OBJECT TECHNOLOGIES CORBA vs. DCOM

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OBJECT TECHNOLOGIESCORBA vs. DCOM

• JAYAKUMAR CHANDRAN

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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.

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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
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• Microsofts Distributed Component Object Model
  (DCOM) and the Object Management Groups 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.

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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.
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CORBA -THE SOFTWARE BUS
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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
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CORBA pros cons

• PROS
• Broad platform support
• Strong programming language support
• Local/Remote transparency
• Static or dynamic invocation
• Strong security - Authentication,authorization,enc
  ryption
• Strong fault-tolerence and load balancing

• CONS
• Proprietary extensions to CORBA.
• Large non standard command sets.
• Non straightforward ORB to ORB inter operation

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DCOM - Pros Cons

• 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

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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.