesosomeproblems,ifneedsestablishmentthedatasynchronismofrealtime,thedatabaseserverthatmustestablish9realtimecommunicationconnectionbetweentwoplacesandmaintainstwolandsisonlinetorun,networkmanagementstaffwillagainwanttodefendandmanageforcustomerendasserverdefendsmanagement,maintenanceandcomplextechsupportandtheinvestmentofthishighneedshaveveryhighcost,maintenancetaskismeasured.Secondly,thesoftwareofthestructureofC/Softraditionneedtodevelopthesoftwareofdifferenteditionaccordingtothedifferentsystemofoperatingsystem,isveryrapidbecauseoftherenovationofproduct,priceisworkingneedshighwithinefficientalreadydonotmeet.InJAVAstepplatformlanguageappearanceafter,theconfigurationofB/SismorevigorousimpactC/S,andformsthreatandchallengeforit.TheadvantageofB/Sconfigurationsoftware(1)TheMaintenanceofinferiorpositionandupgradingwayaresimple.Nowupgradingandtheimprovementofsoftwaresystemmoreandmorefrequently,theproductoftheconfigurationofB/Sembodiesmoreconvenientpropertyobviously.Foronealittlealittlebitbigunit,ifsystematicadministratorneeds,betweenhundredsof1000evenlastcomputersroundtriprun,efficiencyandworkloadistocanimagine,buttheconfigurationofB/Ssoftwareneedsmanagementserverhavebeenallright,allcustomerendsarebrowseronly,neednotdoanymaintenanceatall.Nomatterthescaleofuserhas,iswhat,hashowmanybranchwillnotincreaseanyworkloadofmaintenanceupgrading,isalltooperateneedstoaimatservertogoon;Ifneeddifferentlyonly,netserverconnectionspecially,realizelong-rangemaintenanceandupgradingandshare.Soclientcomputermoreandmorethin,andservermoreandmorefatisthedirectionofmainstreamoffutureinformativedevelopment.Inthefuture,softwareupgradingandmaintenancewillbemoreandmoreeasy,andusecanmoreandmoresimple,thisisforusermanpower,