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ASASINGLEFUNCTIONALUNITTHERUNTIMESUPPORTENVIRONMENTFORAWEBAPPLICATIONISCALLEDAWEBCONTAINERAWEBAPPLICATIONARCHIVEWARFILECONTAINSALLOFTHECLASSFILESANDRESOURCESFORTHEWEBAPPLICATION,ALONGWITHANXMLDEPLOYMENTDESCRIPTORFILETHATCONFIGURESTHEAPPLICATIONSEECHAPTER7INPARTICULARFORMOREONPACKAGINGANDDEPLOYINGWEBAPPLICATIONSTHEPLATFORMSPECIFICATIONDEFINESACONTRACTBETWEENTHEWEBCONTAINERANDEACHWEBCOMPONENT,DEFININGTHECOMPONENTSLIFECYCLE,THEBEHAVIORTHECOMPONENTMUSTIMPLEMENT,ANDTHESERVICESTHATTHESERVERMUSTPROVIDETOTHECOMPONENTTHEPLATFORMSPECIFICATIONALSODEFINESTWOTYPESOFWEBCOMPONENTTECHNOLOGIESJAVASERVLETS“SERVLETS”ANDJAVASERVERPAGESTMJSPTMPAGESTECHNOLOGYASERVLETISAJAVACLASSTHATEXTENDSAJ2EESERVER,PRODUCINGDYNAMICCONTENTINRESPONSETOREQUESTSFROMTHESERVERTHESERVERPASSESSERVICEREQUESTSTOTHESERVLETTHROUGHTHESTANDARDINTERFACEJAVAXSERVLET,WHICHEVERYSERVLETMUSTIMPLEMENTAJSPPAGEISANHTMLPAGEWITHSPECIALMARKUPTHATPROVIDESCUSTOMIZABLEBEHAVIORFORGENERATINGDYNAMICCONTENTATRUNTIMEAJSPPAGEISUSUALLYTRANSLATEDINTOASERVLETWHENITISDEPLOYEDJSPTECHNOLOGYPROVIDESADOCUMENTCENTRIC,RATHERTHANPROGRAMMATIC,WAYTOSPECIFYDYNAMICCONTENTGENERATION423THEWEBCONTAINERAJ2EEWEBAPPLICATIONRUNSINSIDEAJ2EESERVERSWEBCONTAINERTHECONTAINERMANAGESEACHCOMPONENTSLIFECYCLE,DISPATCHESSERVICEREQUESTSTOAPPLICATIONCOMPONENTS,ANDPROVIDESSTANDARDINTERFACESTOCONTEXTDATASUCHASSESSIONSTATEANDINFORMATIONABOUTTHECURRENTREQUESTTHEWEBCONTAINERPROVIDESACONSISTENTINTERFACETOTHECOMPONENTSITHOSTS,SOWEBCOMPONENTSAREPORTABLEACROSSAPPLICATIONSERVERSAND,BECAUSEPACKAGINGANDDEPLOYMENTOFJ2EEWEBAPPLICATIONSARESTANDARDIZED,AWEBAPPLICATIONCANBEDEPLOYEDINTOANYJ2EESERVERWITHOUTRECOMPILINGTHECODEORREBUILDINGTHEAPPLICATIONARCHIVETHENEXTFEWSECTIONSDESCRIBEWEBTIERCOMPONENTSINTHEJ2EEPLATFORMANDEXPLAINTHEBENEFITSTHEIRFEATURESPROVIDE424JAVASERVLETSAJAVASERVLETISAJAVACLASSTHATEXTENDSAJ2EECOMPATIBLEWEBSERVEREACHSERVLETCLASSPRODUCESDYNAMICCONTENTINRESPONSETOSERVICEREQUESTSTOONEORMOREURLSSERVLETSOFFERSOMEIMPORTANTBENEFITSOVEREARLIERDYNAMICCONTENTGENERATIONTECHNOLOGIESSERVLETSARECOMPILEDJAVACLASSES,SOTHEYAREGENERALLYFASTERTHANCGIPROGRAMSORSERVERSIDESCRIPTSSERVLETSARESAFERTHANEXTENSIONLIBRARIES,BECAUSETHEJAVAVIRTUALMACHINEJVMCANRECOVERFROMASERVLETTHATEXITSUNEXPECTEDLYSERVLETSAREPORTABLEBOTHATTHESOURCECODELEVELBECAUSEOFTHEJAVASERVLETSPECIFICATIONANDATTHEBINARYLEVELBECAUSEOFTHEINNATEPORTABILITYOFJAVABYTECODESERVLETSALSOPROVIDEARICHERSETOFSTANDARDSERVICESTHANANYOTHERWIDELYADOPTEDSERVEREXTENSIONTECHNOLOGYINADDITIONTOPRODUCINGCONTENT,SERVLETSHAVESEVERALFEATURESTHATSUPPORTAPPLICATIONSTRUCTUREADEVELOPERCANCREATECLASSESTHATRESPONDTOEVENTSINASERVLETSLIFECYCLEBYIMPLEMENTINGLISTENERINTERFACESTHESAMPLEAPPLICATIONUSESLISTENERINTERFACESTOINITIALIZESERVLETDATASTRUCTURESASERVLETCANALSOBEEXTENDEDBYONEORMORESERVLETFILTERS,WHICHAREREUSABLECLASSESTHATWRAPCALLSTOASERVLETSSERVICEMETHOD,TRANSFORMINGTHEREQUESTORTHERESPONSESERVLETFILTERSCANBEORGANIZEDINTOFILTERCHAINSTHATPERFORMSUCCESSIVETRANSFORMATIONSONSERVLETREQUESTSORRESPONSESSERVLETREQUESTSORRESPONSESDISTRIBUTEDSERVLETSAREMORESCALABLETHANNONDISTRIBUTEDSERVLETSTHEWEBCONTAINERCANPROVIDEANAPPLICATIONWITHLOADBALANCINGANDFAILOVERBYMIGRATINGUSERSESSIONSAMONGCLUSTERNODESDISTRIBUTEDSERVLETSAREMARKEDDISTRIBUTABLEINTHEWEBAPPLICATIONDEPLOYMENTDESCRIPTORTHEYMUSTFOLLOWASETOFRESTRICTIONSBEYONDTHOSEREQUIREDOFNONDISTRIBUTEDSERVLETSTHEADDITIONALRESTRICTIONSENSURETHATSERVLETCODEOPERATESPROPERLYACROSSSESSIONMIGRATIONSFORANINTRODUCTIONTOORREVIEWOFSERVLETS,SEETHESECTIONENTITLED“JAVASERVLETTECHNOLOGY”INTHEJ2EETUTORIAL425JAVASERVERPAGESJSPTECHNOLOGYMOSTWEBAPPLICATIONSPRODUCEPRIMARILYDYNAMICHTMLPAGESTHAT,WHENSERVED,CHANGEONLYINDATAVALUESANDNOTINBASICSTRUCTUREFOREXAMPLE,ALLOFTHECATALOGPAGESINANONLINESTOREMAYHAVEIDENTICALSTRUCTUREANDDIFFERONLYINTHEITEMSTHEYDISPLAYJSPTECHNOLOGYEXISTSFORPRODUCINGSUCHCONTENTAJSPPAGEISADOCUMENTCONTAININGFIXEDTEMPLATETEXT,PLUSSPECIALMARKUPFORINCLUDINGOTHERTEXTOREXECUTINGEMBEDDEDLOGICTHEFIXEDTEMPLATETEXTISALWAYSSERVEDTOTHEREQUESTERJUSTASITAPPEARSINTHEPAGE,LIKETRADITIONALHTMLTHESPECIALMARKUPCANTAKEONEOFTHREEFORMSDIRECTIVES,SCRIPTINGELEMENTS,ORCUSTOMTAGSALSOKNOWNAS“CUSTOMACTIONS”DIRECTIVESAREINSTRUCTIONSTHATCONTROLTHEBEHAVIOROFTHEJSPPAGECOMPILERANDTHEREFOREAREEVALUATEDATPAGECOMPILATIONTIMESCRIPTINGELEMENTSAREBLOCKSOFJAVACODEEMBEDDEDINTHEJSPPAGEBETWEENTHEDELIMITERSCUSTOMTAGSDISCUSSEDLATERINTHISSECTIONAREPROGRAMMERDEFINEDMARKUPTAGSTHATGENERATEDYNAMICCONTENTWHENTHEPAGEISSERVEDTHEJAVASERVERPAGESSPECIFICATIONDEFINESASETOFSTANDARDTAGSTHATAREAVAILABLEINALLPLATFORMIMPLEMENTATIONSCUSTOMTAGSANDSCRIPTINGELEMENTSGENERATEDYNAMICCONTENTTHATISINCLUDEDINARESPONSEWHENAPAGEISBEINGSERVEDJSPPAGESCANSPECIFYDYNAMICCONTENTOFANYTEXTUALTYPE,BUTTHEYAREPRIMARILYUSEDFORCREATINGSTRUCTUREDCONTENTSUCHASHTML,XML,XHTML,ANDSOONJSPPAGESAREEASIERTOWRITETHANSERVLETS,BECAUSETHEYLOOKLIKESTRUCTUREDDOCUMENTSJSPPAGESAREAMORENATURALDEVELOPMENTTECHNOLOGYFORPAGEDESIGNERS,WHOSPECIALIZEINAUTHORINGSTRUCTUREDDOCUMENTSALTHOUGHAJSPPAGELOOKSTOITSAUTHORLIKEADOCUMENT,MOSTJ2EEIMPLEMENTATIONSTRANSLATEAJSPPAGEINTOASERVLETCLASSWHENITISDEPLOYEDJSPPAGESAREALSOCOMPATIBLEWITHAWIDEARRAYOFAUTHORINGTOOLSTHATSIMPLIFYPAGECREATIONJSPPAGESDIFFERFROMSERVLETSINTHEIRPROGRAMMINGMODELAJSPPAGEISPRIMARILYADOCUMENTTHATSPECIFIESDYNAMICCONTENT,RATHERTHANAPROGRAMTHATPRODUCESCONTENTJSPPAGETECHNOLOGYPROVIDESA“DOCUMENTCENTRIC”ALTERNATIVETO“PROGRAMMATIC”SERVLETSFORCREATINGDYNAMIC,STRUCTUREDDATA4251XMLJSPPAGESYNTAXTHEJSPSPECIFICATIONDEFINESANALTERNATEXMLSYNTAXFORJSPPAGESPAGESINSTANDARDJSPSYNTAXCANNOTBEWELLFORMEDXMLBECAUSETHEMARKUPDOESNOTCONFORMTOXMLSREQUIREMENTSPAGESUSINGTHEALTERNATEJSPXMLSYNTAXCANBEVALIDATEDAGAINSTANXMLSCHEMADEFINITIONLANGUAGEXSDLSCHEMATOCHECKFORMANYPOTENTIALERRORSTHATWOULDOTHERWISEAPPEARONLYATRUNTIMEXMLSYNTAX中文翻譯71當(dāng)用戶連接到服務(wù)器時(shí)，要停留分離，只允許一批用戶可以連接到服務(wù)器。在JAVA智能車票采樣應(yīng)用，客戶端允許用戶要找準(zhǔn)確切的議席，他們希望購(gòu)買的。當(dāng)用戶決定什么，表明他或她也不愿看到的，客戶端下載數(shù)據(jù)，為顯示的座位圖，并展示該計(jì)劃給用戶。該計(jì)劃的完成，標(biāo)志著這座位有限，而已采取的，如圖35。這個(gè)例子凸顯了兩個(gè)重要ISSUESFIRST，當(dāng)JAVA客戶操縱企業(yè)數(shù)據(jù)，他們需要了解的有關(guān)模型和部分或全部的業(yè)務(wù)規(guī)則，圍繞著數(shù)據(jù)模型。舉例來說，用戶必須在理解概念的UNBOOKED席，而模式的概念，就像服務(wù)器。再例如，客戶端也必須防止使用者試圖選擇預(yù)訂座位，執(zhí)行業(yè)務(wù)規(guī)則還實(shí)施了對(duì)SERVERGENERALLY，客戶，操縱企業(yè)數(shù)據(jù)必須重復(fù)邏輯上的服務(wù)器，因?yàn)榉?wù)器必須執(zhí)行所有的業(yè)務(wù)規(guī)則，不論什么樣的客戶做的。第二，當(dāng)JAVA客戶操縱企業(yè)數(shù)據(jù)，應(yīng)用程序需要執(zhí)行的數(shù)據(jù)同步計(jì)劃。舉例來說，之間的時(shí)間，當(dāng)用戶下載的座位和時(shí)間，當(dāng)用戶決定哪些議席，他或她想要買，另一用戶可以購(gòu)買部分或全部的那些SEATSTHE應(yīng)用程序需要的規(guī)則和機(jī)制，為解決這樣一個(gè)沖突。在這種情況下，服務(wù)器的數(shù)據(jù)，占盡優(yōu)勢(shì)，客戶的數(shù)據(jù)，因?yàn)檎l(shuí)買了門票首因而更新了服務(wù)器第一獲得TICKETSTHE應(yīng)用，可以繼續(xù)問第二個(gè)用戶，如果他或她想要的座位說第一個(gè)使用者沒有BUYOR，它可以刷新的第二個(gè)用戶的顯示器與更新座位圖，并有用戶挑選的席位都需要再次改革?？偨Y(jié)J2EE平臺(tái)支持一系列的客戶端設(shè)備和客戶端編程MODELSSUPPORTED設(shè)備包括桌面系統(tǒng)，筆記本電腦，PALMTOPS，手機(jī)，以及各種新興的非傳統(tǒng)器件SUPPPORTED編程模型，包括瀏覽器客戶端使用HTML和JAVASCRIPT的瀏覽器插件在客戶如閃光，辦公套件，客戶如STAROFFICE的和可編程的客戶基于JAVA技術(shù)。應(yīng)用開發(fā)商應(yīng)作出努力，為用戶提供盡可能高的服務(wù)水平和功能的支持，每個(gè)客戶器件，主要考慮整個(gè)設(shè)計(jì)的客戶應(yīng)該是網(wǎng)絡(luò)的，因?yàn)榭蛻魠⒓恿司W(wǎng)絡(luò)APPLICATIONAT相同當(dāng)時(shí)，可能還有其他重要因素，例如，開發(fā)和支持能力，縮短上市時(shí)間，以及其他因素，影響到最終的客戶端解決方案所選擇的一個(gè)特定應(yīng)用。35SUMMARY一個(gè)J2EE應(yīng)用的WEB層使得應(yīng)用的業(yè)務(wù)邏輯可在萬(wàn)維網(wǎng)。WEB層處理所有的一個(gè)J2EE應(yīng)用的溝通與WEB客戶端，引用業(yè)務(wù)邏輯和數(shù)據(jù)傳輸?shù)捻憫?yīng)請(qǐng)求。這一章描述了幾種方法利用網(wǎng)絡(luò)層技術(shù)有效地在一個(gè)J2EE應(yīng)用設(shè)計(jì)，包括實(shí)例，從采樣應(yīng)用。一章是專門不是網(wǎng)頁(yè)設(shè)計(jì)。41為了WEB層一臺(tái)服務(wù)器在WEB層工序的HTTP請(qǐng)求。在一個(gè)J2EE應(yīng)用中，WEB層通常管理之間的互動(dòng)的網(wǎng)上用戶和應(yīng)用程序的商業(yè)邏輯。WEB層通常產(chǎn)生HTML或XML內(nèi)容，雖然網(wǎng)路層，可產(chǎn)生和服務(wù)于任何內(nèi)容類型。而商業(yè)邏輯往往是實(shí)施企業(yè)豆類，也有可能實(shí)施完全符合WEB層。WEB層通常履行下列職能在一個(gè)J2EE應(yīng)用。網(wǎng)絡(luò)，使業(yè)務(wù)邏輯網(wǎng)絡(luò)層管理之間的互動(dòng)的網(wǎng)上用戶和應(yīng)用業(yè)務(wù)邏輯產(chǎn)生動(dòng)態(tài)內(nèi)容網(wǎng)絡(luò)層組件GENERTATE動(dòng)態(tài)內(nèi)容，在完全任意的數(shù)據(jù)格式，包括HTML，圖像，聲音和視頻數(shù)據(jù)收集和輸入網(wǎng)絡(luò)層組件翻譯HTTPPUT并獲得行動(dòng)統(tǒng)一到形式，有關(guān)業(yè)務(wù)邏輯的理解和現(xiàn)在的結(jié)果作為網(wǎng)頁(yè)內(nèi)容?？刂破亮鬟壿?，即確定哪些“屏幕“（也就是哪一頁(yè)），顯示在明年通常居住在WEB層，因?yàn)槠聊簧狭鲃?dòng)趨于具體化，以客戶的能力。保持狀態(tài)WEB層有一個(gè)簡(jiǎn)單，靈活的機(jī)制，積累數(shù)據(jù)，為交易和互動(dòng)背景下的整個(gè)使用壽命期間用戶會(huì)話。支持多種和未來的客戶類型可擴(kuò)充的MIME類型描述網(wǎng)站內(nèi)容，使WEB客戶端，可以支持任何現(xiàn)有和未來型的下載內(nèi)容?？梢韵葘?shí)行業(yè)務(wù)邏輯雖然許多企業(yè)應(yīng)用實(shí)施業(yè)務(wù)邏輯在企業(yè)豆類，僅在網(wǎng)站上張貼，低到中等體積的應(yīng)用與簡(jiǎn)單的交易行為，可實(shí)行業(yè)務(wù)邏輯完全符合WEB層。42網(wǎng)絡(luò)技術(shù)的三層本節(jié)介紹一種快速審查的網(wǎng)絡(luò)技術(shù)，在J2EE平臺(tái)上，首先描述遺產(chǎn)技術(shù)，然后在網(wǎng)絡(luò)層組件類型取代他們。隨意跳過這一節(jié)，如果你已經(jīng)熟悉這些技術(shù)。如果你需要刷新你的理解超出了本節(jié)的優(yōu)惠，看到了J2EE教程（參考了J2EE補(bǔ)習(xí)，是列在“參考文獻(xiàn)和資源“127頁(yè)）421傳統(tǒng)的網(wǎng)絡(luò)層技術(shù)了解歷史的動(dòng)態(tài)網(wǎng)頁(yè)內(nèi)容的一代提供了一個(gè)背景下，為了解好處操作系統(tǒng)網(wǎng)絡(luò)技術(shù)在J2EE平臺(tái)上。最早版本的萬(wàn)維網(wǎng)上依賴于基本的HTTP服務(wù)器，以服務(wù)于靜態(tài)的HTML網(wǎng)頁(yè)上的HTML瀏覽器。但是，它很快就成為明確表示，動(dòng)態(tài)內(nèi)容，對(duì)所產(chǎn)生的需求，使網(wǎng)絡(luò)的一個(gè)平臺(tái)提供應(yīng)用以及內(nèi)容。422WEBTIERTECHNOLOGIESINTHEJ2EEPLATFORM網(wǎng)絡(luò)層技術(shù)在J2EE平臺(tái)網(wǎng)絡(luò)層技術(shù)在J2EE平臺(tái)提供帶有優(yōu)勢(shì)的服務(wù)器端腳本，在一個(gè)規(guī)范，安全且廠商中立的環(huán)境中應(yīng)用匯編JAVA。本節(jié)簡(jiǎn)要介紹網(wǎng)絡(luò)層技術(shù)在J2EE平臺(tái)，并提供最佳做法。一個(gè)WEB應(yīng)用是一種集網(wǎng)絡(luò)層的組成，內(nèi)容，并配置中的形成，運(yùn)作，作為一個(gè)單一的功能單位。該運(yùn)行支撐環(huán)境，讓W(xué)EB應(yīng)用稱為WEB容器。一個(gè)WEB應(yīng)用存檔文件中包含了所有的類文件和資源，為WEB應(yīng)用，隨著一個(gè)XML部署描述符文件配置應(yīng)用。見第7章，特別是更多的關(guān)于包裝和部署WEB應(yīng)用程序。該平臺(tái)規(guī)范定義之間的契約WEB容器和每個(gè)WEB組件，確定組件的生命周期，行為組件必須落實(shí)，并使之服務(wù)，服務(wù)器必須提供給元件。該平臺(tái)的規(guī)格，還規(guī)定了兩種類型的WEB組件的技術(shù)JAVA的SERVLET是（“SERVLET是“）及JAVASERVERPAGESTM（JSPTM頁(yè)）的技術(shù)。一個(gè)SERVLET是一個(gè)JAVA類延伸一個(gè)J2EE服務(wù)器，生產(chǎn)動(dòng)態(tài)內(nèi)容，在響應(yīng)請(qǐng)求從服務(wù)器。服務(wù)器通過服務(wù)請(qǐng)求，以在SERVLET通過標(biāo)準(zhǔn)接口JAVAXSERVLET，其中每一個(gè)SERVLET的必須執(zhí)行。一JSP頁(yè)面是一個(gè)HTML頁(yè)面有特殊標(biāo)記，提供可定制的行為產(chǎn)生動(dòng)態(tài)內(nèi)容時(shí)有效。一JSP頁(yè)面通常翻譯成一個(gè)SERVLET時(shí)，它部署。JSP技術(shù)提供了一個(gè)文件為中心，而非以綱領(lǐng)性，路明動(dòng)態(tài)內(nèi)容生成。423THEWEBCONTAINER該WEB容器一個(gè)J2EEWEB應(yīng)用程序運(yùn)行在一個(gè)J2EE服務(wù)器上的WEB容器。集裝箱管理的每一個(gè)組件的生命周期，派遣服務(wù)請(qǐng)求，以應(yīng)用組件，并提供標(biāo)準(zhǔn)接口，以背景資料，如會(huì)話狀態(tài)和信息，介紹當(dāng)前的請(qǐng)求。該WEB容器提供一個(gè)一致的界面，部件，它的主機(jī)，讓網(wǎng)頁(yè)元件便攜式跨應(yīng)用服務(wù)器。而且，由于包裝和部署J2EE應(yīng)用程序是規(guī)范的，一個(gè)WEB應(yīng)用。424JAVASERVLET一個(gè)JAVASERVLET是一個(gè)能擴(kuò)展J2EE兼容的網(wǎng)絡(luò)服務(wù)器的JAVA類別每個(gè)SERVLET類別產(chǎn)生相應(yīng)的動(dòng)態(tài)內(nèi)容服務(wù)一個(gè)或者多個(gè)URLS的要求。SERVLET比早期的動(dòng)態(tài)內(nèi)容時(shí)代的科技提供一些重要的益處。JAVA類別編輯出SERVLET，所以它們比CGI程序或者服務(wù)器端腳本更快。SERVLET比擴(kuò)展圖書館更安全，因?yàn)镴VM能從意外存在的SERVLET中復(fù)原SERVLET在來源密碼層面因?yàn)镴SP規(guī)格和二進(jìn)制層面都是可移動(dòng)的。SERVLET也能提供比任何大范圍采用的服務(wù)器擴(kuò)展科技更為寬泛的標(biāo)準(zhǔn)服務(wù)。還有從產(chǎn)生內(nèi)容上看,SERVLET有幾個(gè)特點(diǎn)，那就是支持應(yīng)用結(jié)構(gòu)一個(gè)開發(fā)者能創(chuàng)建對(duì)事件發(fā)生反映的類別，而這些事件是出現(xiàn)在SERVLET實(shí)施給聽者的界面的生命周期中的。應(yīng)用于聽者界面的樣本的目的是預(yù)置SERVLET的數(shù)據(jù)結(jié)構(gòu)。一個(gè)SERVLET也能擴(kuò)展能一個(gè)或多個(gè)SERVLET過濾器。這些過濾器再次使用的類型，它能包裹對(duì)SERVLET的服務(wù)方法，轉(zhuǎn)變需求或反映的呼叫。SERVLET過濾器能組織過濾表現(xiàn)為連續(xù)的SERVLET的要求或反映的轉(zhuǎn)變的鏈接。分配型SERVLET相較于不分配SERVLET是可以升級(jí)的。WEB容器能提供一個(gè)載有負(fù)荷平衡和由于遷移使用者在集群節(jié)點(diǎn)中的失敗切換的應(yīng)用。分配型SERVLET在網(wǎng)絡(luò)應(yīng)用部署描述中是可分配的。它們必須遵循一系列的而并非對(duì)不分配型SERVLET的約束。這些額外的約束確保SERVLET密碼在會(huì)議移民時(shí)的恰當(dāng)?shù)倪\(yùn)作。對(duì)于SERVLET的的介紹或回顧,請(qǐng)參看在THEJ2EETUTORIAL中的標(biāo)題是“JSP技術(shù)”部分。制定了若干機(jī)制讓網(wǎng)站服務(wù)器產(chǎn)生內(nèi)容需求，所有這些都可以被看作是網(wǎng)絡(luò)服務(wù)器的功能擴(kuò)展。在此背景下，一個(gè)WEB應(yīng)用實(shí)際上是一個(gè)復(fù)雜的網(wǎng)絡(luò)服務(wù)器延期。網(wǎng)絡(luò)層技術(shù)在J2EE平臺(tái)提供一個(gè)超集功能，提供了由上一代技術(shù)制做的功能擴(kuò)展集。與傳統(tǒng)的WEB應(yīng)用相