EJB的安全性中英文资料外文翻译文献.docx

EJB的安全性中英文资料外文翻译文献.docx

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EJB的安全性中英文资料外文翻译文献

（文档含英文原文和中文翻译）

EJB的安全性中英文资料外文翻译文献

EJBsecurity

INTRODUCTION

SecuritymanagementisoneoftheimportantservicesthatEJBoffers.Thelow_levelsecurityinfrastructureinEJBisimplementedbythecontainerprovider.Securitypoliciesaresetatdeploymenttimeinordertomakethebeansportableacrossapplications.EJBsecurityboilsdowntowhichuserhaspermissiontocallwhichmethodofabean.UsersaredefinedoutsideEJBinaspecificoperationalenvironment（forexample,ausernamedGurmailKandola,workingonaUNIXmachinewithusernamekandola,isamemberofusergroupengineering,hasaccesspermissiontoaMySQLdatabaseserverandsoon）.TotheEJBcode,auserisrepresentedbyaninstanceoftheoftheclassjava.security.principal.Principalsaremappedtosecurityroles,whichdeterminethemethodsaprincipalcanaccess.Theapplicationassemblerdefinesthelogicalsecurityroles,andthedeployermapsthemthemtotheprincipals.Amethodcallfromaclientmaytriggerabean-to-beanchainofcalls,asyousawinthepreviouschapterwhileexploringtransactions.Howdoessecuritypropagatealongthischainofcalls?

HowdothevarousEjBrolessplittheresponsibilityforsettingsecuritypolicies?

Thesequestionspointtosomeoftheimportantissuesthatwewillexploreinthischapter.YourgoalforthischapteristounderstandEJBsecurityandhowthesecurityassignmentsandresponsibilitiesflowfrommethodtomethodandroletorole.Toaccomplishthat,wewillexplorethreeavenues:

declarativeandprogrammaticsecurityinEJB,theflowofresponsibilitiesfromroletoroleindeterminingsecuritypolicy,andtheflowofsecurityidentitywithinasequenceofmethodcalls.

IMPLEMENTINGSECURITYINEJB

ThesecurityinfrastructureinEJBisimplementedbythecontainerprovider,whilethesecuritypoliciesaredeterminedbyotherEJBrolesatdeploymentandruntime.Inthissection,wediscussthesecurityrequirementspresentedbytheEJBarchitectureandhowtheyaremet.First,weintroducethebasicsecurityconceptsthatyouneedtograspinordertocomprehendtherestofthematerialinthischapter.

Understandingbasicsecurityconcepts

TounderstandthedifferentfeaturesofEJBsecurityandhowthecariouspiecesfittogether,youneedtoknowwhatthebasicsecuritytermsmean.First,webrieflyintroducethoseterms.

Authenticationandauthorization

Authenticationauthorizationresenttwolevelsofsecurityonasystem,suchasacomputersystemoranapplicationrunningonacomputer.Authenticationinvolvesshowingyouridinordertogetintothesystem,forexample,yourloginandpassword.Authorizationdetermineswhatyoucanandcannotdoonceyouareinthesystem.Forexample,firstyoulogontoafileserverusingauthentication.Bytypinginyourloginandpassword.Onceyouareloggedin,youfindasetoffilesthatyoucanonlyread,anothersetoffilesthatyoucanreadandchange,andyetanothersetthatyoucannotevenread.Thisistheauthorizationpartofsecurity.InEJB,authorizationmeansthataclientisauthorizedtocallabeanmethod.

Principalsandroles

APrincipalisanentitythatcanbeauthenticatedbyasystem.Itcanbe,forinstance,anenduseroranapplicationtryingtoaccessanotherapplication.InJava,onceanentityisauthenticatedtoasystemitisrepresentedbyaninstanceofjava.security.Principal.InEJB,aPrincipalcanbeassociatedwithonceormoresecruityrolesdefinedbytheapplicationassembler.

Asecruityrolehasasetofpermissionsassignedtoit.APrincipalcanbemappedtotheseroles,andthenthePrincipalwillhavethepermissionattachedtotherole.Inotherwords,asecurityroleisasetofapplicationpermissionsthatcanbeassignedtoauser（oragroupofusers）.

Usersandgroups

Auserisarealpersonwithanaccountonasystem.Agroupisacollectionofusers.Eitherauseroragroupcanbemappedtoalogicalsecurityrole.Intheoperationalenvironment,itistheusersandgroupswhousetheapplication,buttheyliveoutsideofEJB.So,inordertogetintotheEJBapplication,theychangeintoPrincipalsandsecurityroles.

AuserofanEJBapplicationlivesinaspecificoperationalenvironmentandenterstheJavaworldasaPrincipal,andthePrincipalaccessestheapplicationbyacquiringoneormorerolesdefinedwithintheEJBarchitecture.

NOTE

TheEJBarchitecturefordistributedandportableenterpriseapplicationshassomeimplicationsastohowEJBsecurityshouldlook.Let’sexplorethisissuenext.

SecutityinEJB

Implementationofsecurityinanysystemgenerallyinvolvestwostages;implementingthesecurityinfrastructureandallowinganadministratortosetandimplementsecuritypoliciesonagivensystem.Keepingthisinmind,notthatthedistributednatureandtheportabilitycharacteristicoftheEJBarchitecturesetthefollowinggoalsforEJBsecurity:

Separatethesecurityinfrastructurefromthebusinesslogicofanapplication,becausethebeanprovider,whoisanexpertinimplementingbusinesslogic,maynotbeasecurityexpert,andsomeotherrolesare.

RememberthatEJBapplicationsshouldbeportableacrossmultipleEJBservers,andthoseserversmaypossiblybeusingdifferentsecuritymechanisms.

Allowsecuritypoliciestobesetatdeploymentratherthanatcodingtimeinordertosupportportability.

TheEJBroleresponsibilitiesthesecurityinfrastructure.Theapplicationassembler,thedeployer,andthesystemadministratorparticipateinsettingsecuritypolicies.TheEJBspecrecommendsthatthebeanprovidershouldneitherimplementsecuritymechanismsnorhard-codethesecuritypoliciesinthebean’sbusinessmethods.

SecurityinEJBisaboutauthorization,forexample,whocanhaveaccesstoacertainbeanmethod.Theclientsofanapplicationexercisecertainsecurityroles,andthepermissiontocallmethodsisassignedtotheroles.

DEFININGTHESECURITYROLES

Itisthedeployer’sresponsibilitytodeploytheapplicationsecurely.Todothiscorrectlythedeployerneedstoknowwhateachbusinessmethoddoesinordertodeterminewhichusercancallit.However,thedeployerisnotexpectedtogointothesourcecode.Sowehaveaproblem.Hereisthesolution:

theapplicationassemblerhelpsthedeployerbyprovidingthesecurityviewofanapplicationinthedeploymentdescriptor.Thesecurityviewcontainsasetoflogicalsecurityrolesandasetofmethodpermissionsforeachsecurityrole.

Thedeploymentdescriptorcontainstwopartshatarerelatedtosecurity:

,whichiswrittenbythebeanprovider,and,whichiswrittenbytheapplicationassembler.Theapplicationassemblerdefinesthesecurityrolesinthepartofthedeploymentdescriptor.

Theapplicationassemblerisresponsibleforthefollowing:

Definingeachsecurityroleusingaelementinthesectionofthedeploymentdescriptor.

Definingtheelementasasubelementoftogivethesecurityroleaname.Thisstepismandatory.

Definingtheelementasasubelementoftoprovideadescriptionforthesecurityrole.Thisstepisoptional.

Asecurityroleappliestoalltheenterprisebeansinthesameejb-jarfile.Listing14.1showstwosecrityrolesdefinedwithintheelement.

Twosecurityrolesnamedemployeeandhr-directordefinedwithintheelement.Theelementistheonlymandatoryelementfora.

Listing14.1

Inagiven,theelementistheonlymandatoryelement.Theelementisusedbythedeployertoassignthesecurityroletoauseroragroupintheactualoperationalenvironment.Theelementisoptionalandistheretohelpthedeployerunderstandwhatthisroleisbeforeassigningittoanappropriateuserorgroup.

Therolenameintheelementisonlylogicalanddoesnotrepresentauseroragroupinarealoperationalenvironment.However,thedeployercanmapittoaPrincipalthatrepresentsauserintherealoperationalenvironment.

NOTE

SecurityinEJBisaboutauthorization,namely,permissionstocallthebeanmethods.Thisisimplementedintwosteps:

grantingmethodpermissionstosecurityrolesandmappingsecurityrolestoPrincipals,whichrepresentusers.

Let’sexaminehowmethodpermissionsaredefinedandgranted.

DEFININGMEHODPERMISSIONS

Afterdefiningthesecurityroles,theapplicationassemblercanassignmethodpermissionstotheroles,thatis,themethodsofabeanthatauserinthatrolecancall.Theassemblercanassignanyofthemethodsexposedinthecomponentandhomeinterfacesofabeantoarole.Wediscussfourdifferenttechniquesforassigningmethodpermissionstoarole.

Grantingpermissiontoallmethods

Byusingthewildcard*,theapplicationassemblercangrantarolepermissiontoallthemethodsinthehomeandcomponentinterfacesofabean.Anexampleisshownhere:

Thiscodemeansthattherolehr–directorhasbeengrantedpermissiontocallallmethodsinthehomeandcomponentinterfacesofthebeansEmployeeRecordBeanandEmployeeProgressBean.Inotherotherwords,abeanclientintheroleofhr-directorcanallanymethodfromtheclientviewsofthebeansEmployeeRecordBeanandEmployeeProgressBean.

Thisisasweepingauthorizationforarolebutnotanultimateone.Theultimateauthorizationwouldbethatanyclientcouldcallanymethodofabeanwithoutbeingcheckedforauthorization,andthatisaccomplishedwiththeelement.Thefollowingcodefragmentmea