OBJECT TECHNOLOGIES CORBA vs. DCOM

1. OBJECT TECHNOLOGIESCORBA vs. DCOM JAYAKUMAR CHANDRAN

2. OBJECTS? DISTRIBUITED OBJECTS? • The grouping of data and the functions that work on a set of data is called an Object. • Components allow objects to live beyond one piece of software code. They are basically prefabricated pieces of binary software code that can be dynamically combined to with other components to create a application. • Distributed components extend objects even further than components. Components extend objects beyond a single program to allow it to run in other programs on a machine. Distributed components allow objects to move beyond a machine - ie run over a network.

3. A COMMON LANGUAGE The challenge of object-based distributed computing lies in building a system that lets software objects transparently communicate and use each other's services, whether the objects are located in the same address space, in different address spaces, or on entirely different machines. Without a way for objects to call one another across a network -- an object bus -- applications are bound to the desktop

4. Microsoft’s Distributed Component Object Model (DCOM) and the Object Management Group’s Common Object Request Broker Architecture (CORBA) are competing architectures for application development. Both approaches apply object technology to the design and use of software components. The problem that both COM and CORBA address is how to define, construct, and deploy the software elements that comprise complex systems. Both architectures are based on the distribution of data and process as objects.

5. CORBA The Common Object Request Broker Architecture is a specification for Object Request Brokers (ORBs). An ORB sends requests from objects executing on one system to objects executing on another system. CORBA developers create their objects in a specific programming language and then create proxy objects called "stubs" and "skeletons." A stub is compiled into the language of the client application. It contains the interface for a remote object, but not the behavior. The skeleton is compiled in the language of the target application and is installed on a server.

6. CORBA -THE SOFTWARE BUS

7. DCOM DCOM, the distributed extension of the Component Object Model (COM), grew from Microsoft's work on OLE compound documents. Unlike CORBA objects, which execute in a particular programming language, COM components and use standardized interfaces and methodologies to pass data, ie by creating a proxy for the object on the local machine and a stub on the remote machine. The proxy communicates with the stub, handling all details

8. PROS Broad platform support Strong programming language support Local/Remote transparency Static or dynamic invocation Strong security - Authentication,authorization,encryption Strong fault-tolerence and load balancing CONS Proprietary extensions to CORBA. Large & non standard command sets. Non straightforward ORB to ORB inter operation CORBA pros & cons

9. PROS High Quality Development tools Easy wizards to generate proxy and stub codes. Static and dynamic interface support Local/remote transparency of server locations multithreaded server support CONS Limited operational system availability Interface inheritance only Lack of robust fault-tolerance and load balancing features steep learning curve for developer DCOM - Pros & Cons

10. CONCLUSION • No perfect solution • Decision of choosing one from the other is OS dependent. • Both CORBA and DCOM making improvements to make it more acceptable. • In future we will find ORBs, ActiveX everywhere, on OS, browsers, applications.