Distributed Component Distributed Component Object Model (DCOM)Object Model (DCOM)

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Deepak Goel & Mukesh Punhani Deepak Goel & Mukesh Punhani

Component Software Component Software ProblemProblem

InteroperabilityInteroperability VersioningVersioning Language IndependenceLanguage IndependenceTransparencyTransparency

Inherently DistributedInherently DistributedFlexibilityFlexibilityScalabilityScalability

Why Distributed Why Distributed Applications ?Applications ?

COM ArchitectureCOM Architecture

COM Components in the same process

COM components in different processes

DCOM : COM components on different machines

DCOM ArchitectureDCOM Architecture

Components ReusabilityComponents Reusability

Using Existing Components to Using Existing Components to Reduce Development CostReduce Development Cost

Future Reusability of Components Future Reusability of Components being Developedbeing Developed

Language NeutralityLanguage Neutrality

Virtually all languages such as Virtually all languages such as Java, Visual C++, Visual Basic, Java, Visual C++, Visual Basic, Delphi, PowerBuilder, COBOL Delphi, PowerBuilder, COBOL interact well with DCOMinteract well with DCOM

Enables Rapid PrototypingEnables Rapid Prototyping

Location IndependenceLocation Independence

Components that interact more Components that interact more should be closer to each othershould be closer to each other

Some components can only be run Some components can only be run on specific machineson specific machines

Small Components : Easy to Deploy Small Components : Easy to Deploy - Increased Network Traffic- Increased Network Traffic

Large Components : Difficult to Large Components : Difficult to Deploy - Reduced Network TrafficDeploy - Reduced Network Traffic

ScalabilityScalability

Parallel Deployment

Isolating Critical Components

ScalabilityScalability

Pipelining

ScalabilityScalability

SecuritySecurity

Provides Security at Component Provides Security at Component Level and Method LevelLevel and Method Level

Uses Access Control Lists (ACL) Uses Access Control Lists (ACL) similar to Windows NT File Systemsimilar to Windows NT File System

Per Interface Security using Registry Keys

SecuritySecurity

Load BalancingLoad Balancing

Static Load BalancingStatic Load Balancing Dynamic Load BalancingDynamic Load Balancing

PlatformsPlatforms

UNIX/MainframeUNIX/Mainframe Apple MacintoshApple Macintosh WindowsWindows JavaJava

Comparison with CORBA Comparison with CORBA and RMIand RMI

DCOM fits best with Microsoft DCOM fits best with Microsoft Platform i.e. Windows 98 and Platform i.e. Windows 98 and Windows NT while CORBA is quite Windows NT while CORBA is quite general. general.

RMI works only with Java but is RMI works only with Java but is quite suitable when application quite suitable when application wants to exploit features of Javawants to exploit features of Java

PerformancePerformance

Parameter Size 4 Bytes Parameter Size 4 Bytes 50 Bytes 50 Bytes

In-Process 0.00031 In-Process 0.00031 0.00031 0.00031

Cross Process 0.42 Cross Process 0.42 0.49 0.49

Remote Call 2.7 Remote Call 2.7 3.27 3.27