1. 9.23 Overview of DCOM The general organization of ActiveX, OLE, and COM.

2. 9.24 Object Model The difference between language- defined and binary interfaces.

3. 9.25 Type Library and Registry The overall architecture of DCOM.

4. 9.26 DCOM Services Overview of DCOM services in comparison to CORBA services. CORBA ServiceDCOM/COM+ ServiceWindows 2000 Service CollectionActiveX Data Objects- QueryNone- ConcurrencyThread concurrency- TransactionCOM+ Automatic TransactionsDistributed Transaction Coordinator EventCOM+ Events- NotificationCOM+ Events- ExternalizationMarshaling utilities- Life cycleClass factories, JIT activation- LicensingSpecial class factories- NamingMonikersActive Directory PropertyNoneActive Directory TradingNoneActive Directory PersistenceStructured storageDatabase access RelationshipNoneDatabase access SecurityAuthorizationSSL, Kerberos TimeNone

5. 9.27 Events Event processing in DCOM.

6. 9.28 Clients Passing an object reference in DCOM with custom marshaling.

7. 9.29 Monikers (1) Binding to a DCOM object by means of file moniker.

8. 9.30 Monikers (2) Binding to a DCOM object by means of file moniker. StepPerformerDescription 1ClientCalls BindMoniker at moniker 2Moniker Looks up associated CLSID and instructs SCM to create object 3SCMLoads class object 4Class object Creates object and returns interface pointer to moniker 5MonikerInstructs object to load previously stored state 6ObjectLoads its state from file 7MonikerReturns interface pointer of object to client

9. 9.31 Monikers (3) DCOM-defined moniker types. Moniker typeDescription File monikerReference to an object constructed from a file URL monikerReference to an object constructed from a URL Class monikerReference to a class object Composite monikerReference to a composition of monikers Item monikerReference to a moniker in a composition Pointer monikerReference to an object in a remote process

10. 9.32 Active Directory The general organization of Active Directory.

11. 9.33 Fault Tolerance Transaction attribute values for DCOM objects. Attribute valueDescription REQUIRES_NEWA new transaction is always started at each invocation REQUIREDA new transaction is started if one not already started SUPPORTEDJoin a transaction only if caller is already part of one NOT_SUPPORTEDNever join a transaction DISABLEDNever join a transaction, even if told to do so

12. 9.34 Declarative Security (1) Authentication levels in DCOM. Authentication levelDescription NONENo authentication is required CONNECTAuthenticate client when first connected to server CALLAuthenticate client at each invocation PACKETAuthenticate all data packets PACKET_INTEGRITYAuthenticate data packets and do integrity check PACKET_PRIVACYAuthenticate, integrity-check, and encrypt data packets

13. 9.35 Declarative Security (2) Impersonation levels in DCOM. Impersonation levelDescription ANONYMOUSThe client is completely anonymous to the server IDENTIFY The server knows the client and can do access control checks IMPERSONATEThe server can invoke local objects on behalf of the client DELEGATEThe server can invoke remote objects on behalf of the client

14. 9.36 Programmatic Security a)Default authentication services supported in DCOM. b)Default authorization services supported in DCOM. ServiceDescription NONENo authentication DCE_PRIVATEDCE authentication based on shared keys DCE_PUBLICDCE authentication based on public keys WINNTWindows NT security GSS_KERBEROSKerberos authentication (a) ServiceDescription NONENo authorization NAMEAuthorization based on the client's identity DCEAuthorization using DCE Privilege Attribute Certificates (PACs) (b)

15. 9.37 Summary (1) Comparison of CORBA & DCOM. IssueCORBADCOM Design goalsInteroperabilityFunctionality Object modelRemote objects ServicesMany of its ownFrom environment InterfacesIDL basedBinary Sync. communicationYes Async. communicationYes CallbacksYes EventsYes MessagingYes Object serverFlexible (POA)Hard-coded Directory serviceYes Trading serviceYesNo Continued …

16. 9.38 Summary (2) Comparison of CORBA & DCOM. IssueCORBADCOM Naming serviceYes Location serviceNo Object referenceObject's locationInterface pointer SynchronizationTransactions Replication supportSeparate serverNone TransactionsYes Fault toleranceBy replicationBy transactions Recovery supportYesBy transactions SecurityVarious mechanisms