计算机科学与技术英文文献

东北石油大学本科毕业设计（英文文献）1IntroductiontoASP.NETDevelopmentToovercometheperformanceandscalabilityproblemsthatCGIbrings,Microsoftdevelopedanewwayfordeveloperstobuildscalableapplications.ThishighperformancealternativeiscalledtheInternetServerApplicationProgrammingInterface(ISAPI).Insteadofhousingfunctionalityinexecutablefiles,ISAPIusesDLLs.UsingDLLsinsteadofexecutableprogramshassomedefiniteperformanceandscalabilityadvantagesTheISAPIextensioncouldalsobecalledwithargumentsthatwillallowasingleISAPIextensiontoperformmultipletasks.JustasintheCGIexample,thedirectorymusthaveexecutepermissionsenabled,ortheDLLwillbedownloadedtotheclientratherthanrunontheserver.ISAPIextensionsaretypicallyusedtoprocessclientrequestsandoutputaresponseasHTML,whichisverysimilartothewayCGIprogramsareused.ISAPIfiltersperformafunctionthatcan’tbedirectlyduplicatedwithCGIapplications.ISAPIfiltersareneverexplicitlycalled;instead,theyarecalledbyIISinresponsetocertaineventsinthelifeofarequest.ThedevelopercanrequestthatanISAPIfilterbecalledwheneveranyofthefollowingeventsoccur:1．Whentheserverhaspreprocessedtheclientheaders2．Whentheserverauthenticatestheclient3．WhentheserverismappingalogicalURLtoaphysicalURL4．Beforerawdataissentfromtheclienttotheserver5．Afterrawdataissentfromtheclienttotheserverbutbeforetheserverprocessesit6．Whentheserverlogsinformation7．WhenthesessionisendingAswithanyfilter,ISAPIfiltersshouldrequestonlythenotificationsitrequiresandprocessthemasquicklyaspossible.OneofthemorecommonusesofISAPIfiltersistoprovidecustomauthentication.AnotheruseistomodifytheHTMLthatwillbesenttotheclient.Forexample,anISAPIfiltercouldbeusedtochangethebackgroundcolorofeachpage.BecauseISAPIfiltersaren’tnearlyascommonasISAPIextensions,Iwon’tcoverthemanyfurtherinthisbook.IfyouwanttolearnmoreaboutISAPIextensions,youcancheckoutmybookInsideServer-BasedApplications(MicrosoftPress,1999).ISAPIspecifiesseveralentry-pointfunctionsthatmustbeexportedfromtheDLL.Usingtheseentrypoints,IIScanloadtheDLL;callthefunctionsthatitimplements,passinginparametersasrequired;andreceivethedatatowritebacktothebrowser.ISAPIrequiresonlytwoentry-pointfunctionstobeimplementedtheseentrypoints,IIScanloadtheDLL;东北石油大学本科毕业设计（英文文献）2callthefunctionsthatitimplements,passinginparametersasrequired;andreceivethedatatowritebacktothebrowser.ISAPIrequiresonlytwoentry-pointfunctionstobeimplementedABetterSolution:ActiveServerPagesIfyou’rewonderingwhywe’vedweltonthealternativestoASP.NETinabookaboutprogrammingASP.NET,theanswerliesinthedetailsoftheimplementationofASP.NETanditspredecessor,ActiveServerPages(ASP).UnderstandingISAPIisrequiredforadeptunderstandingofASPandthusASP.NET.DuringthebetaofIIS2.0,whichbecamepartofWindowsNT4.0,Microsoftintroducedanewtechnologyinitiallycodenamed“Denali.”ThiswasduringMicrosoft’s“Active”periodandsothetechnologywaseventuallynamedActiveServerPages,orASP.SeveralversionsofASP.NEThavebeenreleased,mostnotablytheversionsincludedwithWindowsNT4.0OptionPack(ASP2.0andIIS4.0)andWindows2000(ASP3.0andIIS5.0).Forthepurposesofthisdiscussion,I’llconsiderASPasawhole,withoutreferringtoversiondifferencesASP.NETbecameaninstanthit,inlargepartbecauseitmadesomethingthatwasdifficult(createdynamicWebcontent)relativelyeasy.CreatingCGIapplicationsandISAPIapplicationswasn’tterriblydifficult,butusingASPwasmuchsimplerBydefault,ASPusesVBScript.LiterallymillionsofdevelopersareatleastsomewhatfamiliarwithVisualBasic,VisualBasicforApplications(VBA),orVBScript.Forthesedevelopers,ASPwasthewaytoentertheInternetage.Certainlythedeveloperscouldhavelearnedanewprogramminglanguage,buttheydidn’thavetowithASP.PartlybecauseofitsuseofVBScript,ASPbecameaviablewaytobuildWebapplications.JustasimportantwastherelativelyeasyaccesstodatabasesallowedthroughMicrosoftActiveXDataObjects(ADO).Whenyouneedtogeneratedynamiccontent,thatdynamiccontentobviouslyneedstocomefromsomewhere,andADOmadeiteasytogetatthatdata.Finally,andperhapsmostimportant,theASP.NETdevelopmentmodelalloweddeveloperstoessentiallywritecodeandrunit.Therewasnoneedtoperformcompilationorelaborateinstallationsteps.theASP.NETarchitectswerecarefultocapturethissamedevelopmentmodel,eventhoughwhat’sgoingonunderthecoversisquiteabitdifferent.ANewSolution:ASP.NETWhenversion3.0ofASP.NETwasreleasedalongwithWindows2000,itbecameclearerthatthefutureofsoftwaredevelopmentwascloselytiedtothefutureoftheWeb.Aspartofits.NETinitiative,MicrosofthasintroducedASP.NET,anewversionofASPthatretainsthemodelofdevelopmentASPdevelopershavecometoknowandlove:you东北石油大学本科毕业设计（英文文献）3cancreatethecodeandplaceitinthecorrectdirectorywiththeproperpermissions,anditwilljustwork.ASP.NETalsointroducesinnovationsthatalloweasierseparationofthedevelopmentofthecoreofanapplicationanditspresentation.ASP.NETaddsmanyfeaturestoandenhancesmanyofthecapabilitiesinclassicASP.ASP.NETisn’tmerelyanincrementalimprovementtoASP;it’sreallyacompletelynewproduct,albeitanewproductdesignedtoallowthesamedevelopmentexperiencethatASPdevelopershaveenjoyed.HerearesomeofthenotablefeaturesofASP.NET:.NETFramework:The.NETFrameworkisanarchitecturethatmakesiteas