Oracle英文版培训课件之Security：L11-application-context

UsingApplicationContextsObjectivesAftercompletingthislesson,youshouldbeabletodothefollowing:DescribehowanapplicationcontextisusedDescribethesourcesofapplicationcontextvaluesImplementalocalcontextImplementanapplicationcontextthatisaccessedgloballyApplicationContext:DescriptionAnapplicationcontextisamemorycontainerwithattributes:Thecontaineriscalledanamespace.Anamespacehasattributes.Eachnamespaceisindependentofothers.Thenamespaceispopulatedbyapackage.NamespaceUsetheCREATECONTEXTcommandto:CreateacontextinanamespaceAssociateapackagewiththecontextHRAPPCREATECONTEXThrappUSINGhr_context;UsetheSET_CONTEXTprocedureto:CreateattributesSetvaluesofattributesdbms_session.set_context('hrapp','emp_id',v_emp_id);UsingtheApplicationContextAnapplicationcontext:IsreadbyapplicationsCanbeusedto:AuthorizeusersLimitaccesstodata,calledFGACSetattributesusedintheapplicationSettingtheApplicationContextThecontextattributesaresetbyapackage,which:CreatesattributesinthecontextAssignsvaluestotheattributesofthecontextIsusuallycalledwhenauserconnectsEachapplicationcanuseoneormorecontexts.Acontextmaybeusedbymorethanoneapplication.USERENVisabuilt-incontextwithsessionpropertiesandisavailabletoallapplications.ApplicationContextDataSourcesThebuilt-inUSERENVcontextcontainssessionprimitivesasattributes. Example:ClientIPaddressAlocalcontextusesdatabaseobjects.Thedevelopersetstheseattributes. Example:TheEMPLOYEE_IDcolumnintheEMPLOYEEStableAnexternalizedcontextcangetvaluesfromanexternalsource,suchasOracleCall

Interface(OCI).Aglobalcontextusesvaluesfromthedirectory-entryattributes.ImplementingaLocalContext1. Createanapplicationcontext.2. CreateaPL/SQLpackagethatsetsthecontext.3. Callthepackagetosetthecontextattribute.4. Readthecontextattributeintheapplication.ApplicationcontextPL/SQLpackagePL/SQLprogramSetReadStep1:CreateanApplicationContextCreateauniquecontext:NamesthecontextHRAPPAssociatesitwithanHR_CONTEXTpackageYoucansetthecontextattributesonly:InthepackagenamedinCREATECONTEXTInthefunctionassociatedwithapolicyInthepackage,setattributesbycallingDBMS_SESSION.SET_CONTEXT.Alternatively,youcanuseOraclePolicyManagerGUI.CREATECONTEXThrappUSINGhr_context;Step2:CreateaPL/SQLPackage

ThatSetstheContextCreatetheHR_CONTEXT.SET_EMP_IDprocedure:UseSYS_CONTEXTtogetthesessionusername:sys_context('userenv','session_user');SELECTemployee_idINTOv_emp_idFROMemployees WHEREemail= sys_context('userenv','session_user');dbms_session.set_context('hrapp','emp_id',v_emp_id);UseSET_CONTEXTtosetacontextattribute:UsethesessionusernametogettheemployeeID:Step3:CallthePackage

CreatealogontriggerthatcallstheHR_CONTEXT.SET_EMP_IDprocedure:CREATEORREPLACETRIGGERhr_context_logonAFTERLOGONONphall.SCHEMABEGINhr_context.set_emp_id();END;/Step4:ReadtheContextAttribute

intheApplicationToreturnanattributevalue,use:Therearetwoarguments:NameofthecontextNameoftheattributeExampleinSELECT:sys_context('hrapp','emp_id')SELECT*FROMdepartmentsWHEREmanager_id=

sys_context('hrapp','emp_id');SYS_CONTEXTPL/SQLFunctionSYS_CONTEXTreturnscontextattributes: sys_context('context','attribute')ToreturntheclientIPaddressfromthebuilt-incontext,use:ToreturnEMP_IDfromtheHRAPPcontext,use:sys_context('userenv','ip_address')sys_context('hrapp','emp_id')ApplicationContextAccessedGloballySharesacontextacrosssessionsSimplifiesconnectionpoolingfromamiddletierUsesaclientidentifiertoidentifytheuserofasession

PL/SQLprogramAPL/SQLprogramBUserDatabaseSession2UserDatabaseSession1SGAApplicationcontextisEMPID=101HowtheApplicationContextAccessedGloballyWorks2. Logsin6. Makesanotherrequest8. Logsout1. Buildsconnectionpool3. Establishessession4. Processesrequest5. Completesrequest7. Processessecondrequest9. ClearscontextPHALLApplicationServerOracle9iPL/SQLPackagesandProceduresDBMS_SESSIONmanages:Contexts:Globalidentifiers:dbms_session.set_context ('hrapp','emp_id',v_emp_id);dbms_session.set_identifier(12345);set_context(context,attribute,value);dbms_session.set_identifier(client_id);ImplementingtheApplicationContextAccessedGlobally1. Createtheapplicationcontextaccessedglobally.2. Modifytheprogramthatestablishesasession:Settheapplicationcontext.Setthesessionclientidentifier.Cleartheclientidentifierwhentherequestends.3. Modifytheapplicationserverprogramthathandlessubsequentrequestsinthesamesession:Setthesessionclientidentifierfromthissession.Cleartheclientidentifierwhentherequestends.4. Createormodifytheapplicationserverprogramthatendsasessiontoclearthecontext.Step1:CreatetheApplicationContextAccessedGloballyCreatethecontextbyusing:TheACCESSED

GLOBALLYclauseindicatesthatthecontextcanbeaccessedfrommultiplesessions.CREATECONTEXThrappUSINGhr_contextACCESSEDGLOBALLY;Step2:EstablishaSession1. Getauniquevaluetouseasaclientidentifier.2. Settheapplicationcontext:3. Setthesessionclientidentifier:4. Savetheclientidentifierinacookie.dbms_session.set_context('hrapp','id','phall','APPSMGR',12345);dbms_session.set_context('hrapp','dept','sales','APPSMGR',12345);dbms_session.set_identifier(12345);dbms_session.set_context(context,attr,value,username,client_id);Step3:HandleSubsequentRequests1. Gettheclientidentifierfromthecookie.2. Settheclientidentifierforthissession:3. Cleartheclientidentifierwhentherequestends:dbms_session.set_identifier(12345);dbms_session.clear_identifier();Step4:EndaSession1. Gettheclientidentifierfromthecookie.2. Clearthecontext:EXECdbms_session.clear_context('HRAPP','12345');DataDictionaryViewsSQL>CREATECONTEXThrappUSINGhr_context;Contextcreated.SQL>SELECT*2FROMdba_con