1【原文】TutorialHomePageSessionandApplicationMethodInthispagewewilllearnhowtokeepinformationfromtheuserinourserver(Sessionmethod)andhowtoshareinformationbetweenusers(Applicationmethod).Thisisonlyabasictutorialforbeginners,soonlybasicfeatureswillbedescribed.TheSessionmethodThefirsttimeauseraccessestoaourpagessomeconnectionsanddisconnectionstookplace.Duringthisprocesstheserverandtheclientwillinterchangeinformationtoidentifyeachother.Duetothisexchangeofinformationourserverwillbeabletoidentifyaspecificuserandthisinformationmaybeusetoassignspecificinformationtoeachspecificclient.Thisrelationshipbetweencomputersiscallasession.Duringthetimeasessionisactive,itispossibletoassigninformationtoaspecificclientbyusingSessionmethod.Wewilluseanexampletoexplainthismethod:Letssupposewewanttoallowspecificusertoaccesstheinformationonoursiteordirectoryandwewanttoshowausernameinallpagesvisitedbytheuser.InthiscasewemayusetheSessionmethod.Inthisexample,wewillasktheusernameofthepersoninourindex.asppagerespondtoforms.aspOurprivatepagesInordertoaccessthispagesfilltheformbelow:Username:Password:1234567891011121314151617182OurprivatepagesHi,youareallowtoseethesepages:Page1Page2Errorinusernameorpassword192021222324252627282930313233343536373839404142Letsexplainhowthispageworks:Inline1itischeckedwhetherinformationissubmittedthrowaform.Iftheanswerisnegative(Request.form=),aformisdisplayedaskingforusernameandpassword.Afterfillingtheformandsubmittingit,asRequest.formisnotandthescriptwilljumptoline15.Inline17theyarecheckedtheusernameandpassword.IfusernameisJoeandPasswordisplease,thentwovariablesaresetfortheclient(lines21-22):Session(permission)=YESSession(username)=JoeThesevariableswillbekeptintheserverduringthetimethesessionisactive(normallyitwillexpireafter20minuteswithoutcontact).Finally,ifusernameandpasswordarecorrect,aresponsepagewithlinksissendtotheclientwiththenameoftheuserinthetop.Inthisexample,iftheusernameorpasswordareincorrecttheresponsepagewillincludethetextinline38.3Now,letssupposetheuserclicksinthelinkPage1(page1.asp).Thecodeofpage1.aspwillbethefollowingone:page1.aspPage1Hi,welcometoPage1Thispageisemptyatthemoment,butitwillbeveryinterestinginthenextfutureYouarenotallowedtoaccessthispage1234567891011121314151617Inline1itischeckwhetherthevalueforSession(permission)isYES.Iftheanswerispositiveapagewithinformationissendtotheclient.Iftheanswerisnegative,thetextinline15issend.NOTES:Sessionmethodissuitableforsiteswithalimitednumberofvisitors.Forsiteswithabiggernumberofvisitorsitispreferabletokeeptheinformationintheclientscomputer(byusingcookies).TocreatemorevariablesassociatedtoaspecificclientwemustsubstitutethetextbetweenbracketsinSession(text).Thecorrespondingsecurityfeaturesintheclientsbrowsermustbeenable.TheApplicationmethodWithSessionmethodwehavedefinedavalueforSession(whatever)=Joe,butthisinformationcannotbesharebetweenvisitors(Session(whatever)hasauniquevalueforeachvisitor).ToallowsharinginformationApplicationmethodisused.Forabetterunderstandingofthismethodwewillcreateacounterwhichwillbeshowninthesamepage.Inordertomakeitwork,copythecodebelowtoyourserver:counter.asp4PageunderconstructionUnderconstructionPageviews:123456789101112131415Inthefirstpartofthiscode,asApplicationmethodissharedbetweendifferentclients,itisnecessarytopreventotherclientsfrommodifyingtheinformationinApplication(pagevisits).Application.Lockwillavoidthatbystoppingtheinformationtobeshared,andApplication.Unlockwillallowtheinformationtobesharedagain.Line3increasesthevalueforthecounter.Finallyahtmlcodeissendtotheclient,includingthevalueofthecounter.NOTES:TheinformationsaveasAppli