文献翻译基于J2EE在分布式环境下的底层结构的自动动态配置应用文档格式.doc

文献翻译基于J2EE在分布式环境下的底层结构的自动动态配置应用文档格式.doc

《文献翻译基于J2EE在分布式环境下的底层结构的自动动态配置应用文档格式.doc》由会员分享，可在线阅读，更多相关《文献翻译基于J2EE在分布式环境下的底层结构的自动动态配置应用文档格式.doc（20页珍藏版）》请在冰点文库上搜索。

网络

文献、资料发表（出版）日期：

2007.9

院（部）：

专业：

班级：

姓名：

学号：

指导教师：

翻译日期：

19

外文文献：

InfrastructureforAutomaticDynamicDeployment

OfJ2EEApplicationinDistributedEnvironments

AnatolyAkkerman,AlexanderTotok,andVijayKaramcheti

Abstract:

inordertoachievesuchdynamicadaptation,weneedaninfrastructureforautomatingJ2EEapplicationdeploymentinsuchanenvironment.ThisneedisquiteevidenttoanyonewhohasevertrieddeployingaJ2EEapplicationevenonasingleapplicationserver,whichisataskthatinvolvesagreatdealofconfigurationofboththesystemservicesandapplicationcomponents.

Keywords:

j2ee;

component;

Distributed;

DynamicDeployment;

1Introduction

Inrecentyears,wehaveseenasignificantgrowthincomponent-basedenterpriseapplicationdevelopment.TheseapplicationsaretypicallydeployedoncompanyIntranetsorontheInternetandarecharacterizedbyhightransactionvolume,largenumbersofusersandwideareaaccess.Traditionallytheyaredeployedinacentrallocation,usingserverclusteringwithloadbalancing（horizontalpartitioning）tosustainuserload.However,horizontalpartitioninghasbeenshownveryefficientonlyinreducingapplication-relatedoverheadsofuser-perceivedresponsetimes,withouthavingmucheffectonnetwork-inducedlatencies.Verticalpartitioning（e.g.,runningwebtierandbusinesstierinseparateVMs）hasbeenusedforfaultisolationandloadbalancingbutitissometimesimpracticalduetosignificantrun-timeoverheads（evenifonewouldkeepthetiersonafastlocal-areanetwork）relatedtoheavyuseofremoteinvocations.Recentwork[14]inthecontextofJ2EEcomponentbasedapplicationshasshownviabilityofverticalpartitioninginwide-areanetworkswithoutincurringtheaforementionedoverheads.Thekeyconclusionsfromthatstudycanbesummarizedasfollows:

•Usingproperlydesignedapplications,verticaldistributionacrosswide-areanetworksimprovesuser-perceivedlatencies.

•Wide-areaverticallayeringrequiresreplicationofapplicationcomponentsandmaintainingconsistencybetweenreplicas.

•Additionalreplicasmaybedeployeddynamicallytohandlenewrequests.

•Differentreplicasmay,infact,bedifferentimplementationsofthesamecomponentbasedonusage（read-only,read-write）.

•Newrequestpathsmayreusecomponentsfrompreviouslydeployedpaths.

Applyingintelligentmonitoring[6]andAIplanning[2,12]techniquesinconjunctionwiththeconclusionsofthatstudy,weseeapotentialfordynamicadaptationinindustry-standardJ2EEcomponent-basedapplicationsinwideareanetworks

Throughdeploymentofadditionalapplicationcomponentsdynamicallybasedonactivemonitoring.However,inordertoachievesuchdynamicadaptation,weneedaninfrastructureforautomatingJ2EEapplicationdeploymentinsuchanenvironment.ThisneedisquiteevidenttoanyonewhohasevertrieddeployingaJ2EEapplicationevenonasingleapplicationserver,whichisataskthatinvolvesagreatdealofconfigurationofboththesystemservicesandapplicationcomponents.ForexampleonehastosetupJDBCdatasources,messagingdestinationsandotherresourceadaptersbeforeapplicationcomponentscanbeconfiguredanddeployed.Inawideareadeploymentthatspansmultipleservernodes,thisprovesevenmorecomplex,sincemoresystemservicesthatfacilitateinter-nodecommunicationsneedtobeconfiguredandstartedandavarietyofconfigurationdata,likeIPaddresses,portnumbers,JNDInamesandothershavetobeconsistentlymaintainedinvariousconfigurationfilesonmultiplenodes.

Thisdistributeddeploymentinfrastructuremustbeableto:

•addressinter-componentconnectivityspecificationanddefineitseffectsoncomponentconfigurationanddeployment,

•addressapplicationcomponentdependenciesonapplicationserverservices,theirconfigurationanddeployment,

•providesimplebutexpressiveabstractionstocontroladaptationthroughdynamicdeploymentandundeploymentofcomponents,

•enablereuseofservicesandcomponentstomaintainefficientuseofnetworknodes’resources,

•providethesefacilitieswithoutincurringsignificantadditionaldesigneffortonbehalfofapplicationprogrammers.

InthispaperweproposetheinfrastructureforautomaticdynamicdeploymentofJ2EEapplications,whichaddressesalloftheaforementionedissues.Theinfrastructuredefinesarchitecturedescriptionlanguages（ADL）forcomponentandlinkdescriptionandassembly.TheComponentDescriptionLanguageisusedtodescribeapplicationcomponentsandlinks.Itprovidesclearseparationofapplicationcomponentsfromsystemcomponents.Aflexibletypesystemisusedtodefinecompatibilityofcomponentportsandlinks.Adeclarationandexpressionlanguageforconfigurablecomponentpropertiesallowsforspecificationofinter-componentdependenciesandpropagationofpropertiesbetweencomponents.TheComponent（Replica）AssemblyLanguageallowsforassemblyofreplicasofpreviouslydefinedcomponentsintoapplicationpathsby

Connectingappropriateportsvialinkreplicasandspecifyingthemappingofthesecomponentreplicasontotargetapplicationservernodes.TheComponentConfigurationProcessevaluatesanapplicationpath’scorrectness,identifiesthedependencies

ofapplicationcomponentsonsystemcomponents,andconfigurescomponentreplicasfordeployment.Anattemptismadetomatchandreuseanypreviouslydeployedreplicasinthenewpathbasedontheirconfigurations.WeimplementtheinfrastructureasapartoftheJBossopensourceJavaapplicationserver[11]andtestitonseveral

SampleJ2EEapplications–JavaPetstore[23],Rubies[20]andTPC-W-NYU[32].TheinfrastructureimplementationutilizestheJBoss’sextendablemicro-kernelarchitecture,basedontheJMX[27]specification.ComponentizedarchitectureofJBossallowsincrementalservicedeploymentsdependingontheneedsofdeployedapplications.Webelievethatdynamicreconfigurationofapplicationserversthroughdynamicdeploymentandundeploymentofsystemservicesisessentialtobuildingaresource-efficientframeworkfordynamicdistributeddeploymentofJ2EEapplications.Therestofthepaperisorganizedasfollows.Section2providesnecessarybackgroundforunderstandingthespecificsoftheJ2EEcomponenttechnologywhicharerelevanttothisstudy.Section3givesageneraldescriptionoftheinfrastructurearchitecture,whilesection4goesdeeperindescribingparticularlyimportantandinterestinginternalmechanismsoftheinfrastructure.Section5describestheimplementationoftheframework,andrelatedworkisdiscussedinsection6.

2J2EEBackground

2.1Introduction

Componentframeworks.Acomponentframeworkisamiddlewaresystemthatsupportsapplicationsconsistingofcomponentsconformingtocertainstandards.Applicationcomponentsare“plugged”intothecomponentframework,whichestablishestheirenvironmentalconditionsandregulatestheinteractionsbetweenthem.Thisisusuallydonethroughcontainers,componentholders,whichalsoprovidecommonlyrequiredsupportfornaming,security,transactions,andpersistence.Componentframeworksprovideanintegratedenvironmentforcomponentexecution,asaresultsignificantlyreducetheeffort.ittakestodesign,implement,deploy,andmaintainapplications.CurrentdayindustrycomponentframeworkstandardsarerepresentedbyObjectManagementGroup’sCORBAComponentModel[18],SunMicrosystems’Java2PlatformEnterpriseEdition（J2EE）[25]andMicrosoft’s.NET[17],withJ2EEbeingcurrentlythemostpopularandwidelyusedcomponentframeworkintheenterprisearena.

J2EE.Java2PlatformEnterpriseEdition（J2EE）[25]isacomprehensivestandardfordevelopingmulti-tierenterpriseJavaapplications.TheJ2EEspecificationamongotherthingsdefinesthefollowing:

•Componentprogrammingmodel,

•Componentcontractswiththehostingserver,

•Servicesthattheplatformprovidestothesecomponents,

•Varioushumanroles,

•Compatibilitytestsuitesandcompliancetestingprocedures.

Amongthelistofservicesthatacompliantapplicationservermustprovidearemessaging,transactions,namingandothersthatcanbeusedbytheapplicationcomponents.ApplicationdevelopedusingJ2EEadheretotheclassical3-Tierarchitectures–PresentationTier,BusinessTier,andEnterpriseInformationSystem（EIS）Tier（seeFig.1）.J2EEcomponentsbelongingtoeachtieraredevelopedadheringtothe

SpecificJ2EEstandards.

1.PresentationorWebtier.

Thistierisactuallysubdividedintoclientandserversides.Theclientsidehostsawebbrowser,appletsandJavaapplicationsthatcommunicatewiththeserversideofpresentationtierorthebusinesstier.TheserversidehostsJavaServletcomponents[30],JavaServerPages（JSPs）[29]andstaticwebcontent.Thesecomponentsareresponsibleforpresentingbusinessdatatotheendusers.ThedataitselfistypicallyacquiredfromthebusinesstierandsometimesdirectlyfromtheEnterpriseInformationSystemtier.TheserversideofthepresentationtieristypicallyaccessedthroughHTTP（S）protocol.

2.BusinessorEJBtier.

ThistierconsistsofEnterpriseJavaBeans（EJBs）[24]thatmodelthebusinesslogicoftheenterpriseapplication.Thesecomponentsprovidepersistencemechanismsandtransactionalsupport.ThecomponentsintheEJBtierareinvokedthroughremoteinvocations（RMI）,in-JVMinvocationsorasynchronousmessagedelivery,dependingonthetypeofEJBcomponent.TheEJBspecificationdefinesseveraltypesofcomponents.T