What is CORBA ? Explain its general architecture. Explain its working as middleware.(May10 / Nov 10) (10 Marks))

Ques : What is CORBA ? Explain its general architecture. Explain its working as middleware.(May10 / Nov 10) (10 Marks)

Ans -The Common Object Request Broker Architecture (CORBA) is a specification developed by the Object Management Group (OMG). CORBA describes a messaging mechanism by which objects distributed over a network can communicate with each other irrespective of the platform and language used to develop those objects.
There are two basic types of objects in CORBA.

1. The object that includes some functionality and may be used by other objects is called a service provider. The object that requires the services of other objects is called the client. 
2. The service provider object and client object communicate with each other independent of the programming language used to design them and independent of the operating system in which they run. 
3. Each service provider defines an interface, which provides a description of the services provided by the client.

CORBA Architecture: 

1. CORBA in a Nutshell 

• In CORBA the services that an object provides are expressed in a contract that serves asthe interface between it and the rest of the system
• The Object interface is expressed using a special language namedInterface DefinitionLanguage(IDL).
• For objects to communicate across the network, they need a communication infrastructure named Object Request Broker(ORB).
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• To communicate, the request does not pass directly from client to object implementation;instead every request is passed to the client’s local ORB, which manages.
• Both client and object implementation are isolated from the ORB by an IDL interface.Clients see only the object’s interface, never the implementation.

2. CORBA Reference Model Architecture

• The CORBA standard relies on a reference model named the Object Management Architecture (OMA).
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• A typical CORBA implementation includes:
• An Object Request Broker (ORB) implementation
• An Interface Definition Language (IDL) compiler
• Implementations of Common Object Services (COS), also calledCORBA Services
• Common Frameworks, also called CORBA facilities
• An Internet Inter ORB Protocol (IIOP) implementation

Middleware Systems

• Middleware is software that enables interprocess communication.It provides an API that isolates the application code from the underlying networkcommunication formats and protocols (FAPs).
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• Middleware systems implement the various forms of distribution transparencies by creating the illusion of unity and homogeneity within the network, what is called in other words the “single-system image”. They act as glue between autonomous components and processes (e.g., clients, server) by providing generic services on top of the OS.